The National Measurement System for Cryogenics

Home , Cryogenics

Thomas M. Flynn

NBSIR 75-825

THE NATIONAL MEASUREMENT SYSTEM FOR CRYOGENICS

Thomas M. Flynn

Cryogenics Division Institute for Basic Standards Boulder, Colorado 80302

October 1975

U.S. DEPARTMENT OF COMMERCE, Rogers C. B. Morton, Secretary

James A. Baker, III, Under Secretary Secretary for Science and Technology Dr. Betsy Ancker-Johnson , Assistant

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director FOREWORD

CONCEPT OF A NATIONAL MEASUREMENT SYSTEM

"Concurrently with the growth and industrialization of this nation, there has developed within it a vast, complex system of measurement which has made possible the very growth that brought the system into being. This National Measurement System (NMS) stands today as one of the key elements in a worldwide measurement system that links all major nations together in a consistent, compatible network for communication and trade. "Briefly stated, the essential function of the NMS is to provide a quantitative basis in measurement for (i) interchangeabil ity and (ii) decisions for action in all aspects of our daily life -- public affairs, commerce, industry, science, and engineering. "Our National Measurement System is one of a number of mutually interacting systems within our technologically based society that form the environment in which the individual citizen must live and function. Familiar examples are the communication, transportation, educational, medical, and legal systems, all of which may be included under the general heading of social systems. "In view of the demonstrated value of the systems approach for the understanding and improvement of hardware such as computers and weapons, some of these social systems are being subjected to the same type of analysis. The National Measurement System, which evolved in this country with little formal recognition as a system, is now being examined in this way at the National Bureau of Standards (NBS) which undertook the study of NMS partly because of a growing realization of the al 1 -pervasive nature and great economic importance of the nation's measurement activities, and partly because of the challenge to NBS in putting its splendid new facilities to optimum use for the benefit of the nation. Such optimum use can be approached only when NMS, of which NBS is a central element, and the services it requires for effective operation are sufficiently well understood. "Because the government has wisely refrained from assigning leadership of NMS to NBS by law or executive order, the Bureau of Standards must maintain this leadership through demonstrated competence and general acceptance of its capability. This situation presents both a challenge and a responsibility. The NBS must make a continuous effort to understand the structure and operation of the NMS, to assess the value of its services for national objectives, and to develop means for evaluating its effectiveness. "Our study of the National Measurement System is still in its early stages. There remains much work to characterize inputs and outputs, interactions with other social systems, involvement with national objectives, the functions of NMS elements, and couplings between the elements."

This description of the National Measurement System was first published by Dr. E. D.

Huntoon in Science, 1 58 , 67-71, October 6, 1967. Dr. Huntoon at that time was director of the Institute for Basic Standards, of the National Bureau of Standards. For the reasons stated in the above quotation. Dr. Huntoon began and fostered systematic studies of the National Measurement System of which the following work is a part. CONTENTS

Pa^e FOREWORD

EXECUTIVE SUMMARY 1

1. INTRODUCTION 3

2. STRUCTURE OF THE MEASUREMENT SYSTEM .... 4

2.1 Conceptual System 4

2.2 Basic Technical Infrastructure 5

2.2.1 Documentary Specification System 5

2.2.1.1 Standardization Institutions 5 2.2.1.2 Survey of Documentary Standards 6

2.2.2 Instrumentation System 7

2.2.2.1 Measurement Tools and Techniques 7

2.2.2.2 The Cryogenic Instrumentation Industry . . 13

2.2.3 Reference Data 17

2.2.4 Reference Materials 19

2.2.5 Science and People 21

2.2.5.1 Cryogenic Measurements in Science 21 2.2.5.2 Cryogenic Science in Measurements 22 2.3 Realized Measurement Capabilities 24 2.4 Dissemination and Enforcement Network 26 2.4.1 Central Standards Authorities 26

2.4.2 State and Local Offices of Weights and Measures . . 27

2.4.3 Standards and Testing Laboratories and Services . . 28 2.4.4 Regulatory Agencies 28

2.4.5 Industrial Trade Associations 28

2.5 Direct Measurements Transactions Matrix 28 2.5.1 Analysis of Suppliers and Users 28 2.5.2 Input-Output Direct Measurements Transactions Matrix 30

2.5.3 Highlights re Major Users 32

2.5.3.1 Industrial Gases and Equipment 32 2.5.3.2 Liquefied Natural Gas (LNG) 33 2.5.3.3 Research and Development 34

3. IMPACT, STATUS AND TRENDS OF THE CRYOGENIC MEASUREMENT SYSTEM . 34

3.1 Impact of Measurements 34 3.1.1 Functional, Technological and Scientific Applications 34

3.1.2 Economic Impacts--Costs and Benefits 35 3.1.3 Social, Human, Person-on-the-Street Impacts .... 36 3.2 Status and Trends of the System 37

ii i CONTENTS (continued) Page

'. 4. SURVEY OF NBS SERVICES . 39

4.1 The Past 39

4.2 The Present-Scope of NBS Services 39

4.2.1 Description of NBS Services 39 4.2.2 Users of NBS Services 40

4.2.3 Alternative Sources 42

4.2.4 Funding Sources for NBS Services 42

4.2.5 Mechanism of Supplying Services 45

4.3 Impact of NBS Services 45

4.3.1 Economic Impact of Major User Classes 45

4.3.2 Technological Impact of Services 47

4.3.3 Pay-off from Changes in NBS Services 48

4.4 Evaluation of NBS Program 49

4.4.1 Evaluation Criteria 49

4.4.2 Evaluation Panel Role 50

4.4.3 Why NBS? 51

4.4.4 Program Evaluation 51

4.5 The Future 53

4.5.1 Technology Assessments in Cryogenics 54

4.5.2 Driving Forces 56

4.5.3 Emerging Technologies 57

4.5.4 Impacts of the National Measurement System Study . . 57

, 5. SUMMARY AND CONCLUSIONS 57

5.1 Key Developments 57

5.2 Liquefied Natural Gas 58

5.3 Hydrogen 59

5.4 Superconductivity 59

5.5 Summary 60

Appendix A. Methodology of the Study A-1

REFERENCES R-1

LIST OF FIGURES

FIGURE 1. Internal input 41

FIGURE 2. External outputs 41

FIGURE 3. External inputs 43

FIGURE 4. Outside-outside interactions 43

FIGURE 5. Industrial measurement system 44

FIGURE 6. Liquid nitrogen flow program interactions 46

FIGURE 7. Emerging technologies in cryogenics 57

iv LIST OF TABLES

Page Table 1-1. Organization and outputs of NBS Cryogenics Division 4 Table 2-1. Instrument Society of America Ad Hoc Committee on Cryogenic Flow Measurement 5 Table 2-2. Representative members of the Compressed Gas Association 6

Table 2-3. Flowmeters in custody transfer of oxygen, nitrogen and argon 14

Table 2-4. Typical flowmeter specifications 15

Table 2-5. Typical flowmeter data 15

Table 2-5. Resistance and thermistor thermometers 16 Table 2-7. 1973 Profile: instruments for measurement, analysis, and control 17

Table 2-8 Cryogenic pressure transducers 24 Table 2-9 Some approximate characteristics of the most widely used classes of cryogenic thermometers 25

Table 2-10. Direct measurements transactions matrix 31

Table 2-11. Net sales of major cryogenic companies in the U.S 33 Table 3-1. Instruments for measurement, analysis and control: projections 1973-80 35

Table 4-1. Funding by sources 45 Table 4-2. Distribution of effort 49

Table 4-3. The crucial role of NBS 53

V THE NATIONAL MEASUREMENT SYSTEM FOR CRYOGENICS

Thomas M. Flynn

Cryogenics Division Institute for Basic Standards

October 1975

ABSTRACT

The Cryogenics Division of NBS has evolved as the nation's central laboratory for cryogenics, much as NBS itself has evolved as the nation's central laboratory with both broad and specific responsibilities. Cryogenic measurement and data outputs provide the common foundation for all the institutions and agencies throughout the nation employing cryogenics to solve their problems. This Study of the National Measurement System showed that the Cryogenics Division of NBS provides almost every category of measurement and data service that NBS itself provides: not just an instrumentation system (including, for example, pressure, temperature, density, liquid level, flow rate, etc.), but also properties of fluids (both thermodynamic and transport properties); properties of solids (thermal, mechanical and electrical); an interface with the users through systems integration and advisory and consulting services; and a dissemination network through the Cryogenic Data Center. This study documents the impact, status and trends of the cryogenic measurement system and specifically illustrates these characteristics wherever possible with a specific case study, a recently completed measurements and data program for the flowmetering of liquid nitrogen.

Key Words: Cryogenics; data; flowmeter; instrumentation; measurements; National Measurement System.

V i THE NATIONAL MEASUREMENT SYSTEM FOR CRYOGENICS

Thomas M. Flynn

Cryogenics Division Institute for Basic Standards

October 1975

EXECUTIVE SUMMARY Superconductivity connects cryogenic measurements and data to the electrical power The National Bureau of Standards is not industry, for power transmission, generation, responsible for only one unit of measurement, and storage. Knowledge needed here includes or even a set of measurements. Rather, the heat transfer rates, behavior of helium re- legislative mandate calls for NBS to provide frigerant flow systems, and the degradation a base for such a system, aoordinate that of the superconductors with time and stress. system, and furnish essential services. Thus Other practical uses of superconductivity are it is the responsibility of NBS to assure the becoming apparent, such as the application of proper functioning of the Nation's system of Superconducting Quantum Interference Devices physical measurement, the National Measure- (SQUIDs) to problems ranging from mineral ment System. Accordingly, the present prospecting to magnetocardiography . Accord- microstudy was conducted to examine and ingly, the needs to support this technology document the way in which the NBS Cryogenics encompass instruments and techniques for Division is meeting its particular responsi- physical measurements plus a technical data bility to assure the proper functioning of base. our system of cryogenic measurement. The technologies discussed above show the The Cryogenics Division of NBS provides importance of cryogenics in commerce in the the measurement and data services that sup- U.S. today, and also show its truly diverse port a whole technology. Almost every cate- applications. If there were a "General gory of measurement and data service is Cryogenics Corporation" like a General offered that NBS as a whole provides: not Motors, it would appear in the top 10% of the just an instrumentation system (including, Fortune list of the 500 largest U.S. Indus- for example, pressure, temperature, density, trial Corporations. But it is important to liquid level, flow rate, etc.), but also note that there is not a "Cryogenics Corp- properties of fluids (both thermodynamic and oration", per se. Cryogenics is an infra- transport properties); properties of solids structure industry. Similarly, the national (thermal, mechanical, and electrical); an system of cryogenic measurements is an infra- interface with the users through systems structure of cryogenic technology itself. integration, and advisory and consulting The crucial question of this report is, how services; and our own dissemination network well does the measurement and data structure through the Cryogenic Data Center, support the technology as a whole? This study shows that there are three This study shows that some parts of the specific emerging technologies within this cryogenic measurement system seem to be broad area of Cryogenics which need a com- characterized by adequate services and qual- plete and consistent system of measurements ity assurance (cryogenic temperature mea- and data. surements, for instance). It appears one For instance, a comprehensive measurement should have less confidence in other parts of system for liquefied natural gas needs to be the system. Pressure measurements, for developed, with special emphasis on quantity instance, which are probably the measurement gaging in storage, flow-metering for both most widely made in all of cryogenics, mass and heating value, and basic measure- appear not nearly so well supported, espec- ments of thermal and mechanical properties ially pressure measurements in extreme of structural materials. environments. Attention by NBS to these Basic measurements and data are required issues is in order. to support the development of hydrogen as a Especially apparent at this time is the fuel, to improve hydrogen liquefaction ef- need for a different kind of measurement, ficiency, to recover liquefaction energy, to namely one that describes the quality or document hydrogen-compatible materials of availability of the commodity. Specifically, construction, to develop improved insulation we refer not so much to the flow measurement materials, plus measurement tools and tech- of liquefied natural gas, for example, as to niques for the eventual commercial exchange the need to measure its potential heating of liquid hydrogen. value. It appears that one component of the prob- A goal of this study was to achieve both lem of cryogenic measurement is that the conceptual breadth and depth by examining our field is somewhat static. There has been no role in the national measurement system as a concerted national effort since the peak of whole, and illustrating this role with a the space program. specific case study, the liquid nitrogen A second part of the problem arises from flowmetering program. This program was the way cryogenic measurements fit into the instigated by the needs of state weights and National Measurement System. As long as only measures officials, the industry concerned, a single agency or one sector of our economy and the public for confidence in the custody (National Aeronautics and Space Administra- transfer of liquid nitrogen. This effort used tion, the aerospace industry) was using es- nearly every competence and capability that sentially all of the results of its own mea- NBS has developed: measurement services surements, then that part of the National (tests and calibrations of meters), property Measurement System was internally consistent data (thermodynamic property data for cryo- and in harmony with itself. Now, however, genic fluids), standard codes and practices cryogenics is becoming more commercialized (Handbook 44), dissemination services (Office and moving to the market place, and thus of Weights and Measures, the National Con- external consistency as well as internal ference of Weights and Measures), and both consistency is required to make this part of voluntary and regulatory standards activities the National Measurement System work. (through the most relevant industry group The third part of the problem is perhaps a concerned - the Compressed Gas Association, derivative of the first. Because the field and by adoption in state codes). is relatively static, a crucial question is The general conclusion of this study is not being asked: are there predictable tech- that the cryogenic measurement system is nological developments that will either doing its job adequately at reasonable cost. create a need for new cryogenic instruments, There is no widespread feeling of inadequacy, or possibly provide an altogether new mea- such as that which led to the creation of the surement means? National Bureau of Standards seventy-five Certain parts of the cryogenic measurement years ago. On the other hand, there are both system at the national level seem to be dis- systematic and specific deficiencies that can connected, or working independently of one and should be corrected. Further, there are another at this time. For instance, our several areas in which the cryogenic measure- perception is that the U.S. Coast Guard has ment system will be subjected to severe the necessary authority to regulate certain strains in the foreseeable future, unless aspects of liquefied natural gas transporta- appropriate responsive steps are taken soon. tion by setting certain physical standards, Specific needs and responses, which are measurement codes, and practices. They may do only summarized here, are documented within this without necessarily having recourse to the body of the report. the NBS. Other national authorities, especially in the area of public safety come to mind. Accordingly, it appears that this part of the measurement system is disjointed. There is no objective reason why it should remain so. It would be in accord with the NBS mission and tradition to pursue these issues and resolve them.

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1. INTRODUCTION These applications are not trivial. To illustrate, one peak shaving facility in Iowa National commerce in cryogenics, a vital will cost $23 million. Import terminals, outgrowth of the chemical industry, exceeds including ships and pipelines have been $2 billion annually. It is both a domestic described at costs for $2 to $6 billion. and international business, which may be Superconductivity . Although practical broken down into three areas. They are: uses of superconductivity are not extensive at present, we expect these applications to - Industrial Gases and Equipment grow and mature in the next few years. Pres- - Liquefied Natural Gas ent day superconducting magnets for liquid - Superconductivity. hydrogen bubble chambers rank as the largest

Industrial Gases and Equipment . Indus- solenoid magnets in the world. trial gases provided by cryogenic techniques Cryogenic processes seldom result in an are very important commodities. According to end product in themselves, but rather play an the most recent Department of Commerce sur- essential supporting role in other more visi- vey, the annual production of liquid oxygen ble industries. As mentioned, 50% of the liq- is about $300 million, 50% used in the produc- uid oxygen production goes into steel making tion of steel and 20% in the chemical indus- and another 20% into chemicals. Forty per- try. Aerospace use is less than 2% -- even cent of the space industry is cryogenic less than that used for sewage disposal. based. The steel, chemical, and space indus- Minneapolis, Tampa, New Orleans, and Fairfax tries are highly visible, but the cryogenics County, Va. are among the many places that industry is not. If one were to go shopping use oxygen to speed up sewage treatment by for cryogenic merchandise, he would find factors of 3 to 5. More than 50 oxygen little, for cryogenics is indeed an infra- plants are planned or under construction in structure industry. the U.S. for sewage treatment. It is thus the nature of cryogenics that Fifty to sixty percent of all the hospi- it be largely hidden and obscure to most ob- tals in the U.S. presently store their servers, while at the same time occupying a breathing oxygen as liquid, and the American central position of great potential leverage Hospital Association states that every new on the nation's essential industries - steel, hospital costing $1 million or more uses chemicals, space, transportation, agricul- liquid oxygen. ture, sewage disposal, and so forth. It Annual sales of liquid nitrogen are about would therefore be imprudent to leave the $150 million, with over $50 million being workings of cryogenics to chance, and ac- used for food freezing. cordingly this study of the National Measure- One major airline uses 1.8 million pounds ment System was undertaken to document and of liquid nitrogen per year for galley cool- evaluate the adequacy of our measurement ing. Company officials claim that "the and data services to this vital technology. procedure is wondrously simple and reliable In making an inventory of all of our mea- and that the experience has been so favorable surement services, we find that we offer that all future aircraft will use the same nearly every type of service that NBS as a technique." The Department of Transportation whole does, e.g., conceptual knowledge, in- has watched this system closely to get a strumentation, reference materials, standard "feel" for the logistics of supplying cryo- samples, reference data, and specifications. genics necessary for ground transportation We have also documented our operations through systems the dissemination network, e.g., regulatory Recently, a 400 ton-a-day liquid nitrogen agencies, state offices, and central standards plant was opened at Stafford, Texas to supply authorities. We have achieved both concep- nitrogen to a major semiconductor device tual breadth and depth by examining first our manufacturer to protect electronic parts from role in the National Measurement System as a impurities during manufacture. Similar faci- whole, and then illustrating this role with lities exist in the Bay Area of California to a specific case study. support the electronics industry there.

Liquefied Natural Gas (LNG) . It is predicted that by 1985 10% of our natural gas will be imported as LNG from Alaska or foreign sources. There are approximately 19 applications pending before the Federal Power Commission for permission to import LNG or to liquefy and store it for interstate use.

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2. STRUCTURE OF THE MEASUREMENT SYSTEM We are organized by function to provide these outputs (see table 1-1). We have found The National Bureau of Standards is not that such a functional approach generally responsible for only one unit of measurement, serves us better than a programmatic one. or even a system of measurements. Rather, Cryogenics is an evolutionary technology and our legislative mandate calls for NBS to our strength lies in being able to meet chang- provide a base for such a system, coovdinate ing programmatic needs. We have in fact that system, and furnish essential services. evolved as the Nation's central laboratory for Examination of these statues shows that the cryogenics, much as NBS itself evolved during NBS has both unique and special responsibil- its early years as the Nation's central tech- ities in relation to the Nation's science and nical laboratory with both broad and specific technology, and very broad responsibilities responsibilities. Our outputs provide the as wel 1 common foundation for all the institutions So it is with the cryogenics at NBS. We and agencies throughout the nation employing are not responsible for "a" unit of measure- cryogenics to solve their problems. The fol- ment or even a tidy set of measurements. lowing sections will illustrate how we pro- Just as it is a general NBS role to make sci- vide these services in practice. ence useful, so it is our role to make cryo- 2.1 Conceptual System genics useful. We do not develop technology. We do help others with applied research ser- The Cryogenics Division of NBS is the only vices to produce, diffuse, and enhance the federal laboratory exclusively in cryogenics value of practical knowledge. Our goal is to dedicated to helping develop and promote the strengthen and advance the Nation's cryogenic successful application of all aspects of this science and technology— in short, make cryo- science. As such, the conceptual system that genics useful. encompasses our work ranges from the genera- Accordingly, since we do help support a tion of basic, conceptual knowledge (e.g., whole technology, we find that we must pro- fundamental constants, superconducting quan- vide almost every measurement and data service tum interference phenomena) to specific prob- that NBS as a whole provides: not just an lem solving for government agencies and instrumentation system (including, for example, other public institutions (e.g., technical pressure, temperature, density, liquid level, advice to the Electric Power Research Insti- flow rate, etc.), but also properties of tute on refrigerators for cooling supercon- fluids (both thermodynamic and transport prop- conducting electric power transmission lines). erties); properties of solids (thermal, me- The specific quantities and phenomena that chanical and electrical); an interface with need to be measured relate to the properties the users through systems integration, and of liquids and solids needed by engineers advisory and consulting services; and our own for design and construction purposes and also information dissemination network through the by scientists to improve the understanding Cryogenic Data Center. of the physics of fluids. These properties (see also Section 2.2.3) include, but are not limited to, the thermodynamic property of Table 1-1. Organization and outputs fluids (compressibility, entropy, enthalpy, of NBS Cryogenics Division specific heats, sound velocities); electro- Functional Organization magnetic properties (diekectric constant, refractive index); and transport properties Metrology A (viscosity and thermal conductivity coeffi- Solids Properties Centralized cients). The data required on solids (metals, Fluids Properties National alloys, and composites) used at low tempera- Systems Integration! Effort tures include the mechanical, thermal, and Data Center electrical properties. Effective and reliable measurement systems Outputs are required for certain physical parameters Measurement Techniques at low temperatures, notably: pressure, tem- Data for Decision Making perature, density, liquid level, quantity, Data for Reliable Design and flow rate, and, more often than not a very Technical Analyses difficult parameter to realize in practice, Safety Criteria the total "usable" mass. Impartial Assessment The conceptual system also encompasses the Information Services use of low temperature phenomena as tools for Technology Transfer the measurement of other physical parameters National Standards (see section 2.2.5.2) such as the electrical volt, noise, current, power, flux magnitude, etc. 2.2 Basic Technical Infrastructure Particularly for Cryogenic Fluids" from the first ISA Standards and Practices Panel Ses- As indicated in Section 1., the cryogenic sion held in conjunction with the 1965 Annual measurement system supports an international Conference. The committee membership was technology that ranges from multinational broadly representative of all concerned-- trade in liquefied natural gas to supplying States weights and measures officials, cryo- breathing oxygen for hospitals. Accordingly, genic fluid buyers and sellers, and meter the technical infrastructure that supports manufacturers. The membership is shown in this system in turn runs from the Interna- table 2-1. tional Organization of Legal Metrology to state weights and measures officials, as a Table 2-1. Instrument Society of America minimum. The following sections will describe Ad Hoc Committee on some of the more important institutions and Cryogenic Flow Measurement systems that help make this part of the Na- System function. tional Measurement University of Colorado National Bureau of Standards Specification System 2.2.1 Documentary Transcontinental Gas Pipe Line Company Missiles & Space Division, Douglas Aircraft Institutions 2.2.1.1 Standardization Cox Instruments Wyle Laboratories industry association, Several states, an Potter Aeronautical international organizations and national and Air Reduction Company recently cooperated in a technical program to NASA - MSFC assure adequate quality control in one part California Bureau of Weights & Measures of the cryogenic measurement system, namely flowmetering of liquid nitrogen. We the The abstract of the final report by the shall use this example to highlight the vari- Ad Hoc Committee recommended: (a) a national ous standardization institutions that must standard and transfer standards; (b) an ac- interact to assure effective measurement con- cepted methodology; (c) a national authority a of the cryogenic trol in even so small part to develop the standards, transfer standards, measurement system. and methodology; and (d) educating all per-

Background . Liquid nitrogen is an impor- sonnel in the state-of-the-art of cryogenic article of commerce--approximately tant fluid flow measurements. $150 million worth per year changes hands. The Compressed Gas Association Model Code . Its uses include food freezing, airline gal- The Compressed Gas Association is a non-profit ley cooling, and providing a protective atmo- membership corporation chartered in the State sphere for semiconductor manufacture and of New York that represents all segments of float glass production. Regardless of its the compressed gas industry in the United wide use, it is a difficult commodity to States, Canada, and Mexico. They also have measure for it is nearly always a boiling, associate members in European and Asian two-phase mixture, whose value depends in part countries. Among its membership are over 250 upon its density and in part upon its re- companies (including North America's largest frigeration capability. Commonly used prac- firms) devoted primarily to producing and tices of custody transfer a vague techni- had distributing compressed, liquefied, and cal basis, which inhibited both compliance cryogenic gases, as well as leading chemical and regulation, regardless of how well inten- industry corporations that have compressed tioned either party may have been. and liquefied gas divisions. A few of the In 1966, at least three groups took this members of the Compressed Gas Association problem under consideration. The description who were most interested in liquid nitrogen below is in approximate chronological order, flowmetering are shown in table 2-2. but no great significance should be attached It is estimated that the domestic companies to the dates. The three groups did initiate listed below produce in excess of 95 percent their work separately, but eventually worked of the cryogenic fluids marketed in this coun- together toward a common solution, and often try. with overlapping membership. This example In June 1967, the Compressed Gas Association is presented to show an institutional struc- proposed to the National Conference on Weights ture through which standards are effected. and Measures a model code for flow metering of The Instrument of America Ad Hoc Society cryogenic fluids. Although the Conference on Committee on Cryogenic Flowmetering . The Weights and Measures noted that cryogenic flow decision of the Instrument Society of America measurement problems were, at that time, cen- to establish this Ad Hoc Committee was based, tralized only in a few states, the Compressed in part, on a recommendation for "Calibration Gas Association proposal was a significant Standards for Turbine and Mass Flowmeters, step in national recognition of cryogenic flow measurement problems. Table 2-2. Representative members of the The International Organization of Legal

Compressed Gas Association Metrology . Just as the States preferred a central authority to coordinate these acti- Domestic: vities on a national scale, the gas producers themselves desired to coordinate Air Products and Chemicals, Incorporated such a standardizing activity on an inter- Air Reduction Company national scale. Accordingly, the Inter- Liquid Carbonic Corporation national Organization of Legal Metrology Linde Division - Union Carbide Corporation was brought into the program at the be- National Cylinder Gas Div. - Chemetron Corp. ginning to facilitate the adoption of the International Oxygen Manufacturers Assoc. findings of this program as an international CVI Corporation - Pensalt Chemical code. The collaborating countries are Foreign: Austria, France, India, Italy, Japan, Nether- lands, Poland, United Kingdom, Switzerland, British Oxygen Company Czechoslovakia, and the USSR. L'Air Liquide Linde AG (Lotepro) 2.2.1.2 Survey of Documentary Standards Messer-Griesheim Measurement accuracy must be assured to The California Code on Cryogenic Measur- avoid failure in complex engineering designs ing Devices . The regulatory agencies saw a and sophisticated experiments. But accuracy real need for traceability to a national stan- is even more important when quantities of dard since they are usually obligated by law goods or services in commerce are being to perform "type approval" inspections. In the measured. If a free-enterprise economic sys- fall of 1967, the State of California Bureau tem is to thrive in a modern industrial so- of Weights and Measures began hearings on ciety, buyers and sellers in the marketplace its own proposed code for cryogenic fluid need to have as much confidence in the quan- measurement devices used in California. After tity and performance of goods exchanged as several hearings in the fall and winter of they do in the amount of moneys paid. 1967-68, the code was adopted and made law in We will continue to use the liquid California on June 1, 1968. nitrogen flowmetering program as a specific The State of New Jersey was not far behind example of the process by which practices California such regulations. with respect to and data become codified and have the New Jersey officials stated that with the effect of law. introduction of sales of cryogenic fluids to As mentioned. State regulatory agencies the trucking industry for use as a refriger- have a real need for traceability to a ant, they forced to find some means would be national standard since they are obligated of developing an acceptable proving method. by law to perform type approval inspections. Further, with the advent of the Sales Tax in This is clearly outlined, for example, in of and no exceptions the State New Jersey, the Business and Professions Code of the being known at that time given to the sale of State of California. One provision of this cryogenics at the retail level to trucks, it code reads as follows: was felt that the commodity would be subject to that tax. "2500.5. The directory by rules and reg- such agencies are obligated Because state ulations shall provide for submission for promulgate regulations controlling the use to approval of types or designs of weights, of used weighing or measuring any commercially measures, or weighing, measuring, or devices, including those used in cryogenic counting instruments or devices, used for fluid commercial sales or custody transfers, commercial purposes, and shall issue cer- the needs of these agency officials as expres- tificates of approval of such types or sed by them are pertinent and important to design as he shall find to meet the re- the subject at hand. They summarized their quirements of this code and the tolerances needs as follows: and specifications thereunder.

