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Specifications, Tolerances, and 

Other Technical Requirements for 

Weighing and Measuring Devices

as adopted by the 100th National Conference on Weights and Measures 2015 

Editors:

Tina Butcher

Clark Cooney

Linda Crown

Rick Harshman

Carol Hockert, Chief 

Office of Weights and Measures 

Physical Measurement Laboratory 

This document is available free of charge from:

http://dx.doi.org/10.6028/NIST.HB.44-2016

November 2015 

U. S. Department of Commerce

Penny Pritzker, Secretary

National Institute of Standards and Technology

Willie May, Under Secretary of Commerce for Standards and Technology and Director

NIST Handbook 44

2016 Edition

Supersedes NIST Handbook 44, 2015 Edition
WASHINGTON: 2015

Certain commercial entities, equipment, or materials may be identified in this document in order to describe an 

experimental procedure or concept adequately. Such identification is not intended to imply recommendation or 

endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, 

materials, or equipment are necessarily the best available for the purpose.

National Institute of Standards and Technology Handbook 44, 2016 Edition

Natl. Inst. Stand. Technol. Handb. 44, 2016 Ed., 516 pages (Nov. 2015) 

CODEN: NIHAE2 

This publication is available free of charge from:

http://dx.doi.org/10.6028/NIST.HB.44-2016
iii

Foreword

NIST Handbook 44 was first published in 1949, having been preceded by similar handbooks of various designations 

and in several forms, beginning in 1918.

NIST Handbook 44 is published in its entirety each year following the Annual Meeting of the National Conference 

on Weights and Measures (NCWM). The Committee on Specifications and Tolerances of the NCWM developed 

the 2015 edition with the assistance of the Office of Weights and Measures (OWM) of the National Institute of 

Standards and Technology (NIST). This handbook includes amendments endorsed by the 100th National Conference 

on Weights and Measures during its Annual Meeting in 2015. 

NIST has a statutory responsibility for “cooperation with the states in securing uniformity of weights and measures 

laws and methods of inspection.” In partial fulfillment of this responsibility, NIST is pleased to publish these 

recommendations of the NCWM.

This handbook conforms to the concept of primary use of SI (metric) measurements recommended in the Omnibus 

Trade and Competitiveness Act of 1988 by citing SI units before U.S. customary units where both units appear 

together and placing separate sections containing requirements in SI units before corresponding sections containing 

requirements in U.S. customary units. In some cases, however, trade practice is currently restricted to the use of 

U.S. customary units; therefore, some requirements in this handbook will continue to specify only U.S. customary

units until the NCWM achieves a broad consensus on the permitted SI units.

In accord with NIST policy, the meter/liter spellings are used in this document. However, the metre/litre spellings 

are acceptable, and are preferred by the NCWM.

It should be noted that a space has been inserted instead of commas in all numerical values greater than 9999 in this 

document, following a growing practice, originating in tabular work, to use spaces to separate large numbers into 

groups of three digits. This avoids conflict with the practice in many countries to use the comma as a decimal 

marker.

You are invited to provide online feedback regarding this document 

at: https://www.surveymonkey.com/s/customer-satisfaction-pub

or by e-mail to: owm@nist.gov.

______________________________________________________________________________________________________ 

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Handbook 44 – 2015 

iv

Committee on Specifications and Tolerances

of the 100th Conference

Mahesh Albuquerque, Colorado

Matthew Curran, Florida

Ivan Hankins, Iowa

Rachelle Miller, Wisconsin

Jane Zulkiewicz, Town of Barnstable, Massachusetts 

Luciano Burtini, Measurement Canada, Technical Advisor

Clark Cooney, NIST, Technical Advisor

Rick Harshman, NIST, Technical Advisor

Darrell Flocken, NCWM, NTEP Specialist

Past Chairmen of the Committee

Conference Chairman Conference Chairman

8-11 L.A. Fischer, NBS 71-72 F. Gerk, NM

12-28 F.S. Holbrook, NBS 73 K. Butcher, MD

29-38 J.P. McBride, MA 74 R. Andersen, NY

39-42 R.E. Meek, IN 75 D. Watson, TX

43-44 J.E. Brenton, CA 76 J. Truex, OH

45-47 C.L. Jackson, WI 77-78 C. Carroll, MA

48 T.C. Harris, VA 79 J. Jeffries, FL

49-50 R.E. Meek, IN 80 R. Suiter, NE

51-52 G.L. Johnson, KY 81 G. West, NM

53 H.D. Robinson, ME 82-83 R. Murdock, NC

54-55 R. Rebuffo, NE 84 D. Brown, IA

56-57 D.E. Konsoer, WI 85 M. Hopper, CA

58 J.C. Mays, FL 86 G. Shefcheck, OR

59 T.F. Brink, VT 87 M. Coyne, MA

60 W.S. Watson, CA 88 R. Wotthlie, MD

61 K.J. Simila, OR 89 C. VanBuren, MI

62 W.E. Czaia, MN 90 J. Kane, MT

63 M.L. Kinlaw, NC 91 C. Cooney, OR

64 J.A. Bird, NJ 92 M. Sikula, NY

65 D.A. Guensler, CA 93 C. Fulmer, SC

66 G.A. Delano, MT 94 T. R. Lucas, OH

67 F.C. Nagele, MI 95 B. Saum, San Luis Obispo Co., CA

68 L.H. DeGrange, MD 96-97 S. Giguere, ME

69 S.A. Colbrook, IL 98 K. Ramsburg, MD

70 D.A. Guensler, CA 99 B. Gurney, UT

______________________________________________________________________________________________________ 

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Handbook 44 – 2016 Table of Contents

v 

Table of Contents 

Page

Foreword.......................................................................................................................................................................iii

Committee Members ....................................................................................................................................................iv

Past Chairmen of the Committee.................................................................................................................................. iv 

2015 Amendments.......................................................................................................................................................vii

2015 Editorial Changes ................................................................................................................................................. x 

Introduction .................................................................................................................................................................. 1 

Section 1.

1.10. General Code.........................................................................................................................................1-1 

Section 2.

2.20. Scales ....................................................................................................................................................2-3 

2.21. Belt-Conveyor Scale Systems.............................................................................................................2-57

2.22. Automatic Bulk Weighing Systems....................................................................................................2-73 

2.23. Weights ...............................................................................................................................................2-83

2.24. Automatic Weighing Systems.............................................................................................................2-91

2.25. Weigh-In-Motion Systems Used for Vehicle Enforcement Screening – Tentative Code ................. 2-109

Section 3.

3.30. Liquid-Measuring Devices....................................................................................................................3-3 

3.31. Vehicle-Tank Meters...........................................................................................................................3-29

3.32. Liquefied Petroleum Gas and Anhydrous Ammonia Liquid-Measuring Devices...............................3-45

3.33. Hydrocarbon Gas Vapor-Measuring Devices .....................................................................................3-59

3.34. Cryogenic Liquid-Measuring Devices ...............................................................................................3-71

3.35. Milk Meters.........................................................................................................................................3-83

3.36. Water Meters.......................................................................................................................................3-93

3.37. Mass Flow Meters............................................................................................................................. 3-101

3.38. Carbon Dioxide Liquid-Measuring Devices ..................................................................................... 3-115

3.39. Hydrogen Gas-Measuring Devices – Tentative Code ....................................................................... 3-131

3.40. Electric Vehicle Fueling Systems – Tentative Code ......................................................................... 3-145 

Section 4.

4.40. Vehicle Tanks Used as Measures..........................................................................................................4-3 

4.41. Liquid Measures....................................................................................................................................4-9 

4.42. Farm Milk Tanks.................................................................................................................................4-13

4.43. Measure-Containers ............................................................................................................................4-21

4.44. Graduates ............................................................................................................................................4-27

4.45. Dry Measures......................................................................................................................................4-33

4.46. Berry Baskets and Boxes.....................................................................................................................4-39

Section 5.

5.50. Fabric-Measuring Devices ....................................................................................................................5-3 

5.51. Wire- and Cordage-Measuring Devices................................................................................................5-9

5.52. Linear Measures..................................................................................................................................5-15

5.53. Odometers...........................................................................................................................................5-19

5.54. Taximeters...........................................................................................................................................5-25

5.55. Timing Devices...................................................................................................................................5-35 

5.56.(a) Grain Moisture Meters........................................................................................................................5-43

5.56.(b) Grain Moisture Meters........................................................................................................................5-55 

5.57. Near-Infrared Grain Analyzers............................................................................................................5-65 

5.58. Multiple Dimension Measuring Devices.............................................................................................5-75 

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Table of Contents Handbook 44 – 2016 

vi

Table of Contents (continued)

 

 Page

5.59. Electronic Livestock, Meat, and Poultry Evaluation Systems and/or Devices....................................5-87 

Appendices

A. Fundamental Considerations Associated with the Enforcement of Handbook 44 Codes..................... A-1 

B. Units and Systems of Measurement - Their Origin, Development, and Present Status ....................... B-1

C. General Tables of Units of Measurement............................................................................................. C-1

D. Definitions............................................................................................................................................ D-1

______________________________________________________________________________________________________ 

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Handbook 44 – 2016 Amendments/Editorial Changes

vii

2015 Amendments

The following table lists the codes, paragraphs, and pages in which the 100th National Conference on Weights and 

Measures made amendments. In the column headed “Action,” changes are noted as “added,” “amended,” “deleted,” or 

“renumbered.” Each code, section, or paragraph that has been changed will be noted as “Added 2015” or 

“Amended 2015.”

SECTION CODE S&T

ITEM NO.

PARAGRAPH ACTION PAGE

Introduction BOD 

120-7 

A. Source; 

C. Amendments; Amended 1 

D. Submission of Agenda 

Items – Preamble;

E. Submission Process;

F. Procedures;

G. Criteria for Inclusion on 

the NCWM Committee’s 

Agenda;

H. Exceptions to Policy for 

Submission of Items to a 

NCWM Committee Agenda; 

Submission of “Priority” 

Items;

I. Committee Agenda;

J. Interim Meeting; 

K. Interim Meeting Report;

L. Classifications for 

Agenda Items;

M. Comments on Interim 

Reports; and

N. Annual Meeting

Deleted; 

remaining 

paragraphs relettered

1 to 3

1.10. General Code 310-2 G-UR.4.1. Maintenance 

Equipment Amended 1-11

2.20 Scales 320-2 

T.N.3.5. Separate Main 

Elements: Load 

Transmitting Elements, 

Indicating Elements, Etc.

Amended 2-40

2.21. Belt-Conveyor Scale 

Systems

321-1 A.1. General Amended 2-59

321-2 S.4. Marking Requirements Amended 2-61

321-3 N.2.1. Initial Verification Amended 2-63

321-4 N.2.3. Minimum Test Load Amended 2-64

321-5 N.3.1.1. Determination of 

Zero Amended 2-65

321-6 UR.1.2. Conveyor 

Installation Amended 2-67 

______________________________________________________________________________________________________ 

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Amendments/Editorial Changes Handbook 44 – 2016 

viii

SECTION CODE S&T

ITEM NO.

PARAGRAPH ACTION PAGE

321-7 

UR.3. Maintenance 

Requirements – Scale and 

Conveyor Maintenance 

Amended 2-69 to

2-71 

2.25.

Weigh-In-Motion 

Vehicle Scales for 

Law Enforcement – 

Tentative Code

320-4 

Section 2.25. Weigh-InMotion Vehicle Scales for 

Law Enforcement – 

Tentative Code

Tentative Code 

Added to 

Handbook

2-109 to 

2-118

3.30. Liquid Measuring 

Devices 330-2 

Table S.2.2. Categories of 

Device and Methods of 

Sealing

Amended 3-13

3.40.

Electric Vehicle 

Fueling Systems – 

Tentative Code

360-5 

Section 3.40. Electric 

Vehicle Fueling Systems – 

Tentative Code

Tentative Code 

Added to 

Handbook

3-145 to

3-164

5.54. Taximeters

354-1 S.1.1.1. Recording Elements Amended 5-27

354-3 

S.1.3.3. Passenger 

Indications Added 5-27 to5-28

S.1.3.3.1. Additional 

Information Added 5-28

S.1.3.3.2. Fare and Extras 

Charges Added 5-28

354-4 S.1.8. Protection of 

Indications Amended 5-29

354-5 S.1.9. Recorded 

Representation Amended 5-29

5.55. Timing Devices 360-5 

A.1. General Amended 5-37

S.1.1.1. General Amended 5-37

S.1.1.5. Operation of InService Indicator Light Amended 5-37

S.1.4. Recorded 

Representations Amended 5-38

S.1.4.1. Recorded 

Representations, Electric 

Vehicle Supply Equipment 

Timing Devices

Added 5-38

S.1.4.1.1. Duplicate Receipts Added 5-38

S.1.4.2. Recorded 

Representations, All Other 

Timing Devices

Added 5-39

S.3. Interference Added 5-39

S.4. Provisions for Sealing Added 5-39

S.5. Power Interruption Added 5-39

S.5.1. Power Interruption Added 5-39

S.5.2. User Information Added 5-39

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ix

SECTION CODE S&T

ITEM NO.

PARAGRAPH ACTION PAGE

5.55.

(cont.) Timing Devices 360-5 N.3. Interference Tests, EVSE Added 5-40

5.55.

