Testing of Measuring Equipment
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A111D4 T3fl23^ Ref. U.S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS TESTING OF MEASURING : i l' ; ■ ' • ' 1 * EQUIPMENT ' ; ■; •i ’ A MANUAL FOR WEIGHTS AND MEASURES OFFICIALS NATIONAL BUREAU OF STANDARDS HANDBOOK 4S U. S. DEPARTMENT OF COMMERCE CHARLES SAWYER, Secretary NATIONAL BUREAU OF STANDARDS E. U. CONDON, Director NATIONAL BUREAU OF STANDARDS HANDBOOK 45 TESTING OF MEASURING EQUIPMENT A Manual for Weights and Measures Officials Ralph W. Smith Issued May 15, 1951 UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON: 1951 For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D.C. $1.25 National Bureau of Standards AUG 1 1951 72.2.4-b PREFACE This volume completes the series of four Handbooks of the National Bureau of Standards designed to present in compact form comprehensive information relative to weights and measures regulatory activities. Current editions of the other three handbooks of this series are Handbook H26, Weights and Measures Admin¬ istration, published in 1941 and superseding Handbook Hll of the same title; Handbook H37, Testing of Weighing Equipment, pub¬ lished in 1945; and Handbook H44, Specifications, Tolerances, and Regulations for Commercial Weighing and Measuring Devices, published in 1949, and superseding several earlier publications issued under similar titles. Handbook H26 treats of the general aspects of the subject of weights and measures administration. Handbook H37 describes various types of scales and weights, dis¬ cusses the principles of their operation, and presents methods for their inspection and test. Handbook H44 presents the codes of specifications, tolerances, and regulations for commercial weights and measures and weighing and measuring devices, adopted by the National Conference on Weights and Measures and recom¬ mended by the National Bureau of Standards for State promul¬ gation. Necessarily, the Handbook of specifications, tolerances, and regulations is issued periodically in order to present up-to-date information, incorporating the changes made from time to time by the National Conference. The present volume deals with commercial measures and meas¬ uring devices, and includes descriptions of these instruments, recommendations for the testing apparatus needed for their of¬ ficial examination, and instructions for their inspection and test¬ ing by weights and measures officials. This Handbook is a com¬ panion volume to Handbook H37; taken together, these two Handbooks are intended to provide practical instructions to weights and measures officials for the inspection and testing of all of the types of commerical weighing and measuring devices which such officials are normally called upon to examine. As was done in Handbook H37, the present volume includes step-by-step testing outlines which supplement the several discussions on testing pro¬ cedures. Also included, in the first three chapters, are some gen¬ eral comments relative to inspection and testing, which are appli¬ cable to all classes of commercial devices. It is inevitable that the weights and measures official will en¬ counter in the course of his official duties measures or measuring devices which differ from the general types treated herein. It is believed, however, that no difficulty should be experienced in adapt¬ ing to practically any variation from the general type, the basic principles which are outlined, and in modifying appropriately the testing outlines which are presented. It is desired to acknowledge the valuable assistance rendered by members of the staff of the National Bureau of Standards in reviewing portions of the text of this Handbook that relate to their special fields. Similar assistance has been rendered by numer- iii Preface IV ous representatives of equipment manufacturers and industry, and this assistance is gratefully acknowledged. The courtesy of those individuals and organizations who have supplied photo¬ graphic material and who have permitted reproduction, in whole or in part, of equipment drawings, is greatly appreciated. The collaboration of W. S. Bussey and M. J. J. Harrison, each of whom has reviewed the entire manuscript and offered many valuable suggestions, is especially acknowledged. Although this Handbook has been prepared primarily for use by weights and measures officials of the States, counties, and cities, it is believed that much of the information presented will be useful to persons employed by commercial and industrial establishments in the maintenance of measuring equipment. E. U. Condon, Director. CONTENTS Pa^e Preface _ iii Chapter 1.—Introduction _ 1 Scope of Handbook_ 1 Uniformity of requirements_ 1 O Tolerances for commercial equipment_ o Testing apparatus _ 4 General _ 6 References _ 7 Chapter 2.