"(1) With respect to standards, there "It shall be unlawful to sell or use for should be a national "facility", a final commercial purposes any weight or measure, "authority", a "referee" that would not be or any weighing, measuring, or counting in competition with private industry. instrument or device, of a type or design (2) This "agent" should provide the neces- which has not first been so approved by the sary methodology to preserve the accuracy department; provided, however, that any and precision of field measuring methods. such weight, measure, instrument, or device (3) This "agent" should continue to inves- in use for commercial purposes prior to the tigate new measuring methods in order to effective date of this act may be continued advance the state-of-the-art." in use unless and until condemned under the

6 : .

provisions of this code. (Added by Ch. 893, 2.2.2 Instrumentation System Stas. 1949.)" Cryogenic instrumentation as a discipline After the hearings described in Section is primarily concerned with the condition or 2.2.1.1 had been held, the code was adopted state of cryogenic fluids, such as pressure and made into law in California on June 1, and temperature. Such information is typi- 1968. Of the code specifications, one of the cally required for process optimization and most significant was tolerance. control. In addition, as cryogenic. fluids become increasingly commercially important, "The maintenance tolerance shall be four there is the question of "how much" is there? percent (4%) of the indicated delivery on Accordingly, the instrumentation system must underregistration and two percent (2%) of be able to provide answers in terms of liq- the indicated delivery on overregistration. uid level, density, and flow rate. The acceptance tolerance shall be one-half A derivative question is arising more and the maintenance tolerances." more frequently, namely, of what utility or quality (in the same sense as thermodynamic The State of California also suggested that availability) are the goods? As it is not "best values" of data be included in the Cali- "good enough" to count BTU's alone in energy fornia Code. The gases under consideration conservation questions (the level of thermo- were limited to oxygen, nitrogen, argon, and dynamic availability must be considered), so hydrogen. The scope of the data required was it is that the "availability" of the cryo- increased to include saturation densities over genic fluids must be taken into account. a broad range of pressure and temperature for This was a nagging question during the each gas. At the request of both the Com- space program when a so-called "empty" tank pressed Gas Association and the State of of liquid hydrogen could still contain 2% or California, a document was produced specifi- so of its original mass, as a dense but un- cally to allow traceability of selected usable fluid. It is of importance today in values the metering of liquefied natural gas, for These properties data are specifically instance, where the integrated heating called out in the California Code and accord- value--which depends upon composition--is ingly has the same weight of law as the flow- the preferred unit of commerce, rather than meter calibrations and tolerances themselves, just the volume that has changed hands. viz. This section addresses the measurement tools and techniques that are currently used to "3081.2.6 Saturated Liquid Densities. probe this part of the cryogenic measurement Saturated liquid densities of Oxygen, system. Nitrogen, Argon, and Parahydrogen as prepared by the National Bureau of Stan- 2.2.2.1 Measurement Tools and Techniques dards, Boulder, Colorado, shall apply

(Refer to National Bureau of Standards, (1) Pressure . Of all the measurements Technical Note No. TN-361)." made on cryogenic systems, surely one of the most common must be that of pressure measure- This program on cryogenic fluid transfer ment. Pressure measurements are made not only is only one of the most recent instances where to determine the force per unit area in a common data have proven beneficial to indus- system, but also to determine flow rate (head try and Government. Many other times govern- type meters), quantity (differential pressure ment agencies with to evaluate efficiency liquid level gages), and temperature (vapor claims and production capacities projected by pressure or gas thermometers). Pressure "paper studies". A complete and consistent measurements are thus fundamental to the set of design data is essential to this pur- smooth running of much of this part of the pose. The National Aeronautics and Space National Measurement System. Administration, National Accelerator Lab- Pressure measurements in cryogenic systems oratory, Navy and other government agencies, have, for years, been made by simply running for instance, specify that a common data base gage lines from the point where the pressure be used in its proposals to provide a sound measurement is desired to some convenient basis for evaluation. Data so codified are location at ambient temperatures and attach- in a very real sense "documentary standards", ing a suitable pressure-measuring device, such although not strictly speaking de cure as the familiar Bourdon gage. standards. This system works quite well for most ap- with decreasing bulb temperature, inasmuch plications; however, there are disadvantages as the proportion of gas in the bulb in- to this straightforward approach that may creases. On the other hand, gas imperfec- introduce problems in many systems. The two tion increases with decreasing temperature. most important are: (1) reduced frequency If, however, the sensing bulb is made small, response and (2) thermal oscillations. In as compared to the external volume of the addition, heat leak, uncertainties in hydro- system at ambient temperature, the character- static head within gage lines, and fatigue istic is far from linear, the sensitivity failure of gage lines could become significant increasing greatly as the bulb temperature in some applications. Such problems associ- decreases. By using a Bourdon gage to show ated with pressure measurement at cryogenic the pressure in this device, a simple gas temperatures could be eliminated by installing thermometer is achieved that is useful for pressure transducers at the point of measure- such purposes as monitoring the cool-down of ment, thereby doing away with gage lines. cryogenic apparatus. Like all instruments, the output of a pres- In order to obtain accurate results in gas sure transducer depends not only on the pri- thermometry, it is necessary to make many cor- mary input, in this case pressure, but also rections. One must account for at least: upon extraneous effects, such as the effect of the imperfection of the gas; the effect of temperature on its various components. Erro- the volume of the gas that is not at the neous pressure readings can be caused by both temperature being measured; and the change of steady state temperature effects and tempera- volume of the bulb with changing temperature. ture gradient, or thermal shock effects. Accordingly, for engineering applications, While it is agreed that some available gas thermometry is recommended only for in- pressure transducers are capable of perform- dicating the approximate temperature or tem- ing satisfactorily at low temperature, other perature trend. types, e.g., piezoelectric, diode, inductance, Precision gas thermometry falls in the reluctance, and electrokinetic devices, may category of fundamental thermometers rather perform equally well or better. It is there- than empirical thermometers. It is much too fore necessary, for the purpose of comparison, demanding for common use.

that all types of pressure transducers be Vapor-Pressure Thermometry . As is well tested at low temperature and at various fre- known, vapor pressure is a sensitive but quencies to determine their potential for nonlinear function of temperature, providing cryogenic use. Because pressure sensing de- convenient means for thermometry in limited vices often behave quite differently in a ranges of temperature that unfortunately, cryogenic medium, a systematic, well docu- do not join to provide continuous coverage of mented testing program is presently needed cryogenic temperatures. For example, the before all types can be evaluated and com- range from 40 K to 50 K is above the range of pared. neon and below that of oxygen and nitrogen. A cryogenic calibration system with varied Within its limits, however, this type of capabilities is essential for the successful thermometer is very accurate. completion of such a program described above. These thermometers are most accurate in The details of such a system have been de- the area of the normal boiling point of the scribed by Arvidson and Brennan [2]. liquid used, and hence could be very useful,

(2) Temperature . Most engineering mea- albeit over a very limited temperature range. surements are made with metallic resistance Advantages of this type of thermometry are thermometers, non-metallic resistance ther- that it is sensitive, can have good time mometers, or thermocouples. Gas thermometers response, is not affected by magnetic fields, and vapor pressure thermometers find little and needs no calibration. The primary disad- practical engineering application, and hence vantage is that it can be used only between are mentioned only briefly in the following the triple point and critical point of the paragraphs. A recent compilation of the fill liquid.

commercial availability of thermometers is Metallic Resistance Thermometry . Since given in "Measurements and Data" [3]. the resistivity of an element or compound

Gas Thermometry . Constant-volume gas varies with change in temperature, it has in thermometry is familiar as a technique for many instances been used as a simple and accurate realization of the thermodynamic reliable temperature-measuring device. temperature scale. In such work, the While there exist a number of metals that pressure-temperature behavior is made as are more or less suitable for resistance linear as possible by minimizing the ex- thermometry, platinum has come to occupy a traneous volumes in the manometer and the predominant position, partly because of connecting tubing. Troublesome correc- excellent characteristics, such as chemical tions for these extraneous volumes decrease inertness and ease of fabrication, and

8 partly because of custom: that is, certain germanium thermometer is both rugged and [desirable features such as ready availability reproducible. 'in high purity and the existence of a large The major disadvantage associated with the body of knowledge about its behavior have use of germanium thermometers is the lack of come into being as its use grew and have a simple analytical representation. Each tended to perpetuate that use. Its sensi- thermometer must be calibrated by comparison tivity down to 20 K and its stability are at many points in the range of interest if excellent. the inherent reproducibility of the thermom- A variety of platinum resistance thermometers is to be utilized. eters designed for engineering applica- Thermistor s. Thermistors (thermally sen- tions is now available. As with other trans- sitive resistors) are essentially resistors ducers, these devices are subject to extra- made up of sintered metal oxides. Frequently neous effects (noise). In this case, we wish used materials are nickel, manganese, and to measure only the temperature dependence of cobalt oxides. The fact that these resistors the resistivity. However, we may also unwit- are becoming increasingly popular in measure- tingly measure the strain dependency as well. ment and control circuits is attested to by To avoid this, the engineering thermometers the number of companies selling them [3]. are built to imitate the strain free con- The reasons for the increasing use are in struction of the precision laboratory type part: 1) they are small, which tends to make thermometers. the time response significantly less than one There are two basic designs for engineer- second; 2) they are typically high resistance ing use: immersion probes and surface units, which reduces the overall effect of temperature sensors. The inmersion probes lead resistances, and 3) their temperature- feature a high purity platinum wire encapsu- resistance characteristics are dependent on lated in ceramic or securely attached to a materials and procedures which allows thermo- support frame. Features such as repeat- meters to be developed that are particularly ability after thermal shocks, time response sensitive in limited ranges of temperature. in different environments, interchangeabil- Thermocouples . Thermocouples have the ity, and mechanical shock tolerance differ familiar advantage that the temperature- between companies and specific designs. sensing junction can be reduced in size to The second type of industrial sensor is almost any desired extent, so that the ibroadly known as a surface temperature disturbance to the object being sensed can be sensor, whose geometry is such that they make made very slight, and the response time can good thermal contact with surfaces of various be very fast. They also have a familiar shapes. Sensors are available for clamping disadvantage; rather small voltages must be around small tubing, fitting into milled measured. In addition, they have a less slots, and clamping under bolt heads. The familiar but very serious disadvantage; the principle advantages of these thermometers net emf depends not merely on the materials are that they are small, typically 0.25 cm x nominally used for the two wires, but also 1.25 cm X 1.25 cm, with perhaps a factor of on material inhomogeneities which, if located two variation in any dimension. in a temperature gradient, will introduce

Non-Metallic Resistance Thermometry . A parasitic voltages. These inhomogeneities number of semiconductors also have useful may arise from variations in chemical compo- thermometric properties at low temperatures. sition or may consist of crystal lattice im- A semiconductor has been defined as a ma- perfections introduced, for example, by terial whose electric conductivity is much kinking the wires. Their presence can be less than that of a metallic conductor, but detected by various tests but cannot readily much greater than that of a typical in- be corrected for, so that testing merely sulator. The most promising semiconductors serves to indicate whether a given wire seem to be germanium, silicon, and carbon. should be discarded or not.

The latter, though not strictly a semicon- (3) Quantity or Liquid Level . Liquid ductor, is included in this group because of level is but one link in a chain of measure- its similarity in behavior to semiconductors. ments necessary to establish the contents of Of the three, germanium has received by a container. Other links may include volume far the most attention, and germanium re- as a function of depth and density as a func- sistance thermometers are now available from tion of physical storage conditions. For- several comnercial sources. The resistance tunately, the actual discernment of the liquid element is usually a small single crystal. vapor interface (liquid level) is often the Inasmuch as the resistivity is high, the strongest link in this measurement process element can be short and thick. It is due to the significant progress made here in mounted strain-free in a protective capsule. the course of the Nation's space program. As |Because of this combination of features, the a result of this intense interest, liquid level measurements can be made with an since the critical angle for total internal accuracy and precision comparable to that reflection depends upon the index of refrac- of thermometry, for instance, and often with tion. This type of transducer has a very greater simplicity. high in-out signal ratio, for the light de- This period of development led to many tector is almost totally illuminated or different physical embodiments of liquid totally dark. level sensors, and there are as many ways of There are also several acoustic or ultra- classifying these devices as there are sonic devices that depend upon the fact that authors who write about them. We shall clas- the damping of the vibrating member is sify them according to whether the output is greater in the liquid than in the vapor. discrete (point level sensors) or continuous. Often, a magnetostrictive element is driven

Point Liquid Level Sensors . All liquid at a constant power and is more or less level sensors depend for their operation on dampened, depending whether it is in liquid or the fact that there can be a large property in vapor. The end of these sensors is about change at the liquid vapor interface, a the size of a quarter dollar, but this does significant change in density, for example. not in any way indicate the limit of its This may not always be the case if the fluid resolution. These devices can be tuned to is stored near its critical point, for detect only a fraction of the total damping instance, or if stratification has built up that would occur upon total immersion, so that after prolonged storage. Be that as it may, their sensitivity can be much smaller than point level sensors are tuned to detect a the total end of the device. Piezoelectric sharp property difference and given an on-off versions of this acoustic type liquid level signal. Several of the more commonly used sensor are also available. types are described below. Continuous Liquid Level sensors take many The thermal or hot wire type senses the forms. Some methods determine mass, while large difference in the heat transfer coef- others are merely interface following, and ficient between liquid and vapor. Since the usually are just continuous analogs of some heat transfer coefficient is much larger in point sensor. Among the mass sensors are the the liquid than it is in the vapor, one can direct weighing schemes, nuclear radiation expect, for a given power input, that the attenuation, and RF techniques. The interface transducer will have a different temperature following types include differential pressure and hence resistance, in the liquid than in sensors, capacitance and acoustic techniques. the vapor. It is this change in electrical These are described below. resistance that is actually sensed in a Direct weighing schemes have been used for bridge circuit, and hence these devices can oxygen, nitrogen and other dense fluids, but be made both simple and fast. Small platinum have been handicapped in hydrogen use by the wires, solid carbon resistors, and thin-film fact that the weight of the container is carbon resistors are examples of sensing often large compared to the weight of the elements that are used. contents. In modern weigh-faci 1 ities how- The capacitive type depends upon the ever, the weight of the tank rarely exceeds difference in dielectric constant between the the weight of the contents (when the tank is liquid and vapor, which is essentially a full). Calibrated balance weights and function of the fact that the liquid is more strain-gage load cells are most commonly used dense than the vapor. This sensor is usually in this application. made in the form of a bulls-eye, with alter- Nuclear Radiation Attenuation has found nate rings forming the plates of the capaci- some success in oxygen and nitrogen systems, tor, and are installed so that the plane of but comparatively little use for hydrogen. the rings is parallel to the liquid vapor This is so because hydrogen is nearly trans- interface. parent to the commonly available sources of The optical type senses the change in nuclear radiation, while the tank walls are refractive index between the liquid and relatively "thick" to the same radiation. vapor, which of course is closely related to Hence the fundamental signal to noise ratio the dielectric constant and density. is inherently low. Hydrogen does absorb This type of transducer contains a light beta radiation rather well, but then "windows" source and a light sensitive cell that are of beryllium or equivalent light metals must isolated from one another, but which do com- be placed in the tank walls. On the whole, municate down a prism. The prism is cut in this technique appears too sophisticated for such a way as to have total internal reflec- simple engineering measurements. tion when in gas, and yet let the light RF Cavity Detection . In this system, escape when in liquid. This is possible microwave energy is introduced into a tank since there is a difference in the index of to energize it by setting up electro- refraction of the liquid and the vapor, and magnetic fields throughout the entire volume

10 of the tank. The tank interior is a di el ee- length and variable time of flight is in- rie region completely surrounded by conduct- cluded to provide a measure of the density of ng walls. Such a system is called a cavity, the fluid. The product of the two measure- and the resonant frequencies established are ments tends to give an indication of the mass the normal theoretical modes of the cavity. of the fluid contained in the tank. Considerable development work has been done (4) Density measurements are closely akin recently on both uniform density fluids and to quantity and liquid level measurements non-uniform density fluids, and this technique because: 1) both are often required simul- continues to show considerable promise for taneously to establish the mass contents of a both mass-gaging and level-gaging in a vari- tank, and 2) the same physical principle may ety of cryogenic fluids, including hydrogen. often be used for either measurement, since, RF transmission characteristics through co- as noted, liquid level detectors sense the axial cables can also be used to detect steep density gradient at the liquid-vapor liquid levels by measuring the time of flight interface. Thus, the methods of density of a RF pulse through the cable [4,5]. This determination include the following tech- latter technique is called time domain re- niques: direct weighing, differential pres- f lectometry. sure, capacitance, optical, acoustic, and Differential pressure measurements are nuclear radiation attenuation. In general, simple to visualize, but difficult to realize the comments made above about the various in practice. "Noise" is always high due to liquid level principles apply to density boiling and potential thermal oscillations at measurement techniques as well. the lower pressure tap. Also, the unknown Two exceptions are noteworthy. In the level of the liquid in the gage lines can case of homogeneous pure fluids, density can introduce hydrostatic head errors. In the usually be determined more accurately by an case of hydrogen, the "signal" is low due to indirect measurement; namely, the measurement the unusually low density of hydrogen. of pressure and temperature which is then Better success is obtained with other cryo- coupled with the analytical relationship gens of higher density. between these intensive properties and den- Capacitance sensors are widely used for sity through accurate thermophysical prop- the continuous measurement of the level of erties data. cryogens. They do not truly follow the The case of non-homogeneous fluids is nterface, but sense the total contents of quite different. Liquefied natural gas i he container. That is, the dielectric is often a mixture of five or more components constant of the gas phase contributes to the whose composition and hence density varies output signal, as well as that of the liquid with time and place. Accordingly, tempera- phase. This can be a serious source of error ture and pressure measurements alone will not in hydrogen because the density of the cold suffice. A dynamic, direct measurement is gas (and hence its dielectric constant) is required, embodying one or more of the liquid- significant compared to that of the liquid. level principles described above. Such This problem is especially troublesome in "densitometers" are presently under develop- nearly empty tanks, but is often compensated ment, and it is premature to discuss their for by either: a) segmenting the capacitor capability at this time.

and ignoring the output from those sensor (5) Flow . There are three basic types of sections located in the vapor phase as the flowmeters which are useful for cryogenic liquid level drops, of b) installing a few liquids. These are the: 1) pressure drop or point sensors at critical levels and routinely "head" type, 2) turbine type, and 3) momen- calibrating the continuous sensor against tum type. We shall discuss each in turn.

tern. Rod-to-blade and concentric tube con- Head Meters . This type of meter embodies figurations are most common in this type of the oldest method of measuring flowing fluids. sensor. The distinctive feature of head meters is that In the acoustic devices, the liquid a restriction is employed to cause a reduction itself is used as the transmitting medium. in the static pressure of the flowing fluid. A transmitter feeds an electric pulse to a This pressure change is measured as the transducer where it is converted to an difference between the static heads on the acoustic pulse traveling at sonic velocity to upstream and downstream sides of the restric- the liquid-vapor interface, reflected back at tion. the same speed to the transducer, where it is Theoretical development of the flow equa- reconverted to an electric pulse, and finally tions for head type meters may be found in sent to a receiver. Knowing the velocity of publications of the American Society of sound in a given liquid, the pulse transit Mechanical Engineers [6]. time from transmi tter-to-interface-to-recei ver The appeal of these meters in cryogenics ecomes an indication of liquid level. Some- is more than simplicity, and stems from the imes an acoustic racetrack of known path possibility of eliminating the necessity for

11 calibration, if proper design, application together by means of an elastic restraint. theory, and practices are followed. Design Because of the difference in pitch, they methods for orifices, flow nozzles, and would tend to revolve at different speeds. venturi tubes are available in publications However, this is prevented by the elastic of the American Society of Mechanical Engi- coupling so that they do revolve at the same neers [6]. Recommended practice for flange- speed, but with a "phase angle" between them. mounted sharp-edge orifice plates can be The magnitude of the phase angle is a measure found in publications of the Instrument of the flow rate and is said to be, in fact, Society of America [7] and the International a measure of the mass flow rate. Standards Organization [8]. The vortex shedding meter is also a The characteristics of the head meter are single-phase fluid rate-velocity meter, like as follows. The device is strictly a volu- the turbine meters, but in a distinct class metric meter; that is, it can of itself give by itself. The phenomena upon which it is no information regarding mass flow rate. based is the Karman vortex trail and its With appropriate pressure sensing, the range application to the measurement of flow of can be extended up to 10 to 1. It is the liquids and gases is fairly recent [10], very nature of these devices that they probably because only recently have sensors generate a decrease in pressure by accelerat- become available to detect the vortices. ing the fluid. If we are dealing with a The Karman vortex trail is used to explain saturated cryogen, then this sudden decrease certain phenomena associated with the flow in pressure could lead to vapor formation around cylinders, ellipsoids, and flat (cavitation) in the flowing stream and an plates. For flow around an object, eddys erroneous flow measurement. Many experiments break off alternately on either side in a [9], however, have failed to show any ill- periodic fashion. Behand the object is a effects attributable to cavitation. Nonethe- staggered, stable arrangement or trail of less, it is good design practice to maintain vortices. The alternate shedding produces a static liquid pressures within the meter well periodic force acting on the object normal to above the fluid saturation pressure. In the undisturbed flow. The force acts first spite of all shortcomings, head meters are in one direction and then in the opposite widely used and quite reliable. direction, setting up a natural frequency of The turbine-type volumetric flowmeter is vibration. probably the most popular of the various If the frequency of the vortex peeling flowmeasuring instruments, principally due to approaches or equals the natural frequency of their simple mechanical design and demon- the elastic system, consisting of the bluff strated repeatability. The turbine- type object and its supports, the object may have volumetric flowmeter is a simple mechanism a small alternating displacement normal to that consists of a freely spinning rotor the stream flow. (The vibration of some having a number of blades, each inclined at smoke stacks, the vibration and the fatigue an angle to the axis of flow. The rotor is failure or progressive fracture of some supported in guides or bearings mounted in a transmission lines have been attributed to housing that forms a section of the pipe- this resonance phenomenon). line. The angular velocity (rpm) of the rotor The vortex sensors consist of electron- may be detected by one of a number of methods; ically self-heated resistance elements whose e.g., a permanent magnet encased in a rotor temperatures and therefore resistances vary body will induce an alternating voltage in an as a result of the velocity variations inductive pickup coil mounted on the housing, adjacent to the body. These velocity varia- or the core of the pickup coil may consist of tions reflect directly the action of the a permanent magnet and the rotor constructed vortices as they peel off from the downstream of a magnetic material so that the change in edge of the bluff body. The meter factor magnetic circuit reluctance, as each rotor (pulses/gallon) depends only on the inside blade passes the coil core, causes an alter- diameter of the pipe and the width across the nating current to be induced in the coil. bluff body face. Cryogenic evaluation is Capacitive and photoelectric methods of limited, to date, but performance on liquid observing rotor rpm have also been used. The nitrogen and oxygen shows promise.

primary requirement, however, is that the Momentum Mass Flowmeters . Mass reaction angular velocity of the rotor be directly or momentum flowmeters are of three types. proportional to volumetric flowrate, or more There are those in which an impeller imparts accurately, to some average velocity of the a constant angular momentum to the fluid fluid in the pipe. stream, and then the variable torque on a A variation of the turbine type meter is turbine which removes this momentum, is mea- the "twin turbine" type. In this case, two sured. There are those in which an impeller turbines of different blade pitch are coupled is driven at a constant torque, and then the

12 variable angular velocity of the impeller is quantities of many tons per day. Similarly, measured. And there are those in which a there is no such entity as a cryogenic in- loop of fluid is driven at either a constant strumentation industry. Rather, those same angular speed or a constant oscillatory motion, firms that supply instrumentation to the and then the mass reaction measured. chemical processes industries modified and The performance of such flowmeters was extended their existing capabilities into determined in a National Aeronautics and the cryogenic regime. In a few instances, Space Administration sponsored flowmeter largely due to unique requirements or limited evaluation program [11 J. From the results of applications, the airframe companies devel- this program, it appears that several cryo- oped a special measurement capability them- genic mass flowmeters have been developed selves (e.g., measurement and control systems that are capable of liquid hydrogen mass flow for liquid oxygen in life support systems). measurement accuracies on the order of ±0.5 The result has been the measurement tools and percent. There appears to be degradation of techniques described earlier in Section mass flow measurement accuracy, however, when 2.2.2.1. subjected to a two-phase flow. Economic Magnitude . The economic magni- There are several other concepts of cryo- tude and rate of growth of cryogenic instru- genic fluid flowmeters that are available or ment sales would be interesting to note. are in development. Since they were not However, as indicated above, there is no such evaluated in the previously mentioned entity as a cryogenic instrument industry. National Aeronautics and Space Administration Hence the data we might desire are obscured sponsored program, definitive performance by the data on the measurement industry it- results, on the scale of the previously dis- self, SIC Major Group 38: Measuring, Ana- cussed mass flowmeters, are not yet avail- lyzing, and Controlling Instruments; Photo- able. These flowtieters are inferential mass graphic, Medical, and Optical Goods; Watches flow measurement devices, having in common and Clocks. measurements of fluid density and fluid vol- Close inspection of SIC Group 38 reveals ume flow or fluid volume flow- induced mo- that cryogenic instruments for laboratory use mentum. are found in Code 3811: Engineering, Labora- (6) Summary, Measurement Tools and Tech- tory, Scientific, and Research Instruments niques . Since measurements are the basis of and Associated Equipment. Some of the instru technology and dictate the fineness of our ments found in this category are: physical observations and control, it appears Chemical that this part of cryogenic technology may be Laboratory apparatus lagging. One may conclude: little is 1) Gas analyzing equipment being done to bring the cryogenic instrumen- Laboratory testing and scientific instru- tation technology of the space program to the ments market place, 2) if it were, adequate primary Physics laboratory apparatus and instru- instruments and facilities do not exist to ments, and bring this part of the National Measurement Standards and calibrating equipment. System under control, and 3) no concerted effort exists to explore the consequences or By far the greater number of cryogenic exploit the opportunities of new technologi- instruments will be found in Group 382: cal opportunities. Measuring, Analyzing and Controlling Instru- These conclusions appear to apply gener- ments. For instance, Group 3822--Automatic ally to each area of cryogenic instrumenta- Controls for Regulating Residential and tion, although, of course with varying Commercial Environments and Appliances-- degrees of severity. Specific analyses and includes: conclusions appear in each major instrumen- Float controls tation area in Section 2.3, "Realized Mea- In-built thermostats, filled system, and surement Capabilities." bimetal types Liquid level controls 2.2.2.2 The Cryogenic Instrumentation Refrigeration controls (pressure) Industry Refrigeration thermostats Temperature controls, automatic Commerce in cryogenics is largely an Thermocouples, vacuum: glass. extension of the chemical process industry (SIC Major Group 28). Even such special Group 3823--Industrial Instruments for government programs as the space effort were Measurement, Display, and Control of Process built upon the existing foundation of the Variables; and Related Products--includes industrial gases and equipment industries to establishments primarily engaged in manu- supply liquid hydrogen in unprecedented facturing industrial instruments and related

13 products for measuring, displaying (indicat- electromechanical counters and associated ing and/or recording), transmitting, and metering devices. Instruments of interest controlling process variables in manufactur- found here are: ing, energy conversion, and public service utilities. These instruments operate mechan- Counter type registers ically, pneumatically, electronically, or Gages for computing pressure- temperature electrically to measure process variables corrections such as temperature, humidity, pressure, Impeller and counter driven flow meters vacuum, combustion, flow, level, viscosity, Meters: gas, liquid, tallying, and mechan- density, acidity, alkalinity, specificgrav- ical measuring - except electrical ity, gas and liquid concentration, sequence, Positive displacement meters time interval, mechanical motion, and rota- Propeller type meters with registers tion. Some specific examples pertinent to Totalizing meters, consumption register- this study are: ing, except aircraft Turbine meters, consumption registering Flow instruments, industrial process type Vehicle tank meters. Level and bulk measuring instruments, industrial process type. Close inspection of the 1967 census of Liquid level instruments, industrial manufacturers reveals the not surprising fact process type that all temperature sensors or all pressure Magnetic flow meters, industrial process gages are lumped under one code, regardless type of their use. Accordingly, one cannot di- Pressure gages, dial and digital rectly get at the magnitude of the cryogenic Pressure instruments, industrial process instrument business through such conventional type means, and other means must be found. Primary elements for process flow measure- For instance, an industry association oc- ment: orifice plates, etc. casionally has found it useful to look at a Resistance thermometers and bulbs, indus- specific segment of their industry. The trial process type Instrument Society of America special Temperature instruments: industrial corrmittee mentioned in Section 2.2.1.1 made process type, except glass and bimetal such a survey of flow meters, and their Thermistors, industrial process type findings are shown in table 2-3. Thermocouples, industrial process type Table 2-3 makes no allowance for the flow- Thermometers, filled system: Industrial meters that may be employed for liquid hydro- process type gen and LNG custody transfers from trucks or Turbine flow meters, industrial process trailers. The total investment of flowmeters type. is based on a price range of $700 to $2500 The final classification of interest to us per flowmeter. is Group 3824: Totalizing Fluid Meters and These figures refer only to the custody Counting Devices, which includes establish- transfer (sale) of cryogenic fluids. Much ments primarily engaged in manufacturing more is at stake if one considers the total totalizing (registering) meters monitoring production of industrial gases, which are in fluid flows, such as watermeters and gas- fact made by cryogenic processes and include meters; and producers of mechanical and in-plant process transfers.