(cont.) Timing Devices 360-5 

T.1.3. On Parking Meters 

and Other Timing Devices 

Used to Assess Charges for 

Parking

Amended 5-41

Table T.1.3. Maintenance 

and Acceptance Tolerances 

for Parking Meters and 

Other Timing Devices Used 

to Assess Charges for 

Parking

Amended 5-41

UR.1. Statement of Rates Amended 5-41

Appendix D Definitions

321-8 Weigh-Belt System Added D-28

360-3 Point-of-Sale-System Amended D-21

______________________________________________________________________________________________________ 

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Amendments/Editorial Changes Handbook 44 – 2016 

x 

2015 Editorial Changes

SECTION CODE PARAGRAPH ACTION PAGE

Introduction Form 15 Updated Form 4

2.21. Belt-Conveyor 

Scale Systems UR.3.1. Renumber to UR.3. 2-69

3.32. 

LPG and 

Anhydrous 

LiquidMeasuring 

Devices

S.1.2.2. Reformatted for ease of use 3-48

5.54. Taximeter N.1.3.2. Tire Pressure Replaced “odometer” with 

“taximeter” 5-32

Appendix C

Units of Mass 

Not Greater than 

Pounds and 

Kilograms

1 avdp. pound Corrected figure 453 592.37.37 C-14

Appendix D Definitions

Grain sample Added quantity to “bulk quantity

grain” D-13 

Automatic hopper 

scale Removed term D-6 

______________________________________________________________________________________________________ 

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Handbook 44 – 2016 Introduction

1 

Introduction

A. Source.

The specifications, tolerances and other technical requirements in this handbook comprise all of those adopted by 

the National Conference on Weights and Measures, Inc. (NCWM). Contact NCWM at:

1135 M Street, Suite 100 Phone: (402) 434-4880 E-mail: info@ncwm.net

Lincoln, NE 68508 Fax: (402) 434-4878 URL: www.ncwm.net

The NCWM is supported by the National Institute of Standards and Technology (NIST), which provides its 

Executive Secretary and publishes some of its documents. NIST also develops technical publications for use by 

weights and measures agencies; these publications may subsequently be endorsed or adopted by NCWM.

All of the specifications, tolerances, and other technical requirements given herein are recommended by NCWM for 

official promulgation in and use by the states in exercising their control of commercial weighing and measuring 

apparatus. A similar recommendation is made with respect to the local jurisdictions within a state in the absence of 

the promulgation of specifications, tolerances, and other technical requirements at the state level. 

(Amended 2015)

B. Purpose.

The purpose of these technical requirements is to eliminate from use, weights and measures and weighing and 

measuring devices that give readings that are false, that are of such construction that they are faulty (that is, that are 

not reasonably permanent in their adjustment or will not repeat their indications correctly), or that facilitate the 

perpetration of fraud, without prejudice to apparatus that conforms as closely as practicable to the official standards.

C. Amendments.

Proposed amendments to NIST Handbook 44 are deliberated and developed by NCWM’s Committee on 

Specifications and Tolerances before presentation to the general membership for a vote. In some instances, 

amendments that significantly affect other NIST Handbooks may be processed jointly by two or more committees.

Amendments to the handbooks are made in accordance with NCWM procedures and policies. The process begins at 

the regional weights and measures association meetings in the fall of each year and is culminated at the NCWM 

Annual Meeting in July. After passing through one or more of the regional associations the proposed amendment is 

placed on the agenda of the appropriate NCWM committee for consideration at NCWM’s Interim Meeting in 

January and after final deliberation and development by the committee the amendment may be presented to the 

membership for a vote at the annual NCWM meeting in July. NCWM policy provides for exceptions to the process 

to accommodate urgent or priority items. NIST staff provides technical assistance and advice throughout the 

process.

The policy is available on the NCWM website at www.ncwm.net. For information on the regional weights and 

measures associations, visit www.ncwm.net/resource/regional_associations. 

(Amended 2015)

D. System of Paragraph Designation.

In order that technical requirements of a similar nature, or those directed to a single characteristic, may be grouped 

together in an orderly fashion, and to facilitate the location of individual requirements, the paragraphs of each code 

are divided into sections. Each section is designated by a letter and a name, and each subsection is given a 

letter-number designation and a side title.

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Introduction Handbook 44 – 2016 

2 

The letter that appears first in a paragraph designation has a specific meaning, as follows:

G. The letter G is a prefix and indicates that the requirement is part of the General Code.

A. Application. These paragraphs pertain to the application of the requirements of a code.

S. Specification. These paragraphs relate to the design of equipment. Specification paragraphs are directed 

particularly to manufacturers of devices.

N. Note. These paragraphs apply to the official testing of devices.

T. Tolerance. Tolerances are performance requirements. They fix the limit of allowable error or departure 

from true performance or value.

Sensitivity. The sensitivity requirements, applicable only to nonautomatic-indicating scales, are 

performance requirements and are lettered with a “T.” 

UR. User Requirement. These paragraphs are directed particularly to the owner and operator of a device. 

User requirements apply to the selection, installation, use, and maintenance of devices.

D. Definitions of Terms. A definitions section appears in Appendix D to provide the definition of the 

terms having a special meaning.

The numerical designation after a letter follows the decimal system of paragraph identification that fixes both the 

relationship and the limitation of the requirements of the paragraph. For example, in the Scales Code, under 

Specifications, the following numerical designations occur:

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Zero Indication.

S.1.1.1. Digital Indicating Elements.

S.1.1.2. No-Load Reference Value.

S.1.2. Value of Scale Division Units.

S.1.2.1. Digital Indicating Scales. 

S.1.3. Graduations.

S.1.3.1. Length.

S.1.3.2. Width.

S.1.3.3. Clear Space Between Graduations.

In this example, paragraphs S.1.1., S.1.2., and S.1.3. are directed and limited to paragraph S.1., which pertains to the 

design of indicating and recording elements and of recorded representations. Paragraphs S.1.1.1. and S.1.1.2. are 

directly related to each other, but they are limited to the design of zero indication. Likewise, paragraphs S.1.3.1., 

S.1.3.2., and S.1.3.3. are directly related to each other, but they are limited to the design of graduations.

This handbook conforms to the concept of primary use of SI (metric) measurements recommended in the Omnibus 

Trade and Competitiveness Act of 1988 by citing SI metric units before U.S. customary units where both units 

appear together and placing separate sections containing requirements for metric units before corresponding sections 

containing requirements for customary units. Occasionally, a paragraph or table carries the suffix “M” because the 

requirement in SI units is shown as a separate statement, rather than combined with the U.S. customary units. In 

these few instances, separate requirements were judged to be more easily understood than attempting to combine SI 

and U.S. customary units in a single paragraph or table. In some cases, however, trade practice is currently 

restricted to the use of customary units; therefore, some requirements in this handbook will continue to specify only 

customary units until the Conference achieves a broad consensus on the permitted metric units.

______________________________________________________________________________________________________ 

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Handbook 44 – 2016 Introduction

3 

E. Classification of Requirements.

The classification of requirements into “retroactive” and “nonretroactive” status is made in order that the 

requirements may be put into force and effect without unnecessary hardship and without wholesale condemnation of 

apparatus. Retroactive requirements are enforceable with respect to all equipment and are printed in upright roman 

type. Nonretroactive requirements are those that, while clearly desirable, are not so vital that they should at once be 

enforced with respect to all apparatus. Nonretroactive requirements are printed in italic type.

It is not expected that, after their promulgation in a given jurisdiction, nonretroactive requirements will always 

remain nonretroactive. It is entirely proper that a weights and measures official, following a careful analysis of 

existing conditions, fix reasonable periods for the continuance of the nonretroactive application of particular 

requirements, after which such requirements will become retroactive. These periods should be long enough to avoid 

undue hardship to the owners or operators of apparatus and, in the case of some requirements, should approximate 

the average useful life of the apparatus in question.

In order that all interested parties may have timely and ample notice of impending changes in the status of 

requirements, the following procedure is suggested for the official who plans to change the classification of 

requirements. If sufficient data are available to make such action feasible, publish in combination with the codes 

themselves the date or dates at which nonretroactive requirements are to become retroactive. In other cases, give 

equally effective notice at the earliest practicable date.

A nonretroactive requirement, in italic type, will indicate the year from which it should be enforced and, in some 

cases, the date the requirement shall be changed to retroactive status. For example, [Nonretroactive as of 1978 and 

to become retroactive on January 1, 1985]. As a general rule, each nonretroactive requirement is reviewed after it 

has been in effect for 10 years to determine the appropriateness of its nonretroactive status.

F. Using the Handbook.

Handbook 44 is designed to be a working tool for federal, state, and local weights and measures officials, the 

equipment manufacturers, installers, and service agencies/agents. As noted in Section 1.10. General Code 

paragraph G-A.1. Commercial and Law-Enforcement Equipment, applicable portions of Handbook 44 may be used 

by the weights and measures official to test noncommercial weighing and measuring equipment upon request. 

Additionally, applicable language in Handbook 44 may be cited as a standard in noncommercial applications, for 

example, when the handbook is referenced or cited as part of a quality system or in multiple-party contract 

agreements where noncommercial weighing or measuring equipment is used.

The section on Fundamental Considerations (Appendix A) should be studied until its contents are well known. The 

General Code, with general requirements pertaining to all devices, obviously must be well known to a user of the 

handbook. The makeup of the specific codes, the order of paragraph presentation, and particularly paragraph 

designation are worthy of careful study. It is not deemed advisable for a user to attempt to commit to memory 

tolerances or tolerance tables, even though these are used frequently. For the handbook to serve its purpose, it 

should be available when any of its requirements are to be applied. Direct reference is the only sure way to apply a 

requirement properly and to check whether other requirements may be applicable.

This handbook supplies criteria which enable the user to determine the suitability, accuracy, and repetitive 

consistency of a weighing or measuring device, both in the laboratory and in the field. However, not all code 

sections can be appropriately applied in both settings. Since some sections are designed to be applied specifically to 

tests performed under laboratory conditions, it would be impractical or unrealistic to apply them to field tests. Not 

all tests described in the “Notes” section of the handbook are required to be performed in the field as an official test. 

An inspector may officially approve or reject a device which has been tested in accordance with those sections 

applicable to the type of test being conducted.

(Paragraph added 1996)

______________________________________________________________________________________________________ 

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Introduction Handbook 44 – 2016 

4 

National Conference on Weights and Measures / National Type Evaluation Program 

Form 15: Proposal to Amend NIST Handbooks 

General Information (See Instructions)

1. Date: 2. Regional Association(s): (Not applicable for proposals to the Board of Directors or NTEP Committee)

 Central (CWMA) Northeastern (NEWMA) Southern (SWMA) Western (WWMA)

3. Standing Committee:

__ Laws & Regulations __ Specifications & Tolerances __ Professional Development __ Board of Directors __ NTEP Committee

4. Submitter Name:

5. Street Address:

6. City: 7. State: 8. Zip Code: 9. Country:

10. Phone Number: 11. Fax Number: 12. Email Address:

Proposal Information (See Instructions)

13. Purpose:

14. Handbook to be Amended:

 NIST Handbook 44 NIST Handbook 130 NIST Handbook 133 __ NCWM Bylaws __NTEP Administrative Policy

Section: 

Paragraph: 

15. Proposal:

16. Justification:

17. Other Contacts:

18. Other Reasons For:

19. Other Reasons Against:

20. Evidence:

21. Additional Considerations:

22. Suggested Action:

 Recommend NCWM Voting Item Developing Item Informational Item Other (Please Describe):

23. List of Attachments:

Submit form via e-mail to don.onwiler@ncwm.net Revised: May 2015

1135 M Street, Suite 110 / Lincoln, Nebraska 68508

P. 402.434.4880 F. 402.434.4878 E. info@ncwm.net W. www.ncwm.net/

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Handbook 44 – 2016 1.10. General Code

1-1 

Table of Contents

Section 1.10. General Code ................................................................................................... 1-3

G-A. Application .....................................................................................................................................................1-3

G-A.1. Commercial and Law-Enforcement Equipment...........................................................................1-3

G-A.2. Code Application. ........................................................................................................................1-3

G-A.3. Special and Unclassified Equipment............................................................................................1-3

G-A.4. Metric Equipment.........................................................................................................................1-3

G-A.5. Retroactive Requirements. ...........................................................................................................1-3

G-A.6. Nonretroactive Requirements.......................................................................................................1-3

G-A.7. Effective Enforcement Dates of Code Requirements...................................................................1-4

G-S. Specifications..................................................................................................................................................1-4

G-S.1. Identification. ...............................................................................................................................1-4

G-S.1.1. Location of Marking Information for Not-Built-For-Purpose, Software-Based 

Devices. ....................................................................................................................1-5

G-S.1.2. Devices and Main Elements .....................................................................................1-5

G-S.2. Facilitation of Fraud.....................................................................................................................1-6

G-S.3. Permanence. .................................................................................................................................1-6

G-S.4. Interchange or Reversal of Parts. .................................................................................................1-6

G-S.5. Indicating and Recording Elements. ............................................................................................1-6

G-S.5.1. General. ....................................................................................................................1-6

G-S.5.2. Graduations, Indications, and Recorded Representations.........................................1-6

G-S.5.3. Values of Graduated Intervals or Increments. ..........................................................1-7

G-S.5.4. Repeatability of Indications......................................................................................1-7

G-S.5.5. Money Values, Mathematical Agreement. ...............................................................1-7

G-S.5.6. Recorded Representations. .......................................................................................1-7

G-S.5.7. Magnified Graduations and Indications....................................................................1-8

G-S.6. Marking Operational Controls, Indications, and Features..........................................................1-8

G-S.7. Lettering. ......................................................................................................................................1-8