—Inspection of measuring equipment_ 8 Inspection and testing_ 8 Necessity for inspection_ 8 Specification requirements_ 8 General considerations _ 9 Misuse of equipment_ 11 Recommendations _ 11 Accurate and correct equipment_ 11 References _ 12 Chapter 3.—Adjustment, rejection, and sealing of measuring equipment _ 13 Adjustment of equipment_ 13 Rejection of equipment_ 16 Sealing of equipment_ 18 References _ 20 Chapter 4.—Linear measures_ 21 Description _ 21 Inspection ___ 23 Testing apparatus_ 23 Testing procedure_ 26 Testing outlines _ 29 References _ 31 Chapter 5.—Fabric-measuring devices_ 32 Description _ 32 Inspection _ 34 Testing apparatus _ 35 Testing procedure _ 36 Testing outline_ 39 References _ 40 Chapter 6.—Taximeters _ 41 Description _ 41 Inspection _ 42 Testing apparatus _ 43 Testing procedure _ 45 General considerations _ 45 Time test_ 47 Bench mileage test_ 49 Road mileage test_ 53 Wheel mileage'test_ 54 Sealing _ 55 V VI Contents Page Testing outlines _ 55 Supervision over use_ 59 References _ 60 Chapter 7.—Odometers_ 61 Description _ 61 Inspection _ 61 Testing apparatus _ 61 Testing procedure _ 62 Testing outlines _ 65 Chapter 8.—Liquid measures_ 67 Description _ 67 Inspection _ 68 Testing apparatus _ 68 Testing procedure _ 69 Testing outlines _ 73 References _ 74 Chapter 9.—Graduates _ 75 Description _ 75 Inspection _ 75 Testing apparatus _ 76 Testing procedure _ 77 Testing outlines _ 80 References _ 82 Chapter 10.—Measure-containers_ 83 Description _ 83 Inspection _ 84 Testing apparatus _ 85 Testing procedure ___ 85 Testing outline_ 86 Supervision over use_ 86 Chapter 11.—Milk bottles_ 88 Description _ 88 Inspection _ 89 Testing apparatus _ 90 Testing procedure _ 96 Testing outlines _ 99 Supervision over use_ 100 References _ 102 Chapter 12.—Lubricating-oil bottles_ 103 Description _ 103 Inspection _ 103 Testing apparatus _ 104 Testing procedure _ 104 Supervision over use_ 104 References _ 105 Chapter 13.—Liquid-measuring devices_ 106 Note relative to liquefied petroleum gas measuring devices _ 106 Description _ 106 Inspection _ 116 Testing apparatus _ 117 Testing procedure _ 125 Piston-type devices _ 126 Visible-type devices __i_ 130 Contents vii Page Retail meter-type devices_ 134 Wholesale meters_ 137 Testing outlines _ 139 Supervision over use_ 145 References _ 147 Chapter 14.—Grease-measuring devices_ 148 Description _ 148 Inspection _ 149 Testing apparatus _ 149 Testing procedure _ 152 Testing outlines _ 156 Chapter 15.—Vehicle tanks_ 159 Description _ 159 Inspection _ 164 Testing apparatus_ 166 General considerations _ 166 For compartment calibration_ 167 For vehicle tank meters_ 176 Testing procedure ___ 178 General considerations _ 178 Compartment calibration_ 184 Meter testing _ 190 Testing outlines _ 192 References _ 197 Chapter 16.—Dry measures_ 198 Description _ 198 Inspection _ 198 Testing apparatus_ 198 Testing procedure _ 199 References _ 201 Chapter IT.—Berry baskets and boxes_ 202 Description _ 202 Inspection _ 202 Testing apparatus _ 202 Testing procedure _ 202 Chapter 18.—Water, gas, and electricity meters_ 204 Testing of Measuring Equipment Ralph W. Smith A manual for State and local weights and measures officials, describing various types of commercial measur¬ ing equipment, the principles of their operation, and methods for their inspection and test. Chapter 1.—INTRODUCTION Scope of Handbook.—This Handbook is directed pri¬ marily to procedures recommended for use by weights and measures officials when exercising their routine regu¬ latory controls over commercial measuring equipment. Accordingly, recommendations are conditioned upon the special characteristics of regulatory control as distin¬ guished from commercial or industrial maintenance serv¬ ice, and the limitations under which weights and measures organizations are normally required to operate, particu¬ larly budgetary limitations, have been kept in mind. Testing procedures recommended are, in general, the minimum requirements considered necessary to enable the official to determine whether or not equipment should be approved for commercial use. More exhaustive tests than those specified are frequently desirable; minimum procedures should be expanded to whatever extent is deemed by the official to be appropriate, whenever special conditions or circumstances indicate the advisability of this. Uniformity of Requirements.—Recommendations here¬ in are based upon the codes of specifications, tolerances, and regulations for commercial devices as adopted by the National Conference on Weights and Measures and rec¬ ommended by the National Bureau of Standards for State promulgation.1 Whenever reference is made to speci¬ fications, tolerances, or regulations, the National Con¬ ference material is meant unless the contrary is stated.