Table 2-3. Flowmeters in custody transfer of oxygen, nitrogen, and argon

Year Total No. Total Investment Custody of Flowmeters Flowmeters in Millions Transfer/Year

1966 1000 $ 1.6 200,000 1967 1140 1.8 228,000

1968 1300 2.1 260,000 1969 1482 2.4 296,400 1970 1689 2.7 337,800

1971 1925 3.1 385,000

14 )

These figures were developed by the Instru- Table 2-5. Typical flowmeter performance ment Society of America to help demonstrate that flowmetering had an economic magnitude 1-1/2 Inch such to merit attention, and that, in fact, Oscillating this part of the measurement system could Piston not be certified to be in control. Substructure and Composition; Firms In- Precision (3a) at Start, % ±0.63

volved . Several very recent and comprehen- Precision (3a) at End, % ±0.54 sive reviews of specific cryogenic instruments and measurement systems have been pre- Bias at Start, % +1.33 pared by the Cryogenics Division of the Bias at End, % +0.61 National Bureau of Standards for the National 3 Aeronautics and Space Administration Vol . Metered, m (gal 1225 (323,800) Aerospace Safety Research and Data Institute. 3 Max. Flow Rate, m /s (gpm) 0.0044 (70) This series includes flow measurement technology [12], low temperature measurements Min. Subcooling, K 5 [13], density and liquid level measurements [14], and pressure measurements [2]. These "Data on only one of the 1-1/2 inch nominal are truly benchmark publications that discuss size meters are presented as a second not only the technology of the measurement, meter underwent a reduction in registration but also give specific performance data. by about 1 percent during these tests and The data below are typical of the level of was replaced. The change in bias is signi- detail that may be found in all of the re- ficant and indicates wear." ports. They are taken from the treatise on flow measurement [12] for an oscillating This level of detail is typical of all of piston volumetric flowmeter, as an example: the studies mentioned above, and accordingly they are highly recommended as source docu- "The name plate specifications on the 1-1/2 ments . inch meter are: Certain trade journals also review the size - 0.0381 meters (1-1/2 inch) instrumentation field. Measurements and Data Journal is published bi-monthly by the maximum flow rate - 0.0044m s (70 gal /mi n) Measurements and Data Corporation, 1687 Wash- minimum flow rate - 0.0088m s (14 gal /mi n) ington Road, Pittsburgh, PA 15228. In 1974, 2 for instance, this journal published annual maximum pressure - 2.413 MN/m (300 psia) staff surveys on: material - aluminum piston, brass case. Piezoelectric pressure transducers Force measurement Reluctive, inductive, and eddy- Table 2-4. Typical flowmeter performance current pressure transducers Mass flow Flow Rate LO2 Water Deviation LO2 Capacitive pressure transducers Gal/h Deviation Deviation from water Thermocouples and accessories Resistance and thermistor thermometry 300 -0.4 -0.53 +0.13 Strain-gage pressure transducers Turbine flowmeters 450 -0.55 -0.47 -0.08 Potentiometric pressure transducers. 800 +0.8 -0.5 +1.3 These commercial surveys usually include 1700 +0.35 -0.7 +1.05 a glossary of terms, physical theory, range, sensitivity, stability, cost, and 2100 +0.22 -1.05 +1.27 accuracy. A small part of a typical table "From this table, the mean deviation of LO2 on resistance and thermistor thermometers

from water calibration is equal to 0.73 from Measurements and Data , Vol. 8, No. 2, percent (deviation from standard 14.67 (March/April 1974), is given in table 2.6 counts per gallon). It may be expected to illustrate the very practical and com- that water can be used for the routine prehensive data that may be found. testing of meters of this type and a factor applied to obtain the correct liquid oxygen calibration.

15 r

Table 2-6. Resistance and thermistor thermometers

riuuc 1 r r I VrfC

Thermal Systems 1001 Ni, Pt -100/600F Industrial probe; 100 ohms $32 Hpriprril niimn

. Model 1064 -452/500F . Cryogenic platinum RTD $400

1 lUUC 1 1 U 1 VJ $Rnn i?5 1 sjKj/ uuu Mnrlpl RIdR 1 lUUC 1 J I to riiiticiLurc pruuc

ThoKTnn Plo^'f"^'!^ Pri lilcilllU QfcV.'Ul 1^ UU« 9 1 t 11., • 16301 Pt Sensor -200/500C 0.26C at OC for 50-ohm element; 3 C at 500C

Thermometries, Inc. Series. P20, P30^ -100/300C To +.5% thermistor probe $1 (Quantity) P60, PlOO Series HTP60, -100/450C Same; hi temp thermistor probes $5 (Quantity) HTPlOO Series B10,B14,B43 -100/300C To +.5% thermistor beads $l-$4

Series HTB43 -100/450C Same; hi temp thermistor beads $5 Series 1F,2F, FM -50/150C To +.5% thermistor flakes $3-$20 Series FM Same Same $.60

Every manufacturer that wishes to cooper- "Additional industrial instruments are ate is included. Coverage is very close to needed for the construction of plants to 100% indeed. The above data were chosen manufacture synthetic natural gas (SNG) simply as an illustrative but not nearly from light oil, and for the facilities exhaustive example. required to process and transport {at Trends. Trends in instruments for mea- avyogenia temperatures in liquid form) surement, analysis»and control as a whole natural gas from overseas sources to can be a helpful indicator even though the depots in the U.S. actual value of the cryogenic instruments specifically may evade use. The following discussion of trends is taken almost en- tirely from the "U. S. Industrial Outlook, "Maintaining the pace required of a dynamic 1974, with Projections to 1980", a U. S. high-technology industry, manufacturers Department of Commerce annual publication. of measuring and control instruments continue to make substantial investments "Total industry shipments by manufacturers in newly designed products. These of measuring and controlling instruments developments reflect customer demands are expected to reach $1.92 billion in for monitoring and control systems that 1974, a 7 percent rise over the $1.8 improve process management, maintain billion estimated for 1973. Industrial tighter product specifications, achieve process instruments compose approximately economy in production, enhance operating 50 percent of this composite group. safety, and add to the protection of the Business prospects for process instru- environment. New high-temperature and ments are closely related to the trend cryogenic technology imposes require- in capital expenditures for plant and ments for innovative measuring instru- equipment. Major sectors of the process ment sensors capable of performing group are the petro'leum and chemical dependable and accurate measurements of industries, prime markets for industrial ultra-hot and super-cold processes." process instruments. 16 : .

International Trade . With respect to The Industry as a Whole . A profile of international trade patterns, the same this industry as a whole is given in the source continues: Box:

"Technology continues to foster automated Table 2-7. 1973 Profile: monitoring and control of industrial instruments for measurement, processes, and residential and com- analysis and control mercial facilities in the U.S. and world-wide. The automatic temperature SIC code 3821 control industry, and manufacturers of 3822 Value of industry shipments measuring and control instruments, $1800 $740 (millions) produce and distribute instruments whose Number of establishments 661 common technology crosses national bound- 105 Total employment (thousands) 67 aries. 40 Exports as a percent of 27.8 4.3 product shipments "Industrial processes and building methods Imports as a percent of 5.5 n.a. are universal, and can be served through- apparent consumption out the world by instrumentation of sim- Compound annual average ilar design. Global leadership demands rate of growth 1967-73 alert attention to chanqinq reauirements (percent) in various market sectors, and continuous Value of shipments 3.6 3.0 advances in new product design. Manufac- (current dollars) turers in these industries take part in Value of exports numerous trade shows and exhibits in the 9.4 4.2 (current dollars) U.S., and actively participate in sched- Value of Imports uled trade shows and trade missions 25.7 n.a. (current dollars) organized by the Office of International Employment 9.2 Marketing to reach foreign markets. 0.8 Exports by both sectors of the instru- n.a.= Not available. ment industry have steadily increased since 1968, with exports of the measuring and control instrument group pro- gressing at an annual growth rate of 9 2.2.3 Reference Data percent from 1967 to 1973. "The Office of International Marketing has Reference data are needed by the cryo- prepared a Global Market Survey on genic community on both fluids and solids.

Industrial and Scientific Instruments , The following sections describe some data depicting business prospects in se- producing activities, their users, and the lected foreign markets: Global Market principal means of dissemination.

Survey, Industrial and Scientific Instru- Properties of Fluids . Pure fluids of ments, Office of International Marketing, interest in the Cryogenic Measurement 1972, U.S. Department of Commerce." System include helium, neon, argon, hydrogen, deuterium, nitrogen, oxygen, fluorine, Examples of specific international inter- methane, ethane, ethylene, propane, carbon actions may be found in Section 2.2, where monoxide and carbon dioxide. the NBS cryogenic flowmetering program is used to illustrate the process. In this The mixtures include air (N„, O^, Ar), program alone, the NBS Cryogenics Division: natural gas (CH4, other hydrocarbons, nitro- cooperated with the International Orga- gen), synthetic natural gas (CH4, H2, CO, nization of Legal Metrology (OILM) to CO2), FLOX (F2, O2) and GDL laser fluids facilitate final adoption of our technical (He, N?, CO2). recommendations; performed "type testing" of meters of foreign manufacture -- affil- Properties of interest are the thermo- iates of U.S. concerns; and encouraged and dynamic properties (compressibility, entropy, facilitated the visits and participation of enthalpy, specific heats, sound velocities); international observers from the PTB; electromagnetic properties (dielectric Linde, AG; Messer-Griesheim GMBH; Compteurs constant, refractive index); and transport Schlumberger, France; and the British Oxy- properties (viscosity and thermal conduc-

gen Co. , London. tivity coefficients).

17 Properties of Solids . The solids (metals, Methods of Dissemination . The NBS Cryo- alloys and composites) used at low tempera- genic Data Center [16] was established in tures include aluminum and aluminum alloys, 1958 and publishes a bi-weekly current copper and copper alloys, nickel and nickel awareness list of articles in the fields of alloys, the austenitic stainless steels, cryogenic engineering and cryogenic physics titanium alloys, selected ferritic steels, a which have appeared in the open literature. variety of superconducting materials, glass In collaboration with the Standard Refer- epoxy composites, and many more. The data on ence Data Program, an accumulated total of these materials at the required low operating nearly 100,000 technical articles have been temperatures include the mechanical, thermal, received, cataloged and indexed for ready and electrical properties. access. In addition, specialized quarterly

Needs for Data and Their Users . These bibliographies are prepared for: Super- data are required for many, and often diffuse, conducting Devices and Materials; Liquefied purposes including: a) data for material Natural Gas; and Hydrogen as a Future Fuel. selection in the decision-making phase pro- The cryogenic community, including libraries, grams; b) data for equipment or process de- purchase these documents on a subscription sign and optimization (for example, refrig- basis, which covers the NBS cost of prepara- erator and liquefaction equipment, separation tion. Subscriptions to these periodicals of gases, and storage and transport of liq- total nearly 1300 [17]. uids); c) data for analysis of the system or In addition, the staff of the Data Center experiment, including safety criteria; and d) responds to over 500 technical inquiries data for instrumentation and gaging, in- each year. Some of these requests require cluding sale or custody transfer. the use of an automated information system, It is important to note that these data in which case the user pays a fee for just are used by the entire cryogenic community, the costs involved in the automated search. the $2 billion per year industry that sup- The Cryogenics Division is the focal point ports a wide variety of technologies. To for the measurement and data requirements of illustrate, the use of less expensive but the cryogenic community. We established the structurally adequate metal could save $0.3 National Cryogenic Engineering Conferences million on the cost of a single liquefied (CEC), now in their 20th year and NBS con- natural gas storage tank or $1.0 million on tinues to be the secretariat. The 20 vol- the cost of a single ship carrying liquefied umes of the conference proceedings "Ad- natural gas--a total cost saving of as much vances in Cryogenic Engineering" are major as $15 million per year. In addition, eco- resource documents for the workers in this nomic analyses show that the value of the field. In addition, we sponsor specialized thermodynamic data to the design of a plant conferences, like the International Cryogenics or facility is worth 1 percent or more of the Materials Conference, and workshops to aid in capital cost of the entire unit— of consider- dissemination of data. able value when used for the design of large The most prestigious of our outputs are the cryogenic units, many of which run into tens individual research publications, approxi- of millions of dollars [15]. mately 60 per year, or roughly one open- A less quantifiable but equally important literature publication per professional man- use of the reference data base is in estab- year. Special purpose publications are much lishing codes, standards, and recommended more numerous, and often more specific and practices. These data often form the tech- timely. For instance, progress reports and nical foundation for regulatory decisions by NBS Technical Notes are frequently distrib- such agencies as the Federal Power Conmis- uted directly to other agency sponsors and sion, the Department of Transportation, and known users on a quarterly basis. the Office of Pipeline Safety, as well as the Pattern of Use of the Data in the Mea-

National Fire Protection Agency. surement System . As mentioned, the users of

Methods of Acquisition . Data on fluid and reference data by the cryogenic community solid properties at cryogenic temperatures are many and varied. Selected examples have are obtained by a wide variety of groups in been chosen to illustrate these uses. industrial, government, university, and non- a) Nat. Bur. Stand. (U.S.) Tech. Note No. profit laboratories. These data are ref- 361 "Standard Liquid Densities of Oxygen, erenced, compiled, correlated, and critically Nitrogen, Argon and Parahydrogen" by Roder, evaluated by our staff and form the basis for McCarty and Johnson, was prepared in 1968 at deciding what new measurements are required the request of the Compressed Gas Association and which ones are not needed. Our staff and the State of California, Office of Weights performs comprehensive accurate measurements and Measures. Subsequent revisions (1972 and to fill important da£a gaps and reconcile 1974) have extended the range of data and inconsistencies where necessary.

(

18 .

provided a metric supplement. The latter As the composition of LNB mixtures vary was requested and paid for by the German considerably, depending on the sources of the Government for use in the European trade in gas and the processing conditions, accurate cryogenic fluids. These data have now been methods are needed for calculating liquid adopted as a tentative code (law) by the densities at arbitrary compositions, temper- "57th National Conference on Weights and atures, and pressures. The accuracy is impor- Measures" and are now used as the data base tant because of the extremely large volumes for custody transfer (sale) in all commerce of liquid involved (e.g., 125,000 cubic meters in the Western World for these fluids. per ship). This project is being funded and b) A comprehensive program on the thermo- guided by a consortium of 18 energy compa- physical properties of pure methane has nies, and the results will be the industry recently been completed. Nat. Bur. Stand. "agreed upon" reference data. (U.S.) Tech. Note No. 653 "The Thermophysical Properties of Methane, from 90 to 500 K at 2.2.4 Reference Materials pressures to 700 Bar", by R. D. Goodwin, contains the most comprehensive and accurate Reference materials are well characterized tables and interpolation functions available (and sometimes certified) materials produced for methane, and NBS has already convinced in sufficient quantity to assure long term the American Gas Association to accept these integrity of the measurement process. Refer- reference data as "agreed upon" data for the ence materials for low temperature applica- Nation's gas industry. NBS has made similar tions are continually being developed and recommendations to the American National characterized to help fulfill our goal of Standards Institute (ANSI) and the Interna- furnishing complete and comprehensive service tional Liquefied Natural Gas Conference, to the cryogenic coimunity. The materials LNG-4, held in Algiers in the Suirmer of 1974. studied are primarily metals, alloys, and c) A compilation and critical evaluation composites. The electrical, thermal, and of data: "Thermal Conductivity of Solids at mechanical properties are the prime charac- Room Temperature and Below" by Chi Ids, terization parameters. These activities are Ericks and Powell, NBS Circular 131, is the described below. basic reference document for all thermal Nature of the Data . Reference materials conductivity data in this field. In addition for cryogenic measurement standardization are to presenting the available data, it points principally solids, especially pure metals to the data gaps and guides future research, and alloys. Because of the economic signi- d) Many times NBS is called upon by other ficance of heat loss minimization and energy government agencies to evaluate efficiency conservation, insulating reference materials claims and production capacities projected by are also of considerably importance at this "paper studies". A complete and consistent time. set of design data is essential for this Properties of interest include the thermal purpose. The National Aeronautics and Space conductivity, thermal diffusivity, thermal Administration, Department of Defense and the expansion, specific heat, and electrical Energy Research and Development Agency, for resistivity. These properties are among those instance, specify that NBS data be used in that depend significantly on variable ma- its proposals to provide a coninon, sound terial production factors, basis for evaluation. Similarly, our recom- A broad range of reference materials for mendations to the regulatory agencies would each useful property is required to include be open to question if it were not for a the range of measurements encountered in sound foundation of valid and consistent data. practice. For example, thermal conductivity e) Accurate density measurements and cal- reference materials are required to span culation methods for liquefied natural gas conductivities from the low conductivity mixtures are being obtained to provide a insulating materials to the very high con- basis for custody transfer agreements and for ductivity pure metals, a range of one million mass, density, and heating value gaging or more. The reference data for these ref- throughout the fuel gas industry. erence materials must be accurate to near The basis for the custody transfer of state-of-the-art levels. At this stage in liquefied natural gas is its heating value. the evolution of cryogenic technology, how- It is difficult to determine and agree on the ever, the prime requirement is for charac- heating value of extremely large volumes of terizing more new materials, rather than natural gas in the liquid state. For example, higher accuracy measurements on "older" methods for calculating the heating value of materials a liquefied natural ^as mixture require knowing its density, which in turn depends on its composition, temperature, and pressure.

19 It should be noted that reference data may The NBS Office of Standard Reference Mate- be of little use without corresponding ref- rials, as the world's largest source of reference materials. Reference data of mate- erence materials, offers approximately 850 rial properties can be grouped into two broad different items for sale. About 33,000 units categories: those which are not significantly worth approximately $1.6 million are sold affected by variations in production tech- annually. Information regarding these ref- niques and those which are. The latter class erence materials is available directly from of reference data require reference materials the Technical Representative of the Office of for their continued usefulness and are of Standard Reference Materials, Mr. R. W. principal importance at low temperatures. Seward, phone (301) 921-2045, and also by

Need for Data and Their Users . Reference catalog [23]. materials and concomitant reference data are Certificates are issued with these mate- required primarily for three purposes, all rials listing the property and their ac- of which form a basis for our national cryo- curacies . genic measurement system's compatibility and "Uncertified" reference materials, usually . accuracy: 1) to perform comparative mea- known as research materials, are also pro- surements in which the measured property vided by this office and other components of value is given directly in terms of the NBS. They serve a very valuable purpose as standard; 2) to perform apparatus check-out, common source materials in round-robin inter- thus basing the performance of the apparatus comparison, as do the Standard Reference on the standard; and 3) to train new person- Materials. They also play a unique role in nel, thus propagating a high level of reli- the calibration of research apparatus and ability and expertise. We must be prepared methods, as opposed to engineering, or process to fulfill all three of these requirements to quality control uses. These research ma- ensure compatibility within the Nation's terials are especially valuable as a founda- measurement system and to promote meaningful tion for comparing data obtained from dif- measurements. ferent sources or by different means during

Methods of Acquisition . Reference mate- the course of an experimental program. rials are produced by industry and government Patterns of Use of Materials in the Mea- under carefully controlled production condi- surement System . A few specific examples may tions to assure maximum homogeneity of the be helpful to illustrate how reference ma- material lot. The NBS Office of Standard terials are used. For instance, Hust [18] Reference Materials (OSRM) produces, certi- describes the preparation and character- fies, and issues reference materials and, as ization of an electrolytic iron. This such, is the world's largest. Reference data thermal conductivity sample was characterized for these materials must be determined by over the range 4 to 300 K to meet industry standards laboratories of the highest recog- and government needs in 1971. The tempera- nized expertise in order to realize their ture range of this material was just recently full utility. extended by Hust and Giarratano [21] to 1000 K. The Properties of Solids Section of the Only a few of these materials are sold annu- Cryogenics Division of NBS has been active in ally, especially when compared to the large establishing thermal conductivity, electrical volume of chemical composition samples that resistivity, and thermoelectric reference ma- are distributed. However, the impact of terials. Recent efforts have resulted in this small number of samples may nonetheless establishing three metal reference materials be comparable, if one considers the improved covering a wide range of conductivity and reliability and confidence in the data that temperature. These reference materials have are subsequently published, following the been described by Hust, Sparks, and Giarratano common use of these materials in many labora- [18, 19, 20, 21]. Another pertinent cryo- tories employing many different procedures. genic reference device, and associated ref- Many research groups routinely "prove" erence materials for measuring very low temp- their apparatus with these research materials eratures, has been described by Schooley [22]. before publishing any data. In the past, Current plans are to extend this effort to discrepancies of 50% in thermal conductivity insulating materials and other solid mate- data were not uncommon. In one documented rials. One program to establish several instance, a team at a major Mid-Western insulating reference specimens, in conjunc- University has spent two years improving tion with the National Aeronautics and their data accuracy and credibility through Space Administration space effort, was under- the use of precisely the research material taken by this laboratory, but remains in- just described. In another instance, during complete at this time.. the late 1960's, NBS was requested to provide consultation services for a thermal and electrical properties project in conjunction with a nuclear powered rocket program for the 20 National Aeronautics and Space Administration. 1920 Charles Guillaume Several measurement laboratories were in- Finding cheaper materials for volved, and the question of data accuracy national prototype standards between laboratories became a significant (Ni-Steel) INVAR problem. To answer this question, we ar- ranged a round-robin study on four reference *1934 H. C. Urey materials. The results of this study were Discovery of D2--was produced essential to the laboratories involved. In by distillation general, it showed that good agreement could be expected, but it also showed that large 1936 P. J. W. Debye discrepancies could occur, even with simple Debye theory of specific heats measurements such as electrical resistivity. For instance, one of the four laboratories *1949 W. F. Giauque reported vastly different results that were For his contribution in the later proven to be erroneous. field of chemical thermometry, NBS has initiated a conscious and delib- particularly concerning the erate program of establishing selected re- behavior of substances at search materials. These are referred to as extremely low temperatures "uncertified reference materials" since they are not accompanied by reference data. They *1957 T. D. Lee and C. N. Yang are, however, highly characterized from the Upsetting the principle of standpoint of homogeneity. These materials conservation of parity as a provide an excellent basis for intercom- fundamental law of physics parisons of data. Subsequent studies performed on them allow a more logical inter- 1960 D. A. Glaser comparison of data, thus improving our Invention of bubble chamber theoretical knowledge of the behavior of materials. This program is still in its 1961 R. L. Mossbauer infancy, and while much remains to be done, Recoilless nuclear resonance it also shows much promise. absorption of gamma radiation

2.2.5 Science and People *1962 L. D. Landau Pioneering theories of condensed 2.2.5.1 Cryogenic Measurements in Science matter, especially liquid helium (He^) Cryogenics and measurements at cryogenic temperatures are widely used in research and *1968 Luis W. Alvarez investigation in basic science. Many Nobel Decisive contributions to ele- Laureates received their honors either be- mentary particle physics, in cause of work directly in cryogenic sciences particular "for his discovery or because of work in which cryogenic mea- of resonant states" through his surements were indispensable. An imposing development of hydrogen bubble list of such Nobel Prize winners follows: chamber techniques and data analysis 1902 Pieter Zeeman Influence of magnetism upon *1972 John Bardeen, Leon N. Cooper, radiation and J. Robert Schrieffer Exposition of the "B-C-S" theory 1904 Lord Rayleigh to explain superconductivity on Density of gases and his a microscopic basis discovery in this connection of Argon *1973 B. D. Josephson, Ivar Giaever, and Leo Esaki *1910 Johannes Van der Waals The discovery of tunnelling For his work concerning the supercurrents (the Josephson- equation of state of gases Junction) and liquids

*1913 H. Kammerlingh Onnes Cryogenics crucial to the investigation For his investigations into the properties of bodies at low temperature that led, among other things, to the preparation of liquid helium ) s

The kinds of people working in this part simplest atom, consisting only of a proton of the National Measurement System, and the and an electron, it interferes little with fields of science that support it, are in the high-energy processes being studied with part illuminated by the above list, espe- the giant accelerators, although it is read- cially during the last decade or so. There ily ionized and serves well as the detector may be a trend away from the very basic work in the bubble chamber. of Mossbauer and Landau, for example, to work The first large liquid hydrogen bubble of almost immediate practicality (BCS, Joseph- chamber was installed at the Lawrence Ra- son, etc.). This is probably only an ap- diation Laboratory of the University of parent trend, for who is to say that any work California and first operated in March 1959. meriting the Nobel prize in physics is not A remark was made that this 72-inch liquid basic? hydrogen bubble chamber would be the equiv- Of more immediate concern to us is not alent of a Wilson cloud chamber one-half mile only the ubiquitous nature of cryogenics in long. They could not really be equal, basic science, but also how often NBS has however, because the cloud chamber does not directly played a key role. For instance, have the great advantage of utilizing the the Lee-Yang parity hypothesis was experi- simplest molecules as the detector. mentally proven by an NBS team--Dr. E. The most recent application of cryogenic Ambler, and others. The BCS Theory was phenomena to measurement science involves the supported in part by the "isotope effect" so-called Josephson junction. Some of the experiments by Emmanuel Maxwell at NBS in the most exciting phenomena worth, exploiting in 1950's. Luis W. Alvarez, in his Nobel ac- instruments and devices occur at weak elec- ceptance speech, said in part: trical contacts between superconductors, known as Josephson junctions. They can be ". . . problems involved in building and simple structures, consisting only of two housing the 72-inch bubble chamber. We pieces of superconducting metal lightly were also extremely fortunate in being touching together. Often one of them is a able to interest the National Bureau of fine wire reminiscent of the "cat whisker" of

Standards in the Project. Dudley Chelton , the early days of radio. Sometimes the

B ascom Birmingham , and Doug Mann spent a structures are thin evaporated films, with great deal of time with us, first edu- barriers consisting of very thin layers of cating us in large-scale liquid hydrogen insulating material (or normal metal) or very techniques, and later cooperating with us narrow constrictions. The importance of in the design and initial operation of the Josephson junctions arises from the extra- big chamber." ordinary way they respond to voltage and magnetic flux. (The first publication on the 72-inch bubble Under the influence of a small applied chamber was authored by NBS Cryogenics voltage, the current through a Josephson Division Staff. junction oscillates at a frequency strictly proportional to the voltage. The factor of 2.2.5.2 Cryogenic Science in Measurements proportionality (about 484 MHz per yV) is a fundamental constant of nature; twice the This list of Nobel Laureats may also serve electric charge of the electron divided by to illustrate the use of cryogenic science in Planck's constant. It has been measured with measurements--employing cryogenics per se to high accuracy (about one part in 10^) by develop new or improved measurement technol- Langenberg and his group at the University of ogy in fields outside of cryogenics. Pennsylvania. The accuracy of this measure- For instance, Donald Glaser invented ment was limited at the time by the defini- the bubble chamber that won him his Nobel tion of the volt. Frequency was (and still Prize. Glaser recognized the principal limi- is) the quantity which could be measured tation of the Wilson cloud chamber namely, best, and the standard volt was maintained by that the low density particles in the cloud a group of chemical cells. However, the could not intercept enough high-energy par- Josephson junction has proven itself, and the ticles that were speeding through it from the legal volt has been maintained by this means beams of powerful accelerators- Glaser' since July 1 , 1972. first bubble chamber operated near room If a Josephson junction serves to close a temperature and used liquid diethylether. To small superconducting loop, it becomes sen- avoid the technical difficulties presented by sitive to magnetic flux as a result of such a complex target as diethylether. Pro- quantum mechanical interference between fessor Luis Alvarez of the University of electrons travelling around the loop. This California devised a bubble chamber charged results in a periodic response to magnetic with liquid hydrogen. Since hydrogen is the flux, the period being the magnetic flux 10"^ quantum (h/2e, or about 2 x ^W),

22 ,

another fundamental constant of nature. have at normal radio frequencies. The This device has come to be known as a SQUID, pioneering work was done by Grimes, Richards, an acronym for Superconducting QUantum Inter- and Shapiro when they were all at the Bell ference Device. It is the world's most Telephone Laboratories. An NBS team, notably sensitive magnetic sensor. McDonald and Evenson, are synthesizing sig- A most promising application of the SQUID nals of stable and accurately known frequency

is in magnetocardiography . The action of a throughout this range by using Josephson beating heart generates small electric junctions to generate harmonics and mixtures currents that can be magnetically recorded of signals from the primary sources. One of with the aid of a SQUID. The resulting their objectives is to extend this activity record bears a strong resemblance to an up to the range of visible light (using electrocardiogram, but no electrodes are used devices other than Josephson junctions for to obtain it. Mere proximity of the instru- the final stages) and to measure the fre- ment is sufficient. It has been discovered quency of visible light of a well defined that, in addition to the short pulses of wavelength, such as is used for the standard current generated by normal action of the of length. This raises the possibility of heart, steady currents associated with using a single standard for both length and various kinds of injury may also be detected. time. Such a standard will have practical This may give useful diagnostic information advantages as well as satisfying admirers of that is not readily obtainable in any other the theory of relativity. The technology way without surgery. they are generating will be directly usable Another application that has been estab- for the other purposes mentioned. lished in the field is electromagnetic These are just a few examples of the many sounding to depths of a few kilometers in the existing and future applications of cryo- earth. A SQUID magnetometer has proven to be genics, especially superconductivity, applied the best instrument for these measurements to electronics. The first few commercial and has been used to map a geothermal energy instruments are appearing on the market; we basin in California. can expect their number to grow. Other applications of these very sensitive One of the barriers to the widespread magnetometers include magnetoencephalography application of superconducting devices is of geomagnetism, and conmiuni cation through course the need to provide a liquid-helium ground or water at frequencies of a few environment. For small instruments, dis- hertz, which would rapidly attenuate signals sipating minute quantities of power, this is at higher frequencies. not such a severe problem as it might be for The periodic response of the SQUID to big machines. Liquid helium is widely magnetic flux suggests a new style of elec- available. Compact, portable containers trical metrology. One could measure current can be engineered to run for several days by counting off magnetic flux quanta in the between refills. In fact, the development of same way that we measure length by counting the SQUID, which has an established reputa- off wavelengths of light. The Cryoelectron- tion as the world's most sensitive magnetic ics Section at NBS is working on this now. sensor, has now reached the stage that it is Preliminary results indicate that it will be becoming the most convenient and portable a powerful technique both for direct current instrument for many geophysical measurements. and for radio frequencies up to the microwave In collaboration with the United States range. Another advantage of electrical Geological Service, a SQUID magnetometer measurements employing cryogenic devices in was tested for electromagnetic prospecting general is the high sensitivity attainable for geothermal sources in the geyser basin because of the freezing out of thermal near Clear Lake, California. It proved background noise. to be a handy instrument for this purpose. The last area of activity to mention in The same instrument was also taken as air- applying cryogenics to other measurements is line hand luggage to the Republic of Chad the extension of radio technology into the in Africa to make magnetic observations submi 1 1 imeter-wave to far-infrared range of during the solar eclipse. Weighing only frequency. Possibilities include communi- 10 kg, the instrument gave no trouble and cation, radar, and astronomy. The recent showed that it is ready for use in even the development of powerful, coherent sources most remote parts of the world. (such as the hydrogen-cyanide, water-vapor, and carbon-dioxide lasers) has stimulated exploration in this field. Receivers have lagged behind the development of transmit- ters, but with Josephson junctions we can hope for receivers of the same quality as we

23 )

2.3 Realized Measurement Capabilities the National Measurement System in control. Industrial type platinum resistance ther- This section summarizes state-of-the-art mometers are routinely used, for instance. technology for cryogenic instruments. Improvements in their interchangeabi 1 ity Pressure transducers are normally placed would be desirable, as well as some simple indications in a temperature controlled environment near thermometry for crude temperature room temperature. Some available pressure and the monitoring of process trends. transducers are capable of performing satis- Table 2-9 summarizes some representative factorily at low temperatures, but new types characteristics of the best known types of such as piezoelectric, diode, electrokinetic, cryogenic thermometers. etc., may perform equally well or better. In- The terms "reproducibility" and "accuracy" formation on their performance is needed. require some explanation. Reproducibility For a detailed review of the ranges, means the variability observed in repeat- accuracies, and precisions attained in ing a given measurement using the best pressure measurements, see the comprehensive present-day laboratory techniques. Changes review by Arvidson [2]. Table 2-8 below is produced on thermal cycling of the thermom- reproduced from that work. eter to and from ambient are included in this Temperature measurements are unquestion- parameter. Accuracy means the significance ably in better shape than any other cryogenic with which the thermometer can indicate the measurements. Adequate calibration facili- absolute thermodynamic temperature. This ties exist, as well as a large body of know- includes errors of calibration and as ledge that together help keep this part of errors due to nonreproducibil ity, the

Table 2-8. Cryogenic pressure transducers.