G-S.8. Provision for Sealing Electronic Adjustable Components. ..........................................................1-8

G-S.8.1. Multiple Weighing or Measuring Elements that Share a Common Provision for 

Sealing......................................................................................................................1-9

G-N. Notes................................................................................................................................................................1-9

G-N.1. Conflict of Laws and Regulations. ...............................................................................................1-9

G-N.2. Testing With Nonassociated Equipment. .....................................................................................1-9

G-T. Tolerances.......................................................................................................................................................1-9

G-T.1. Acceptance Tolerances.................................................................................................................1-9

G-T.2. Maintenance Tolerances...............................................................................................................1-9

G-T.3. Application.................................................................................................................................1-10

G-T.4. For Intermediate Values. ............................................................................................................1-10

G-UR. User Requirements............................................................................................................................1-10

G-UR.1. Selection Requirements..............................................................................................................1-10

G-UR.1.1. Suitability of Equipment.........................................................................................1-10

G-UR.1.2. Environment. ..........................................................................................................1-10

G-UR.1.3. Liquid-Measuring Devices. ....................................................................................1-10

G-UR.2. Installation Requirements...........................................................................................................1-10

G-UR.2.1. Installation. .............................................................................................................1-10

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G-UR.2.2. Installation of Indicating or Recording Element.....................................................1-10

G-UR.2.3. Accessibility for Inspection, Testing, and Sealing Purposes. .................................1-10

G-UR.3. Use Requirements. .....................................................................................................................1-11

G-UR.3.1. Method of Operation. .............................................................................................1-11

G-UR.3.2. Associated and Nonassociated Equipment. ............................................................1-11

G-UR.3.3. Position of Equipment. ...........................................................................................1-11

G-UR.3.4. Responsibility, Money-Operated Devices. .............................................................1-11

G-UR.4. Maintenance Requirements. .......................................................................................................1-11

G-UR.4.1. Maintenance of Equipment.....................................................................................1-11

G-UR.4.2. Abnormal Performance...........................................................................................1-11

G-UR.4.3. Use of Adjustments. ...............................................................................................1-11

G-UR.4.4. Assistance in Testing Operations............................................................................1-12

G-UR.4.5. Security Seal...........................................................................................................1-12

G-UR.4.6. Testing Devices at a Central Location....................................................................1-12

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Section 1.10. General Code

G-A. Application

G-A.1. Commercial and Law-Enforcement Equipment. – These specifications, tolerances, and other technical 

requirements apply as follows:

(a) To commercial weighing and measuring equipment; that is, to weights and measures and weighing and 

measuring devices commercially used or employed in establishing the size, quantity, extent, area, 

composition (limited to meat and poultry), constituent values (limited to grain), or measurement of 

quantities, things, produce, or articles for distribution or consumption, purchased, offered, or submitted for 

sale, hire, or award, or in computing any basic charge or payment for services rendered on the basis of 

weight or measure.

(Amended 2008)

(b) To any accessory attached to or used in connection with a commercial weighing or measuring device when 

such accessory is so designed that its operation affects the accuracy of the device.

(c) To weighing and measuring equipment in official use for the enforcement of law or for the collection of 

statistical information by government agencies.

(These requirements should be used as a guide by the weights and measures official when, upon request, courtesy 

examinations of noncommercial equipment are made.)

G-A.2. Code Application. – This General Code shall apply to all classes of devices as covered in the specific 

codes. The specific code requirements supersede General Code requirements in all cases of conflict.

(Amended 1972)

G-A.3. Special and Unclassified Equipment. – Insofar as they are clearly appropriate, the requirements and 

provisions of the General Code and of specific codes apply to equipment failing, by reason of special design or 

otherwise, to fall clearly within one of the particular equipment classes for which separate codes have been 

established. With respect to such equipment, code requirements and provisions shall be applied with due regard to 

the design, intended purpose, and conditions of use of the equipment.

G-A.4. Metric Equipment. – Employment of the weights and measures of the metric system is lawful throughout 

the United States. These specifications, tolerances, and other requirements shall not be understood or construed as 

in any way prohibiting the manufacture, sale, or use of equipment designed to give results in terms of metric units. 

The specific provisions of these requirements and the principles upon which the requirements are based shall be 

applied to metric equipment insofar as appropriate and practicable. The tolerances on metric equipment, when not 

specified herein, shall be equivalent to those specified for similar equipment constructed or graduated in the 

U.S. customary system.

G-A.5. Retroactive Requirements. – “Retroactive” requirements are enforceable with respect to all equipment. 

Retroactive requirements are printed herein in upright roman type.

G-A.6. Nonretroactive Requirements. – “Nonretroactive” requirements are enforceable on or after the effective 

date for devices: 

(a) manufactured within a state after the effective date;

(b) both new and used, brought into a state after the effective date; 

(c) used in noncommercial applications which are placed into commercial use after the effective date; and

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(d) undergoing type evaluation, including devices that have been modified to the extent that a new NTEP 

Certificate of Conformance (CC) is required.

Nonretroactive requirements are not enforceable with respect to devices that are in commercial service in the state as 

of the effective date or to new equipment in the stock of a manufacturer or a dealer in the state as of the effective 

date.

[Nonretroactive requirements are printed in italic type.]

(Amended 1989 and 2011) 

G-A.7. Effective Enforcement Dates of Code Requirements. – Unless otherwise specified, each new or amended 

code requirement shall not be subject to enforcement prior to January 1 of the year following the adoption by the 

National Conference on Weights and Measures and publication by the National Institute of Standards and 

Technology.

G-S. Specifications

G-S.1. Identification. – All equipment, except weights and separate parts necessary to the measurement process 

but not having any metrological effect, shall be clearly and permanently marked for the purposes of identification 

with the following information:

(a) the name, initials, or trademark of the manufacturer or distributor;

(b) a model identifier that positively identifies the pattern or design of the device;

(1) The model identifier shall be prefaced by the word “Model,” “Type,” or “Pattern.” These terms may 

be followed by the word “Number” or an abbreviation of that word. The abbreviation for the word 

“Number” shall, as a minimum, begin with the letter “N” (e.g., No or No.). The abbreviation for the 

word “Model” shall be “Mod” or “Mod.” Prefix lettering may be initial capitals, all capitals, or all 

lower case.

[Nonretroactive as of January 1, 2003]

(Added 2000) (Amended 2001)

(c) a nonrepetitive serial number, except for equipment with no moving or electronic component parts and notbuilt-for-purpose, software-based devices;

[Nonretroactive as of January 1, 1968]

(Amended 2003)

(1) The serial number shall be prefaced by words, an abbreviation, or a symbol, that clearly identifies the 

number as the required serial number.

[Nonretroactive as of January 1, 1986]

(2) Abbreviations for the word “Serial” shall, as a minimum, begin with the letter “S,” and abbreviations 

for the word “Number” shall, as a minimum, begin with the letter “N” (e.g., S/N, SN, Ser. No., and 

S. No.).

[Nonretroactive as of January 1, 2001]

(d) the current software version or revision identifier for not-built-for-purpose, software-based devices;

[Nonretroactive as of January 1, 2004]

(Added 2003)

(1) The version or revision identifier shall be prefaced by words, an abbreviation, or a symbol, that 

clearly identifies the number as the required version or revision.

[Nonretroactive as of January 1, 2007]

(Added 2006)

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(2) Abbreviations for the word “Version” shall, as a minimum, begin with the letter “V” and may be 

followed by the word “Number.” Abbreviations for the word “Revision” shall, as a minimum, begin 

with the letter “R” and may be followed by the word “Number.” The abbreviation for the word 

“Number” shall, as a minimum, begin with the letter “N” (e.g., No or No.).

[Nonretroactive as of January 1, 2007]

(Added 2006)

(e) an National Type Evaluation Program (NTEP) Certificate of Conformance (CC) number or a 

corresponding CC Addendum Number for devices that have a CC. The CC Number or a corresponding CC 

Addendum Number shall be prefaced by the terms “NTEP CC,” “CC,” or “Approval.” These terms may 

be followed by the word “Number” or an abbreviation of that word. The abbreviation for the word 

“Number” shall, as a minimum, begin with the letter “N” (e.g., No or No.).

[Nonretroactive as of January 1, 2003]

The required information shall be so located that it is readily observable without the necessity of the disassembly of 

a part requiring the use of any means separate from the device.

(Amended 1985, 1991, 1999, 2000, 2001, 2003, and 2006)

G-S.1.1. Location of Marking Information for Not-Built-For-Purpose, Software-Based Devices. – For notbuilt-for-purpose, software-based devices either:

(a) The required information in G-S.1 Identification. (a), (b), (d), and (e) shall be permanently marked or 

continuously displayed on the device; or

(b) The Certificate of Conformance (CC) Number shall be:

(1) permanently marked on the device;

(2) continuously displayed; or

(3) accessible through an easily recognized menu and, if necessary, a submenu. Examples of menu 

and submenu identification include, but are not limited to, “Help,” “System Identification,” 

“G-S.1. Identification,” or “Weights and Measures Identification.”

Note: For (b), clear instructions for accessing the information required in G-S.1. (a), (b), and (d) shall be listed on the 

CC, including information necessary to identify that the software in the device is the same type that was evaluated.

[Nonretroactive as of January 1, 2004]

(Added 2003) (Amended 2006)

G-S.1.2. Devices and Main Elements Remanufactured as of January 1, 2002. – All devices and main 

elements remanufactured as of January 1, 2002, shall be clearly and permanently marked for the purposes of 

identification with the following information:

(a) the name, initials, or trademark of the last remanufacturer or distributor; and

(b) the remanufacturer’s or distributor’s model designation, if different than the original model 

designation.

(Added 2001) (Amended 2011)

Note: Definitions for “manufactured device,” “repaired device,” and “repaired element” are included (along with definitions 

for “remanufactured device” and “remanufactured element”) in Appendix D, Definitions.

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G-S.2. Facilitation of Fraud. – All equipment and all mechanisms, software, and devices attached to or used in 

conjunction therewith shall be so designed, constructed, assembled, and installed for use such that they do not 

facilitate the perpetration of fraud.

(Amended 2007)

G-S.3. Permanence. – All equipment shall be of such materials, design, and construction as to make it probable 

that, under normal service conditions:

(a) accuracy will be maintained; 

(b) operating parts will continue to function as intended; and

(c) adjustments will remain reasonably permanent.

Undue stresses, deflections, or distortions of parts shall not occur to the extent that accuracy or permanence is 

detrimentally affected.

G-S.4. Interchange or Reversal of Parts. – Parts of a device that may readily be interchanged or reversed in the 

course of field assembly or of normal usage shall be:

(a) so constructed that their interchange or reversal will not affect the performance of the device; or

(b) so marked as to show their proper positions.

G-S.5. Indicating and Recording Elements.

G-S.5.1. General. – All weighing and measuring devices shall be provided with indicating or recording 

elements appropriate in design and adequate in amount. Primary indications and recorded representations shall 

be clear, definite, accurate, and easily read under any conditions of normal operation of the device.

G-S.5.2. Graduations, Indications, and Recorded Representations.

G-S.5.2.1. Analog Indication and Representation. – Graduations and a suitable indicator shall be 

provided in connection with indications designed to advance continuously.

G-S.5.2.2. Digital Indication and Representation. – Digital elements shall be so designed that:

(a) All digital values of like value in a system agree with one another.

(b) A digital value coincides with its associated analog value to the nearest minimum graduation.

(c) A digital value “rounds off” to the nearest minimum unit that can be indicated or recorded.

(d) A digital zero indication includes the display of a zero for all places that are displayed to the right 

of the decimal point and at least one place to the left. When no decimal values are displayed, a 

zero shall be displayed for each place of the displayed scale division.

[Nonretroactive as of January 1, 1986]

(Amended 1973 and 1985)

G-S.5.2.3. Size and Character. – In any series of graduations, indications, or recorded representations, 

corresponding graduations and units shall be uniform in size and character. Graduations, indications, or 

recorded representations that are subordinate to, or of a lesser value than others with which they are 

associated, shall be appropriately portrayed or designated.

[Made retroactive as of January 1, 1975]

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G-S.5.2.4. Values. – If graduations, indications, or recorded representations are intended to have specific 

values, these shall be adequately defined by a sufficient number of figures, words, symbols, or 

combinations thereof, uniformly placed with reference to the graduations, indications, or recorded 

representations and as close thereto as practicable, but not so positioned as to interfere with the accuracy of 

reading.

G-S.5.2.5. Permanence. – Graduations, indications, or recorded representations and their defining 

figures, words, and symbols shall be of such character that they will not tend easily to become obliterated 

or illegible.

G-S.5.3. Values of Graduated Intervals or Increments. – In any series of graduations, indications, or 

recorded representations, the values of the graduated intervals or increments shall be uniform throughout the 

series.

G-S.5.3.1. On Devices That Indicate or Record in More Than One Unit. – On devices designed to 

indicate or record in more than one unit of measurement, the values indicated and recorded shall be 

identified with an appropriate word, symbol, or abbreviation.

(Amended 1978 and 1986)

G-S.5.4. Repeatability of Indications. – A device shall be capable of repeating, within prescribed tolerances, 

its indications and recorded representations. This requirement shall be met irrespective of repeated 

manipulation of any element of the device in a manner approximating normal usage (including displacement of 

the indicating elements to the full extent allowed by the construction of the device and repeated operation of a 

locking or relieving mechanism) and of the repeated performance of steps or operations that are embraced in the 

testing procedure.

