o NBS SPECIAL PUBLICATION 250 1982 EDITION U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards] Calibration and Related Measurement Services of the National Bureau of Standards NATIONAL BUREAU OF STANDARDS The National Bureau of Standards* was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and the Institute for Computer Sciences and Technology. THE NATIONAL MEASUREMENT LABORATORY provides the national system of physical and chemical and materials measurement; coordinates the system with measurement systems of other nations and furnishes essential services leading to accurate and uniform physical and chemical measurement throughout the Nation's scientific community, industry, and commerce; conducts materials research leading to improved methods of measurement, standards, and data on the properties of materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; develops, produces, and distributes Standard Reference Materials; and provides calibration services. The Laboratory consists of the following centers: Absolute Physical Quantities^ — Radiation Research — Chemical Physics — Analytical Chemistry — Materials Science THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities; provides engineering measurement traceability services; develops test methods and proposes engineering standards and code changes; develops and proposes new engineering practices; and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers: Applied Mathematics — Electronics and Electrical Engineering^ — Manufacturing Engineering — Building Technology — Fire Research — Chemical Engineering^ THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and provides the technical foundation for computer-related policies of the Federal Government. The Institute consists of the following centers: Programming Science and Technology — Computer Systems Engineering. 'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. 'Some divisions within the center are located at Boulder, CO 80303. Calibration and Related Measurement Services of the National Bureau of Standards 1982 EDITION L. J. Kieffer, Editor Office of Measurement Services National Bureau of Standards Washington, DC 20234 Supersedes NBS Special Publication 250 - 1980 Edition U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director Issued October 1982 Library of Congress Catalog Card Number: 63-60099 National Bureau of Standards Special Publication 250 - 1982 Edition Natl. Bur. Stand. (U.S.), Spec. Publ. 250 - 1982 Ed., 114 pages (Oct. 1982) CODEN: XNBSAV U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1982 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 Price $6.00 (Add 25 percent for other than U.S. mailing) FOREWORD NBS Special Publication 250 provides detailed descriptions of the currently available NBS calibration services, special test services, and measurement assurance programs. This revised edition reflects the services available as of the first quarter of 1982 and reflects a number of important changes since the 1980 Edition of SP250 was published. Future editions of SP250 will be published periodically as NBS services change. An Appendix to SP250 is published every 6 months (April and October) that lists current prices for the services described in this publication and the NBS points of contact (addresses and phone numbers) from whom additional information can be obtained. NBS will notify users of SP250 of changes in services or proposed changes in services by means of announcements in the Appendix. In addition, information about upcoming NBS Measurement Seminars is announced there. If you are not already on our mailing list for SP250 Appendices and wish to be, fill in and return the card at the back of this document. Many users of this publication find it convenient ta keep SP250 and the current price list (Appendix) in a three-ring binder. It is important that you refer to the current issue of the Appendix in order to have up-to-date information with respect to NBS points of contact. We call your attention to the availability of a variety of new Measurement Assurance Program (MAP) services. These are carefully designed quality control programs for critical measurements that allow the user to achieve a high level of confidence that the measurements being made in the user's laboratory are consistent with national standards and adequate for their intended use. As noted in the text. Measurement Assurance Program services are available for some traditional units (e.g., mass) and for some units associated with new technologies (e.g., laser power and energy). The Office of Measurement Services welcomes suggestions on how this publication can be made more useful to those who rely on NBS measurement services. Suggestions are also welcome concerning needs for new calibration services, measurement assurance programs, or other measurement services. BRIAN C. BELANGER, Chief Office of Measurement Services iii ABSTRACT This publication provides descriptions of the currently available NBS calibration services, special test services, and measurement assurance programs. In addition, each section describing specific services contains references to additional publications giving more detail about the measurement techniques and procedures used. This revised edition reflects the services available as of the first quarter of 1982. NBS Special Publication 250 was last issued in 1980. The Appendix to SP250 is reissued every 6 months (April and October). It lists current prices for the services described in this publication and the NBS points of contact (addresses and phone numbers) from whom additional information can be obtained. Key words: calibration; measurement assurance; measurement services; standards; traceability. iv CONTENTS Page Foreword in Abstract iv Chapter I I. General Information 1 A. Introduction 1 B. How to Use This Publication 2 C. Request Procedure 3 D. Shipping, Insurance, and Risk of Loss 3 E. Priorities and Time of Completion 4 F. Use of NBS Reports 4 G. Units 4 H. Measurement Assurance Programs 5 I. Classification of NBS Measurement Services 6 J. Traceability 7 K. Policy on Fees for Services 7 L. Legislative Authority 7 Chapter II II. Dimensional Measurements 9 A. Length 9 B. Dimensional Metrology 11 C. Flatness, Roundness, and Angular Measurements 13 D. Surface Texture 14 E. Volume and Density 15 Chapter III III. Mechanics 19 A. Mass , 19 B. Force 21 C. Vibration Measurements 22 D. Acoustics 23 E. Ultrasonics 24 F. Fluid Flow 25 G. Aerodynamics 26 Chapter IV IV. Electrical Measurements—DC and Low Frequency 27 A. Resistance Measurements 29 B. Precision Apparatus 32 C. Impedance Measurements 32 D. Voltage Measurements 35 E. Electrical Instruments (ac-dc) 37 F. Instrument Transformers and Comparators 38 G. High Voltage and Energy Measurements 39 H. Data Converters 42 I. AC Voltage Calibrations in Range of 0.1 Hz - 10 Hz 45 V 1 Chapter V V. Electromagnetic Measurements at Radio, Microwave and Millimeter Wave Frequencies 47 A. Introduction 47 B. Attenuation Measurements 48 C. Electromagnetic Fields and Antenna Measurements 50 D. Impedance and/or Reflection Coefficient 53 E. Noise Temperature Measurements 56 F. Phase Shift 57 G. Power Measurements 58 H. Voltage Measurements 61 I. Baseband Pulse Parameters 62 J. Electromagnetic Interference Measurements 64 Chapter VI VI. Time and Frequency 67 A. NBS Frequency Standard 67 B. NBS Time and Frequency Dissemination Services 67 C. Direct Signal Source Calibration Services 67 Chapter VII VII. Thermodynamic Quantities 69 A. Thermometry 69 B. Pressure and Vacuum Measurements 72 C. Humidity Measurements 74 D. Cryogenic Measurements 75 Chapter VIII VIII. Optical Measurements 77 A. Radiometry