Characterlitic > Strain Cage Capacitance Crystal Reluctance

Frequency rciponse, Hz to 40 k Hs to 500 K Hs 0. 5 to 1 M Ha 1 K Hz (approx.

Nominal •ensitivlty, 0.5 1.0 0.5 1.0 % full (cale

Thermal stability Excellent for compensated Approx. temperature Good Approx. 0.02% per deg F bridge winding drift; 0.025 % per deg F

Linearity, % < 0.1 -1.0 0.5 -1.0

Response to vibration, Negligible for light-dia* Low, but noticeable Can be appreciable; also Low, but noticeable; about noise, acceleration phragm and fully-rigid highly sensitive to 1.0% per 100 G types electrical "noise"

Drirt, % negligible 1.0 (excluding temperature 2.0 drift)

Hysteresis, % Approx, 0. 2 1.0 negligible 0. 5

Open-circuit full-scale Order of 50 mv Order of 5 v Order of 1 mv Order of 5 v output

Overload, % Generally about 100; to Order of 100 Satisfactory for elastic Order of 100 500 for special types limit of crystal; poor for liigher loads

Ease of calibration straightforward straightforward No static calibration slraightforward possible; dynamic calibration tricky

Typlcal^resBure sensing tube or diaphragm diaphragm c rystal fliaplira);m or twisted device torsion tube

Cooling Some designs air or water Some designs air or water Generally none possible Generally none possible cooled (special types have cooled (special types have heat-transfer rates to heat-transfer rates to about 7.0 nxU/lnV" about 7.0 DTU/inV»

Remarks and limitations Good all-around. Expensivic Excellent instrument ex- Unique In ultra-high fre- Maximvmi (cmpcralure repair and replacement of cept for drift. Larger and quency range. Not use- 200 F. Low frequency parts on high-performance more complex than strain able below about 5 tiz. rt-sponHO doflign.s Rage

24 class of doped germanium crystals. A former usually being much more significant. given point comparison calibration is required The approximate numbers given for these many inherent stability of the resistor quantities represent good current practice. if all the is to be utilized. It may be possible to do better by extreme Vapor pressure and gas thermometry offer care. On the other hand, in most engineering methods of temperature measurement measurements a lower order of accuracy is sensitive advantage that no calibration is permissible, and this may allow relaxation of with the Further advantages are that these certain requirements such as strain-free necessary. are not sensitive to magnetic mounting of resistors, homogeneity of ther- transducers electric fields. In the case of mocouple materials, purity of vapor-pressure fields or pressure thermometers, the time re- fluid, sensitivity, and accuracy of associated vapor made comparable to the resis- instruments, etc. sponse may be For temperatures above about 20 K, the tance thermometers. recommendation about which type metallic resistance thermometers are more A sensible made without knowing the sinsitive than the nonmetallic resistance to use cannot be measurement requirements. The thermometers. Temperatures above 20 K can specific generalization most likely to hold true, be measured routinely with an industrial type following: for crude temp- platinum resistance thermometer with an accu- however, is the indications and monitoring trends, a racy of better than 100 mK and time responses erature gas thermometer will probably be suitable; somewhat better than 1 second. Accuracy at more accurate work, vapor pressure or the millidegree level requires a precision for thermometry is recommended; for capsule type platinum resistance thermometer resistance application in this latter area, and careful calibration. engineering inexpensive devices that do Carbon thermometers are generally used for the need is for for unique calibration. low temperature measurements (T < 80 K) when not call review of cryogenic temp- accuracies of ± 0.1 K or ± 1% of the absolute An outstanding recently been temperature are needed. Millidegree accuracy erature measurements has published by Sparks [13]. The above material is attainable using germanium resistance from this excellent benchmark thermometers at temperatures below 20 K. The borrows freely primary drawback to germanium thermometers is study. detectors for cryogenic fluids were that no simple analytical representation is Level developed during the space available that represents the resistance extensively is remarkable how little versus temperature characteristics, even for a program, but it

Table 2-9. Some approximate characteristics of the most widely used classes of cryogenic thermometers.

BEST BEST RESPONSE TYPE RANGE REPRODUCIDILXTY accuracy" TIME K K S

RESISTANCE THERMOMETERS Platinum 10-900 io"3-io-^ 10-2-10"* 0.1-10

Carbon 1-30 io"2-io-3 10-2-10-3 0.1-10

Gcrraanlum 1-100 io"3-io"* 10-2-10-3 0.1-10

THERMOCOUPLES -1 -2 Cold-Cobalt va Copper A-300 10 -10 10-1 0.1-1

ConstanCan V3 Copper 20-600 10-1-10-2 10-1 0.1-1

VAPOR PRESSURE Ucllum 1-5 lO'-'-io"* 10-3 0.1-100

Hydrogen 14-33 10-3 10-2 0.1-100

Nitrogen 63-126 10-2-10-3 10-2 0.1-100

Oxygen 54-155 10"2-10-3 10-2 0.1-100

a-Includlng nonreproduclbllltyt calibration errors and tcmperoture scale uncertainty

25 .

space hardware is actually used in the of the National Measurement System work. commercial sector. A deliberate effort to Primary instruments and facilities to adapt space instrumentation to commercial and calibrate the derived quantities--liquid industrial applications may be worthwhile. level, density, and flow--do not exist. Primary instruments and facilities to Accordingly, there is less confidence calibrate liquid level devices do not exist, that this part of the cryogenic measurement and accordingly it is questionable whether system is as well under control as tempera- this part of the National Measurement System ture is. is in control. Furthermore, a large body of The third part of the problem is perhaps knowledge and experience needs to be devel- a derivative of the first. Because the field oped to move with assurance from this rela- is static, a crucial question is not being tively clean measurement to the practical asked: are there predictable technological measurement question of "how much does the developments that will either create a need tank really contain?" for new cryogenic instruments or possibly Performance characteristics vary widely, provide an altogether new measurement means? depending upon the fluid being measured, its temperature, pressure, and even orientation. 2.4 Dissemination and Enforcement Accordingly, no brief summary is possible. Network The best complete review of this measurement Standards are the means used to judge may be found in the work of Roder [14]. something as authentic, good, or adequate. Density is an inferential measurement and, They are the measures to determine what a as such, it should be traceable to a national thing should be, or whether it is correct. standard, such as a national density refer- Thus, there are standards for measurements-- ence system. Primary instruments to cali- prototypes, artifacts, the physical real- brate densitometers do not exist. ization of a conceptual measurement--stan- Several physical principles of cryogenic dard constants, including property data; density measurement have been brought well standards of quality, of performance, and of forward by the space program. Notable are practice (codes). The public outputs are the capacitance, vibration, and nuclear usually pieces of paper--documentary stan- radiation attenuation schemes. Microwave dards. Behind all of these paper standards methods are recently moving to the forefront. are the physical measurement standards that Roder [14] has recently summarized this field national authorities keep in their custody as as wel 1 artifacts, or that they define in terms of Flow . There is no shortage of physical some physical phenomena. principles upon which to base a cryogenic Every form of standard, from the docu- flowmeter. Depending on the need, they range mentary standards to the physical embodiments, from simple pressure drop meters to sophis- are essential to the proper functioning of ticated mass reaction types. Flow, however, the measurement system. In the discussion is a derived quantity, and as such flowmeters below, the word standard will be used delib- require traceability to a reference system to erately ambiguously to indicate that all establish credibility. types of standards are involved in the Summary . One component of the problem of dissemination and enforcement network. cryogenic instrumentation is that it is Much of the Dissemination and Enforcement largely static. Not much has been accom- Network has been discussed in Section 2.2,1.1, plished technically since the peak of the "Standardization Institutions" and 2.2.1.2, space program. There is little evidence "Survey of Documentary Standards." Here, we of the commercialization of these instru- shall highlight this network with a specific ments . case study, the Cryogenics Division's liquid A second part of the problem arises from nitrogen flowmetering program. the way cryogenic measurements fit into the National Measurement System. As long as only 2.4.1 Central Standards Authorities a single agency or one sector of our economy National Conventions . In the case chosen (National Aeronautics and Space Administration, as the illustrative example, NBS itself was the aerospace industry) were using essentially the relevant national authority. all of the results of their own measurements, This came in part because NBS has the then that part of the National Measurement ability to provide both national standards System was internally consistent and in har- and international standards through such well mony with itself. Now, however, the prospects established NBS mechanisms as NBS Handbook are that cryogenics is becoming more commer- 44. It also came in part because our most cialized and moving tq the market place and useful and important type of standard setting thus external consistency as well as internal activities may be the de facto standards -- consistency is now required to make this part

26 t .

which exist and are accepted just because NBS during the nearly eight year life of the exists and is accepted -- such as the thermo- program. In addition, state weights and dynamic properties work mentioned in Section measures officials routinely attended 2.2.1 .2. these meetings, which provided an invalu- The State of California, during the able forum for the cooperative solution of hearings in the fall and winter of 1967-68, vexing problems. The real impact of this clearly developed and documented their need type of program may indeed lie in this for a central, national authority. The kind of cooperation and communication. record shows in part: NBS-Infrastructure . Within the NBS itself, there is a very strong and viable "With respect to standards, there should be a infrastructure that undergirds the whole national facility, a final authority, a standards setting activity. In this case, referee, that would not be in competition for instance, it included: with private industry." •The Institute for Basic Standards This expresses rather clearly the need for itself, whose statutory responsibility to a centralized national effort in such matters provide basic measurements and standards that at first do not appear to transcend made the cryogenic flowmetering program state boundaries. possible. International Conventions . The Com- pressed Gas Association was strongly •The Office of Measurement Services, motivated to deal with one national labora- which provided guidance on accuracy state- tory rather than 50 state laboratories. ments, and experience in conducting round Recognizing this problem on an inter- robins national scale, we at NBS have: •The Patent Advisor, who provided guide- • Cooperated with the International lines for handling proprietary information on Organization of Legal Metrology (OILM) to the performance of specific flow meters. facilitate the adoption of the findings of •The Office of Weights and Measures, this program as an international code; (OWM), which publishes Handbook 44 and pro- • Performed type testing of meters of vides the secretariat to the National Con- foreign manufacture as an integral part of ference on Weights and Measures (NCWM). The the program. (See for instance, NBS Tech. OWM gave our program the direction and Note 624, "An Evaluation of Several Cryo- mechanism to make its results have the effect genic Turbine Flowmeters"); of law.

•Promoted and facilitated a six week •The Applied Mathematics Division, which visit by Dr. Josef A. Eberle of the helped plan experiments for statistical Physi kal i sch-Techni sche Bundesanstal soundness and assisted in analyzing the (PTB). One result of Or. Eberle's visit results. This provided a scientific basis was his translating into German of our NBS for interpreting claims in the trade litera- Report 9778, "Cryogenic Flow Research ture of "accuracy" and "repeatability". Facility Provisional Accuracy Statement" • The Cryogenics Division itself provided to be used as a model by the PTB. Other the essential technical base and resources. international observers included Dr. It is true time and again that the sound Walter Linde and Dr. Klaus Schmidt of fixing of standards cannot occur in an ivory Lotepro, Inc., (a subsidiary of Linde, tower. It requires good judgment, and this Germany); Dr. Helmut Peter and Dr. S. K. can be applied only when there is sound Windgassen of Messer-Griesheim, Germany; comprehension not only of the science in- Dr. Heribert Wenzel of Linde (Munich, volved, but also of the ways in which it is Germany); Dr. Jacques Hermel of Compteurs being applied, and more subtly, of the ways Schlumberger, France; and Dr. J. B. Gardner in which it is likely to be applied in the of the British Oxygen Co., England. future. •One of the most important trans- 2.4.2 State and Local Offices of Weights and actions occurred in an un-official way. Measures Specifically, the Compressed Gas Associa- tion, which supported the eventual flow- The state regulatory agencies saw a real metering program, formed a steering com- need for traceability to a national standard mittee to help provide a degree of quality since they are obligated by law to perform control to the program, but especially to "type-approval" inspections. In the fall of help substantially b^ providing guidance 1967, the State of California Bureau of and advice at critical stages of planning Weights and Measures began hearings which and implementation of the program. This have already been described in Section committee met three to four times a year 2.2.1.1. With the assistance of NBS, a code 27 was adopted that was felt to represent unresolved technical controversy between equitably the capability of the meters then certain state weights and measures bodies used in commerce. It must be admitted, how- and the producers of a specific commodity. ever, that the tolerances chosen were arbi- Accordingly, federal agencies, other than trary, with little or no cryogenic testing to our own, had little or no interest or part back them up. The State of California, to play; direct contact with the consumer frustrated by their legal requirement to was not necessary. The consumer's view- regulate the sale of liquid nitrogen, but point was adequately represented by the with no technical capability to do so, essen- State bodies, and in fact, the California tially had no other choice. They set the hearings deliberately solicited the con- same standard for liquid nitrogen as was then sumer's opinion. The National Conference of in force for gasoline. The suppliers, in Standards Laboratories (NCSL) as a whole was effect, said "prove it". This impasse was of little interest to this particular resolved by the liquid nitrogen flow program. study, for a much more narrow and intense Fortunately, perhaps, the original toler- resource existed as a sub-set of the NCSL, ances proposed by the State of California namely the ISA Ad-Hoc committee already were later demonstrated by NBS to be rea- mentioned. listic and feasible, a finding which facil- 2.4.5 Industrial Trade Associations itated the early adoption of the code. The producers were especially pleased to be An unusually significant and interesting able to deal with one central laboratory interaction occurred in the following way. rather than 50 separate state labs. We The Compressed Gas Association, which sup- regard this as a good example of "New ported the eventual flowmetering program, Federalism" at work--as NBS competence is formed a steering committee to help provide a directly transferred to the states. degree of quality control to the program, but especially to help substantially by providing 2.4.3 Standards and Testing Laboratories guidance and advice at critical stages of and Services. planning and implementation of the program. Round-robin intercomparisons are at the As mentioned, this committee met three to heart of transferring the NBS measurement four times a year during the nearly eight- capability to the states, producers, and year life of the program. In addition, state meter manufacturers. For instance, espe- weights and measures officials routinely cially in the earlier stages of the physical attended these meetings at our request, and evaluation of our own flow system, round- often with our financial support. This robins were conducted with industrial provided an invaluable forum for the co- testing laboratories. These included the operative solution of vexing problems. The facilities of the Linde Co. at Tonawanda, real impact of this program may indeed lie in N.Y., Air Liquide near Paris, The British this kind of cooperation and communication-- Oxygen Co. in London, and Messer-Griesheim structured yet unofficial. at Dusseldorf, Germany. This cooperation 2.5 Direct Measurements Transactions not only gave us a feeling of confidence Matrix in our own facility, but also opened the door for international agreement (via the Understanding the National Cryogenic OILM, for instance). Measurement System is closely related to In addition, it is known that the State understanding the cryogenic community, which of California has already calibrated over is largely related to the production and use 95% of all the meters used there in liquid of cryogenic fluids. The following section nitrogen commerce. To further facilitate profiles the supply and use of cryogenic such intercomparisons, NBS has built and fluids. is currently proving a transfer standard 2.5.1 Analysis of Suppliers and Users of its own. The cryogenic fluids with the largest 2.4.4* Regulatory Agencies dollar value of sales are: oxygen, nitrogen, For this case study, consumer organiza- helium, hydrogen, argon, and liquefied nat-

tions per se , federal agencies (regulatory ural gas. Krypton, neon, and fluorine are and otherwise), and the National Confer- also considered to be cryogenic fluids, but ence of Standards Laboratories (NCSL), a the quantities produced are very small and quasi -governmental regulatory unit, did are not discussed here. not play a major role, although they The value of the six fluids considered surely would in other types of studies. here was about $166 million in 1960. By 1968 This is so because the specific program the value had tripled to about $532 million. highlighted here, concerning the metering (These are values of liquids and gases proof liquid nitrogen, was prompted by an duced by cryogenic processes and do not 28 . .

include low-purity gases or gases produced by bubbling, thus improving the bacterial electrolysis.) From 1960 to 1968 the annual degradation rate and helping the environ- growth rate averaged about 15%. However, the ment support aquatic life. The amounts of market began leveling off at $795 million in oxygen needed for this purpose in two or 1973. By examining each fluid and its market three decades could equal the amounts now in turn, we see that it is not reasonable to used in steel expect both a constant and uniform growth Nitrogen . The economic importance of rate for all fluids. The arguments for this nitrogen is about half that of oxygen. It less optimistic projection follow for each is the fastest growing of the major indus- fluid. trial gases. Nearly all high purity

Oxygen . High purity (greater than 99.5% nitrogen is produced by the air separation pure) 1 iquid oxygen is mainly produced by process. More liquid nitrogen is shipped cryogenic air separation processes (elec- (as opposed to in-plant transfers) than is trolytic oxygen amounts to much less than 1% the case with oxygen. This is apparently of high purity production). Low purity so because the producers (often located near production (less than 99.5% pure) is about oxygen consumers) are not always located 1/6 of the high purity oxygen production. close to the nitrogen consumers, such as the A major use of oxygen is in the basic food freezing industry. Nitrogen is used as oxygen process for steel, which consumes an inert atmosphere in many metal, electro- about 80 X 10^ std ft^ per year, and nic, chemical, and aerospace industries. open-hearth steelmaking where oxygen (See Section 1 .0) lances use over 50 x 10^ std ft^ annually. Looking beyond 1975, industry spokesmen These uses are the main factors in the feel that the past rate of growth will not be growth of oxygen production in recent years. maintained, but will be greater than that of The chemical industries come next, using oxygen [24]. From 1960 to 1968, the rate was some 15% of production, followed by welding, about 26%, but this is predicted to level out nonferrous metal refining, aerospace and at 15-20% in the next decade. breathing uses. It might be pointed out Nitrogen is already widely used for food that the chemical industry is growing much preservation, refrigerated transportation, faster than most segments of the United and cryo-biology. Practically all the frozen States economy and thus might be expected shrimp in the U.S. are processed in this way, to contribute even more to the growth of and nearly all the west coast lettuce shipped oxygen production than does steel. to the East comes under a cold nitrogen Shipments^ of liquid oxygen are de- blanket. There are now approximately 500 creasing as a fraction of total produc- truck stops in the U.S. where a truck can tion. This can be attributed to the fact take on diesel fuel at one end, and liquid that more liquid oxygen facilities are nitrogen at the other. The essential feature being built right at the users' doorsteps, is that each truck now carries a simple tank and also that National Aeronautics and of liquid nitrogen instead of a mechanical Space Administration consumption of liquid refrigerator. oxygen is decreasing. Hel ium . The great majority of the proven, Looking ahead, the industry itself economically recoverable helium sources in predicts annual growth rates of 5-15% for the Western Hemisphere are found in the the coming decade [24]. Using an average Texas-Oklahoma-Kansas area of the United of 10%, we should reach 10^^ std ft^ by States. These known reserves are estimated 1983. at over 150 x 10^ std ft^ New uses of oxygen could change this Most of the helium used in the United outlook materially. For example, the States has gone to government agencies such treatment of sewage and wastes by bubbling as the National Aeronautics and Space Admin- large amounts of oxygen through the tanks istration, the Department of Defense, and the offers cleaner discharge, better phosphate Atomic Energy Commission, which are required and nitrate removal, and reduces the need to buy their helium from the Bureau of Mines for agitation, which speeds the sludge in order to finance the conservation program. separation process. Approximately four Private producers entered the market with times the oxygen concentration can be deliveries almost equal to that of the Bureau achieved in this way as compared to air of Mines in 1967. The decreasing aerospace budget has resulted in smaller deliveries by Shipments is used in the special sense the Bureau of Mines, which means less helium that it occurs in the Census of Manufactur- can be bought for conservation. (Each cubic ers. It means the value of shipments, foot of lost sales reduces the reserve pur- which is the net selling value, f.o.b. chases by 2.4 cubic feet.) These factors plant, after discounts and allowances and indicate that a readjustment of helium price excluding freight charges and excise taxes. structures may occur in the near future. 29 One of the first tasks assigned by the LNG is used as a replacement for gaso- Congress to the newly created Energy Re- line in some vehicles to reduce pollution search and Development Administration is to and gain in operating economy. All the conduct a thorough study of the need for fleet vehicles of San Diego Gas and Elec- helium in energy applications (e.g., super- tric run on LNG, as well as about half the conducting electrical power systems). The buses of the Chicago Transit Authority. recommendations of this study will doubt- All the off-the-road equipment of U.S. lessly have a profound effect upon future Steel in the Mesabi range likewise use helium conservation efforts in the United LNG. States. Other uses investigated include tem-

Hydrogen . Liquid hydrogen production porary consumer supply during pipeline depends more on defense and aerospace acti- disruption or maintenance, as a petro- vity than does oxygen or helium. Since chemical feedstock, desalinization of sea the National Aeronautics and Space Adminis- water through freezing, and refrigeration tration used between 1/3 and 1/5 of the and power supply for food freezing plants. hydrogen produced, its variations had a large The concept of clustering several industries effect on the total picture. While the that need refrigeration around a re-gasifi- average rate of annual growth was greater cation facility should be considered more than 30% during the 60' s, it would appear thoroughly. Many re-gasification plants that 10% is more likely during the 70's. waste the huge cold-potential by absorbing Fields of hydrogen use, which seem likely to their heat from the air or ocean. grow, are hydrogenation of edible oils, Profile Summary . In conclusion, then, it atmospheric control in the electronic and would appear that the growth of the cryogenic electrical machinery industries, and de- fluids industry will continue, but at a rate oxidation in heat treating of metals. If somewhat smaller than during the past decade, hydrogen realizes its potential as a fuel, LNG excepted. A growth rate of around 10% there may be explosive growth here (See seems a reasonable expectation, arrived at by Section 5.0). weighting the growth rates of the individual

Argon . Some 70% of the argon produced gases according to the 1968 production fig- is used for welding reactive metals, but ures. However, if LNG fulfills its promise, the continuous casting process of steel the rate could be much higher. production could potentially use many 2.5.2 Input-Output Direct Measurements times the current production (worth around Transactions Matrix $32 million in 1968) as a blanketing agent. Argon has shown an historical General . A matrix has been constructed to growth of about 17% annually from 1960 to show the transactions between suppliers and 1968, matching the growth rate of oxygen users. The elements indicated on table 2-10 for the same period. This is logical, include, for instance: The knowledge com- since argon is produced cryogenically as a munity, standards organizations, the instru- by-product in the air separation process ment industry, NBS, regulatory agencies at for oxygen. If the continuous casting all levels, industrial associations, and the technology develops sufficiently to create general public. The entries in the inter- a huge demand for argon, it would also section boxes describe the interaction as a give impetus to the oxygen producers whole within the Cryogenics Measurement located near the steel mills. If this new System, not just those involving the Cryo- market does not develop, the growth of genics Division of NBS alone, and certainly argon will probably be held to about the not just the flowmetering program used same rate as oxygen, or 10%. elsewhere in this report as a specific ex-

Liquefied Natural Gas (LNG) . In 1968, ample. the least economically important of the Format . In the center of each box is a cryogenic fluids was LNG, worth about $24 numeral indicating the magnitude of the million. However, in 1972 it had already transaction on a semi -quantitative "volume" grown {o third place and may be first short- basis: ly after 1976. LNG is used mainly for 0 = Trivial peak shaving purposes in areas where large 1 = Minor volume gas reservoirs are unavailable, and 2 = Moderate also for base load supplies where pipeline 3 = Important gas is not feasible. It is predicted that 4 = Major LNG produced in the United States will have a value of about a billion dollars a year In the lower left hand corner , there is a by 1976 [25], or over^ 10% of the total digit describing the rate of change of trans- natural gas production of the country. actions at this intersection:

30 —

Table 2-10. Direct measurements transactions matrix 1 j j i i DIRECT & OWM's Defen- Govt. I'lCMOUnLI lull 1 o Agencies

Community Authorities Trade TRANSACTIONS U Nat'l. MATRIX FOR S of Industrial Organizations Organizations Local Local p Stds. t. Federal Q_ Laboratories Metrological R Instrumentation U.S. & & Commercial International Standards Agencies Agencies S Industry Industrial Documentary Regulatory Assoc. Knowledge Stds. oDepartment Private (U (/I Other State Other State c ca Misc.