G-S.5.5. Money Values, Mathematical Agreement. – Any recorded money value and any digital 

money-value indication on a computing-type weighing or measuring device used in retail trade shall be in 

mathematical agreement with its associated quantity representation or indication to the nearest 1 cent of money 

value. This does not apply to auxiliary digital indications intended for the operator’s use only, when these 

indications are obtained from existing analog customer indications that meet this requirement.

(Amended 1973)

G-S.5.6. Recorded Representations. – Insofar as they are appropriate, the requirements for indicating and 

recording elements shall also apply to recorded representations. All recorded values shall be printed digitally. 

In applications where recorded representations are required, the customer may be given the option of not 

receiving the recorded representation. For systems equipped with the capability of issuing an electronic receipt, 

ticket, or other recorded representation, the customer may be given the option to receive any required 

information electronically (e.g., via cell phone, computer, etc.) in lieu of or in addition to a hard copy.

(Amended 1975 and 2014) 

G-S.5.6.1. Indicated and Recorded Representation of Units. – Appropriate abbreviations.

(a) For equipment manufactured on or after January 1, 2008, the appropriate defining symbols are 

shown in NIST Special Publication SP 811 “Guide for the Use of International System of Units 

(SI)” and Handbook 44 Appendix C – General Tables of Units of Measurement.

Note: SP 811 can be viewed or downloaded at http://physics.nist.gov/cuu/pdf/sp811.pdf or by going 

to http://www.nist.gov/pml/wmd/index.cfm and selecting Weights and Measures Publications and the link to 

Special Publications (SP 811), “Guide for the Use of the International System of Units (SI).” 

(Added 2007)

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(b) The appropriate defining symbols on equipment manufactured prior to January 1, 2008, with 

limited character sets are shown in Table 1. Representation of SI Units on Equipment 

Manufactured Prior to January 1, 2008, with Limited Character Sets.

(Added 1977) (Amended 2007)

Table 1. 

Representation of SI Units on Equipment Manufactured Prior to January 1, 2008, 

with Limited Character Sets

Representation

Form I Form II

Name of Unit

International 

Symbol (common 

use symbol)

(double case) (single case lower) (single case upper)

Base SI Units

meter m m m M

kilogram kg kg kg KG

Derived SI Units

newton N N n N

pascal Pa Pa pa PA

watt W W w W

volt V V v V

degree Celsius °C °C °c °C

Other Units

liter l or L L l L

gram g g g G

metric ton t t tne TNE

bar bar bar bar BAR

(Table Amended 2007)

G-S.5.7. Magnified Graduations and Indications. – All requirements for graduations and indications apply 

to a series of graduations and an indicator magnified by an optical system or as magnified and projected on a 

screen.

G-S.6. Marking Operational Controls, Indications, and Features. – All operational controls, indications, and 

features, including switches, lights, displays, push buttons, and other means, shall be clearly and definitely 

identified. The use of approved pictograms or symbols shall be acceptable.

[Nonretroactive as of January 1, 1977]

(Amended 1978 and 1995)

G-S.7. Lettering. – All required markings and instructions shall be distinct and easily readable and shall be of 

such character that they will not tend to become obliterated or illegible.

G-S.8. Provision for Sealing Electronic Adjustable Components. – A device shall be designed with provision(s) 

for applying a security seal that must be broken, or for using other approved means of providing security (e.g., data 

change audit trail available at the time of inspection), before any change that detrimentally affects the metrological 

integrity of the device can be made to any electronic mechanism.

[Nonretroactive as of January 1, 1990]

A device may be fitted with an automatic or a semi-automatic calibration mechanism. This mechanism shall be 

incorporated inside the device. After sealing, neither the mechanism nor the calibration process shall facilitate 

fraud.

(Added 1985) (Amended 1989 and 1993)

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G-S.8.1. Multiple Weighing or Measuring Elements that Share a Common Provision for Sealing. – A 

change to any metrological parameter (calibration or configuration) of any weighing or measuring element 

shall be individually identified.

[Nonretroactive as of January 1, 2010]

Note: For devices that utilize an electronic form of sealing, in addition to the requirements in G-S.8.1., any appropriate audit 

trail requirements in an applicable specific device code also apply. Examples of identification of a change to the 

metrological parameters of a weighing or measuring element include, but are not limited to:

(1) a broken, missing, or replaced physical seal on an individual weighing, measuring, or indicating element or active 

junction box;

(2) a change in a calibration factor or configuration setting for each weighing or measuring element; 

(3) a display of the date of calibration or configuration event for each weighing or measuring element; or

(4) counters indicating the number of calibration and/or configuration events for each weighing or measuring element.

(Added 2007)

G-N. Notes

G-N.1. Conflict of Laws and Regulations. – If any particular provisions of these specifications, tolerances, and 

other requirements are found to conflict with existing state laws, or with existing regulations or local ordinances 

relating to health, safety, or fire prevention, the enforcement of such provisions shall be suspended until conflicting 

requirements can be harmonized. Such suspension shall not affect the validity or enforcement of the remaining 

provisions of these specifications, tolerances, and other requirements.

G-N.2. Testing With Nonassociated Equipment. – Tests to determine conditions, such as radio frequency 

interference (RFI) that may adversely affect the performance of a device shall be conducted with equipment and 

under conditions that are usual and customary with respect to the location and use of the device.

(Added 1976)

G-T. Tolerances

G-T.1. Acceptance Tolerances. – Acceptance tolerances shall apply to equipment: 

(a) to be put into commercial use for the first time;

(b) that has been placed in commercial service within the preceding 30 days and is being officially tested for 

the first time;

(c) that has been returned to commercial service following official rejection for failure to conform to 

performance requirements and is being officially tested for the first time within 30 days after corrective 

service;

(d) that is being officially tested for the first time within 30 days after major reconditioning or overhaul; and

(e) undergoing type evaluation.

(Amended 1989)

G-T.2. Maintenance Tolerances. – Maintenance tolerances shall apply to equipment in actual use, except as 

provided in G-T.1. Acceptance Tolerances.

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G-T.3. Application. – Tolerances “in excess” and tolerances “in deficiency” shall apply to errors in excess and to 

errors in deficiency, respectively. Tolerances “on overregistration” and tolerances “on underregistration” shall apply 

to errors in the direction of overregistration and of underregistration, respectively. (Also see Appendix D, 

Definitions.)

G-T.4. For Intermediate Values. – For a capacity, indication, load, value, etc., intermediate between two 

capacities, indications, loads, values, etc., listed in a table of tolerances, the tolerances prescribed for the lower 

capacity, indication, load, value, etc., shall be applied.

G-UR. User Requirements

G-UR.1. Selection Requirements.

G-UR.1.1. Suitability of Equipment. – Commercial equipment shall be suitable for the service in which it is 

used with respect to elements of its design, including but not limited to its weighing capacity (for weighing 

devices), its computing capability (for computing devices), its rate of flow (for liquid-measuring devices), the 

character, number, size, and location of its indicating or recording elements, and the value of its smallest unit 

and unit prices.

(Amended 1974)

G-UR.1.2. Environment. – Equipment shall be suitable for the environment in which it is used including, but 

not limited to, the effects of wind, weather, and RFI.

(Added 1976)

G-UR.1.3. Liquid-Measuring Devices. – To be suitable for its application, the minimum delivery for 

liquid-measuring devices shall be no less than 100 divisions, except that the minimum delivery for retail analog 

devices shall be no less than 10 divisions. Maximum division values and tolerances are stated in the specific 

codes.

(Added 1995)

G-UR.2. Installation Requirements.

G-UR.2.1. Installation. – A device shall be installed in accordance with the manufacturer’s instructions, 

including any instructions marked on the device. A device installed in a fixed location shall be installed so that 

neither its operation nor its performance will be adversely affected by any characteristic of the foundation, 

supports, or any other detail of the installation.

G-UR.2.1.1. Visibility of Identification. – Equipment shall be installed in such a manner that all 

required markings are readily observable.

(Added 1978)

G-UR.2.2. Installation of Indicating or Recording Element. – A device shall be so installed that there is no 

obstruction between a primary indicating or recording element and the weighing or measuring element; 

otherwise there shall be convenient and permanently installed means for direct communication, oral or visual, 

between an individual located at a primary indicating or recording element and an individual located at the 

weighing or measuring element. (Also see G-UR.3.3. Position of Equipment.) 

G-UR.2.3. Accessibility for Inspection, Testing, and Sealing Purposes. – A device shall be located, or such 

facilities for normal access thereto shall be provided, to permit:

(a) inspecting and testing the device;

(b) inspecting and applying security seals to the device; and

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(c) readily bringing the testing equipment of the weights and measures official to the device by customary 

means and in the amount and size deemed necessary by such official for the proper conduct of the test.

Otherwise, it shall be the responsibility of the device owner or operator to supply such special facilities, 

including such labor as may be needed to inspect, test, and seal the device, and to transport the testing 

equipment to and from the device, as required by the weights and measures official.

(Amended 1991)

G-UR.3. Use Requirements.

G-UR.3.1. Method of Operation. – Equipment shall be operated only in the manner that is obviously 

indicated by its construction or that is indicated by instructions on the equipment.

G-UR.3.2. Associated and Nonassociated Equipment. – A device shall meet all performance requirements 

when associated or nonassociated equipment is operated in its usual and customary manner and location.

(Added 1976)

G-UR.3.3. Position of Equipment. – A device or system equipped with a primary indicating element and 

used in direct sales, except for prescription scales, shall be positioned so that its indications may be accurately 

read and the weighing or measuring operation may be observed from some reasonable “customer” and 

“operator” position. The permissible distance between the equipment and a reasonable customer and operator 

position shall be determined in each case upon the basis of the individual circumstances, particularly the size 

and character of the indicating element.

(Amended 1974 and 1998)

G-UR.3.4. Responsibility, Money-Operated Devices. – Money-operated devices, other than parking meters, 

shall have clearly and conspicuously displayed thereon, or immediately adjacent thereto, adequate information 

detailing the method for the return of monies paid when the product or service cannot be obtained. This 

information shall include the name, address, and phone number of the local responsible party for the device. 

This requirement does not apply to devices at locations where employees are present and responsible for 

resolving any monetary discrepancies for the customer.

(Amended 1977 and 1993)

G-UR.4. Maintenance Requirements.

G-UR.4.1. Maintenance of Equipment. – All equipment in service and all mechanisms and devices attached 

thereto or used in connection therewith shall be continuously maintained in proper operating condition 

throughout the period of such service. Equipment in service at a single place of business shall not be considered 

“maintained in a proper operating condition” if:

(a) predominantly, equipment of all types or applications are found to be in error in a direction favorable 

to the device user; or

(b) predominantly, equipment of the same type or application is found to be in error in a direction 

favorable to the device user.

(Amended 1973, 1991, and 2015) 

G-UR.4.2. Abnormal Performance. – Unstable indications or other abnormal equipment performance 

observed during operation shall be corrected and, if necessary, brought to the attention of competent service 

personnel.

(Added 1976)

G-UR.4.3. Use of Adjustments. – Weighing elements and measuring elements that are adjustable shall be 

adjusted only to correct those conditions that such elements are designed to control, and shall not be adjusted to 

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compensate for defective or abnormal installation or accessories or for badly worn or otherwise defective parts 

of the assembly. Any faulty installation conditions shall be corrected, and any defective parts shall be renewed 

or suitably repaired, before adjustments are undertaken. Whenever equipment is adjusted, the adjustments shall 

be so made as to bring performance errors as close as practicable to zero value.

G-UR.4.4. Assistance in Testing Operations. – If the design, construction, or location of any device is such 

as to require a testing procedure involving special equipment or accessories or an abnormal amount of labor, 

such equipment, accessories, and labor shall be supplied by the owner or operator of the device as required by 

the weights and measures official.

G-UR.4.5. Security Seal. – A security seal shall be appropriately affixed to any adjustment mechanism 

designed to be sealed.

G-UR.4.6. Testing Devices at a Central Location.

(a) When devices in commercial service require special test facilities, or must be removed from service for 

testing, or are routinely transported for the purpose of use (e.g., vehicle-mounted devices and devices 

used in multiple locations), the official with statutory authority may require that the devices be brought 

to a central location for testing. The dealer or owner of these devices shall provide transportation of 

the devices to and from the test location.

(b) When the request for removal and delivery to a central test location involves devices used in 

submetering (e.g., electric, hydrocarbon vapor, or water meters), the owner or operator shall not 

interrupt the utility service to the customer or tenant except for the removal and replacement of the 

device. Provisions shall be made by the owner or operator to minimize inconvenience to the customer 

or tenant. All replacement or temporary meters shall be tested and sealed by a weights and measures 

official or bear a current, valid approval seal prior to use.