SUPPLIERS ^ -J ^ _, _ _, " _, \ OJ 5 .D 15 1 4 1 4 1 4 1 2 1 4 1 3 1 3 2 1 3 1 2 1 3 1 2 2 2

Knowledge Community 2 2 2 3 4 1 2 3 2 3 2 1 4 3 ? 2 2 2 2 2 2

2lnternational 4 1 4 4 1 2 1 4 3 3 1 2 2 3 3 2 1 1

Metrological 2 4 2 2 4 1 1 2 2 1 1 2 2 Organizations N 2 2 N N

3Documentary 4 1 4 4 1 3 1 4 1 3 1 3 1 2 1 3 1 3 2 2 2 1 2 2 1

Standards 2 2 4 3 3 1 3 2 4 1 2 2 3 3 1 tlrganizatinns ? 7 2 2 2 2 2 2 2 2

4 2 1 2 1 3 1 2 3 1 3 1 3 1 2 3 1 2 2 2 2 1 1 Instrumentation 3 3 3 3 3 1 2 4 2 3 2 1 3 3 T n H 1 1 c "f" 1'* \y 1 ilUUb LI jr 2 2 2 2 2

5 4 1 4 3 4 1 3 1 4 1 3 2 3 1 2 2 1 3 2 1 2 1 2 1 2 1 1 2

NBS 4 4 3 3 3 1 2 2 1 4 4 2 4 3 1 2 2 2 ? 2 2_ 2 , 2 Z 2 2^ 2 2

3 1 3 1 3 1 3 1 3 2 3 2 2 2 3 2 1 1 2 1 2 ^Other U.S. Nat'l. 1 1 1 1 3 1 1 2 3 2 1 2 1 JLU^> MULrlUl ILICD 2 ?. 2 2 2 2 2 2 2 2 2 2

7 3 3 3 1 3 1 3' 1 3 4 1 2 1 3 1 1 2 1 2 1 2 1

state & Local OWM's 2 3 2 2 1 4 3 1 1 3 1 1 2 2 2 2 2 2 2 2 o 1 2 1 2 2 1 2 2 1 2 2 2 2 2 2 1 Private Stds. 3 2 4 2 1 3 2 1 1 2 2 2 2 1 Laborator i es 2

9 3 1 3 3 1 2 1 2 3 1 2 2 1 1 1 1 1 1 1 2 1 2 1 2 2

Regulatory Agencies 2 2 1 2 1 1 2 1 2 2 3 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2

10 2 1 3 3 2 3 3 2 1 1 2 1 2 1 1 1 2 1 1

Department of Defense 3 1 3 4 3 1 1 4 3 1 1 1 1 2 2 2 2 2 2 2 2

3 1 2 2 2 2 1 2 1 2 1 1 2 1 2 1 2 1 2 1 1 1 2 2 ^^Other Federal 4 2 2 4 2 2 2 3 3 2 3 1 1 Agencies 2 2 2 2 2 2 2 2 2 2

2 2 2 2 1 1 1 2 1 1 1 1 2 1 2 2 1 1 2 2 ^^State & Local Govt. %' 1 2 1 2 1 1 2 2 1 2 2 1 2 Agencies ? ? 2 2 2 2 2 2 2 2 2

13 2 1 2 1 2 2 1 2 1 12 1 2 2 1 2 2 1 2 1 2 1 2 1 2 2 Industrial Trade 4 3 3 3 4 2 3 2 3 1 3 3 2 3 1 Assoc. 2 2 2 2 2 2 2 2 2 2 2

14 2 1 2 1 2 1 2 2 1 2 2 1 1 h 1 1 1 2 1 2 2 1 Misc. Industrial &

3 1 1 1 2 1 ! 1 1 3 3 1 3 3 3 1 2 Commercial ! 2 2 2 12 ^2_ 2 15 2 1 jl 1 2 2 1 T 2 1 ^ 2 \ -tIt 1

' General Public 1 1 1 1 1 1 2 1 1

i 2 2 2 2 2

KEY TO MATRIX ENTRIES

IMPORTANCE OF TRANSACTIONS D - (IN)ADEQUACY OF SERVICES

1 = Purely convenience 0 = No improvements needed

2 s= Strongly desirable 1 = Could be improved 3 = No real alternatives 2 = Marginal 4 = Essential 3 = Serious deficiencies 4 = Out of control USERS

B - RATE OF CHANGE C D MAGNITUDE OF TRANSACTIONS SUPPLIERS A- N = Declining B 0 = Trivial

0 = Stable 1 = Minor 2 = Growing 2 = Moderate 4 = Growing explosively 3 = Important 4 = Major Unknown, X = Not studied, Blank = 0

31 :

N = Declining volume or needs sets minimum specification and performance 0 = Stable standards for ships that may use U.S. 2 = Growing ports. We help by supplying technical 4 = Explosive growth or discontinuity on information on the properties of LNG, hand potential hazards, handling procedures, and structural materials. The volume of this In the upper left hand corner , a digit indi- transaction is minor at present (1, center); cates the importance or critical ity of the is growing lower left); is strongly transaction (2, desirable (3, upper left); and could be

1 = Purely a matter of convenience; significantly improved (2, upper right). transaction not essential; It appears that the U.S. Coast Guard has reasonable alternatives readily final legal authority to set the standards available required and to define the measurement 2 = Economically important; strongly codes and practices to test whether or not desirable the standards are being met. The U.S. 3 = No satisfactory alternate source; Coast Guard may do this without neces- legally required sarily having recourse to the NBS. Accord- 4 = Essential; sole source; matters ingly, it appears that this part of the of life and death measurement system is disjointed at the present time. There is no objective reason In the upper right hand corner , another why it should remain so. digit indicates the (in)adequacy of the Item 12, State and Local Government transaction goods or services: Agencies, for this microstudy includes: The 0 = No foreseeable improvements New York City Fire Department and similar needed or desirable jurisdictions concerned with the safety of

1 = Under control, but could be LNG. improved The General Public has little direct 2 = Only marginally O.K.; significantly contact with cryogenics, since it is essen- inadequate tially an infrastructure industry. However, 3 = Seriously deficient transactions do occur in such diverse areas = 4 Out of control ; thoroughly un- as liquid oxygen for breathing therapy, satisfactory artificial insemination, cryo-embalming, and questions of safety regarding the storage and The general code for a stable field is transportation of cryogenic fluids. a zero. For ease in reading, all zeros have been suppressed in the table. There 2.5.3 Highlights re Major Users are no intentional omissions, as an "X" It has been claimed that cryogenics is would have been used to indicate a factor nearly a $2 billion industry, and that there deliberately excluded. is widespread interest in it. The discussion Double-lines are used to help subdivide below gives a few indicators leading to these the large matrix into smaller ones. For claims and highlights the major users. instance, double lines are found on either side of "NBS", and they are also used 2.5.3.1 Industrial Gases and Equipment between the Department of Defense Sector Industrial gases are at present the back- and the Regulatory agencies. bone of this industry, and will continue to Hiqhl iqhts . International Metrologiaal be while the liquefied natural gas component Organizations and NBS, in the field of builds up. At some time in the future, LNG this microstudy , have only a moderate may surpass industrial gases (Carbon Dioxide, volume of transactions between them, hence Acetylene, Nitrogen, Oxygen, Argon and Hydro- the "2" in the center of the box. These gen --SIC Code 2813), but the value of ship- transactions are growing -- "2" in the ments of industrial gases was $795 million in lower Jeft hand corner -- as the importation 1974, produced in 507 establishments employ- of LN6 increases. The interaction is ing 9,000 people [26]. A "rule-of-thumb" for essential -- "4" in the upper left corner. this industry is that it has roughly three They are under control, but could be equal components: liquids, gases, and equip- improved as the volume and variety of the ment. Therefore, if the liquids and gases transaction increases -- "1" in the upper sold were worth about $800 million, then the right corner. cryogenic equipment is worth about half of NBS and Other U.S. National Standards this again, $400 million, making the total Authorities. A useful example here is our about $1.2 billion. interaction with the'U.S. Coast Guard, The annual investment in capital equip- which is indeed a national authority that ment is at least 15% of sales [27] or about

32 )

$280 million. Thus the total expenditure in natural gas was imported as liquid from cryogenics is about $1.5 billion per year. Algeria and Canada in 1972. In addition, These figures exclude LNG, but it is not hard it states that 47.9 billion ft^ of LNG was to imagine the value of LNG bringing the exported to Japan from Alaska during 1972. total close to $2 billion. Therefore, 50 billion ft^ of natural gas in In order to be more specific, we have liquid form was involved in import-export analyzed the public Annual Reports of a few commerce in 1972. By applying a conservative of the major corporations engaged in cryo- $1 per thousand std ft\ it is possible to genics. The findings are given below, and we estimate a value of $50 million for the LNG may safely assume that the figures given are import-export trade.

realistic, as such reports are carefully LNG Produced for Internal Consumption . controlled by the Securities and Exchange We may estimate the value of LNG produced Commission (SEC). Not all of the reports are for internal consumption from the gross from the same year. One is from 1971, for liquefaction capacity of peak shaving and instance, but this discrepancy will only satellite liquefaction facilities presently serve to make the figures conservative, as operating. Although LNG is generally not newer figures would be greater due to real considered a cormodity in peak shaving growth, inflation, etc. operations, it is nonetheless possible to estimate its value from the size of the Table 2-11. Net sales of major cryogenic national liquefaction capacity by assuming companies in the U.S. the market value of LNG at $1 per thousand std ft^ equivalent. "Gas Facts" [29] Corporation Net Sales cites gross liquefaction capacity of 206 million ft^ per day which computes to be 75 Chemtron Gases Group, $ 156.4 M billion ft^ per year with a dollar value formerly National Cylinder of $75 mill ion. Gas (1972) LNG Ship Building Construction . There are Union Carbide, Linde Div. 581.0 presently 16 LNG ships under construction in Gases and related products the U.S. [30]. It is assumed that these (1973) ships were ordered in the period 1973-1974 for delivery in the five year period 1975 to Air Products and Chemicals, 209.6 1980. We estimate each ship's value Gases and Equipment Group at $90 million [31]. Assuming that these 16 ships (1971) will be delivered over the five-year period Airco, Industrial Gases and 240.0 mentioned, we thus derive an average yearly Cryogenics Group, formerly value of $288 million for LNG ship construc- the AiReduction Co. (1972) tion. Cryogenic Technology Inc. 33.0 LNG Storage and Peak Shaving Plant Con-

(1974) struction . Hale [32] states that up to 10 or Total $1,220.0 M more LNG peak shaving plants will be built each year for the next 10 years. Further These are not all the companies doing more, there are 19 applications pending business in cryogenics, but they are before the Federal Power Commission for representative of the principal ones. permission to import LNG or to liquefy and (Note that this demonstrable figure of store it for interstate use alone. These $1.22 billion compares favorably with our applications are not trivial. To illustrate, previous "rule-of-thumb" estimate of $1.20 one peak shaving facility in Iowa is esti- bi 1 1 ion. mated to cost $23 million. The import ter- We can still add approximately 15% [27] minals proposed by Western LNG is estimated for the annual capitalization rate, or to cost $1.7 billion, and the El Paso-Alaska $183 million, and thereby get $1,403 export terminal to supply part of the west billion as the annual size of the cryo- coast (including 11 ships and a pipeline) is genic gases, liquids, and equipment indus- estimated to cost billion. try. $5.6 Hale [32] cites a recent Northern Natural Gas Company 2.5.3.2 Liquefied Natural Gas (LNG) plan for a $20 million facility. With his value as a conservative average, we may The following is a brief summary from estimate investment in peak shaving faci- the published literature that tends to lities to be at a level of $200 million per establish the dollar value of the LNG in- annum. The size of the U.S. LNG industry is dustry on an annual basis. therefore approximately: Import-Export . The Minerals Yearbook [28J states that 2.2615 billion cu. ft. of

33 Component Value, $ M/yr genics plays a crucial role in the advancement of national programs. In the examples 1. Import-Export Trade $ 50 below, the measurement infrastructure sup- 2. LNG produced for Internal 75 ports the commerce in cryogenic fluids, al- Consumption though measurements per se may be peripher- 3. LNG Ship Construction 288 al to the applications listed. They are 4. Peak Shaving Plant 200 mentioned primarily because of their in- Construction herent interest. $613 M In the area of health: blood for trans- Therefore, the approximate size of the fusions can be stored at. liquid nitrogen cryogenic industry in the United States is temperature for extended periods of time, $1,403 million plus $613 million or $2,016 while storage for over 2 weeks at 4°C is the bil 1 ion. maximum allowed with conventional technology. Recently, the Food and Drug Administration 2.5.3.3 Research and Development has approved such blood as a commodity for None of the above includes research and interstate commerce. development, or any estimate of the future. Biological samples (like tissue, cancer There are a few indicators in this area: cells, tumors, cornea, and bone marrow) can About $26 million per year is spent on be stored without serious degradation for superconductivity programs in the U.S. [33]. study and inter! aboratory comparison. The This total includes: $3 to 4 million for National Cancer Institute maintains just such electrical generators; $3-1/2 to $4 million an archive. for electrical power transmission; $6 million There are several applications in agricul- for electrical propulsion systems; $6-1/2 ture, but one of the most noteworthy is that million for energy storage, magneto-hydro- more than 50% of all cattle are bred by dynamics and controlled thermonuclear re- artificial means with the bull sperm stored actors; $7-1/2 million for high energy physics and transported at liquid nitrogen tempera- experiments; and $2-1/2 million for basic ture. research on superconducting materials. Another agriculture related use of liquid The importance of helium is noted in nitrogen is in food freezing, a well estab- the Energy Research and Development Admin- lished technology--over $50 million worth of istration (ERDA) legislation, which directs liquid nitrogen is used for this purpose the Administrator to conduct a study of annually. Since the use of liquid nitrogen the potential applications of helium, and has been so advantageous, developments are to report his recommendations to the underway to extend its use further back into President and the Congress within six the food chain. For instance, sweet corn and months of enactment. These recommendations sweet peas are being harvested experimentally will concern the management of the helium with the aid of cryogenics. This process is program from the standpoint of energy R&D said to enhance their value by retaining the [34]. "field sweetness" of the produce. Soybeans, The Institute of Gas Technology reports a valuable source of protein, are being that the natural gas utilities feel the cryogenical ly harvested also. It is said need to demonstrate to their investors that the objectionable (to some) flavor of that they have prospects for participating soybeans is due to the highly perishable in a "perpetual" energy industry, not nature of the newly picked beans. Cryogenic subject to depletion. They see hydrogen harvesting is said to enhance the value of as a substitute fuel gas to move through this product several times over by helping to their pipelines [35]. retain the highly desirable fresh-picked Many feel that cryogenics may be to the flavor. second half of the twentieth century what In transportation there are already a high temperature processing was to the limited number of cars and trucks using LNG first^half. We at NBS certainly agree and hydrogen, but the auto industry does use that at least it is an important, large, cryotechniques extensively, including oxygen growing and dynamic industry. for steel making, grinding paint pigments, and deflashing parts at low temperatures. 3. IMPACT, STATUS AND TRENDS OF THE In addition, float glass is inerted with CRYOGENIC MEASUREMENT SYSTEM gaseous nitrogen. Even the reclamation of 3.1 Impact of Measurements scrap metal from old cars and tires uses cryogenic technology — cooling to low 3.1.1 Functional, Technological, and Scienti- temperature permits fracturing and component fic Appl ications separation. The impact of cryogenic measurements may be illustrated by some examples where cryo- 34 .

The aerospace industry is committed to of 130 industries surveyed by the Depart- cryogenics and about 40% of the National ment of Commerce during 1973-74. The Aeronautics and Space Administration's average growth rate was 7%. budget is cryo-related. The two principal subcodes within this In research, the National Accelerator group are 3821 and 3822. Projections [36] Laboratory (NAL) has recently purchased through 1980 are shown in table 3-1. 15,000 lbs. of NbTi ingots at a cost of A specific example of benefit-cost esti- approximately $500,000 to build a supercon- mation may prove useful at this point and ducting energy doubler. This amount of help bridge the gap between instrument and material is enough for only 1/6 of the user. Our example shall turn around the magnets around the 4 mile ring, or $3 cryogenic flowmetering program, especially million worth of raw NbTi. Other scien- the summary report [37] prepared by The tific applications of cryogenics y/ere dis- Instrument Society of America Ad Hoc Com- cussed extensively in Section 2.2.5. mittee mentioned in Section 2.2.1.1. The Navy is building 3000 HP supercon- As mentioned, NBS contributed to this ducting motors and generators for ship pro- report and excerpts are given below: pulsion and has design studies underway for a "The previous section has developed some 30,000 HP version. These motors could of the needs for cryogenic fluid flow revolutionize the use of hydrofoils and even measurement and standards. However, conventional ships. it is one thing to have needs and another In some of these examples, the NBS role to economically justify the solution of is rather diffuse and indirect, while in these needs. Since this was part of the other cases, our aid is quite explicit. charge to the Ad Hoc Committee, an attempt In all cases, cryogenic measurements are was made to come up with an economic justi- central to the infrastructure that supports fication. As in many situations such the technological and scientific applica- as this, this economic justification is tions mentioned. not easy to prove and verify by actual numbers because so many intangibles must 3.1.2 Economic Impacts--Costs and Benefits be considered as part of the economics of Some examples of the value of cryogenic such a problem. However, using statements measurements were given in Sections 2.2.2.2 and estimates from various Ad Hoc Commit- and 2.5.2. We shall highlight a few of tee members and other interested contrib- these values again below, and conclude utors, plus statements and estimates with a specific case study sponsored by gathered from technical papers, letters, The Instrument Society of America. and telephone conversations, a brief report has been prepared in an attempt •Approximately 2,000 cryogenic flow- to at least demonstrate the economic mag- meters are in use today with a value of nitude of cryogenic fluids. For the pur- over $3 million, making approximately poses of this section of the report, the 400,000 custody transfers per year. cryogens of concern at this time are Flowmeters are considerably less numerous oxygen, nitrogen, argon, hydrogen, and and less widely used than other cryogenic liquefied natural gas." instruments The report continues in this realistic •In terms of rate of growth, the fashion and estimates the value of cryogenic industry as a whole, of which cryogenic fluids. It continues: measurements are a part, ranked 59th out

Table 3-1

Instruments for measurement, analysis and control: projections 1973-80 (value of shipments in millions of dollars)

SIC Industry 1973 1974 Percent Percent code increase increase 1973-74 Low High 3821 Measuring and controlling

instruments 1,800 1 ,920 7 4.8 6.0 3822 Automatic temperature controls 740 780 5 5.2 6.5

35 " "

"A study of this table indicates that if the crease in payload for a given booster. custody transfer of these fluids were in Accordingly, the improvement in flowmeter error by only one percent (present codes calibration assumed here reflects an allow two percent), a billing error could increase in payload capability of (1.56) amount to more than 15 million dollars. (25) = 39 lbs for a given booster. This point is emphasized in the table "The value of increased flowmeter cali- below. bration certainty may be reflected in other ways. The above example indicates Year Possible an increased payload capability of nearly Billing Error/Yr 40 lbs. This also means that for a given 1966 $ 2,158,000 payload, the booster has a payload capabil- 1971 5,705,000 ity of 40 lbs more than necessary, due to 1976 15,372,000 flowmeter calibration uncertainty. By In Section 2.2.2.2, we estimated that decreasing this uncertainty to the levels the total value of flowmeters in service assumed, the booster size can be decreased in 1971 was about $3.1 million. One by 40 payload-lbs equivalent. can choose for himself whether or not "In a typical system, each pound of payload to divide the figures above by one requires some 60 lbs of additional another. If he does, a ratio of between propel lant. Decreasing the flowmeter

2 and 4 to 1 is obtained. uncertainty means that, in this case, the booster size could be reduced by (40) (60) The report continues on another tack: = 2,400 lbs of propel lant. Corresponding "Previous discussion has outlined the econo- reduction in tankage, lines, valves, mic worth of the cryogenic fluids in terms engines, launch facilities, personnel, of custody transfer. However, this is not liquefier capacity, test sites, booster the only place where an increased cryo- transportation, etc., occur. genic fluid meter calibration certainty "If the economic worth of cryogenic fluids, would be desirable. For example, in the the possible billing error to consumers, aerospace industry an increase in fluid the improved rocket performance, the meter calibration certainty would go a improved regulatory agency relations, long way to guarantee engine performance. the improved customer relations, etc., Present uncertainties in the factors are considered, it is safe to assume involved in mixture ratio trim cause that the net value of improved flow approximately a 2% uncertainty in guaran-

, measurements in custody transfer, teed engine performance. Accordingly, diagnostics, and standards is a multi- guaranteed engine performance is down- million dollar per year proposition . graded by 2% in order to insure overall mission success when engine and vehicle Please recall that all of the above is quoted are mated. Any decrease in this 2% un- from the ISA report. certainty would raise the mission capabil- 3.1.3 Social, Human, Person-on-the-Street lity by some corresponding amount. Impacts "In the case of one oxygen-hydrogen engine under development, the 3a error in flow We have already mentioned in Section measurement is 0.433 and 0.541% for fuel 2.2.5.1 that 15 Nobel prizes in physics were and oxygen, respectively. The corres- awarded for work in or related to cryogenics. ponding percent error in mixture ratio While these are hardly "man-on-the-street" (3o) is 0.727%, which is clearly a sub- impacts, it must be recognized that cryo- stantial portion of the overall 2% genics has had significant impact on basic uncertainty. research and education, which does affect us "If a facility were available that could all. reduce the flowmeter calibration A much more down-to-earth educational uncertainty to 0.2% each, the correspond- need involves the plant operators, truck ing percent error in mixture ratio (3o) drivers, police and fire departments. The ' would be reduced from 0.727 to 0.282%. following statements have been collected Hence, the uncertainty in engine perfor- to help reinforce this point. mance is reduced by 0.444%. If the spe- "There is a broad feeling among those cific impulse of the engine is around 350 responsible for the measurement of LNG seconds, the corresponding increase in that much needs to be learned as to the engine performance certainty is (350) best methods for measuring and calibrat- (0.444%) or 1.56 seconds. ing flowmeters, tank level gauges, and "In the special case under considera- densimeters. Plans for LNG measurement tion, each second of additional guaranteed techniques and standards, at this performance is equivalent to a 25 lbs in- point, are nebulous. It is probably a

36 case in which operating experience is system (See Section 4.5.1).

expected to focus attention on the need The Overview . Two overviews have been for specific programs in this area by made to document the infrastructure position the operating companies." M. H. November, of cryogenics in large national programs

Potter Aeronautical . (space, health, transportation, etc.) and to "It is a responsibility of the program of identify leading indicators of trends of the the NBS to train county personnel in health of cryogenics.

the proper procedures of inspection." Applications for Specific Customers . Once W. Watson, California Bureau of Weights the network of cryogenics in technology as a

and Measures . whole had been defined and tested, it was " — that a committee or organization useful to look at specific functional rela- (possibly such as the CGA) work closely tionships between terminals in that network, with the regulatory agencies and cryogen or the leverage of cryogenics in specific producers to educate both to the prob- applications. Such studies were made on the lems and to develop any necessary application of cryogenics in atomic energy guides for product handling and meter- programs, transportation, biology, and water

ing." G. C. Nubel , Air Reduction pollution abatement.

Company . Applications to a Specific National Need -

"The cryogen producers also need more Energy . Technology assessments have been information for fire prevention codes. prepared in three energy areas -- LNG, hydro- This information is needed by the gen, and superconductivity.

public, such as fire department and Analysis of Major Technical Threats . police department officials." W. Spencer, Since cryogenics is a rather well bounded and

American Cryogenics . self contained technology, it is not likely to be replaced by a competing technology. To cite educational needs (almost The principal threats are from among the everyone agrees to education) is one rivals within the technology itself, as from thing, but to meet these needs is another. abroad. Two foreign technology assessments These needs are not essentially simple have been made. ones easily met by bulletins, pronounce- Analysis of Major Technical Barriers . The ments, or regulations, but rather they are question of reliability and cost is always complex ranging from technical and scien- raised whenever a commercial application of tific down to operational. Some of these cryogenics is suggested. Accordingly, a complex educational needs include: (1) survey of the state-of-the-art of commercial study of safety practices; (2) education refrigerators was first published in 1969 and of police and fire officials; (3) educa- updated in 1973. tion of driver-operator in proper proce- Analysis of Major Technical New dures -- the why and how of these proce- Opportunities . Assessments of cryoelectro- dures, and so forth. Measurements are nics, superconducting engineering and the needed to help develop educational programs, commercialization of cryogenics have also specify codes, etc., which have the direct been prepared. human/man-on-the-street impact. The synthesis of these studies is that the The point of the cryogenic measurement major developments in cryogenics in the next system is to foster and help develop a new few years that will have significant impact technology, the infrastructure technology on the technology of the country and its of cryogenics itself. It is generally balance of trade are the widespread inter- accepted that such technological innovation national use of liquefied natural gas can help us expand our markets at home and potential uses of hydrogen, and applications abroad, strengthen old industries, create of superconductors. These developments new ones, and generally provide more jobs are a result of the national sense of in the labor market. urgency regarding energy problems and the The direction of private technological established trends toward the uses of: (1) activities is determined in large measure by liquefied natural gas to meet local peak thousands of private decisions -- and this energy requirements (peak shaving) and to should always be the case -- but we cannot accommodate the transportation of natural ignore the fact that federal policy, such as gas in the dense cryogenic form; (2) undergirding a new technology, also has a liquid hydrogen as a potential synthetic profound effect upon what happens in the fuel of the near future; and super- private sector. (3) conductivity in applications for electric 3.2 Status and Trends of the System power generation, transmission, and storage. The cryogenic measurement system must Several special studies have been prepared respond with design data, metrology, and to characterize the cryogenic measurement related applied cryogenic research.

37 Along with this "commercialization" of developed. Flowmetering for commodity cryogenics comes a new role that gives transfer and equity in trade has been de- even greater leverage to the measurements veloped for more conventional cryogens and data, and which is one way to assure (Handbook 44). An equivalent program for the effective transfer of measurements LNG will be unique in conception because into the hands of the users. This new it will require the integration of mass role is a partnership between cryogenics and heating value measurements. Nonethe- and the regulatory agencies. For in- less, traceability to national standards stance, results of the NBS flowmetering (NBS) is already written into existing inter- program (e.g., tolerances and basic prop- national agreements (El Paso Gas-Algeria erty data) have been adopted into NBS and Algonquin Gas-Algeria) with little or Handbook 44 as a result of cooperative no technical basis in fact. work with the states of California and New Basic measurements of the thermal and Jersey. The Maritime Administration and mechanical properties of structural mate- the U.S. Coast Guard are interested in rials are the key to realizing the potential new, inexpensive, but safe materials for of LNG as a major source of fuel . For seagoing tankers. The Federal Power instance, the fatigue crack growth rate and Commission (FPC) needs cryogenic mea- fracture toughness of many potential con- surements and data on the cryogenic safety struction materials have not yet been mea- and design aspects of current applications sured for cryogenic applications. Such before the FPC for authorization of LNG data are essential to ship construction as terminal and storage facilities. Under- well as to stationary storage of LNG. lying and supporting each of the specific Hydrogen . Hydrogen is a prime candidate technologies of LNG, hydrogen, and super- to satisfy many long-term national (and conductivity is the necessity of: (1) international) fuel requirements. It seems establishing and providing an information no longer necessary to justify the relevance base for cryogenic measurements and prop- of hydrogen fuel research since hydrogen is erties of materials at low temperatures; a clear contender for the synthetic fuel and (2) characterizing the behavior of market of the future -- only the time scale materials at low temperatures by definitive for implementation of this fuel is uncer- studies involving mechanical, thermal, and tain. Its use in the period 1985-2000 electrical property measurements. Some of appears guaranteed. Thus basic measurements the strengths and weaknesses of the current and data are required now. cryogenic measurement system are described Priority research elements that have been below. identified are: (1) improve hydrogen lique-

Liquefied Natural Gas (LNG) . Over 30 faction efficiency, (2) evaluate methods of percent of the basic energy supply in the recovering liquefaction energy, and (3) U.S. is provided by natural gas. The evaluate hydrogen compatible materials of demand for this relatively inexpensive, construction. Longer term priorities include ecologically satisfactory fuel has sub- the development of improved insulation sys- stantially exceeded the domestic supply. tems and the establishment of instrumentation Even with responsible conservation and and measurement methodology for commercial development of alternative sources, large exchange of liquid hydrogen. quantities must be secured not only through Superconductivity . Cryogenic measurements foreign importation, but also from Alaska, and data are intimately bound together with by 1985. Domestically, major facilities the electrical energy industry through the have been established in large population application of superconductivity to power centers to permit peak shaving and redistri- transmission, generation, and storage. bution. These large scale applications re- All three applications have at least three quire handling the natural gas in liquid problems in common. First, conductors form. New measurements and data are re- tailored to each of the above areas are quired, to permit the U.S. to participate still under development, and their perform- successfully in domestic and imported lique- ance depends in part upon the rate of heat fied natural gas programs in order to transfer to the helium heat sink under develop; (1) advanced concepts, (2) environ- transient conditions. Second, the behavior mental impact statements, (3) regulations, of the entire helium refrigerant flow (4) economics, (5) safety, and (6) reliabi- system, including responsiveness to instabil- lity. Accordingly, a complete and com- ities must be known (pressure, tempera- prehensive physical measurement system for ture, and flow rate vs. time). Third, LNG needs to be developed. degradation, or aging, of the superconduc- Today, quantity gaging in storage and tor may result from the various different ship tanks is uncertain and requires accu- stresses -- thermal, electrical, or mechani- racy statements and traceability yet to be cal -- with long term reduction of system 38 :

capacity. The problem areas -- refrigeration - Assisted in 1970 in the investigation and superconductor behavior -- are common of the cause of the Apollo 13 cryogenic to each and every superconducting applica- tankage failure and helped to establish the tion and at present represent a weakness basis of safe redesign. in the cryogenic measurement system. Thus it is apparent that NBS has provided Helium is, of course, the indispensable cryogenic measurements, data, and services refrigerant for all known superconducti- for nearly 70 years. The present holds vity technology. The importance of helium every bit as much promise as cryogenics was recognized in the bill creating the matures and finds more and more use. Energy Research and Development Adminis- 4.2 The Present Scope of NBS Services tration (ERDA), which directs the Adminis- trator to conduct a study of the potential The present scope of NBS services to the energy applications of helium and to cryogenic measurement system is indeed sig- report his recommendations to the President nificant. We have already indicated that and the Congress within six months after cryogenic measurement and data services are the enactment of this Act. These recommen- offered in nearly every field that NBS as a dations will concern the management of the whole does: conceptual knowledge, instrumen- helium program from the standpoint of tation, reference materials, standard samples, national energy research and development, reference data, and specifications (See and will undoubtedly have a profound Section 1.). Accordingly, it may be more effect upon the future of the cryogenic edifying at this time to illustrate these measurement system. services with our case study, the liquid nitrogen flowmetering program. We shall 4. SURVEY OF NBS SERVICES attempt to illustrate not only the NBS services, but also their uses and interactions 4.1 The Past through an Input-Output analysis. This Ever since the Federal Government estab- matrix is essentially a four terminal network lished the Bureau, NBS has been involved in to describe the flow of information between cryogenic measurement science and has fre- NBS and various users. quently been sought out to settle technical Block I is "from NBS to NBS", or Internal controversies or to solve problems whose Input. sophistication lay beyond the capabilities Block II is "from the outside to NBS" or of other agencies. External Input. In fact, the NBS program in cryogenics Block III is "from NBS to the Outside" or itself dates back to 1904 when Congress External Output. approved the purchase of a hydrogen lique- And Block IV, since it describes inter- fier exhibited by the British at the St. actions "from the Outside to the Outside" Louis world's fair. A somewhat larger and does not involve NBS per se, appears facility was established in Boulder in 1952 to hold little interest for us at the at the request of the AEC, and ever since moment. then, the Cryogenics Division of NBS has 4.2.1 Description of NBS Services participated significantly at the critical stages of planning and execution of every A description of NBS services should not major national program using cryogenics. A only include those services that NBS supplies brief historical background follows: to the outside, but to internal users as - Established the National Cryogenic well. Accordingly, we shall subdivide this Engineering Conferences, now in their 20th section into two parts: Internal Inputs-- year. NBS to NBS; and External Outputs--NBS to - Assisted in the development of the the outside. first large liquid hydrogen bubble chamber, Internal Inputs: NBS to NBS . This block which won for Dr. Luis Alvarez the Nobel i ncludes, for instance (Figure 1 ) Prize in Physics in 1968 and also a commen- •The Institute for Basic Standards-- dation 'for the NBS team. whose statutory responsibility to - Developed the OP catalyst essential to provide basic measurements and standards the long term storage of hydrogen. made the program possible. - Produced the first text book in cryo- •The Office of Measurement Services - genic engineering; co-edited the first provided guidance on accuracy state- journal of cryogenics and taught the first ments, and experiences in conducting college accredited course in cryogenic round robins. engineering. •Patent Advisor--guidel ines for hand- - Received the DoC Gold Medal for Mea- ling proprietary information on the surement and Publication of Definitive performance of specific flow meters. Properties of Hydrogen.