(Added 1994)

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Handbook 44 – 2016 Section 2

2-1

Section 2

Table of Contents

Page

2.20. Scales ............................................................................................................................... 2-3 

2.21. Belt-Conveyor Scale Systems ........................................................................................ 2-57 

2.22. Automatic Bulk Weighing Systems............................................................................... 2-73 

2.23. Weights.......................................................................................................................... 2-83 

2.24. Automatic Weighing Systems........................................................................................ 2-91 

2.25. Weigh-In-Motion Systems Used for Vehicle Enforcement Screening – 

Tentative Code ............................................................................................................. 2-109 

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2-2 

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Table of Contents

Page

Section 2.20. Scales ................................................................................................................... 2-7

A. Application .....................................................................................................................................................2-7

A.1. General..................................................................................................................................................2-7

A.2. Wheel-Load Weighers, Portable Axle-Load Weighers, and Axle-Load Scales....................................2-7

A.3. Additional Code Requirements.............................................................................................................2-7

S. Specifications..................................................................................................................................................2-7

S.1. Design of Indicating and Recording Elements and of Recorded Representations. ...............................2-7

S.1.1. Zero Indication......................................................................................................................2-7

S.1.2. Value of Scale Division Units. ..............................................................................................2-8

S.1.3. Graduations. ..........................................................................................................................2-9

S.1.4. Indicators...............................................................................................................................2-9

S.1.5. Weighbeams........................................................................................................................2-10

S.1.6. Poises. .................................................................................................................................2-10

S.1.7. Capacity Indication, Weight Ranges, and Unit Weights.....................................................2-11

S.1.8. Computing Scales. ..............................................................................................................2-11

S.1.9. Prepackaging Scales............................................................................................................2-13

S.1.10. Adjustable Components. .....................................................................................................2-13

S.1.11. Provision for Sealing. .........................................................................................................2-13

S.1.12. Manual Weight Entries. ......................................................................................................2-14

S.1.13. Vehicle On-Board Weighing Systems: Vehicle in Motion. ...............................................2-14

S.2. Design of Balance, Tare, Level, Damping, and Arresting Mechanisms. ............................................2-14

S.2.1. Zero-Load Adjustment........................................................................................................2-14

S.2.2. Balance Indicator. ...............................................................................................................2-16

S.2.3. Tare. ....................................................................................................................................2-16

S.2.4. Level-Indicating Means. .....................................................................................................2-17

S.2.5. Damping Means. .................................................................................................................2-17

S.3. Design of Load-Receiving Elements. .................................................................................................2-17

S.3.1. Travel of Pans of Equal-Arm Scale.....................................................................................2-17

S.3.2. Drainage..............................................................................................................................2-18

S.3.3. Scoop Counterbalance.........................................................................................................2-18

S.4. Design of Weighing Elements. ...........................................................................................................2-18

S.4.1. Antifriction Means. .............................................................................................................2-18

S.4.2. Adjustable Components. .....................................................................................................2-18

S.4.3. Multiple Load-Receiving Elements. ...................................................................................2-18

S.5. Design of Weighing Devices, Accuracy Class. ...................................................................................2-18

S.5.1. Designation of Accuracy Class. ..........................................................................................2-18

S.5.2. Parameters for Accuracy Class...........................................................................................2-18

S.5.3. Multi-Interval and Multiple Range Scales, Division Value. ...............................................2-19

S.5.4. Relationship of Load Cell Verification Interval Value to the Scale Division......................2-19

S.6. Marking Requirements........................................................................................................................2-21

S.6.1. Nominal Capacity; Vehicle and Axle-Load Scales..............................................................2-21

S.6.2. Location of Marking Information. ......................................................................................2-21

S.6.3. Scales, Main Elements, and Components of Scales or Weighing Systems.........................2-21

S.6.4. Railway Track Scales..........................................................................................................2-25

S.6.5. Livestock Scales..................................................................................................................2-27

S.6.6. Counting Feature, Minimum Individual Piece Weight, and Minimum Sample Piece 

Count...................................................................................................................................2-27

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2-4 

N. Notes 2-27

N.1. Test Procedures...................................................................................................................................2-27

N.1.1. Increasing-Load Test...........................................................................................................2-27

N.1.2. Decreasing-Load Test (Automatic Indicating Scales).........................................................2-27

N.1.3. Shift Test.............................................................................................................................2-27

N.1.4. Sensitivity Test....................................................................................................................2-31

N.1.5. Discrimination Test.............................................................................................................2-31

N.1.6. RFI Susceptibility Tests, Field Evaluation..........................................................................2-31

N.1.7. Ratio Test............................................................................................................................2-31

N.1.8. Material Tests......................................................................................................................2-31

N.1.9. Zero-Load Balance Change.................................................................................................2-31

N.1.10. Counting Feature Test.........................................................................................................2-32

N.1.11. Substitution Test. ................................................................................................................2-32

N.1.12. Strain-Load Test..................................................................................................................2-32

N.2. Verification (Testing) Standards.........................................................................................................2-32

N.3. Minimum Test Weights and Test Loads. ............................................................................................2-32

N.3.1. Minimum Test-Weight Load and Tests for Railway Track Scales. ....................................2-32

N.3.2. Field Standard Weight Carts. ..............................................................................................2-34

N.4. Coupled-in-Motion Railroad Weighing Systems................................................................................2-34

N.4.1. Weighing Systems Used to Weigh Trains of Less Than Ten Cars. ....................................2-34

N.4.2. Weighing Systems Placed in Service Prior to January 1, 1991, and Used to Weigh Trains of 

Ten or More Cars. ...............................................................................................................2-34

N.4.3. Weighing Systems Placed in Service on or After January 1, 1991, and Used to Weigh Trains 

of Ten or More Cars............................................................................................................2-34

N.5. Uncoupled-in-Motion Railroad Weighing System. ............................................................................2-35

N.6. Nominal Capacity of Prescription Scales............................................................................................2-35

T. Tolerances Applicable to Devices not Marked I, II, III, III L, or IIII.....................................................2-36

T.1. Tolerance Values. ...............................................................................................................................2-36

T.1.1. General................................................................................................................................2-36

T.1.2. Postal and Parcel Post Scales. .............................................................................................2-36

T.2. Sensitivity Requirement (SR). ............................................................................................................2-38

T.2.1. Application..........................................................................................................................2-38

T.2.2. General................................................................................................................................2-38

T.2.3. Prescription Scales. .............................................................................................................2-38

T.2.4. Jewelers’ Scales. .................................................................................................................2-38

T.2.5. Dairy-Product Test Scales...................................................................................................2-38

T.2.6. Grain Test Scales. ...............................................................................................................2-38

T.2.7. Vehicle, Axle-Load, Livestock, and Animal Scales............................................................2-38

T.2.8. Railway Track Scales..........................................................................................................2-38

T.3. Sensitivity Requirement, Equilibrium Change Required....................................................................2-39

T.N. Tolerances Applicable to Devices Marked I, II, III, III L, and IIII.........................................................2-39

T.N.1. Principles. ...........................................................................................................................................2-39

T.N.1.1. Design. ................................................................................................................................2-39

T.N.1.2. Accuracy Classes. ...............................................................................................................2-39

T.N.1.3. Scale Division. ....................................................................................................................2-39

T.N.2.Tolerance Application.........................................................................................................................2-39

T.N.2.1. General................................................................................................................................2-39

T.N.2.2. Type Evaluation Examinations. ..........................................................................................2-39

T.N.2.3. Subsequent Verification Examinations. ..............................................................................2-39

T.N.2.4. Multi-Interval and Multiple Range (Variable Division-Value) Scales................................2-39

T.N.2.5. Ratio Tests. .........................................................................................................................2-39

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T.N.3.Tolerance Values. ...............................................................................................................................2-40

T.N.3.1. Maintenance Tolerance Values. ..........................................................................................2-40

T.N.3.2. Acceptance Tolerance Values. ............................................................................................2-40

T.N.3.3. Wheel-Load Weighers and Portable Axle-Load Weighers of Class IIII.............................2-40

T.N.3.4. Crane and Hopper (Other than Grain Hopper) Scales.........................................................2-40

T.N.3.5. Separate Main Elements: Load Transmitting Element, Indicating Element, Etc. ..............2-40

T.N.3.6. Coupled-In-Motion Railroad Weighing Systems................................................................2-40

T.N.3.7. Uncoupled-in-Motion Railroad Weighing Systems. ...........................................................2-41

T.N.3.8. Dynamic Monorail Weighing System.................................................................................2-41

T.N.3.9. Materials Test on Customer-Operated Bulk Weighing Systems for Recycled Materials. ..2-41

T.N.3.10. Prescription Scales with a Counting Feature.......................................................................2-41

T.N.3.11. Tolerances for Substitution Test. ........................................................................................2-41

T.N.3.12. Tolerances for Strain-Load Test..........................................................................................2-41

T.N.4. Agreement of Indications....................................................................................................................2-41

T.N.4.1. Multiple Indicating/Recording Elements. ...........................................................................2-41

T.N.4.2. Single Indicating/Recording Element. ................................................................................2-42

T.N.4.3. Single Indicating Element/Multiple Indications..................................................................2-42

T.N.4.4. Shift or Section Tests. .........................................................................................................2-42

T.N.4.5. Time Dependence. ..............................................................................................................2-42

T.N.4.6. Time Dependence (Creep) for Load Cells during Type Evaluation....................................2-43

T.N.4.7. Creep Recovery for Load Cells During Type Evaluation. ..................................................2-44

T.N.5.Repeatability. ......................................................................................................................................2-44

T.N.6. Sensitivity. ..........................................................................................................................................2-44

T.N.6.1. Test Load. ...........................................................................................................................2-44

T.N.6.2. Minimum Change of Indications.........................................................................................2-44

T.N.7. Discrimination. ...................................................................................................................................2-45

T.N.7.1. Analog Automatic Indicating (i.e., Weighing Device with Dial, Drum, Fan, etc.).............2-45

T.N.7.2. Digital Automatic Indicating...............................................................................................2-45

T.N.8.Influence Factors.................................................................................................................................2-45

T.N.8.1. Temperature. .......................................................................................................................2-45

T.N.8.2. Barometric Pressure. ...........................................................................................................2-46

T.N.8.3. Electric Power Supply.........................................................................................................2-46

T.N.9.Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility. ...........2-46

UR. User Requirements ......................................................................................................................................2-47

UR.1. Selection Requirements. .....................................................................................................................2-47

UR.1.1. General................................................................................................................................2-47

UR.1.2. Grain Hopper Scales. ..........................................................................................................2-48

UR.1.3. Value of the Indicated and Recorded Scale Division. .........................................................2-48

UR.1.4. Grain-Test Scales: Value of the Scale Divisions................................................................2-48

UR.1.5. Recording Element, Class III L Railway Track Scales........................................................2-48

UR.2. Installation Requirements. ..................................................................................................................2-49

UR.2.1. Supports. .............................................................................................................................2-49

UR.2.2. Suspension of Hanging Scale..............................................................................................2-49

UR.2.3. Protection From Environmental Factors. ............................................................................2-49

UR.2.4. Foundation, Supports, and Clearance..................................................................................2-49

UR.2.5. Access to Weighing Elements.............................................................................................2-49

UR.2.6. Approaches. ........................................................................................................................2-49

UR.2.7. Stock Racks.........................................................................................................................2-50

UR.2.8. Hoists. .................................................................................................................................2-50

UR.2.9. Provision for Testing Dynamic Monorail Weighing Systems..............................................2-50

UR.3. Use Requirements. ..............................................................................................................................2-50

UR.3.1. Recommended Minimum Load...........................................................................................2-50

UR.3.2. Maximum Load...................................................................................................................2-50

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UR.3.3. Single-Draft Vehicle Weighing...........................................................................................2-52

UR.3.4. Wheel-Load Weighing........................................................................................................2-52

UR.3.5. Special Designs...................................................................................................................2-53

UR.3.6. Wet Commodities. ..............................................................................................................2-53

UR.3.7. Minimum Load on a Vehicle Scale.....................................................................................2-53

UR.3.8. Minimum Load for Weighing Livestock.............................................................................2-53

UR.3.9. Use of Manual Weight Entries............................................................................................2-53

UR.3.10. Dynamic Monorail Weighing Systems. ..............................................................................2-53

UR.3.11. Minimum Count..................................................................................................................2-54

UR.3.12. Correct Stored Piece Weight...............................................................................................2-54

UR.4. Maintenance Requirements.................................................................................................................2-54

UR.4.1. Balance Condition...............................................................................................................2-54

UR.4.2. Level Condition...................................................................................................................2-54

UR.4.3. Scale Modification. .............................................................................................................2-54

UR.5. Coupled-in-Motion Railroad Weighing Systems................................................................................2-54

Scales Code Index ...................................................................................................................................................2-55

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Section 2.20. Scales

A. Application

A.1. General. – This code applies to all types of weighing devices other than automatic bulk-weighing systems, 

belt-conveyor scales, and automatic weighing systems. The code comprises requirements that generally apply to all 

weighing devices, and specific requirements that are applicable only to certain types of weighing devices.

(Amended 1972 and 1983)

A.2. Wheel-Load Weighers, Portable Axle-Load Weighers, and Axle-Load Scales. – The requirements for 

wheel-load weighers, portable axle-load weighers, and axle-load scales apply only to such scales in official use for 

the enforcement of traffic and highway laws or for the collection of statistical information by government agencies.

A.3. Additional Code Requirements. – In addition to the requirements of this code, devices covered by the

Scales code shall meet the requirements of Section 1.10. General Code. 

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Zero Indication.

(a) On a scale equipped with indicating or recording elements, provision shall be made to either indicate 

or record a zero-balance condition. 

(b) On an automatic-indicating scale or balance indicator, provision shall be made to indicate or record an 

out-of-balance condition on both sides of zero.

(c) A zero-balance condition may be indicated by other than a continuous digital zero indication, provided 

that an effective automatic means is provided to inhibit a weighing operation or to return to a 

continuous digital indication when the scale is in an out-of-balance condition.

(Added 1987) (Amended 1993)

(Amended 1987)

S.1.1.1. Digital Indicating Elements.

(a) A digital zero indication shall represent a balance condition that is within ± 1⁄2 the value of the 

scale division.

(b) A digital indicating device shall either automatically maintain a “center-of-zero” condition to 

± 1⁄4 scale division or less, or have an auxiliary or supplemental “center-of-zero” indicator that 

defines a zero-balance condition to ± 1⁄4 of a scale division or less. A “center-of-zero” indication 

may operate when zero is indicated for gross and/or net mode(s).

[Nonretroactive as of January 1, 1993]

(Amended 1992 and 2008)

S.1.1.2. No-Load Reference Value. – On a single draft manually operated receiving hopper scale 

installed below grade, used to receive grain, and utilizing a no-load reference value, provision shall be 

made to indicate and record the no-load reference value prior to the gross load value.

(Added 1983)

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S.1.2. Value of Scale Division Units. – Except for batching scales and weighing systems used exclusively for 

weighing in predetermined amounts, the value of a scale division “d” expressed in a unit of weight shall be 

equal to:

(a) 1, 2, or 5; or

 

(b) a decimal multiple or submultiple of 1, 2, or 5; or

Examples: scale divisions may be 10, 20, 50, 100; or 0.01, 0.02, 0.05; or 0.1, 0.2, 0.5, etc.

(c) a binary submultiple of a specific unit of weight.

Examples: scale divisions may be 1⁄2, 1⁄4, 1

/8, 1/16, etc.

[Nonretroactive as of January 1, 1986]

S.1.2.1. Digital Indicating Scales, Units. – Except for postal scales, a digital-indicating scale shall 

indicate weight values using only a single unit of measure. Weight values shall be presented in a decimal 

format with the value of the scale division expressed as 1, 2, or 5, or a decimal multiple or submultiple of 

1, 2, or 5.

The requirement that the value of the scale division be expressed only as 1, 2, or 5, or a decimal multiple or 

submultiple of only 1, 2, or 5 does not apply to net weight indications and recorded representations that 

are calculated from gross and tare weight indications where the scale division of the gross weight is 

different from the scale division of the tare weight(s) on multi-interval or multiple range scales. For 

example, a multiple range or multi-interval scale may indicate and record tare weights in a lower weighing 

range (WR) or weighing segment (WS), gross weights in the higher weighing range or weighing segment, 

and net weights as follows:

55 kg Gross Weight (WR2 d = 5 kg) 10.05 lb Gross Weight (WS2 d = 0.05 lb)

– 4 kg Tare Weight (WR1 d = 2 kg) – 0.06 lb Tare Weight (WS1 d = 0.02 lb)

= 51 kg Net Weight (Mathematically Correct) = 9.99 lb Net Weight (Mathematically Correct)

[Nonretroactive as of January 1, 1989]

(Added 1987) (Amended 2008)

S.1.2.2. Verification Scale Interval.

S.1.2.2.1. Class I and II Scales and Dynamic Monorail Scales. If e ≠ d, the verification scale 

interval “e” shall be determined by the expression:

d < e < 10 d

If the displayed division (d) is less than the verification division (e), then the verification division shall 

be less than or equal to 10 times the displayed division.

The value of e must satisfy the relationship, e = 10k of the unit of measure, where k is a positive or 

negative whole number or zero. This requirement does not apply to a Class I device with d < 1 mg 

where e = 1 mg. If e ≠ d, the value of “d” shall be a decimal submultiple of “e,” and the ratio shall not 

be more than 10:1. If e ≠ d, and both “e” and “d” are continuously displayed during normal operation, 

then “d” shall be differentiated from “e” by size, shape, color, etc. throughout the range of weights

displayed as “d.”

(Added 1999)

S.1.2.2.2. Class III and IIII Scales. The value of “e” is specified by the manufacturer as marked 

on the device. Except for dynamic monorail scales, “e” must be less than or equal to “d.”

(Added 1999)

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S.1.2.3. Prescription Scale with a Counting Feature. – A Class I or Class II prescription scale with an 

operational counting feature shall not calculate a piece weight or total count unless the sample used to 

determine the individual piece weight meets the following conditions:

(a) minimum individual piece weight is greater than or equal to 3 e; and

(b) minimum sample piece count is greater than or equal to 10 pieces.

(Added 2003)

S.1.3. Graduations.

S.1.3.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.3.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the clear space between graduations. The width of main graduations shall be not more than 

50 % greater than the width of subordinate graduations. Graduations shall be not less than 0.2 mm 

(0.008 in) wide.

S.1.3.3. Clear Space Between Graduations. – The clear space between graduations shall be not less 

than 0.5 mm (0.02 in) for graduations representing money-values, and not less than 0.75 mm (0.03 in) for 

other graduations. If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations. 

S.1.4. Indicators.

S.1.4.1. Symmetry. – The index of an indicator shall be of the same shape as the graduations, at least 

throughout that portion of its length associated with the graduations.

S.1.4.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case, the distance between the end 

of the indicator and the ends of the graduations, measured along the line of the graduations, shall be not 

more than 1.0 mm (0.04 in).

S.1.4.3. Width. – The width of the index of an indicator in relation to the series of graduations with 

which it is used shall be not greater than:

(a) the width of the narrowest graduation;

[Nonretroactive as of January 1, 2002]

(b) the width of the clear space between weight graduations; and

(c) three-fourths of the width of the clear space between money-value graduations. 

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width 

throughout the length of the index that coincides with the graduation.

S.1.4.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no 

case be more than 1.5 mm (0.06 in).

S.1.4.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

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S.1.5. Weighbeams.

S.1.5.1. Normal Balance Position. – The normal balance position of the weighbeam of a beam scale 

shall be horizontal.

S.1.5.2. Travel. – The weighbeam of a beam scale shall have equal travel above and below the 

horizontal. The total travel of the weighbeam of a beam scale in a trig loop or between other limiting stops 

near the weighbeam tip shall be not less than the minimum travel shown in Tables 1M and 1. When such 

limiting stops are not provided, the total travel at the weighbeam tip shall be not less than 8 % of the 

distance from the weighbeam fulcrum to the weighbeam tip.

Table 1M.

Minimum Travel of Weighbeam of Beam Scale

Between Limiting Stops

Table 1.

Minimum Travel of Weighbeam of Beam Scale

Between Limiting Stops

Distance From 

Weighbeam Fulcrum to 

Limiting Stops

(centimeters)

Minimum Travel 

Between

Limiting Stops

(millimeter)

Distance From 

Weighbeam Fulcrum to 

Limiting Stops

(inches)

Minimum Travel 

Between 

Limiting Stops

(inch)

30 or less 10 12 or less 0.4

30+ to 50, inclusive 13 12+ to 20, inclusive 0.5

50+ to 100, inclusive 18 20+ to 40, inclusive 0.7

Over 100 23 Over 40 0.9

S.1.5.3. Subdivision. – A subdivided weighbeam bar shall be subdivided by scale division graduations,

notches, or a combination of both. Graduations on a particular bar shall be of uniform width and 

perpendicular to the top edge of the bar. Notches on a particular bar shall be uniform in shape and 

dimensions and perpendicular to the face of the bar. When a combination of graduations and notches is 

employed, the graduations shall be positioned in relation to the notches to indicate notch values clearly and 

accurately.

S.1.5.4. Readability. – A subdivided weighbeam bar shall be so subdivided and marked, and a 

weighbeam poise shall be so constructed, that the weight corresponding to any normal poise position can 

easily and accurately be read directly from the beam, whether or not provision is made for the optional 

recording of representations of weight.

S.1.5.5. Capacity. – On an automatic-indicating scale having a nominal capacity of 15 kg (30 lb) or less 

and used for direct sales to retail customers:

(a) the capacity of any weighbeam bar shall be a multiple of the reading-face capacity; 

(b) each bar shall be subdivided throughout or shall be subdivided into notched intervals, each equal 

to the reading-face capacity; and

(c) the value of any turnover poise shall be equal to the reading-face capacity. 

S.1.5.6. Poise Stop. – Except on a steelyard with no zero graduation, a shoulder or stop shall be 

provided on each weighbeam bar to prevent a poise from traveling and remaining back of the zero 

graduation.

S.1.6. Poises.

S.1.6.1. General. – No part of a poise shall be readily detachable. A locking screw shall be 

perpendicular to the longitudinal axis of the weighbeam and shall not be removable. Except on a steelyard 

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with no zero graduation, the poise shall not be readily removable from a weighbeam. The knife-edge of a 

hanging poise shall be hard and sharp and so constructed as to allow the poise to swing freely on the 

bearing surfaces in the weighbeam notches.

S.1.6.2. Adjusting Material. – The adjusting material in a poise shall be securely enclosed and firmly 

fixed in position; if softer than brass, it shall not be in contact with the weighbeam.

S.1.6.3. Pawl. – A poise, other than a hanging poise, on a notched weighbeam bar shall have a pawl that 

will seat the poise in a definite and correct position in any notch, wherever in the notch the pawl is placed, 

and hold it there firmly and without appreciable movement. The dimension of the tip of the pawl that is 

transverse to the longitudinal axis of the weighbeam shall be at least equal to the corresponding dimension 

of the notches.

S.1.6.4. Reading Edge or Indicator. – The reading edge or indicator of a poise shall be sharply defined, 

and a reading edge shall be parallel to the graduations on the weighbeam.

S.1.7. Capacity Indication, Weight Ranges, and Unit Weights. 

(a) Gross Capacity. – An indicating or recording element shall not display nor record any values when 

the gross load (not counting the initial dead load that has been canceled by an initial zero-setting 

mechanism) is in excess of 105 % of scale capacity. 

(b) Capacity Indication. – Electronic computing scales (excluding postal scales and weight classifiers)

shall neither display nor record a gross or net weight in excess of scale capacity plus 9 d.

[Nonretroactive as of January 1, 1993]

The total value of weight ranges and of unit weights in effect or in place at any time shall automatically be 

accounted for on the reading face and on any recorded representation.

This requirement does not apply to: (1) single-revolution dial scales, (2) multi-revolution dial scales not 

equipped with unit weights, (3) scales equipped with two or more weighbeams, nor (4) devices that indicate 

mathematically derived totalized values.

(Amended 1990, 1992, and 1995)

S.1.8. Computing Scales.

S.1.8.1. Money-Value Graduations, Metric Unit Prices. – The value of the graduated intervals 

representing money-values on a computing scale with analog indications shall not exceed:

(a) 1 cent at all unit prices of 55 cents per kilogram and less;

(b) 2 cents at unit prices of 56 cents per kilogram through $2.75 per kilogram (special graduations

defining 5-cent intervals may be employed but not in the spaces between regular graduations);

(c) 5 cents at unit prices of $2.76 per kilogram through $7.50 per kilogram; or

(d) 10 cents at unit prices above $7.50 per kilogram.

Value figures and graduations shall not be duplicated in any column or row on the graduated chart. (Also

see S.1.8.2. Money-Value Computation.) 

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S.1.8.2. Money-Value Graduations, U.S. Customary Unit Prices. – The value of the graduated 

intervals representing money-values on a computing scale with analog indications shall not exceed:

(a) 1 cent at all unit prices of 25 cents per pound and less;

(b) 2 cents at unit prices of 26 cents per pound through $1.25 per pound (special graduations defining 

5-cent intervals may be employed but not in the spaces between regular graduations);

(c) 5 cents at unit prices of $1.26 per pound through $3.40 per pound; or

(d) 10 cents at unit prices above $3.40 per pound.

Value figures and graduations shall not be duplicated in any column or row on the graduated chart. (Also

see S.1.8.2. Money-Value Computation.) 

S.1.8.3. Money-Value Computation. – A computing scale with analog quantity indications used in 

retail trade may compute and present digital money-values to the nearest quantity graduation when the 

value of the minimum graduated interval is 0.005 kg (0.01 lb) or less. (Also see Sec. 1.10. General Code 

G-S.5.5. Money-Values, Mathematical Agreement.) 

S.1.8.4. Customer’s Indications. – Weight indications shall be shown on the customer’s side of 

computing scales when these are used for direct sales to retail customers. Computing scales equipped on 

the operator’s side with digital indications, such as the net weight, unit price, or total price, shall be 

similarly equipped on the customer’s side. Unit price displays visible to the customer shall be in terms of 

single whole units of weight and not in common or decimal fractions of the unit. Scales indicating in 

metric units may indicate price per 100 g.

(Amended 1985 and 1995)

S.1.8.4.1. Scales that will function as either a normal round off scale or as a weight classifier shall 

be provided with a sealable means for selecting the mode of operation and shall have a clear 

indication (annunciator), adjacent to the weight display on both the operator’s and customer’s side 

whenever the scale is operating as a weight classifier. 

[Nonretroactive as of January 1, 2001]

(Added 1999)

S.1.8.5. Recorded Representations, Point-of-Sale Systems. – The sales information recorded by cash 

registers when interfaced with a weighing element shall contain the following information for items 

weighed at the checkout stand:

(a) the net weight;

1

(b) the unit price;

1 

(c) the total price; and

(d) the product class or, in a system equipped with price look-up capability, the product name or code 

number.

 

1 For devices interfaced with scales indicating in metric units, the unit price may be expressed in price per 

100 grams. Weight values shall be identified by kilograms, kg, grams, g, ounces, oz, pounds, or lb. The “#” symbol 

is not acceptable.

[Nonretroactive as of January 1, 2006]

(Amended 1995 and 2005)

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S.1.9. Prepackaging Scales.

S.1.9.1. Value of the Scale Division. – On a prepackaging scale, the value of the intervals representing 

weight values shall be uniform throughout the entire reading face. The recorded weight values shall be 

identical with those on the indicator. 