39 . ) .

•The Office of Weights and Measures-- •Codes, Standards, and Recommended Prac- publishes Handbook 44 and provides the tices, such as adopted in Handbook 44. secretariat to the National Conference •Properties Data. The NBS property data on Weights and Measures (NCSM). Gave for liquid nitrogen were also adopted in our program the direction and mechanism Handbook 44. See Sections 2.2.1.2 and 2.2.3. to make its results have the effect of •International Conventions. As mentioned law. earlier, the Compressed Gas Association was •Applied Math Division--planning experi- strongly motivated to deal with one national ments for statistical soundness and laboratory rather than fifty state labora- analyzing the results. tories. We extended this philosophy on an •Cryogenics Di vision--provided the international scale via the lOLM. See essential technical base and resources. Section 2.4.1 For more detail on these Internal Inputs, •Performed type testing of meters of see Section 2.4.1, especially NBS Infra- foreign manufacture as an integral part of

structure . the program. (See Tech. Note 624, "An Evaluation of Several Cryogenic Turbine External Outputs: NBS to the Outside . Flowmeters" The analogy has been drawn that basic mea- . •Promoted and facilitated many visits by surements and standards are the "currency" international observers. The result of one or medium of exchanges in business. The such visit was the direct translating into analogy may be broadened by recognizing that German of NBS Report 9778, "Cryogenic Flow a currency has no intrinsic value of its Research Facility Provisional Accuracy own, but is only as good as the user's Statement" to be used as a model by the PTB. confidence. The same is true for basic For more discussion, see Section 2.4.1. measurements and standards. Standards as the "currency" of science can be a revealing analogy, for standards are the 4.2.2 Users of NBS Services key to the commercialization of science. The principal users of NBS services, in Each scientist works within a self contained the representative sample chosen for illus- system using "his" thermometer, "his" balance, tration, can readily be identified by the and "his" meter, which could be the distance inputs they had to the program. This may at between two marks on a barn door, as far as first seem to be a backward approach, but it he is concerned. As long as his measurement is surely the most direct way to identify system is internally consistent, he has no those who needed the services the most - namely need to refer to or compare against an ex- those who helped influence and "design" ternal set of standards. Only when he steps those services. We call these External out of his system to put his work into general Inputs use, to gain general acceptance, to put his work into circulation, as it were, does he External Inputs: Outside to NBS . The need to refer to a set of external standards. principal external inputs (Figure 3) came from Basic standards then are not the analog of regulatory agencies, and trade associations. currency, but are the currency of fact, since Their role was fundamental in both initi- they are indeed the medium of exchange that ating and guiding the program and was de- causes the scientific work to become commonly scribed in detail in Section 2.2.1.1. These accepted, used, and repeated. Thus, basic included the Instrument Society of America standards are the transfer agent from which (ISA) Ad Hoc Committee on Cryogenic Flow the benefits of science are derived. Metering, The Compressed Gas Association, It is a paradox that "basic" has come to and the State of California. There are mean in the minds of some "undirected" or three factors in common between NBS and "exploratory", for indeed the sole need for these groups that bear further comment. standards is to communicate with others. In 1. The regulatory agencies need a sound this sense, standards provide the dictionary technical basis for their codes so that they of tedinology and commerce. are feasible as well as enforceable. The Standards are the means used to judge NBS, having no regulatory authority (and something as authentic, good, or adequate. desiring none), needs the leverage of regu- They are the measures to determine what a latory agencies for its basic measurements thing should be, or whether it is correct. and standards to be adopted rapidly and Thus, there are standards for measurements uniformly. (property data) for performance (tolerance) 2. Because the NBS has no regulatory and for products (type testing). In this functions, our basic measurements and stan- program, these standards were embodied as dards must stand on their own merit. They "External Outputs" (Figure 2). must be the best in the country to be accepted, for they are not promulgated by law.

40 INFORMATION INPUT - OUTPUT MATRIX NBS To OUTSIDE INTERNAL INPUT

• IBS • OMS • Patent Adviser • OWM • Applied Math Division • Cryogenics Division

OUTSIDE

FIGURE 1. Internal input.

NBS To OUTSIDE INTERNAL INPUT EXTERNAL OUTPUTS • Codes • IBS • Standards • OMS • Recommended Practices • Patent Adviser • Properties NBS • OWM • Measurement Techniques • Applied Math Division • Correlations • Cryogenics Division • Literature Services • MAP • International Conventions

OUTSIDE

FIGURE 2. External outputs.

41 :

(The analogy has already been drawn that Note that these examples are essentially basic measurements and standards are the non-technical policy level determinations, "currency" or medium of exchanges in busi- and accordingly appear not to be the concern ness). of NBS. But note these common traits. 3. Because of our unbiased outlook, the 1. Vantage points of enormous leverage parties involved, each with his own self where the most fundamental decisions are interest or view points, feels free to come made. to us as the impartial third party. The ISA 2. Opportunities of largest possible specifically recommended recourse to a na- economic impact (it is more economical for tional laboratory. The State of California everyone concerned to get a code that is also expressed the need for traceability to feasible in the first place, rather than a national standard, since they are obligated testing and re-writing the code after the by law to perform type approvals. The CGA fact.) was strongly motivated to come to a central 3. Taken as a whole, they represent the laboratory, for the alternative was to deal "Industrial Measurement System", a sub-set with fifty state laboratories. of the National Measurement System. (Figure Our responsibility lies not only in 5). providing the competence in advance of need, This is the arena where decisions are the but also making that aompetenae known to most fundamental, and where the opportunities our customer's^ and making it easy for him to and problems originate. Accordingly, it is do business with us. not only in our sphere of responsibility, but also in our own interest, to consciously and 4.2.3 Alternative Sources systematically monitor and influence the We offer to the Cryogenic Measurement course of technology in the political (people), System essentially every service that NBS as technical, economic, ecological, and social a whole offers to the entire measurement environments. If we are to serve the cryo- system. Therefore, the list of every actual genic measurement system adequately, then we or potential alternate source is, for all must continuously identify, analyze, evaluate practical purposes, endless. We have at- and participate in the transactions occurring tempted to tether such a discussion by in this essential, but sometimes overlooked tying it to a specific scenario: namely, part of the measurement system. what would happen if NBS were to stop its 4.2.4 Funding Sources for NBS Services cryogenic measurement services tomorrow? This scenario is developed in Section 4.3 In Section 3.1 we identified the impact "Impact of NBS Services", especially Section of our measurement services, and noted that 4.3.1. in some of the examples given (health, Here, we shall limit our discussion to agriculture) the NBS impact had been rather means of identifying user needs possibly not diffuse and indirect. In other cases (space being met, and the NBS role vis-a-vis such exploration, LNG), the NBS cryogenic measure- needs. One way to do this is to identify ment services were explicit and direct. So the Outside-Outside interactions. By def- it is with the funding sources for our inition, these interactions do not involve services. Some services result in wide NBS, but perhaps they should. public benefit, meriting wide public support

Outside-Outside Interactions . The input- (e.g., appropriated funds). On the other output functions of Block IV at first do not hand, where specific beneficiaries can be appear to interest us, for they do not identified, then these beneficiaries have

involve NBS per se . They include, for in- paid, because "full recovery of costs" is stance (Figure 4) the rule. A few specific examples may prove Regulatory Agencies - California and New helpful and are given below.

Jersey state weights and measures officials Cryogenic Flowmetering . We have used collaborating on a model code in order to this specific case study throughout our facilitate trade among their states, as well microstudy to help illuminate general princi- as intra-state commerce. ples. As discussed in Section 2.2.1.1, the Meter Manufacturers--an instrument maker Compressed Gas Association was a specific planning his flow meter design and distri- beneficiary, and the member companies most bution to conform not only with U.S. conven- interested in the problem (see Table 2-2) tion, but also with that of the PTB, for contributed funds and helped provide program instance. definition that allowed the program to Fluid Producers--especial ly those in proceed to its ultimate technical conclusion. interstate or international commerce. Reference Data . Accurate density mea- Professional Societies--such as non- surements and analytical calculation methods technical policy board meetings of the ISA. for liquefied natural gas are essential to

42 INFORMATION INPUT OUTPUT MATRIX NBS To OUTSIDE INTERNAL INPUT EXTERNAL OUTPUTS • Codes • IBS • Standards • QMS • Recommended Practices • Patent Adviser • Properties NBS • OWM • Measurement Techniques • Applied Math Division • Correlations • Cryogenics Division • Literature Services • MAP • International Conventions From EXTERNAL INPUT • National Conference on Weights & Measures • Federal Agencies OUTSIDE • Trade Associations (C6A, AGA) • Regulatory Agencies (State, National, International)

FIGURE 3. External inputs.

NBS To OUTSIDE INTERNAL INPUT EXTERNAL OUTPUTS • Codes • IBS • Standards • QMS • Recommended Practices • Patent Adviser • Properties NBS • OWM • Measurement Techniques • Applied Math Division • Correlations • Cryogenics Division • Literature Services • MAP • International Conventions From EXTERNAL INPUT • National Conference on Weights & Measures • Regulatory Agencies • Federal Agencies • Meter Manufacturers OUTSIDE • Trade Associations • Fluid Producers (CGA, AGA) • Consumer • Regulatory Agencies • Professional Societies (ASTM) (State, National, International)

FIGURE 4. Outside - outside interactions.

43 INFORMATION INPUT OUTPUT MATRIX NBS To OUTSIDE INTERNAL INPUT EXTERNAL OUTPUTS • Codes • IBS • Standards • QMS • Recommended Practices • Patent Adviser • Properties NBS • OWM • Measurement Techniques • Applied Math Division • Correlations • Cryogenics Division • Literature Services • MAP • International Conventions From EXTERNAL INPUT INDUSTRIAL • National Conference on Weights MEASUREMENT SYSTEM & Measures • Regulatory Agencies • Federal Agencies • Meter Manufacturers

• 1 race OUTSIDE Associaiions • Fluid Producers (CGA, AGA) • Consumer • Regulatory Agencies • Professional Societies (ASTM) (State, National, International)

FIGURE 5. Industrial measurement system.

provide an unequivocal basis for custody topics: (1) cost and availability of hydro- transfer. These same data provide the basis gen, (2) hydrogen in the electrical utility for mass, density and heating value measure- industry, (3) applications of hydrogen in ments throughout the fuel gas industry. A transportation, (4) survey of materials for technical program to meet these needs is hydrogen service, (5) instrumentation for presently underway, funded and guided by a cryogenic hydrogen fuel, (6) transmission consortium of 18 energy companies (See and distribution of energy, (7) solar energy Section 2.2.3 for technical description). liquid hydrogen, (8) industrial applications

Hydrogen-Future Fuel . In the fall of of hydrogen, and (9) hydrogen fuel literature 1972 the NBS Cryogenics Division NAS-NAE-NRC These analyses demonstrated, among other evaluation panel recommended renewal of a things, that even now hydrogen appears modest effort on hydrogen fuel technology. attractive as an aircraft and aerospace The scientific staff responded enthusiasti- fuel, in certain integrated utility systems cally and a state-of-the-art evaluation was (e.g., use of hydrogen to store solar released in the summer of 1973. An economic energy), for transport of energy from nuclear analysis of hydrogen-fueled electrical or solar sea power plants and is already an utility systems was published in March 1974, essential ingredient in a wide variety of and a benchmark literature bibliography was industrial processes (ammonia synthesis, completed in June 1974. The work described hydrocracking, hydrotreating, and methanol below was initiated in July 1973, and efforts synthesis). This example was chosen to were accelerated by support of management illustrate how internal re-direction of at all levels of the NBS , e.g.. Institute of funds by an alert management can quickly Basic Standards Director's Reserve funds produce results not otherwise possible. were made available to initiate this study. Liquefied Natural Gas . This present The goal of this work is to provide study of the cryogenic measurement system innovative cryogenic technology so that (now in its second year) has helped document hydrogen may be liquefied, stored, and dis- for us the complete process that must be tributed efficiently on an unprecedented undertaken to provide a complete measurement scale and with safety and fairness to the service. Specifically, our LNG Budget consumer. Specifically, analyses and sum- Initiative submitted in the Spring of 1974 mary reports were prepared on the following was deliberately constructed to include all

44 three necessary elements: measurement cations, special bibliographies. Standard science, data base, and technology transfer Reference Data, and several Current Awareness (includes safety, interstate and inter- services were described there. national cooperation, effective use of Reference Materials were described in Office of Weights and Measures and training). section 2.2.4. These included the Standard Thanks (in part) to the National Measurement Reference Materials incorporated in the NBS System study, new work proposals now use the program of that name. Also mentioned was the guidelines so developed to assure a complete importance of corollary reference data and and comprehensive approach. round robins utilizing "uncertified" refer- Even though this particular initiative ence materials. did not survive the government budget process, National trade associations, other federal we are nonetheless pursuing other avenues of agencies, and international mechanisms were funding, perhaps even multiple sources, but described in Section 2.4, "Dissemination and with the objective of nothing less than a Enforcement Network". comprehensive program. This example was These descriptions, while as complete and chosen to illustrate the course of a new comprehensive as possible, nonetheless appear budget initiative pf potentially large public rather sterile compared to actuality. Sup- benefit, which could reasonably be assumed plying services is never "pure". Usually a to merit public support (appropriated funds). mix of services, e.g., reference data along Thus the answer to "Sources of Funds for with reference materials, must be supplied to NBS Services" is: "It depends". Table 4-1 a mix of users, e.g., several laboratories in gives a more explicit answer. a round robin interchange. The cryogenic flowmetering program serves well again as an Table 4-1 example of the mechanisms required in prac- Funding by sources tice. Fiscal Year 1974 Figure 6 illustrates the truly staggering NBS Percent number of mechanisms for supplying services Direct appropriation 31 that came into play. Note for instance: Postdoctoral s 01 Regulatory Agencies--State Standard Reference Data 03 Regulatory Agencies--Foreign Standard Reference Materials 01 Professional Societies NBS TOTAL 36% Industrial Meter Manufacturers--Domestic OTHER AGENCY R&D Industrial Meter Manufacturers--Foreign National Aeronautics and Industrial Producers--Domestic Space Administration 11 Industrial Producers--Foreign. Atomic Energy Commission 05 Specific detail is given in Figure 6. Department of Defense 23 Maratime Administration 05 4.3 Impact of NBS Services Navy 01 We shall attempt to examine the impact of Federal Power Commission 02 NBS services by following a specific scenario National Science Foundation 01 namely, what would happen if NBS were to stop OTHER AGENCY TOTAL 48% its cryogenic measurement services tomorrow? IN DUSTRIAL ASSOCIATIONS For this approach, we are indebted to Pro- American Gas Association 11 fessor Charles Howe, who is Chairman of the International Copper Economics Department at the University of Research Association 01 Colorado. Professor Howe is a consultant to Other 01 the State Legislature of Colorado and his INDUSTRIAL ASSOC. TOTAL 13% specialty is establishing criteria for public supported programs. He has served as a TESTING, CALIBRATION, SERVICES 03 consultant in this capacity to Ghana, Kenya, GRAND TOTAL 100% Botswana, and lately to the Cryogenics Divi- sion of NBS. 4.2.5 Mechanism of Supplying Services We shall try to follow this scenario down Dissemination mechanisms are as varied as two roads, one leading to the potential the services themselves. economic impact; the other to the techno- Calibrations, and Maps were described in logical impact. Sections 2.2.1.1 and 4.2.1 in conjunction 4.3.1 Economic Impact of Major User Classes with the cryogenic flowmetering program.

Reference Data , whether distributed in an One possible scenario is that cryogenics unstructured way by individuals, or in a would simply disappear. We believe, however, systematic way by the Cryogenic Data Center, that cryogenics is here to stay; we have were discussed in Section 2.2.3. Publi- shown that it is an infrastructure technology 45 H

NBS Institute for Basic Standards Patent Advisor Office of Measurement Services Applied Mathematics Federal Agencies Mechanics National Aeronautics and Space Administra Quantum Electronics United States Air Force Electromagnetics T" Atomic Energy Commission Cryogenics Instrument Shops Plant Division Office of Weights and Measures Electronics Technology Industrial Trade Association Compressed Gas Association U. American Gas Association (AGA) Regulatory Agencies - State and Federal Pipeline Research Committee Office of Weights and Measures — Federal Power Commission

Cryogenic Flow Research Facility

NBS Industrial - Meter Manuf. - Domestic Institute for Basic Standards Brooks Inst. Div. Emerson Electric Co. Patent Advisor Daniel Industries Management and Organization —J Eastech Inc. Cryogenics ITT Barton Office of Weights and Measures Foxboro Company Conference on Weights and Measures Liquid Controls Corp. Electronics Technology National Cylinder Gas, Division of Chemetron Corp. Union Carbide Corp. - Linde Division Rockwell Meter Co.

Industrial - Meter Manuf. - Foreign

• British Oxygen Company - London, England Regulatory Agencies - State I - 1 1 Compagnie des Compteurs Paris, France Cal ifornia Linde, A.G. West Germany Colorado Nebraska 1 Wyoming Industrial - Producers - Foreign Conference on Weights and Measures (50 States) British Oxygen Co., London L'Air Liquide, Paris Linde, A.G., West Germany Regulatory Agencies - Foreign Messer-Griesheim, West Germany Physi kal isch-Techni sche Bundesanstal t. West Germany —I Ministere de la Consommation et des Industrial - Producers - Domestic Corporations, Canada Air Products and Chemicals, Inc. Air Reduction Company American Cryogenics, Inc. Professional Societies Burdette Oxygen Company American Inst, of Physics ._L_ National Cylinder Gas, Division of American Society of Mechanical Engineers Chemetron Corp. Instrument Society of America Liquid Air, Inc. Liquid Carbonic Messer-Griesheim Union Carbide Corp. - Linde Division

FIGURE 6. Liquid nitrogen flow program interactions.

46 .

that is used wherever it is more economical, ready acceptance, no preferred alternative, or wherever it permits some higher level of and no centralized national effort. While performance. Accordingly, every user of this is true, it is neither very helpful nor cryogenics would create his own in-house very satisfying. We would like to be more competence a piece at a time. It follows specific and I believe we can be, by looking that: at some specific technological examples Such redundant facilities and data illustrating the points made above. gathering would likely cause expensive and Redundant data/facilities cause expensive slow response to national needs, while at the and slow response to national needs . The same time wasting national resources . cryogenics measurement system is supplied It seems inevitable that such duplicate reference data by many experimental systems. efforts would produce inconsistent design One of these is our Pressure-Volume-Tempera- data which would prevent both process opti - ture system for the thermodynamic properties mization and safety evaluation . The corrolary of fluids, which was built up over many years questions are: "Who is right?"; "Where is by the National Aeronautics and Space Admin- the arbiter to judge, and how does he decide?". istration and NBS at a cost of approximately It is argued by some that while propri- $1.6 million. If it did not exist, something etary data of a basic nature may give its like it would have to be built up many times owner' a slight edge for a short time, keeping over by every user who needs the data; and data proprietary may sometimes impede national operated by scientists relatively "low" on technological advancement and hence our abi- the learning curve. As it is, it is avail- lity to compete successfully in international able for any priority work regardless of its trade . origin. It is, in fact, being employed now In the absence of a centralized effort to produce industry wide data on LNG for the such as NBS provides, arbitrary or even AGA. conflicting standards could be adopted, leading to questionable practices in custody Inconsistent design data prevents optimization transfer and in safety evaluation . If a and evaluation . Many times NBS has been free enterprise economic system is to survive called upon by the government to evaluate in a modern industrial society, buyers and efficiency claims and production capacities sellers in the marketplace need to have as projected by "paper studies". A complete and much confidence in the quantity and performance consistent set of design data is essential to of goods exchanged as they do in the amount this purpose. The National Aeronautics and of moneys paid. Space Administration, for instance, specifies The government would find itself in the that NBS data be used in its proposals to co nflicting role of trying to regulate the provide a common, sound basis for evaluation. very technology it is trying to promote . Similarly, NBS recommendations to the FPC A vague technical base inhibits both would be open to question if it were not for compliance and regulation , no matter how our sound foundation of valid, consistent well-meaning or good intentioned either data. party may be. Arbitrary/confl icting standards : question- If there were no centralized effort, able custody transfer and safety evaluation . both government and commerce would find The State of California, frustrated by their themselves with a generally unsatisfactory legal requirement to regulate the sale of basis for decision making and impartial liquid nitrogen, but with no technical backup, judgments were forced to set arbitrary standards. The key to impact of NBS services appears Specifically, they set the same standard for to lie in their centralized, coordinated liquid nitrogen as was then in force for nature. Our legislative mandate does indeed gasoline. The suppliers demanded a technical call for us to provide a base for a national demonstration of the feasibility of these system of measurement, and to furnish essen- standards. This impasse was resolved by the tial services. The congress has also wisely NBS liquid nitrogen flow program. The pro- chosen language that calls for us to coordi- ducers benefited dealing with one central nate that system as well. Perhaps it can laboratory rather than 50 separate state best be summed up that "no coordinated laboratories. The states benefited by not effort" would lead rather shortly to dis- having to construct 50 times over such a cordant and hence wasteful national programs. complex cryogenic test facility. The public 4.3.2 Technological Impact of Services benefited by the rapid proof and adoption of the codes. As mentioned, we feel that this Let us continue our scenario of: is a practical realization of the "New "What if NBS were not involved? What Federalism" at work - as NBS competence was would happen if we stopped cryogenic directly transferred to the states. technology tomorrow?" There would be no

47 - Conflicting government role : regulate/pro the national commitment and sense of urgency

mote technology . The federal government has to achieve a greater degree of national occassionally found itself in the awkward energy self-sufficiency in the near time position of attempting to regulate and pro- frame. mote a technology at the same time. The These trends represent our best informed effective and safe use of atomic energy is judgment of our prime teehniadl opportunities perhaps such an example. Recently, the for service over the next five years. In Atomic Energy Commission as such was abolish- addition, largely as a result of this present ed the regulatory functions assigned to a study of the National Measurement System new commission, and the technology advance- operational opportunities are emerging. ment functions assigned to a separate energy The historical role of cryogenics at NBS has development agency. been one of technical problem solving to The National Bureau of Standards, having complement the monolithic mission of other no regulatory function, is free of this type government agencies (e.g.. Atomic Energy of mission conflict. Commission, National Aeronautics and Space Administration), and we continue to look Vague technical basis inhibits both compli - forward to this exciting and mutually bene- ance and regulation . A liquefied natural gas ficial partnership. We now see another role explosion in 1944 was not only the worst emerging that gives even greater leverage disaster in Cleveland's history, but it also to our measurements and data, and which in- helped to set back the use of LNG for 20 or deed assures the effective transfer of mea- 30 years. surements into the hands of the users. This One hundred and thirty-one persons were emerging role is a partnership with the re- killed when one of the LNG tanks failed from rulatory agencies. For instance, the results low temperature embrittlement/fatigue. of the flowmetering program (e.g., toler- Neither the plant builders and operators nor ances and basic property data) have been the public safety agencies had an adequate adopted into NBS Handbook 44 as a result of technical basis (the properties of 3-1/2% our cooperation with the states of Califor- nickel steel, in this case), although both nia and New Jersey. A metals combustion were conscientious in their respective program resulted from an initial tasks. Department of Transportation request following an Unsatisfactory basis for decision making/ - oxygen tank truck disaster in Brooklyn.

impartial judgment . Because of the enduring Much of the present LNG program came from energy shortage and the great potential of interests by The Maritime Administration hydrogen as a future fuel, a large number of and the U.S. Coast Guard in new, inexpen- laboratories, both public and private, have sive, but safe materials for seagoing moved speedily to verify the feasibility of tankers. Consultation and advisory services hydrogen as a fuel, e.g., numerous graduate are provided to the Federal Power Commission students have converted automobile internal on the cryogenic safety and other technical combustion engines to run on hydrogen gas. design aspects of several current applica- While this has been interesting and has tions before the Federal Power Commission attracted a great deal of attention, we have for authorization of LNG terminal and storage preferred to produce a benchmark study that facilities. will be used as th_e technological base for Table 4-2 shows how the beneficiaries of all further programs of any agency or uni- our outputs are expected to change as a versity on hydrogen: future fuel. This consequence of the trends mentioned above. report will do much to remove most of the Some of the reasons behind the expected speculation from this area and to provide a changes shown in Table 4-2 are: sound and common basis for decision making. •Services to specific manufacturing firms will increase, reflecting the fact that 4.3.3 Pay-off from Changes in NBS Services cryogenics in general and superconductivity Services provided to the National Measure- in particular are coming of age. More ment System for cryogenics will always be practical devices and instruments, such as embodied in measurements, data, and technology; SQUID'S, will be manufactured. but the thrust of the effort may change with •Interaction with the service industries time. will also increase as we interact more with As mentioned, major developments in the the public energy utilities (hydrogen fuel, field of cryogenics are occurring at three LNG, applied superconductivity). distinct regions of the cryogenic tempera- •We have little direct measurement

ture scale, namely: 110 K (liquefied natural contact with the consumer per se , and expect gas), 20 K (hydrogen: future fuel) and 4 K no significant change. Contact will con- (superconductivity technology). These tinue to be made through service industries trends are not only valid, but also are and regulatory agencies. taking on added significance in the light of 48 Table 4-2. Distribution of effort Percent of Cryogenics Division Total Effort Beneficiaries of Outputs Current 5 years from now

directly to specific manufacturing firms 8% 10% or industries directly to specific service industries 5% 8% directly to the individual consumer n 1%

to the Defense Department 30% 33% to Federal regulatory agencies 2% 5% to State government needs 1% 3% to other Federal government agencies 43% 30% to other NBS groups 5% 5% to university research and other research 5% 5% at the frontiers of science

• Direct support of the Department of wisely chosen a statement of the Bureau's Defense mission will continue, reflecting mission broad enough to allow the Bureau to the fact that the Department of Defense respond to changing needs. By the same supports about half of all research in this token, such a freedom of choice demands of us country [38] and that the first practical a continual appraisal of the most important applications of superconductivity will problems to tackle. Of the criteria for probably be to Department of Defense needs. choice, and therefore for action, four seem •Both federal and state regulatory needs to be vital to success: will grow. The federal interest (Federal •Needs in Relation to Mission (what is Power Commission, Coast Guard) will be in the relevance on either a long or short range the safe and efficient handling of cryogens. basis?) The State's interest lies primarily in •Technical Opportunity (is it timely to effective metering, sale and taxation of take on a new program; is there a good idea?) cryogens. •Resources (can we bring enough manpower •Non Department of Defense agencies will and money to bear on the problem to ensure an show a decline of the total, primarily due adequate contribution?) to the growth of the regulatory agencies. •Leadership (is there an energetic "ball- •"Other" will remain small and constant, carrier" who wants to do the job?) as instruments become standards and as Unless all four criteria are met, any problem conceptual knowledge is developed to the that is tackled is not likely to have strik- point of useful research. ing success. 4.4 Evaluation of NBS Program However, there are three characteristics of our other agency work that do set them 4.4.1 Evaluation Criteria apart from our own, and these evolve in the Needs for NBS services to the cryogenic following way: measurement system fall into two major •We wish to promote the efficiency of categories: those determined by our own government through effective utilization of studies and initiatives, and those brought federal laboratories. When approached for to our attention otherwise, such as sugges- help by another agency, we consider what they tions from within other units of NBS or would have to spend to achieve our existing requests from other agencies, both federal capabil ity. and state. In any case, however, a similar •The applied measurement programs of decision process is made, carefully account- other agencies give our staff practical ing for a balanced program, internal capa- experience with problems in the field, and bility and facilities, staff wisdom, and the thereby automatically enhance the relevance promotion of the mission and functions of of their work. We give priority to problems Institute for Basic Standards and NBS. that add to our capabilities to carry out our Programs in support of these needs, whether primary statutory functions. funded by direct appropriation or by transfer •We provide technical assistance to of funds from other agencies, must be chosen agencies that issue regulatory standards. for the same basic reasons. The Congress has The appropriateness and fairness of the tests

49 :

and measurement standards that define such The final key to our program evaluation regulations are critically important to fair is how well the proposed program fits the and rational management of the Nation's Division strategic plan. This strategic plan technology. is established by the cooperative action of If further consideration is warranted, we senior technical staff. Institute for Basic proceed through checklists (sometimes for- Standards and NBS management, and the Evalu- mally and documented, sometimes informally) ation Panel. Planning is, of course, a con- that include at least the following criteria: tinuous process, but this strategic plan is formally documented and articulated annually Evaluation Criteria - External in the Division's Planning and Budgeting •Appropriate federal role?^ Document (usually prepared each fall in •Match to NBS mission time for the annual Evaluation Panel meeting, •Potential high impact and the initiation of the budget cycle). •Leverage of NBS measurement and data In this part of the evaluation process, services on given sectors of it is important to realized that both the the economy plan and the program are tested. Sometimes •Importance of these services to fields we do modify the plan to fit the program, other than immediately represented but if so, we try to do this consciously and by measurements and data systematically, to be fully aware of why the •Importance of these fields within the strategic plan needed changing and what the scope of national priorities consequences are. •Absence of alternative institutions who 4.4.2 Evaluation Panel Role can provide this information The Evaluation Panel always plays an im- Evaluation Criteria - Internal portant role in this evaluation process. •Utilize unique facilities, competences, The background and affiliation of the members and staff wisdom are perhaps more germane to this present •Maintain and strengthen staff competence discussion than the names of the members •Provide scientific and technical exper- themselves. The affiliations of the Panel tise to NBS programs members over the last few years (1975 back •Provide Institute for Basic Standards through 1970) are given below: and NBS programmatic coherence Department of Physics, •Implement long-range strategic plan University of Pennsylvania Admittedly, these are only qualitative San Diego Gas & Electric Co. guidelines, but since the process is iterative and open to discussion over a period of Mechanical Engineering Department, time, some arguments begin to take on weight University of California, and become demonstrable while others do not. Lawrence Berkeley Laboratory For instance, a "must" is that the program Department of Physics, be somehow quantifiable -- that it have University of Connecticut milestones for measuring progress versus plans. The decision is ultimately the line Director, Superconductivity and Cryogenics manager's responsibility, and he must bear Programs, the consequences. We find the above guide- Westinghouse Research Laboratories lines invaluable and useful. They are Controlled Thermonuclear Reaction, especially useful as tie points tether to Lawrence Livermore Laboratory the arguments and to make the decision process open and visible. Department of Chemical Engineering, University of California ^ This is of course, a most vexing question. Department of Mechanical Engineering Guidance is found in the NBS and Institute and Applied Mechanics, for Basic Standards mission statements, University of Rhode Island several NBS internal Policy Guides, and Ad- ministration interest. Guidance is also Los Alamos Scientific Laboratory found in the following statement by a pre- The Evaluation Panel is charged with both vious administration: "The legitimate broad and specific responsibilities. The object of government is to do for a community Evaluation Panel of people whatever they need have done, to •Provides Bureau management assistance but cannot do at all, or cannot so well do in planning for themselves, in and their separate •Considers importance and relative individual capacities". (A. Lincoln, Spring- priority of projects field, Illinois, July 1, 1854).

50 . . .

•Makes recommendations on new program The federal role of NBS is to provide the initiatives basic measurements, data, and standards that •Identifies areas of redirection are required to support and enhance a diverse •Provides forum for technical staff national technology --the infrastructure •Identifies barriers to progress technology of cryogenics itself. NBS does •Provides communication link with scien- this in part by providing a sound technical tific and industrial organizations basis for regulations that will stand up in We find the Panel especially valuable in court. NBS was established by the Congress to evaluating our strategic plan and promoting a be helpful, and this assigned function is a certain degree of discipline in exposing our critical link between the basic research programs to critical review and evaluation. community and those who have to put science to work. 4.4.3 Why NBS? The coordination of such a nationwide In Section 4.3, we discussed the impact of effort as this is best centralized so that NBS services and gave some specific examples the Nation can have a strategic and inte- of the consequences of not providing those grated program rather than a piecemeal one, services. In this Section, we shall examine and can further benefit from the synergism some of the factors that help make the NBS that naturally occurs in a centralized, role crucial coordinated effort. Part of the reason is historical. NBS has These principles are the lifeblood of the supplied data and services to the cryogenic National Bureau of Standards and are strongly measurement system for nearly 70 years (see and deeply felt by each and every one of the Section 4.1). As a result, we have developed Cryogenics Division's professional staff unique capabilities -- not just in facilities, members, just as they are by every member of but more importantly, in staff experience -- the NBS as a whole. a resource difficult, if not impossible, to Table 4-3 summarizes the crucial role of duplicate elsewhere. NBS. (See page 53). Industry values the third party indepen- 4.4.4 Program Evaluation dence and integrity of NBS, i.e., our impartial judgment. Companies and industrial "We judge ourselves by what we feel capable associations frequently plead with us to of doing; others judge us by what we have establish a first line measurement competence done." Henry Wadsworth Longfellow. in their technical area, even though they may The previous sections have described the already have competent research laboratories. evaluation process; the following gives the Those industries who know they have an excel- results of that process, in particular, the lent product want their customers to be able judgment of the Evaluation Panel appointed to make accurate and objective evaluations of by the National Academy of Sciences/National that product. If their own product claims Academy of Engineering/National Research are based on measurements traceable to NBS, Counci 1 customer confidence is enhanced. This is The members of the Evaluation Panel are important also in foreign trade, for the chosen by the above associations for re- Bureau is regarded as highly abroad as it is cognized scholarly competance. The members at home. We call it neutrality and acceptance; of the 1973-74 panel were: Donald N.

"neutrality" in the sense of an independent Langenberg, Chairman , University of Pennsyl- third party; and "acceptance" in two ways. vania; Paul L. Hathaway, San Diego Gas and Not only does the integrity, competence, and Electric Co.; H. Paul Hernandez, University independence of NBS often lead to the ready, of California; John L. Mason, The Garrett universal acceptance of our work, but also we Corporation; John M. Prausnitz, University are able to accept proprietary data in con- of California; Clyde E. Taylor, Lawrence fidence, which often facilitates the process Livermore Laboratory. of objective technical review and evaluation. The following material quotes the summary Providing a fast and timely response is and general conclusions of the 1973-1974 possible in part to this ready acceptance. report. NBS is also able to respond rapidly and "Summary credibly because of the experienced staff, having diverse backgrounds, which is avail- "The Cryogenics Division's coupling with able to assist in problem solutions requiring outside client agencies, industries, and many technical disciplines (as in the Apollo associations is good, though more effort 13 and Staten Island LNG incidents). should be made to achieve visibility at NBS alone has the charter to provide both the highest managerial levels of these national standards and international standards organizations through the aegis of the Treaty of the Meter.

51 "The Panel believes that all three of effectiveness and achieving more general the Division's new program initiatives recognition of the importance of this are timely, relevant, compatible with facet of its work." the Division mission and goals, and The 1974-1975 panel members were Donald worthy of support. On the basis of the N. Langenberg, Chairman University of irmediaay of the problems being , Pennsylvania, Paul L. Hathaway, San Diego addressed, rather than long-term impor- Gas & Electric Co., H. Paul Hernandez, tance or quality, the Panel ranked the Lawrence Berkeley Laboratory, Paul G. initiatives as follows: Liquefied (1) Klemens, University of Connecticut, James Natural Gas Technology, (2) Cryotech- H. Parker, Jr., Westinghouse Research nology for Superconducting Equipment, Laboratories, Clyde E. Taylor, Lawrence and Hydrogen: Future Fuel. Within (3) Livermore Laboratory. each initiative, portions of relatively The following sections are quoted directly higher or lower priority were identi- from the panel's 1974-1975 report: fied and discussed. "THE ROLE OF NBS IN CRYOGENIC TECHNOLOGY "General Comments "The Panel was informed that the involvement "The Division's technical and managerial of NBS (primarily through the Cryogenics competence remains high. With the Division) in cryogenic technology is some- possible exception of certain aspects times questioned. The rationale for such of its Liquefied Natural Gas (LNG) questions is apparently that, since cryo- Program, it maintains a good balance genic technology is a primary concern of between work related to its essential a variety of private-sector institutions, basic-standards mission and work that many of the cryogenic programs currently responds to national problems, such as in progress within NBS might better be the energy crisis. Even in the latter carried out in these institutions. area, the proposals and activities are "It is the view of the Panel that the current clearly within the basic mission of activities of the Cryogenics Division in the Division. the area of cryogenic technology are en- "The Division effectively maintains tirely consistent with the goals and close coupling with its counterpart purposes of NBS and should not (and in industries and industrial associations. many instances could not) be left to Because these interactions are essential private sector institutions, particu- and contribute to the Division's larly when the independent position and success, they must be continued and the high quality of the Division's work enhanced. The Division is well-known is recognized. at the operational level in industry. "Let us consider some examples: However, the Panel does not believe that "A. Liquefied Natural Gas (LNG). The Cryo- U.S. industrial leadership at the vice- genics Division is studying the thermo- presidential level is aware enough of physical properties of pure components the Division's capabilities in trouble- and of mixtures of the components of shooting and contributions to LNG. The purpose of this work is to engineering research. It is to the develop the basic reference data and Division's advantage ensure that to measurement techniques required to assure those individuals who are in a position equity in the handling and transfer of to influence policy in government and LNG, an activity which is rapidly be- in industrial research foundations know coming a major factor (billions of about its industrially important activ- dollars) in our fuel importation in- ities and well-earned international dustry. The assurance of equity in reputation. Accordingly, the Panel strongly trade and certifiable measurement of recormends that the Cryogenics Division trade quantities is sel f-evidently an consider ways to increase its visibility NBS function. If the LNG industry were in general and especially in high-level to assume responsibility for this program, industrial management circles. it could do so only be replicating, "An important Division contribution probably several -fold and at consider- outside NBS has been its consultative able cost in time and money, the unique services to industry and other govern- facilities and expertise already in men.t agencies. The Panel urges that as existence in the Cryogenics Division. many permanent technical staff, We would then have one party to commerc- including its younger members, as ial transactions specifying reliability possible participate in this activity of the measurements involved, or two as a means of ensuring continued

52 parties in conflict over the applicability On the whole, this outside review of our of different measurement systems. This program is rather favorable. is just the sort of thing it is NBS's function to avoid. That all of this is Table 4-3. The crucial role of NBS fully recognized by the LN6 industry is evidenced by the fact that it is providing • Federal Role major funding for the NBS program through - Need for data and services to accom- its trade organization, the American Gas plish a specific government function, Association. such as health and safety regulation "B. Cryogenic Materials. The Cryogenics - Importance of these data and services Division is studying the mechanical and within the scope of national priorities electrical properties of a wide variety - Leverage of NBS data and services on of materials for use in cryogenic en- a given sector of the economy vironments. The purpose here is to •Diverse National Need develop bench mark data for use in design, - Lack of direct incentives to a single a function which could be carried out organization to perform the "services" elsewhere only at considerable cost in needed duplication and general credibility - Diffuse benefit--high risk, low gain and acceptability. Here again, the - Multiple beneficiaries special capabilities of the Cryogenics Division are recognized in funding •Provide National Standards supplied by the Advanced Research Projects - Model established: measurement develop- Agency and the U.S. Maritime Administra- ment, plus transfer of technology tion. •Impartial Judgment "C. Cryoelectronics. Several divisions of - Neutrality NBS are engaged in developing applica- - Acceptance tions of superconducting electronics. Here the primary and immediate import •Unique Capability will be on the Bureau's own needs for - Unique NBS capability in equipment, precision measurements and standards. facilities, personnel, or experience There simply is no other institution - Past success; acceptance which is in a position to supply the - Experience in related fields technology needed for these special needs. •Fast Response Time "D. Properties of Cryogenic Fluids. The - Ability to respond rapidly and credibly Cryogenic Division has provided a unique to a recognized need public service in acquiring available physical properties data, in performing •Technology Transfer experimental measurements, and in for- - Needs identified by cryogenic community; mulating these data for use in thermal well identified needs; well documented computations for such fluids as helium, successes hydrogen, nitrogen, methane and the like. •Preferred Alternative The integrity of their work is recognized - Absence of alternative institutions who worldwide and has led to the broad accept- can provide this information ance of this basic data." - Mission orientation

Evaluation Summary . Each year, the •Acceptance Panel is charged with specific responsi- - De facto standards of measurement, of bilities in addition to its overall duty, quality, of performance, and of prac- and accordingly, the response each year tices centers about a different theme. Nonethe- •Coordinated National Effort less, some general conclusions may be - Importance of these data and services drawn from the above reports. Others judge to fields other than those requesting us as having good coupling with our out- the data side clients; having a timely, relevant and - Other agencies conjoined; synergism balanced program; maintaining high technical and managerial competence; and making an 4.5 The Future important contribution through our consul- We have indicated that cryogenics is tation services. Our special capabilities largely an infrastructure technology. It is are recognized in funding supplied by by and large hidden from the casual observer, counterpart institutions. We ai^e criticized while at the same time occupying a central for having poor visibility at high level position of great potential leverage on the management circles. Correcting the latter Nation's essential science and industry. The deficiency could add leverage to our work.

53 cryogenic measurement system is in turn, an the floating of trains above a track on an infrastructure of cryogenic technology. air cushion, or supporting it on magnetic Therefore, to anticipate the needs of the cushions that may or may not use supercon- future, it is necessary to assess the state ducting magnets. This study documented the of cryogenic technology itself and the state precise role of cryogenics in high speed of the measurement system within that tech- ground transportation and proposed several nology. Such assessments are carried out possible ways to anticipate and resolve periodically and systematically. The frame- potential cryogenic measurement problems. work of the studies is discussed below. "Current Developments in Cryomedicine" [43] was meant to define what role, if any, 4.5.1 Technology Assessments in Cryogenics NBS should play in the field of cryo-medicine.

Overview . As mentioned briefly in Section There did not appear to be a unique opportun- 3,2, two overviews were made at the division- ity for NBS in the field of measurement as-a-whole level to document the infrastruc- science in cryo-biology . Accordingly, no ture position of cryogenics in large national particular course of action was deemed to programs (space, health, transportation, have a striking chance of success. A con- etc.) and to identify leading indicators of scious decision was made not to enter this trends of the health of cryogenics. field. The first, "Cryogenics and National Goals", "Water Pollution Abatement" (internal [39] was in 1968. At the height of the space study by Chelton) was the Cryogenics Divi- effort, it predicted the demise of that sion's first systematic look at environmental program, its need for hydrogen technology, problems. Again, a program was deliberately and foresaw the growing importance of a not recommended, although both the need and practical helium technology and LNG as a the technical opportunity (but for others) fuel. It is perhaps interesting to note that were present. Two technical conclusions were the Oil and Gas Journal at that time said reached: (1) The most extensive potential that "The U.S. is not generally regarded as application of cryogenics is that of supply- an energy starved nation, and imports of LNG ing (liquid) oxygen instead of air to second- will never be significant." ary waste water treatment plants to accelerate The motivation for the second overview, decomposition, and thus upgrade present "Trends in Cryogenic Fluid Production in the plants and facilities; and (2) the most U.S." [40], was to verify and update the sophisticated application of cryogenics is findings of the first. It seemed important the use of superconducting magnets for to let a little time pass, and then test the colloidal filtration of river water. None- structure and underlying assumptions of the theless, criteria for NBS entering the field first benchmark study. It was an experi- were missing. Specifically, the first case mental check of the 1968 study and did was not really a cryogenic research problem, document the critical supporting role cryo- for the handling of liquid oxygen is a well genics plays in essential national indus- established business. Neither was the second, tries. necessarily, since the construction of large

Applications for Specific Customers . Once superconducting magnets has been accomplished the network of cryogenics in technology as a at the national laboratories. whole had been defined and tested, it was Applications to a Specific National Need- - useful to look at specific functional rela- Energy . We have prepared technology assess- tionships between terminals in that network, ments in three energy areas: LNG, hydrogen, or the leverage of cryogenics in specific and superconductivity. Measurement services customer applications. Four such studies and data to support these three technologies were formally done and published. promise to be the main enterprise of the "Superconductivity Programs of the AEC" Cryogenics Division for the foreseeable [41], predicted the need for efficient future. cooling of long lines to helium temperatures Liquefied Natural Gas was addressed for power transmission. There are now four at two levels — simply its peculiarities as major research groups involved in the develop- a cryogenic fluid, and as a commodity. ment of just such superconducting power "LNG as a Cryogenic Fluid" [44] assumed transmission lines in the U.S. Precise that the Nation is just now entering an era measurements (especially pressure measure- of the large scale use of liquid natural gas. ments) are crucial to achieving the effective This report then predicted potential LNG cool-down of such long lines. problems, based on similar experience gained "Superconducting Levitation of High Speed when the Nation just began handling liquid Vehicles" [42], was prompted by need of the hydrogen as a commodity. It predicted specific Department of Transportation to decide between instrumentation problems in measuring pres- competing levitation technologies, such as sure, temperature, liquid level, and flow. It also predicted specific problems from 54 .

property data that are insufficient, have had rivals within the technology itself, es- insufficient analysis, or are internally pecially from abroad. Since cryogenics was inconsistent. This study documented the "invented" abroad, we have never suffered practical utility of basic measurements and the delusion of thinking that NBS has the launched the American Gas Association program world's supply. Instead, world-wide aware- on LNG. ness is central to our supplying timely and Since LNG was a significant commodity in essential measurement and data services to trade, "Measurements of LNG in Commerce" the U.S. cryogenics community. [45] examined the measurement basis for The most recent systematic foreign tech- purchase of LNG. This study found a six-step nology assessment was the monitoring of measurement process which has, at present, no applications of superconductivity in the USSR, quality control or quality assurance built Switzerland, W. Germany, France, England, and in, and which is based essentially on a bid Japan (internal study). For instance, NBS and barter system. For instance, tank volumes staff visited the Fawley (U.K.) power station are fixed at room temperature by "strapping" to inspect the 3250 HP superconducting motor; the tank with a tape measure, and then estab- discussed national funding of private enter- lishing some functional relationship between prise with the U.K. - National Research liquid level and volume. This paper docu- Development Council; discussed the German ments the advantage of basing the commercial superconducting levitated train in Munich; custody transfer on modern mass flowmetering and witnessed the Japanese 4-passenger and property data instead. The goal is to demonstration superconducting train. We establish an orderly, systematic, and scien- found foreign efforts to be aggressive, well tific basis for LNG trade. ahead of our own, and funded in cooperation "Hydrogen: Future Fuel" [46] showed the with their national governments. This study many technical, economical, and ecological documented the magnitude of the foreign advantages that make hydrogen a prime candi- exploitation of U.S. technology and helped date as a substitute chemical fuel of the provide a sound basis for designing our own future. It was the first step in documenting measurements and data program. the needs for the present technical program. Analysis of Major Technical Barriers . "Superconducting Electrical Power Systems" The question of reliability and cost is [47] was an effort to accelerate the applica- always raised whenever a commercial appli- tion of this technology to an old, established, cation of cryogenics is suggested. Helium and reliable industry. It found, among other supply, management, and control lie at the things, that: heart of realizing practical superconducting •Technological leadership in supercon- systems ducting machinery in the United States Strobridge [48] documented that enough can help to reduce generator imports experience has been accumulated in the design by up to 50%. and operation of low temperature refrigerators •Technological leadership by foreign and liquefiers to safely assume that any companies can help them to capture a cooling requirement can be met. This study larger share of the U.S. market. frequently obviates proposals for new refri- •Superconducting generators may be geration surveys, or, in some cases, re- essential to realizing the full advan- frigeration development programs, and pro- tage of the large fast breeder reactors. vides a common data base for refrigeration Specific technical program plans were dependent technologies (e.g., accelerators drawn to enable the development of supercon- and transportation). ducting electrical generators, in cooperation We have seen that cryogenics is an with the large electrical machinery manu- infrastructure industry, serving in an facturers. This effort helped stimulate indispensable way the needs of other indus- the development of applied superconductivity tries. Similarly, the science of cryogenics in this country, made public much privately is an infrastructure science. Seldom are held information, and has led to major new the low temperatures themselves of interest, thrusts to provide adequate measurement except perhaps to establish some record. services in support of this field. Rather, their real importance lies in

Analysis of Major Technical Threats . enabling the basic understanding of other Since cryogenics is a rather well -bounded phenomena, i.e., increasing conceptual and self-contained technology, it is not understanding. likely to be replaced by a competing tech- The essential point is that here, too, nology, such as electrical measurements re- cryogenics plays an essential but invisible placing mechanical or optical measurements, role. It is usually not the cryogenics per or TV phones replacing business commuting. se under study, but rather that the ultra The principal threats are from among the low temperatures cause basic physical

55 .

phenomena to be greatly simplified and thus generation and distribution; and cryoelec- be more susceptible to understanding and tronics. As a result, the President's use. Science Advisor formally requested the Accordingly, we conducted in 1969 an Department of Commerce to take a leadership internal planning study to define needs in position for the exploitation of cryogenics millikelvin research and propose specific and the creation of new industries. action to meet those needs. This study As a result of this briefing, a plan was recommended specific measurement and data developed to help assure the successful needs in the millikelvin and sub-mi 1 1 i kelvin commercial exploitation of cryogenics. The range. These plans included the development goal was to assist the Department of Commerce and improvement of standards and measurement to create its own policy for the effective techniques, as well as techniques for application of cryogenic technology for obtaining and maintaining low temperatures. public benefit. Analysis of Major Technical New Oppor- Summary of Cryogenic Technology Assess- tunities . The studies above have in common ments . These studies have given visibility the motivation of need in relation to to our decision making, and invited staff mission. A parallel requirement of a sound participation by those most likely to be program is the existence of a timely technical affected by the decisions. A stronger, more opportunity, and our formal technology timely program has been the result. assessments have not been without this 4.5.2 Driving Forces component as wel 1 Cryoelectronics has been addressed in The overall goal of the National Bureau this fashion twice, in harmony with the of Standards is to strengthen and advance notion of reviewing and checking our pre- the Nation's science and technology and to dictions periodically. The first was an facilitate their effective application for internal planning study which documented public benefit. Accordingly, it is not developments in superconducting devices in surprising that we find both technical and d.c. voltage, direct current, magnetic societal driving forces at work, influencing field, RF current, RF power, pulse technology, the trends of our program. RF noise, and temperature (internal study). Technical driving forces (applied super- It articulated a measurement role for NBS and conductivity, hydrogen fuel, LNG imports, formed a new organization to consolidate an etc.) were noted in the specific technical NBS program in cryoelectronics. sections above. In addition, as implied in "Developments in Cryoelectronics" [49] the NBS Goal, we must continually give was published to document the development of special attention to the public and private new electronic instrument, s taking advantage institutions through which our measurement of the unique properties of superconductors. and data services benefit people. Some It found that commercial activity has been in noteworthy trends in such societal driving the nature of an investment in the future: forces and our expected response to them very few devices have actually been sold yet. follow below: It suggested that computers, information •Services influencing the manufacturing transmission lines and magnetocardiography sector will increase, reflecting the may become commercially significant appli- fact that cryogenics in general, and cations of superconductivity. superconductivity in particular, are It suggested that many other superconduc- coming of age. ting devices also perform specialized •Interaction with the service industries functions uniquely, and would repay the will also increase as the interaction cost of development without necessarily with the public energy utilities and generating a large market. This study is the Energy Research and Development helping to provide the basis for future Administration increase. measurement and data programs. •There is little direct contact with An intense and in-depth effort on super- the consumer per se, and no significant conductivity was conducted at the request change is expected. Contact will of the President's Science Advisory Com- continue to be made through service mittee (PSAC), which required the partici- industries and regulatory agencies. pation of many experts outside of NBS. •Both federal and state regulatory In a sense, it was a conference-style Delphi needs will grow. The federal interest exercise. The result was an oral briefing to will be in the safe handling of cryogens. PSAC on the current status and future promise The state's interest lies in effective of superconductivity. It covered such topics metering, sale, and taxation of cryogens. as new superconductors; magnets and their As a result, we shall have to maintain a application to transportation, ore benefi- balanced program supplying both measurement cation, and water pollution; electric power services and data to the cryogenic measurement system. 4.5.3 Emerging Technologies transfer (includes safety, interstate and international We have seen that the major developments cooperation, effective use of the Office of Weights in cryogenics in the next few years that will and Measures, and training). Thanks have significant impact on the technology of (in part) to the NMS study, new programs the country and its balance of trade are the now use the guidelines so developed widespread international use of liquefied to assure a complete and comprehensive natural gas, applications of superconductors, approach. and potential uses of hydrogen. Cryogenic In addition, we have become more sensitive to the measurement and data services are essential measurement system concept in all our programs, to meet the developing needs for metrology, not just the LNG program. For instance, design data and applied cryogenic research. we are making an inventory of all of our measurement Figure 7 shows these technological trends services. We also are documenting and our response to them. The check marks are our operations throughout the dissemination a qualitative representation of our present network, e.g., regulatory agencies, state emphasis, which is in harmony with the time- offices, central standard authorities, liness (or urgency) of the technological and education programs. Left to trends. LNG is upon us now; superconduct- our own devices, we would most likely have conducted ivity is a technology that is finding wider a technological impact study use; while the most pressing need for hydro- (the science and technology profile of gen -- Future Fuel is data for decisions. the cryogenics industry needs updating) These emerging technologies will demand and not an examination of our part of continued NBS support for the foreseeable the National Measurement System. Left on our own, we future. See Section 5. for specific re- would have benefited by commended actions. documenting new and other needs and develop- ^ ing programs accordingly. We would have 4.5.4 Impacts of the National Measurement lost the understanding we now have of a System Study "complete" program, and our role in the infrastructure This study of the National Measurement of the National Measurement System. System documented for us the complete process that must be undertaken to provide 5. SUMMARY AND CONCLUSIONS a complete measurement service. For instance, 5.1 Key Developments our LNG budget initiative submitted in the spring of 1974 was deliberately constructed This study has shown that there are three to include all three necessary elements: emerging technologies within the broad field measurement science, data base, and technology Cryogenics with a need for a complete and

TECHNOLOGY TRENDS |

OUTPUTS Liquefied Hydrogen: Superconductivity Natural Gas Future Fuel

Physical Measurement

Materials Data Base

Cryoengineering Services

FIGURE 7. Emerging technologies in cryogenics.