S.1.9.2. Label Printer. – A prepackaging scale or a device that produces a printed ticket to be used as 

the label for a package shall print all values digitally and of such size, style of type, and color as to be clear 

and conspicuous on the label.

S.1.10. Adjustable Components. – An adjustable component such as a pendulum, spring, or potentiometer 

shall be held securely in adjustment and, except for a zero-load balance mechanism, shall be located within the 

housing of the element.

(Added 1986)

S.1.11. Provision for Sealing.

(a) Except on Class I scales, provision shall be made for applying a security seal in a manner that 

requires the security seal to be broken before an adjustment can be made to any component affecting 

the performance of an electronic device.

[Nonretroactive as of January 1, 1979]

(b) Except on Class I scales, a device shall be designed with provision(s) for applying a security seal that 

must be broken, or for using other approved means of providing security (e.g., data change audit trail

available at the time of inspection), before any change that detrimentally affects the metrological 

integrity of the device can be made to any electronic mechanism.

[Nonretroactive as of January 1, 1990]

(c) Except on Class I scales, audit trails shall use the format set forth in Table S.1.11. Categories of 

Device and Methods of Sealing.

[Nonretroactive as of January 1, 1995]

A device may be fitted with an automatic or a semi-automatic calibration mechanism. This mechanism shall be 

incorporated inside the device. After sealing, neither the mechanism nor the calibration process shall facilitate 

fraud.

(Amended 1989, 1991, and 1993)

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S.1.12. Manual Weight Entries. – A device when being used for direct sale shall accept an entry of a manual 

gross or net weight value only when the scale gross or net* weight indication is at zero. Recorded manual 

weight entries, except those on labels generated for packages of standard weights, shall identify the weight 

value as a manual weight entry by one of the following terms: “Manual Weight,” “Manual Wt,” or “MAN 

WT.” The use of a symbol to identify multiple manual weight entries on a single document is permitted, 

provided that the symbol is defined on the same page on which the manual weight entries appear and the 

definition of the symbol is automatically printed by the recording element as part of the document.

[Nonretroactive as of January 1, 1993] [*Nonretroactive as of January 1, 2005]

(Added 1992) (Amended 2004)

S.1.13. Vehicle On-Board Weighing Systems: Vehicle in Motion. – When the vehicle is in motion, a 

vehicle on-board weighing system shall either:

(a) be accurate; or 

(b) inhibit the weighing operation.

(Added 1993)

S.2. Design of Balance, Tare, Level, Damping, and Arresting Mechanisms.

S.2.1. Zero-Load Adjustment.

S.2.1.1. General. – A scale shall be equipped with means by which the zero-load balance may be 

adjusted. Any loose material used for this purpose shall be enclosed so that it cannot shift in position and 

alter the balance condition of the scale.

Table S.1.11. Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration 

capability.

Seal by physical seal or two event counters: one for calibration 

parameters and one for configuration parameters.

Category 2: Remote configuration capability,

but access is controlled by physical hardware.

The device shall clearly indicate that it is in 

the remote configuration mode and record 

such message if capable of printing in this 

mode.

The hardware enabling access for remote communication must be 

at the device and sealed using a physical seal or two event 

counters: one for calibration parameters and one for 

configuration parameters.

Category 3: Remote configuration capability 

access may be unlimited or controlled through 

a software switch (e.g., password).

An event logger is required in the device; it must include an event 

counter (000 to 999), the parameter ID, the date and time of the 

change, and the new value of the parameter. A printed copy of the 

information must be available through the device or through 

another on-site device. The event logger shall have a capacity to 

retain records equal to 10 times the number of sealable 

parameters in the device, but not more than 1000 records are 

required. (Note: Does not require 1000 changes to be stored for 

each parameter.)

[Nonretroactive as of January 1, 1995]

(Table added 1993)

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Except for an initial zero-setting mechanism, an automatic zero adjustment outside the limits specified in 

S.2.1.3. Scales Equipped with an Automatic Zero-Tracking Mechanism is prohibited.

(Amended 2010)

S.2.1.2. Scales used in Direct Sales. – A manual zero-setting mechanism (except on a digital scale with 

an analog zero-adjustment mechanism with a range of not greater than one scale division) shall be operable 

or accessible only by a tool outside of and entirely separate from this mechanism, or it shall be enclosed in 

a cabinet. Except on Class I or II scales, a balance ball shall either meet this requirement or not itself be 

rotatable.

A semiautomatic zero-setting mechanism shall be operable or accessible only by a tool outside of and 

separate from this mechanism or it shall be enclosed in a cabinet, or it shall be operable only when the 

indication is stable within plus or minus: 

(a) 3.0 scale divisions for scales of more than 2000 kg (5000 lb) capacity in service prior to 

January 1, 1981, and for all axle load, railway track, and vehicle scales; or

(b) 1.0 scale division for all other scales.

S.2.1.3. Scales Equipped with an Automatic Zero-Tracking Mechanism.

S.2.1.3.1. Automatic Zero-Tracking Mechanism for Scales Manufactured Between 

January 1, 1981, and January 1, 2007. – The maximum load that can be “rezeroed,” when either 

placed on or removed from the platform all at once under normal operating conditions, shall be for: 

(a) bench, counter, and livestock scales: 0.6 scale division;

(b) vehicle, axle load, and railway track scales: 3.0 scale divisions; and

(c) all other scales: 1.0 scale division.

(Amended 2005)

 S.2.1.3.2. Automatic Zero-Tracking Mechanism for Scales Manufactured on or after 

January 1, 2007. – The maximum load that can be “rezeroed,” when either placed on or removed from 

the platform all at once under normal operating conditions, shall be:

(a) for vehicle, axle load, and railway track scales: 3.0 scale divisions; and

(b) for all other scales: 0.5 scale division.

(Added 2005)

S.2.1.3.3. Means to Disable Automatic Zero-Tracking Mechanism on Class III L Devices. – 

Class III L devices equipped with an automatic zero-tracking mechanism shall be designed with a 

sealable means that would allow zero tracking to be disabled during the inspection and test of the 

device.

[Nonretroactive as of January 1, 2001]

(Added 1999) (Amended 2005)

S.2.1.4. Monorail Scales. – On a static monorail scale equipped with digital indications, means shall be 

provided for setting the zero-load balance to within 0.02 % of scale capacity. On a dynamic monorail 

weighing system, means shall be provided to automatically maintain these conditions.

(Amended 1999)

S.2.1.5. Initial Zero-Setting Mechanism. – Scales of accuracy Classes I, II, and III may be equipped 

with an initial zero-setting device.

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(a) For weighing, load-receiving, and indicating elements in the same housing or covered on the same 

CC, an initial zero-setting mechanism shall not zero a load in excess of 20 % of the maximum 

capacity of the scale unless tests show that the scale meets all applicable tolerances for any amount 

of initial load compensated by this device within the specified range.

(b) For indicating elements not permanently attached to weighing and load-receiving elements 

covered on a separate CC, the maximum initial zero-setting mechanism range of electronic 

indicators shall not exceed 20 % of the configured capacity.

[Nonretroactive as of January 1, 2009]

(Added 2008)

(Added 1990) (Amended 2008)

S.2.1.6. Combined Zero-Tare (“0/T”) Key. – Scales not intended to be used in direct sales applications 

may be equipped with a combined zero and tare function key, provided that the device is clearly marked as 

to how the key functions. The device must also be clearly marked on or adjacent to the weight display with 

the statement “Not for Direct Sales.”

(Added 1998)

S.2.2. Balance Indicator. – On a balance indicator consisting of two indicating edges, lines, or points, the 

ends of the indicators shall be sharply defined. When the scale is in balance, the ends shall be separated by not 

more than 1.0 mm (0.04 in).

S.2.2.1. Dairy-Product Test, Grain-Test, Prescription, and Class I and II Scales. – Except on digital 

indicating devices, a dairy-product test, grain-test, prescription, or Class I or II scale shall be equipped with 

a balance indicator. If an indicator and a graduated scale are not in the same plane, the clearance between 

the indicator and the graduations shall be not more than 1.0 mm (0.04 in).

S.2.2.2. Equal-Arm Scale. – An equal-arm scale shall be equipped with a balance indicator. If the 

indicator and balance graduation are not in the same plane, the clearance between the indicator and the 

balance graduation shall be not more than 1.0 mm (0.04 in).

[Nonretroactive as of January 1, 1989]

(Added 1988)

S.2.3. Tare. – On any scale (except a monorail scale equipped with digital indications and multi-interval 

scales or multiple range scales when the value of tare is determined in a lower weighing range or weighing 

segment), the value of the tare division shall be equal to the value of the scale division.* The tare mechanism 

shall operate only in a backward direction (that is, in a direction of underregistration) with respect to the 

zero-load balance condition of the scale. A device designed to automatically clear any tare value shall also be 

designed to prevent the automatic clearing of tare until a complete transaction has been indicated.*

[*Nonretroactive as of January 1, 1983]

(Amended 1985 and 2008)

Note: On a computing scale, this requires the input of a unit price, the display of the unit price, and a 

computed positive total price at a readable equilibrium. Other devices require a complete weighing operation, 

including tare, net, and gross weight determination*

[*Nonretroactive as of January 1, 1983]

S.2.3.1. Monorail Scales Equipped with Digital Indications. – On a static monorail weighing system 

equipped with digital indications, means shall be provided for setting any tare value of less than 5 % of the 

scale capacity to within 0.02 % of scale capacity. On a dynamic monorail weighing system, means shall be 

provided to automatically maintain this condition.

(Amended 1999)

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S.2.4. Level-Indicating Means. – Except for portable wheel-load weighers and portable axle load scales, a 

portable scale shall be equipped with level-indicating means if its weighing performance is changed by an 

amount greater than the appropriate acceptance tolerance when it is tilted up to and including 5 % rise over run 

in any direction from a level position and rebalanced. The level-indicating means shall be readable without 

removing any scale parts requiring a tool.

[This requirement is nonretroactive as of January 1, 1986, for prescription, jewelers’, and dairy-product test

scales and scales marked Class I and II.]

Note: Portable wheel-load weighers and portable axle-load scales shall be accurate when tilted up to and including 5 % 

rise over run in any direction from a level position and rebalanced.

(Amended 1991 and 2008)

S.2.4.1. Vehicle On-Board Weighing Systems. – A vehicle on-board weighing system shall operate 

within tolerance when the weighing system is tilted up to and including 5 % rise over run in any direction 

from a level position and rebalanced. If the accuracy of the system is affected by out-of-level conditions

normal to the use of the device, the system shall be equipped with an out-of-level sensor that inhibits the 

weighing operation when the system is out of level to the extent that the accuracy limits are exceeded.

(Added 1992) (Amended 2008)

S.2.5. Damping Means. – An automatic-indicating scale and a balance indicator shall be equipped with 

effective means to damp oscillations and to bring the indicating elements quickly to rest.

S.2.5.1. Digital Indicating Elements. – Digital indicating elements equipped with recording elements

shall be equipped with effective means to permit the recording of weight values only when the indication is 

stable within plus or minus: 

(a) 3.0 scale divisions for scales of more than 2000 kg (5000 lb) capacity in service prior to 

January 1, 1981, hopper (other than grain hopper) scales with a capacity exceeding 22 000 kg 

(50 000 lb), and for all vehicle, axle load, livestock, and railway track scales; and

(b) 1.0 scale division for all other scales.

The values recorded shall be within applicable tolerances. 

(Amended 1995)

S.2.5.2. Jewelers’, Prescription, and Class I, and Class II Scales. – A jewelers’, prescription, Class I, 

or Class II scales shall be equipped with appropriate means for arresting the oscillation of the mechanism.

S.2.5.3. Class I and Class II Prescription Scales with a Counting Feature. – A Class I or Class II 

prescription scale shall indicate to the operator when the piece weight computation is complete by a stable 

display of the quantity placed on the load-receiving element.

(Added 2003)

S.3. Design of Load-Receiving Elements.

S.3.1. Travel of Pans of Equal-Arm Scale. – The travel between limiting stops of the pans of a 

nonautomatic-indicating equal-arm scale not equipped with a balance indicator shall be not less than the 

minimum travel shown in Table 2M. and Table 2.

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Table 2M.

Minimum Travel of Pans of

Nonautomatic Indicating Equal-Arm Scale

without Balance Indicator

Table 2.

Minimum Travel of Pans of

Nonautomatic Indicating Equal-Arm Scale

without Balance Indicator

Nominal Capacity

(kilograms)

Minimum Travel of Pans

(millimeters)

Nominal Capacity

(pounds)

Minimum Travel of Pans

(inch)

2 or less 9 4 or less 0.35

2+ to 5, inclusive 13 4+ to 12, inclusive 0.5

5+ to 12, inclusive 19 12+ to 26, inclusive 0.75

Over 12 25 Over 26 1.0

S.3.2. Drainage. – A load-receiving element intended to receive wet commodities shall be so constructed as 

to drain effectively.

S.3.3. Scoop Counterbalance. – A scoop on a scale used for direct sales to retail customers shall not be 

counterbalanced by a removable weight. A permanently attached scoop-counterbalance shall indicate clearly on 

both the operator’s and customer’s sides of the scale whether it is positioned for the scoop to be on or off the 

scale.

S.4. Design of Weighing Elements.

S.4.1. Antifriction Means. – Frictional effects shall be reduced to a minimum by suitable antifriction 

elements. Opposing surfaces and points shall be properly shaped, finished, and hardened. A platform scale 

having a frame around the platform shall be equipped with means to prevent interference between platform and 

frame.