57 consistent system of measurements and data. •LNG is primarily an energy storage Specif ical ly: media, because its energy content is about 600 times that of natural gas at Liquefied Natural Gas . A complete and com- atmospheric conditions. prehensive measurement system for the liquefied natural gas industry needs to be de- Peak shaving accounts for the largest veloped, with special emphasis on quantity number of LNG facilities with 106 being gaging in storage and ship tanks, flow- completed within the U.S. This number includes metering for determination of both mass and 55 actual peak shaving plants (which include heating value, and basic measurements of liquefaction, storage and gasification equip- thermal and mechanical properties of struc- ment), and 51 satellite facilities (which tural materials. comprise a total storage capacity of approximately sixty-five billion cubic feet (equi- Hydrogen . Basic measurements and data are valent gas volume) and a total liquefaction required now to support the development of capacity of approximately 295 million cubic hydrogen as a fuel, in such areas as improve- feet per day. ment of hydrogen liquefaction efficiency, LNG presents not only a nationwide problem, evaluation of methods of recovering lique- but an international one. Contrary to faction energy, of hydrogen-compatible ma- popular opinion, the U.S. is not dependent terials of construction, and development upon just one source. Imports are planned of improved insulation materials and an in- from Malaysia, Australia and South America, strumentation and measurement methodology for instance. We will also "import" from for the commercial exchange of liquid hydro- Alaska. In fact, the U.S. is presently a gen. net exporter of LNG (to Japan) due to con-

Superconducti vi ty . Superconductivity contracts signed in 1968. nects cryogenics measurements and data to Industry desires NBS assistance in this the electrical power industry, for power national problem. For instance, the president transmission, generation, and storage. of the American Gas Association has written Knowledge needed includes heat transfer the Secretary of Commerce, requesting mea- rates, behavior of helium refrigerant surements and data assistance from the flow systems (including the response to Department of Commerce and the NBS. instabilities), and the degradation of the The Secretary gets many such letters, to superconductors with time and stress. be sure, but our study has shown that the Superconductivity is also a means of Department of Commerce and NBS have been employing cryogenics to develop new or earmarked as the international and inter- improved measurement techniques in fields state connection agency. International outside of cryogenics. The SQUID (Super- contracts call out NBS as the measurement conducting Quantum Interference Device) is authority. In addition, we also have an demonstrating promising applications in inter-state responsibility to provide LNG magnetocardiography , geothermal prospect- assistance to a variety of federal, state ing, determining molecular constants, and and local authorities on the inter-state spectroscopy of all kinds. Indeed, the transfer of LNG. SQUID appears to be as versatile as the LNG has grown so fast and to such a size Laser as a measurement technique, and is, and complexity that our NMS study revealed of course, fundamentally a cryogenic device. that it is now timely for the Department Some of the needs of each of these parts of Commerce to take steps to assure quality of the National Measurement System for control and continuity in this part of the Cryogenics are illustrated below. NMS. The overall measurement and data needs 5.2 Liquefied Natural Gas (LNG) for LNG identified in the course of this study LNG is a Cryogenic Fluid (NBP 110-140 K) include: but unlike the simple fluids of our usual •Heating Value (Energy) metering for experience it is: national and international trade •A non-ideal mixture of five or more •Quantity gaging hydrocarbon fluids and nitrogen; •Thermophysical properties no known mixing rules exist at this •Properties of structural materials time, and therefore the mixture pro- •Instrumentation and data for Energy perties are not yet predictable; all Conservation must be measured. • Safety Criteria •Furthermore, the mixture fraction varies The needs for the safe and effective with source-time-and storage treatment. utilization of liquefied natural gas are

58 ;

most urgent. They include both tools and gaging. Liquid hydrogen instrumentation techniques for physical measurements as well has not significantly advanced in the past as a data base for materials selection and ten years since the peak of the space pro- use. gram. Major efforts will be required to meet the needs of a commercial cryogenic 5.3 Hydrogen hydrogen fuel market. Instruments suitable With respect to hydrogen, there seems for aerospace applications are not usually to be little doubt that it will become a appropriate for commerce and vice versa. major source of fuel for the future. Needs Measurement standards are needed to bring are centered about providing an adequate all aspects of hydrogen instrumentation into data base--reference data, reference ma- quality control within the National Mea- terials and performance standards--to give surement System. a rational basis for decision making in this 5.4 Superconductivity field. Candidate Markets for cryogenic hydrogen, Superconductivity was discovered at about without regard to priority or imminency, the same time as the Wright brothers first are: flight, yet remains largely an undeveloped technology. This is indeed curious since •Transportation--to fuel aircraft, autos the potential practical applications of super and ships; conductivity are staggering. For instance, •Aerospace--rocket and spacecraft fuel; it is widely held that superconductors could •Energy storage and transmission--carrier be used to advantage to transmit electrical of nuclear or solar energy from sea-to- power with almost no loss, to make magnets shore or overland; of a size not heretofore possible for energy •Utilities--fuel for integrated gas- storage; to upgrade low quality iron ore in electric utility operations and a magnetic mineral processing; to improve the portable fuel for rural communities; quality of kaolin; to purify water via and to a lesser extent: colloidal filtration; or to float high speed •Superconducting and cryoresistive trains on a magnetic cushion. electrical power cables--to be used as Yet none of these possibilities are a closed-loop coolant (electricity approaching commercial realization in the and hydrogen are del i vered) United States. The problem does not appear •Industrial processes--to provide high to lie with the superconducting wires them- purity hydrogen gas upon demand. selves, as over 500 materials are already Assuming that a future market exists for known to be superconductors. Furthermore, liquid hydrogen we must dispense the fuel in a dozen manufacturers here and abroad are an efficient, fair and safe manner. producing superconducting wire and cables The efficiency of liquid hydrogen fueled in nearly commercial quantities at prices systems can be improved on three fronts: approximately one- tenth that of copper wire (1) lightweight, efficient and inexpensive for the same current carrying capacity. insulation materials are needed, together with The problem appears to lie instead in national insulation transfer-standards; providing a reliable, safe and convenient (2) data are needed on advanced construc- supporting cryogenic environment. We need tion materials that are lightweight, strong, to provide the helium measurements and inexpensive, resistant to hydrogen em- data base essential to the successful develop brittlement and brittle fracture, and hav- ment of superconductivity. NBS need not ing low heat capacity and thermal conductivity. address the applications of superconductors (3) liquid hydrogen handling procedures, mentioned above, but does need to provide though highly developed and successful in the supporting measurements and data on: the aerospace program, will have to be re- 1) helium heat transfer and fluid dynamics; vised for commercial applications. 2) instrumentation and measurement systems Liquid hydrogen enjoys an enviable safety for helium management, and 3) data on the record in the aerospace industry. However, degradation of superconductors. the safe use of hydrogen in commerce will Since heat transfer and fluid dynamics require thorough re-evaluation of: 1) com- are strongly interrelated, a thorough under- patible materials of construction, 2) handl- standing of the fluid dynamic aspects is ing procedures and regulations, and 3) ex- essential. The important consideration is plosion hazards. that all flow irreversibilities ultimately We must also be able to guarantee equity show up in the form of heat, thus reducing in hydrogen commerce. Thus, traceable the capacity of the helium to absorb other measurement standards are required for mass losses. We need to provide basic data and flow, pressure, temperature, and quantity- understanding on the properties and behavior

59 .

of helium to provide engineering and process and industry; and to extend the impact area designs, predictions, and scaling of equip- of the measurement program. Since physical ment. measurements are almost always reduced to Effective helium management will require, electrical measurements, the list of cryo- at least, sensors for pressure, temperature, electronic applications is almost endless. quantity and flow rate. We need to provide Accordingly, it is particularly timely to such instruments through developments which open up the way for extensive new applica- take advantage of the low temperatures and tions of cryogenics to physical measurements optimize the instrument output. For instance, units and standards. superconductors themselves may be used for 5.5 Summary thermometers and level gages. We need a new generation of instruments and measurement Our study of the National Measurement techniques tailored to liquid helium as a System for Cryogenics has shown that major technical fluid. developments in the next few years will The third consideration arises from the occur in cryoelectronics, the widespread fact that practical superconducting systems international use of liquefied natural gas, will not operate under ideal laboratory potential uses of hydrogen, and applica- conditions. They will be subjected to tions of superconductors. Major other mechanical stresses during shop and field- federal agencies will doubtlessly continue site fabrication; they will, at least to solve their specific cryogenic techno- occasionally, be subjected to unduly rough logical problems through a variety of handling; they will have unprogrammed ex- means, including, but not limited to, cursions in current, temperature, and mechan- soliciting the services of the Cryogenics ical stress during fault conditions. Even Division. We regard this constituent of more fundamentally, they will certainly our total program as a necessity to main- show typical manufacturing variabilities taining our institutional health, and our and may show time dependent deterioration sustaining a current awareness of national of their desired design properties. needs and goals. The foregoing discussion has focused on However, no other instrument of the govern- the physical measurements, units, standards ment has the prime responsibility to assure and essential technical data needed to the proper functioning of the Nation's system support the needs of the National Measure- of cryogenic measurement. The needs as ment System for cryogenics. In addition, discussed briefly above and documented within cryogenics itself may be used to advantage the body of this study, demonstrate that to develop new or improved measurement now, more than ever, it is time for a central, technology outside of the field of cryogenics. coordinated, coherent national effort on the Specifically, the SQUID is being used to part of NBS to bring and keep the cryogenic improve technology transfer from our physical part of the National Measurement System into measurements program to other federal agencies qual ity control

60 1

METHODOLOGY OF THE STUDY of the national needs for cryogenic flow measurements and standards, and we used this APPENDIX A. resource extensively to illustrate the prac- One purpose of the Cryogenics Division tical realization of general principles. study of the National Measurement System was Invaluable help was obtained from the to clarify and understand what is necessary Compressed Gas Association (CGA). The CGA is to provide a "complete" measurement service, a nonprofit corporation which represents all and to identify the role cryogenic measure- segments of the compressed gas industry in ments in the infrastructure of the National the United States, Canada, and Mexico. They Measurement System. also have associate members in European and We hoped by this process to document the Asian countries. Among its membership are way information was gathered, how conclusions over 250 companies, including North America's were reached, and how the results were vali- largest firms, devoted primarily to producing dated. Such hindsight could then be applied and distributing compressed, liquefied, and to the systematic development of new mea- cryogenic gases, as well as leading chemical surement services in the future, as well as industry corporations that have compressed to improving present services. In the follow- and liquefied gas divisions. They contri- ing material, we shall examine our particular buted valuable insights to the mechanics of methodology in four categories: the National Conference on Weights and Mea- sures, especially as to how a code is devel- 1. Mechanism for Selection of Data oped and promulgated through the documentary Sources; system. Perhaps prompted by the interest of 2. Transmission Mechanics, the means by the CGA and the states in "type approval" of which the desired data was meters, members of the instrumentation in- conveyed; dustry were very helpful. 3. Contact Mechanisms, used to obtain the desired data; The U.S. Department of Commerce (DoC) 4. Sources of Information or Validation, compiled and published many statistical summaries that were invaluable to this type Table A-1 is a matrix designed by Dr. R. of study. For instance, the SIC codes lead C. Sangster, National Measurement System immediately to the "Current Industrial Coordinator, that conveys at a glance much Reports", in our case Series M28C, which about the study. The blocks in the matrix are gives frequent and accurate summaries of the divided by a diagonal. The upper left corner production of cryogens. The "Alphabetic refers to the process of obtaining results; Index of Manufactured Products" is a com- the one in the lower right deals with the panion to the better known "Standard In- process of val idating the results. "0-L-M-H" dustrial Classification Manual " . Other gives a rough quantitative estimate of the useful Department of Commerce publications importance (to this study) of the results in include "Industry Profiles", and the annual terms of zero, low, medium, or high. "U.S. Industrial Outlook". The latter is The following narrative describes each especially useful, for it not only summarizes of the four tactical means listed above. statistical data, but also forecasts growth and the reasons (e.g., new uses for old 1. Mechanism for Seclection of Data products) for this growth. "Mineral Facts Sources. and Problems", published by the U.S. Depart- An analysis of NBS clientele was very ment of the Interior, provides a resource important to obtaining data. Many of the similar to the "U.S. Industrial Outlook", but clientele (state weights and measures offi- is even more exhaustive in its treatment of cials and compressed gas suppliers) played an cryogenic gases. essential role in validating our results. In Private compilations, such as the Dunn the case study cited in this report, our and Bradstreet's "Million Dollar Directory", results were crucial to the commerce between while giving a brief overview of a particular many of our clientele. They were profoundly company, also gives the SIC codes for the affected (by law) by the results, and there- products manufactured by that company. For fore had a vested interest in promoting valid instance, "Cryostats" do not appear in the results. SIC Manual, but can be found in a roundabout The NCSL membership, per se, was not way from Dunn and Bradstreet, if one knows used because the Instrument Society of even the name of only one firm in the cryo- America (ISA) had already formed an Ad Hoc stat business. Once the SIC code is found committee on a specific measurement, namely for a particular product, then this resource cryogenic flow measurement. This committee lists al firms reporting under that code. provided an extensive review and definition In this way, every firm in that business is

A-1 ———— ————'

TABLE A-1. Means used to obtain and validate data. OBTAIN ^^^^-^^ 1. MECHANISM FOR SELECTION OF SOURCES ^-^'"^/ALIDATE

Analyses of NBS Clientele

Analyses of NCSL Membership ^^""^ Analyses of Instrumentation Industry 1 Analyses of Other, Similar List _IL-'--^''h Use of SIC Codes for Analyses

Staff Judgment/Wisdom

Analyses of Statistical Compilations

2. TRANSMISSION MECHANICS

Ul — ^ Published Literature ^^-^^ H " LI Formal Meeting Presentation ^-—^ H ^ ' Ul Organizational Statement — ^^'^^ H L1 Personal Statement — ^-^^ H M Advertisements ^ — 0 L1 Clientele Customer Lists -""^_^ ^— 0 3. CONTACT MECHANISM u — —- Literature Search —-—^ H M — Retention of Consultants fl — h —- nu ^ Conversation - Visitor to NBS —H nu —^ - ^ At off-site location h

rt - By telephone _^ ^ —h Ul — - By visit to source's site ^^-^^ H M —— rn ^ Correspondence - M n Formal Pol 1 ing/Canvass/Questionnaire 0 - L1 — Delphi Studies L ' ' Ul ^— Other Formal Forecasting Techniques ^-"-^""^ 0 u n Special Conferences (NBS Sponsorship) ^ H U Trade Show Exhibits by NBS ^ ^--^^^ 0 U Round-Robin/Inter Comparison ^ ^^-^^'^ H Training Courses ^^^^ 0 0 Construction of New Institution ^-^^^ 0

A-2 ——^"

TABLE A-1. Means used to obtain and validate data (continued) OBTAIN ^^^^'^ ^--^^/ALIDATE

Attendance at Conferences & Meetings

Statistical Compilations

4. SOURCE OF INFORMATION OR VALIDATION

L — Academic People & Institutions M H — Prof., Tech. Soc, & Publishers ^ H

International & Foreign Organizations ^^^^^^^^ L Documentary Standards Bodies ^— ^H H Ref. Data & Mat' Is Organizations ^^^^^ H H Instrumentation Industry ^^^^^ H L NBS Evaluation Panels M H — Other NBS Units -"""''^ ^— H Nat'l Conf. WTs & Meas/St. etc. OWM's ^^"'^ H 0 Nat'l Conf. of Standards Laboratories ^^^-^ ^^—^ 0 M Stds & Testing Labs & Services ^-——"^'^ H 0 " Governmental Regulatory Agencies 0 Other Federal Government Agencies ^---^^ H State and Local Governmental Agencies ^ ^ —H H Trade Associations ^ ^-^^^^ H M — Trade Press ^ 0 H — Private Companies — H L Consumer Organizations ^ ^^^^^ 0 0 ^ Popular Press ^--^^ 0 H — Other (See Text) —'— H H ^^^--^ Staff Wisdom/Previous Studies — — ^ H

A-3 revealed with certain of its vital statis- program; and promoted and facilitated tics. visits by many representatives from other nations, including Germany, The use of these statistical resources France, and the United Kingdom. led us immediately to corporate Annual Re- ports, which are required annually by the •Steering Committee. In the case SEC, and whose accuracy must be unquestion- history used for illustration, the able. We gathered a number of such reports, Compressed Gas Association formed a and they proved to be one of our most valu- steering committee to help provide able resources of specific, fine-grained a degree of quality control to the information, plus giving projections for the program, but especially to help sub- future. We plan to keep a comprehensive and stantially by providing guidance and current set of corporate Annual Reports as a advice at critical stages of planning ready reference to answer "who needs it", and and implementation of the program. "what are they doing with it?" This committee met three to four times a year during the nearly eight-year 2. Transmission Mechanisms life of the program. In addition, When the State of California began state weights and measures officials public hearings on a code for fluid metering routinely attended these meetings, of cryogens, it was suggested that the Cryo- which provided an invaluable forum genics Division of NBS provide "best values" for the cooperative solution of vexing data for inclusion in the California Code. problems. The gases under consideration were limited to Advertisements and other trade litera- oxygen, nitrogen, argon, and hydrogen. At ture were of moderate importance in locating the request of both the Compressed Gas Asso- meter manufacturers and documenting accuracy ciation and the State of California, we claims. They played no role in validating generated skeleton tables, which were pub- the results, unless one cares to note any lished in the California Code. In addition, changes in advertising copy that might have the Cryogenics Division provided a source occurred after the program. document, NBS Technical Note 361 "Saturated Liquid Densities of Oxygen, Nitrogen, Argon, 3. Contact Mechanism and Parahydrogen" [1]. The latter document Contact mechanisms may be viewed as the was produced specifically to allow trace- terminals of the transmission mechanics ability of the selected values. It was described above, and accordingly will not be revised in 1972 to include compressed liquid re-addressed at any length here. Only a few densities, and again in 1974 in a metric observations may be in order: format. These NBS property data are specifically called out in the California Code •Conversations - especially face-to-face and accordingly have the same weight of law meetings, such as described under "Steering as the flowmeter calibrations and tolerances Committee" above were a prime source of themselves. really useful data.

Other transmission mechanisms include: •Forecasting plays a major role. For instance "Normative" forecasting was per- •Codes, Standards, and Recommended formed by the ISA Ad Hoc committee mentioned Practices, such as adopted in Handbook in the study. Goals, needs, and desires were 44; specified, and the Ad Hoc committee then •Properties Data. NBS property data for worked backwards to the (then) present to several cryogens were adopted in Hand- define what capabilities either existed or book 44. In addition, there is no doubt could be extrapolated to meet the goals. that the wide dissemination and know- Section 4.5 described the major role fore- ledge of the NBS cryogenic fluid pro- casting plays in developing the Division's perty work was the original factor total program of measurement and data ser-

leading the regulatory agencies and vices . the CGA to come to NBS in the first •Round-robin intercomparisons are at the place. heart of transferring the NBS measurement •International Conventions. At one time capability to the states, producers, and or another, we have cooperated with meter manufacturers. For instance, the State the International Organization of Legal of California has now calibrated no less than Metrology (OILM) to facilitate the 58 out of the 60 meters used there in liquid adoption of international codes; per- nitrogen commerce by this means. To further formed type testing of instruments of facilitate such intercomparisons, NBS has foreign manufacture as part of the built and is currently proving a transfer

A-4 standard of its own. Similar round-robins our flow system, round-robins were conducted have been conducted for years on thermocouple with industrial testing laboratories. This materials. Section 2.4 describes other cooperation not only gave us a head start in inter-comparisons accomplished through the our own facility, but also opened the door use of other reference materials. for eventual international agreement (via the OILM, for instance). Numerous contacts were made within the NBS and described in Section 2.4.1, under The fourth group ranks "high" on both

NBS Infrastructure . input and validation, and accordingly was included in the previous sections. For 4. Sources of Information or Validation completeness, they may be listed as: pro- Many sources of information were of fessional and technical societies (e.g.. necessity described in the previous three Instrument Society of America, Compressed sections. Accordingly, the purpose of this Gas Association); reference data organiza- section will be to summarize the above, and tions (e.g., the National Conference of to comment in a general way on the utility of Weights and Measures for Handbook 44; and some of the sources. our own Tech. Note No. 361); the instrument industry (via the Instrument Society For this particular study, the Popular of America and instrument manufacturers). Press, Consumer Organization per se the Trade Other NBS units were invaluable in helping Press, Federal Agencies (regulatory and design the experiments (e.g., Applied Math otherwise), the National Conference of Division), in codifying the results (e.g.. Standards Laboratories (NCSL) and academic Office of Weights and Measures) and in institutions did not constitute a major furnishing other essential services (patent resource, although they surely would in other advice). The role of state agencies, trade types of studies. associations (Compressed Gas Association) Some groups ranked low as input sources, and private companies (cryogen producers, but were virtually indispensable to validat- instrument makers) have already been men- ing the results. Such groups include inter- tioned. The Annual Reports of these pri- national and foreign organizations and do- vate companies have proven to be gold mines cumentary standards bodies (the NCWM provided of documented needs and opportunities. little input, but was essential to codifying Finally, we come to "staff wisdom". the results); the main contribution of the This study of the National Measurement NBS Evaluation Panel was in providing an System is based on 20 years of work by overview of the study as a whole and aiding literally hundreds of men and women in the in the technical quality control. Cryogenics Division of NBS. This resource, A third group could be ranked as "medium" especially in terms of accumulated experi- on the input side, but "high" in terms of ence, would be impossible to duplicate validation. For instance, especially in the elsewhere. Accordingly, "staff wisdom" was earlier stages of the physical evaluation of of inestimable value throughout the study.

A-5

REFERENCES

[I] Roder, H. M., Standard Liquid Densities [12] Mann, D. B., ASRDI Oxygen Technology of Oxygen, Nitrogen, Argon and Para Survey, Flow Measurement Instrumenta- Hydrogen, Nat. Bur. Stds. (U.S.) Tech. tion, NASA SP-3084 (1974). (For sale Note No. 361 (1968) (Revised-1972; Metric by the National Technical Information Supplement-1974) Service, Springfield, VA 22151, Price $4.50). [2] Arvidson, J. M., and Brennan, J. A., Pressure Measurement, ASRDI Technology [13] Sparks, L. L., Low Temperature Mea- Survey, (to be published). surement, ASRDI Oxygen Technology Survey, Volume IV, NASA SP-3073 (1974). [3] Measurements and Data 1_, No. 2, 101-112 (For sale by the National Technical (Mar-Apr 1973). Information Service, Springfield, VA 22151, Price $3.75). [4] Cruz, J. E., Rogers, E. H., and Heister, A. E., Continuous Liquid Level Mea- [14] Roder, H. M., ASRDI Oxygen Technology surements with Time-Domain Reflecto- Survey, Volume V: Density and Liquid metry. Book, Advances in Cryogenic Level Measurement Instrumentation Engineering, 18, 323-(Ed.) K. D. for the Cryogenic Fluids Oxygen, Timmerhaus (Plenum Press, Inc., New Hydrogen and Nitrogen, NASA SP-3083 York, N.Y., 1973). (1974). (For sale by the National Technical Information Service, Spring- [5] Willis, W. L., Disturbance of Capacitive field, VA 22151, Price $3.75). Liquid Level Gauges by Nuclear Radia- tion, Book, Advances in Cryogenic [15] Zudkevitch, D., and Gray, R. D., Jr., Engineering, 12^, 665-72, (Ed.) K. D. Impact of Fluid Properties on Design Timmerhaus (Plenum Press, Inc., New of Equipment for Handling LNG, Ad- York, N.Y., 1967): See also, Willis, W. vances in Cryogenic Engineering, 20, L., and Taylor, J. F., Time Domain (Ed.) K. D. Timmerhaus (Plenum Press, Ref lectometry for Liquid Hydrogen Level Inc., New York, N.Y., 1967). Detection, Unclass. Rept. LA-3473-MS, Los Alamos Scientific Laboratory, Los [16] Olien, N. A., The Cryogenic Data Center, Alamos, New Mexico (Feb. 1966). An Information Service in the Field of Cryogenics, Cryogenics Vol. 11, No. 1, [6] ASME, Fluid Meters, Their Theory and 11-8 (Feb. 1971). Applications, 6th Edition (ASME, New York, N.Y., 1971). [17] Mendenhall, J. R., Johnson, V. J., and Olien, N. A,, Publications and Services [7] ISA, Standard Practices for Instru- of the National Bureau of Standards, mentation, Instrument Society of Cryogenics Division, Institute for America, Pittsburgh, PA. (1970). Basic Standards, Boulder, Colorado 80302 1953-1972, Nat. Bur. Stand.

[8] ISO Recommendation R541 , Measurement of (U.S.) Tech. Note No. 639 (Aug. 1973). Fluid Flow by Means of Orifice Plates and Nozzles (Jan. 1967). [18] Hust, J. G., and Sparks, L. L., Thermal Conductivity of Electrolytic Iron, [9] Richards, R. J., Jacobs, R. B., and SRM 734, from 4 to 300 K, NBS SP 260-31 Pestalozzi, W. J., Measurement of the (1971). This work has been extended Flow of Liquefied Gases with Sharp-edged to include temperatures from 4 to Orifices, Book, Advances in Cryogenic 1000 K by J. G. Hust and P. J. Giarratano Engineering, 4, 272-285 (Ed.) K. D. (In press). Timmerhaus, (Plenum Press, Inc., New York, N.Y., 1960). [19] Hust, J. G., and Sparks, L. L., Thermal Conductivity of Austenitic Stainless [10] Rodeley, A. E., Vortex Shedding Flow- Steel, SRM 735, from 5 to 280 K, NBS meter, Measurements and Data, No. 18, SP 260-35 (1972). This work has been (Nov. -Dec. 1969). extended to include temperatures from 4 to 1200 K by J. G. Hust and P. J. [II] Wyle Laboratories, Final Report, Con- Giarratano (In press). tract No. NASB-1526, Liquid Hydrogen Mass Flowmeter Evaluation (Jan. 1965).

R-1 [20] Must, J. G., Electrical Resistivity of [32] Hale, D., Editor, LNG Growth Continues Electrolytic Iron, SRM 797, and Auste- to Escalate, Pipeline and Gas Journal, nitic Stainless Steel, SRM 798, from 5 pp. 27-32 (June 1974). to 280 K, NBS SP 260-47 (1973). This work has been extended to include tem- [33] Programs on Large Scale Applications peratures up to 1200 K by J. G. Must of Superconductivity in the United and P. J. Giarratano (In press). States, by Powell, Fickett and Birmingham. Appears in Superconducting [21] Hust, J. G., and Giarratano, P. J., Machines and Devices, Proc. NATO Ad- Thermal Conductivity and Electrical vanced Study Institute, Plenum Press Resistivity Standard Reference Materials: (1974). Arc cast and Sintered Tungsten, SRM's 730 and 799, from 4 to 3000 K, NBS [34] Weekly Energy Report, Vol. 2, No. 41 SP-260-XX (In review). (October 14, 1974).

[22] Schooley, J. F., et al . , Preparation and [35] Weekly Energy Report, Vol. 2, No. 48 Use of Superconductive Fixed Point (Dec. 2, 1974). Devices, SRM 767, NBS SP 260-44 (1972). [36] U.S. Industrial Outlook 1974, with [23] Standard Reference Materials 1973 Projections to 1980 (for sale by the Catalog, National Bureau of Standards Superintendent of Documents, U.S. Special publication No. 260 (available Government Printing Office, Washington from the U.S. Government Printing D.C. 20234, Price $3.40). Office, Washington, D.C. 20402, Price

$1.25 ; or through the Office of [37] Instrument Society of America Ad Hoc Standard Reference Materials, National Committee Report on Cryogenic Flow Bureau of Standards, Washington, D.C. Measurement, prepared under the Spon- 20234). sorship of the ISA Technical Department, T. J. Kehoe, Vice President (June [24] Curto, J. M., Growth of the Compressed 1967). Gas Industry, Paper presented at 55th Annual Meeting, Compressed Gas Assoc., [38] Federal Funds for Research, Development 5-21 (Jan. 1968). and other Scientific Activities, Fiscal Years 1972, 1973 and 1974, [25] Lofstrom, J., Uses of LNG for the Future, (the National Science Foundation, Pipe Line Industry 29, No. 4, 95-97 NSF-74-300, Vol. 22, Dec. 1973). (Oct. 1968). [39] Flynn, T. M., Cryogenics and National [26] U. S. Industrial Outlook 1974, U.S. Dept. Goals, paper A-1 in Advances in Cryo- of Commerce (available from USGPO, genic Engineering, (Proc. 1968 Cryo- Stock No. 0325-0004). genic Engineering Conf.), Vol. 14, 1-12. Plenum Press, New York (1969). [27] Industry Profiles, U.S. Dept. of Commerce (available from the USGPO). [40] Flynn, T. M., and Smith, C. N., Trends in Cryogenic Fluid Production in the [28] Minerals Yearbook - 1972, Vol. I, Metals, United States, Bull. Inst. Int. Froid, Minerals, and Fuels, Dept. of the Annexe 1970-2 (Proc. Comm. I, Conf. Interior, Bur. of Mines, p. 807 (1974). on Cryophysics and Cryoengineering, Tokyo, Japan, Sept. 11-12, 1970) [29] Gas Facts - A Statistical Record of p. 241-7. the Gas Utility Industry, 1972 data, p. 58, table 53 (The American Gas [41] Birmingham, B. W., Superconductivity Association, 1973). Programs of the AEC, Special Publica- tion of the AEC, WASH-1081 (June 1967). [30] Hale, D., Editor, World LNG Carrier Fleet Growing, Pipeline and Gas Journal, [42] Arp, V. C, Clark, A. F., and Flynn, pp. 42-44 (June 1974). T. M., Superconducting Levitation of High Speed Vehicles, Transp. Eng. J., [31] National Gas Survey, Federal Power Vol. 99, No. TE4, 873-85 (Nov. 1973). Commission, Vol. II, Supply Task Force Reports, p. 390; Federal Power Com- mission, 1973).

R-2 [43] Smith, R. V., Current Developments in

Cryomedicine, Cryogenics, 7_, No. 2, 84-9 (April 1969).

[44] Mann, D. B., and Roder, H. M. , Liquefied Natural Gas as a Cryogenic Fluid-- Instrumentation and Properties, Proc. Transmission Conf. of AGA, New Orleans, La., (May 26-27, 1969).

[45] Mann, D. B., Diller, D. E., and Olien, N. A., Measurements of Liquefied Na- tural Gas in Commerce, Proc. Distri- bution Conf. of AGA, Washington, D.C., (May 1973).

[46] Hord, J. (Ed.), Selected Topics on Hydrogen Fuel, Nat. Bur. Stds. (U.S.) Spec. Publ. No. 419 (May 1975). Avail- able from the USGPO, Stock No. C-13. 410:419, $2.80.

[47] Flynn, T. M. , et al.. Superconducting Electrical Generators of Central Power Station Use, Advances in Cryogenic Engineering, j[9, (Ed.) K. D. Timmerhaus (Plenum Press, Inc., New York, N.Y., 1974).

[48] Strobridge, T. R., Cryogenic Refrigerators --An Updated Survey, Nat. Bur. Stand. (U.S.), Tech. Note No. 655, (June 1974). Available from the USGPO Stock No. C13. 46:655, $0.30.

[49] Kamper, R. A., and Sullivan, D. B., Developments in Cryoelectronics, Nat. Bur. Stand. (U.S.), Tech. Note No. 630, (Nov. 1972). Available from the USGPO, Stock No. C13. 46:630, $0.70.

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bibl lofiraphy or literature survey, mention it here.)

The Cryogenics Division of NBS has evolved as the nation's central laboratory for cryogenics, much as NBS itself has evolved as the nation's central laboratory with both broad and specific responsibilities. Cryogenic measurement and data outputs provide the common foundation for all the institutions and agencies throughout the nation employing cryogenics to solve their problems. This Study of the National Measurement System showed that the Cryogenics Division of NBS provides almost every category of measurement and data service that NBS itself provides: not just an instrumentation system (including, for example, pressure, temperature, density, liquid level, flow rate, etc.), but also properties of fluids (both thermodynamic and transport properties); properties of solids (thermal, mechanical and electrical); an interface with the users through systems integration and advisory and consulting services; and a dissemination network through the Cryogenic Data Center. This study documents the impact, status and trends of the cryogenic measurement system and specifically illustrates these characteristics wherever possible with a specific case study, a recently completed measurements and data program for the flow- Tietering of liquid nitrogen.

17. Kl > WORDS (.SIX to twelve entries; alphabetic al order, capitalize only the first letter of the first key uord unless a proper

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Cryogenics; data; flowmeter; instrumentation; measurements; National Measurement System.

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