S.4.2. Adjustable Components. – An adjustable component such as a nose-iron or potentiometer shall be 

held securely in adjustment. The position of a nose-iron on a scale of more than 1000 kg (2000 lb) capacity, as 

determined by the factory adjustment, shall be accurately, clearly, and permanently defined.

(Amended 1986)

S.4.3. Multiple Load-Receiving Elements. – Except for mechanical bench and counter scales, a scale with a 

single indicating or recording element, or a combination indicating-recording element, that is coupled to two or 

more load-receiving elements with independent weighing systems, shall be provided with means to prohibit the 

activation of any load-receiving element (or elements) not in use, and shall be provided with automatic means to 

indicate clearly and definitely which load-receiving element (or elements) is in use.

S.5. Design of Weighing Devices, Accuracy Class.

S.5.1. Designation of Accuracy Class. – Weighing devices are divided into accuracy classes and shall be 

designated as I, II, III, III L, or IIII. 

[Nonretroactive as of January 1, 1986]

S.5.2. Parameters for Accuracy Class. – The accuracy class of a weighing device is designated by the 

manufacturer and shall comply with parameters shown in Table 3.

[Nonretroactive as of January 1, 1986]

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S.5.3. Multi-Interval and Multiple Range Scales, Division Value. – On a multi-interval scale and multiple 

range scale, the value of “e” shall be equal to the value of “d.”2

(Added 1986) (Amended 1995)

S.5.4. Relationship of Load Cell Verification Interval Value to the Scale Division. – The relationship of the 

value for the load cell verification scale interval, vmin, to the scale division, d, for a specific scale installation 

using National Type Evaluation Program (NTEP) load cells shall comply with the following formulae where N 

is the number of load cells in the scale (such as hopper or vehicle scale weighing/load-receiving elements):

(a) for scales without lever systems; and

 

(b) for scales with lever systems.

[*When the value of the scale division, d, is different from the verification scale division, e, for the 

scale, the value of e must be used in the formulae above.]

This requirement does not apply to complete weighing/load-receiving elements or scales, which satisfy all the 

following criteria:

- the complete weighing/load-receiving element or scale has been evaluated for compliance with 

T.N.8.1. Temperature under the NTEP;

 

- the complete weighing/load-receiving element or scale has received an NTEP Certificate of 

Conformance; and

- the complete weighing/load-receiving element or scale is equipped with an automatic 

zero-tracking mechanism which cannot be made inoperative in the normal weighing mode. (A test 

mode which permits the disabling of the automatic zero-tracking mechanism is permissible, 

provided the scale cannot function normally while in this mode.

[Nonretroactive as of January 1, 1994]

(Added 1993) (Amended 1996)

 

2 Footnote 1 to Table 3 Parameters for Accuracy Classes.

( )

* min N scalemultiple

d

v

×

≤

N

d

v * min ≤

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Table 3.

Parameters for Accuracy Classes

Class Value of the Verification Scale Division 

(d or e1

)

Number of Scale4 Divisions (n)

Minimum Maximum

SI Units

I equal to or greater than 1 mg 50 000 --

II 1 to 50 mg, inclusive 100 100 000

equal to or greater than 100 mg 5 000 100 000

III2,5 0.1 to 2 g, inclusive 100 10 000

equal to or greater than 5 g 500 10 000

III L3 equal to or greater than 2 kg 2 000 10 000

IIII equal to or greater than 5 g 100 1 200

U.S. Customary Units

III5 0.0002 lb to 0.005 lb, inclusive 100 10 000

0.005 oz to 0.125 oz, inclusive 100 10 000

equal to or greater than 0.01 lb 500 10 000

equal to or greater than 0.25 oz 500 10 000

III L3 equal to or greater than 5 lb 2 000 10 000

IIII greater than 0.01 lb 100 1 200

greater than 0.25 oz 100 1 200

1 For Class I and II devices equipped with auxiliary reading means (i.e., a rider, a vernier, or a least significant 

decimal differentiated by size, shape, or color), the value of the verification scale division “e” is the value of the 

scale division immediately preceding the auxiliary means.

2 A Class III scale marked “For prescription weighing only” may have a verification scale division (e) not less than 

0.01 g. 

(Added 1986) (Amended 2003)

3 The value of a scale division for crane and hopper (other than grain hopper) scales shall be not less than 0.2 kg 

(0.5 lb). The minimum number of scale divisions shall be not less than 1000.

4 On a multiple range or multi-interval scale, the number of divisions for each range independently shall not exceed 

the maximum specified for the accuracy class. The number of scale divisions, n, for each weighing range is 

determined by dividing the scale capacity for each range by the verification scale division, e, for each range. On a 

scale system with multiple load-receiving elements and multiple indications, each element considered shall not 

independently exceed the maximum specified for the accuracy class. If the system has a summing indicator, the nmax

for the summed indication shall not exceed the maximum specified for the accuracy class.

(Added 1997)

5 The minimum number of scale divisions for a Class III Hopper Scale used for weighing grain shall be 2000.)

[Nonretroactive as of January 1, 1986]

(Amended 1986, 1987, 1997, 1998, 1999, 2003, and 2004)

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S.6. Marking Requirements. – (Also see G-S.1. Identification, G-S.4. Interchange or Reversal of Parts, 

G-S.6. Marking Operational Controls, Indications, and Features, G-S.7. Lettering, G-UR.2.1.1. Visibility of 

Identification, and UR.3.4.1. Use in Pairs.)

S.6.1. Nominal Capacity; Vehicle and Axle-Load Scales. – For all vehicle and axle-load scales, the marked 

nominal capacity shall not exceed the concentrated load capacity (CLC) times the quantity of the number of 

sections in the scale minus 0.5.

As a formula, this is stated as: nominal capacity < CLC × (N − 0.5)

 where N = the number of sections in the scale.

[Nonretroactive as of January 1, 1989]

Note: When the device is used in a combination railway track and vehicle weighing application, the above formula shall 

apply only to the vehicle scale application.

(Added 1988) (Amended 1999 and 2002)

S.6.2. Location of Marking Information. – Scales that are not permanently attached to an indicating 

element, and for which the load-receiving element is the only part of the weighing/load-receiving element 

visible after installation, may have the marking information required in Section 1.10. General Code, G-S.1. 

Identification and Section 2.20. Scales Code, S.6. Marking Requirements located in an area that is accessible 

only through the use of a tool; provided that the information is easily accessible (e.g., the information may 

appear on the junction box under an access plate). The identification information for these scales shall be 

located on the weighbridge (load-receiving element) near the point where the signal leaves the weighing 

element or beneath the nearest access cover.

(Added 1989)

S.6.3. Scales, Main Elements, and Components of Scales or Weighing Systems. – Scales, main elements

of scales when not contained in a single enclosure for the entire scale, load cells for which Certificates of 

Conformance (CC) have been issued under the National Type Evaluation Program (NTEP), and other 

equipment necessary to a weighing system, but having no metrological effect on the weighing system, shall be 

marked as specified in Table S.6.3.a. Marking Requirements and explained in the accompanying notes in 

Table S.6.3.b. Notes for Table S.6.3.a.

(Added 1990)

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Table S.6.3.a.

Marking Requirements

Weighing Equipment 

To Be Marked With ⇓

Weighing, 

LoadReceiving, and 

Indicating 

Element in 

Same Housing 

or Covered on 

the Same CC1

Indicating 

Element not 

Permanently 

Attached to 

Weighing and 

Load-Receiving 

Element or 

Covered by a 

Separate CC

Weighing and 

Load-Receiving

Element Not 

Permanently 

Attached to 

Indicating 

Element or 

Covered by a 

Separate CC

Load Cell 

with CC

(11)

Other 

Equipment 

or Device

(10)

Manufacturer’s ID (1) X X X X X

Model Designation and Prefix (1) X X X X X

Serial Number and Prefix (2) X X X X X (16)

Certificate of Conformance Number 

(CC) (23) X X X X X (23)

Accuracy Class (17) X X (8) X (19) X

Nominal Capacity (3)(18)(20) X X X

Value of Scale Division, “d” (3) X X

Value of “e” (4) X X

Temperature Limits (5) X X X X

Concentrated Load Capacity (CLC)

(12)(20)(22) X X (9)

Special Application (13) X X X

Maximum Number of Scale 

Divisions (nmax) (6) X (8) X (19) X 

Minimum Verification Scale 

Division (emin) X (19)

“S” or “M” (7) X

Direction of Loading (15) X

Minimum Dead Load X

Maximum Capacity X

Safe Load Limit X

Load Cell Verification Interval

(vmin) (21) X 

Section Capacity and Prefix

(14)(20)(22)(24) X X 

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Table S.6.3.a.

Marking Requirements

Note: For applicable notes, Table S.6.3.b. 1 Weighing/load-receiving elements and indicators which are in the same housing or which are permanently attached 

will generally appear on the same CC. If not in the same housing, elements shall be hard-wired together or sealed 

with a physical seal or an electronic link. This requirement does not apply to peripheral equipment that has no input 

or effect on device calibrations or configurations.

(Added 2001)

(Added 1990) (Amended 1992, 1999, 2000, 2001, 2002, and 2004)

Table S.6.3.b.

Notes for Table S.6.3.a. Marking Requirements

1. Manufacturer's identification and model designation and model designation prefix.*

[*Nonretroactive as of January 1, 2003] 

(Also see G-S.1. Identification.) [Prefix lettering may be initial capitals, all capitals or all lower case]

(Amended 2000)

2. Serial number [Nonretroactive as of January 1, 1968] and prefix [Nonretroactive as of January 1, 1986]. (Also see

G-S.1. Identification.) 

3. The device shall be marked with the nominal capacity. The nominal capacity shall be shown together with the value of 

the scale division (e.g., 15 × 0.005 kg, 30 × 0.01 lb, or capacity = 15 kg, d = 0.005 kg) in a clear and conspicuous 

manner and be readily apparent when viewing the reading face of the scale indicator unless already apparent by the 

design of the device. Each scale division value or weight unit shall be marked on multiple range or multi-interval

scales. 

[Nonretroactive as of January 1, 1983]

(Amended 2005)

4. Required only if different from “d.” 

[Nonretroactive as of January 1, 1986]

5. Required only on Class III, III L, and IIII devices if the temperature range on the NTEP CC is narrower than and 

within − 10 °C to 40 °C (14 °F to 104 °F). [Nonretroactive as of January 1, 1986]

(Amended 1999)

6. This value may be stated on load cells in units of 1000; e.g., n: 10 is 10 000 divisions. 

[Nonretroactive as of January 1, 1988]

7. Denotes compliance for single or multiple load cell applications. It is acceptable to use a load cell with the “S” or 

Single Cell designation in multiple load cell applications as long as all other parameters meet applicable 

requirements. A load cell with the “M” or Multiple Cell designation can be used only in multiple load cell 

applications. 

[Nonretroactive as of January 1, 1988]

(Amended 1999)

8. An indicating element not permanently attached to a weighing element shall be clearly and permanently marked with 

the accuracy Class of I, II, III, III L, or IIII, as appropriate, and the maximum number of scale divisions, nmax, for 

which the indicator complies with the applicable requirement. Indicating elements that qualify for use in both 

Class III and III L applications may be marked III/III L and shall be marked with the maximum number of scale 

divisions for which the device complies with the applicable requirements for each accuracy class. 

[Nonretroactive as of January 1, 1988]

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Table S.6.3.b.

Notes for Table S.6.3.a. Marking Requirements

9. For vehicle and axle-load scales only. The CLC shall be added to the load-receiving element of any such scale not 

previously marked at the time of modification. 

[Nonretroactive as of January 1, 1989]

(Amended 2002)

10. Necessary to the weighing system but having no metrological effect, e.g., auxiliary remote display, keyboard, etc.

11. The markings may be either on the load cell or in an accompanying document; except that, if an accompanying 

document is provided, the serial number shall appear both on the load cell and in the document. [Nonretroactive as of 

January 1, 1988] The manufacturer’s name or trademark, the model designation, and identifying symbols for the 

model and serial numbers as required by paragraph G-S.1. Identification shall also be marked both on the load cell 

and in any accompanying document. 

[Nonretroactive as of January 1, 1991]

12. Required on the indicating element and the load-receiving element of vehicle and axle-load scales. Such marking 

shall be identified as “concentrated load capacity” or by the abbreviation “CLC.”* 

[*Nonretroactive as of January 1, 1989]

(Amended 2002)

13. A scale designed for a special application rather than general use shall be conspicuously marked with suitable words, 

visible to the operator and to the customer, restricting its use to that application, e.g., postal scale, prepack scale, 

weight classifier, etc.* When a scale is installed with an operational counting feature, the scale shall be marked on 

both the operator and customer sides with the statement “The counting feature is not legal for trade,” except when a 

Class I or Class II prescription scale complies with all Handbook 44 requirements applicable to counting features.

[*Nonretroactive as of 1986] 

(Amended 1994 and 2003)

14. Required on livestock* and railway track scales. When marked on vehicle and axle-load scales manufactured before 

January 1, 1989, it may be used as the CLC. For livestock scales manufactured between January 1, 1989, and 

January 1, 2003, required markings may be either CLC or section capacity. 

[*Nonretroactive as of January 1, 2003]

(Amended 2002)

15. Required if the direction of loading the load cell is not obvious. 

[Nonretroactive as of January 1, 1988]

16. Serial number [Nonretroactive as of January 1, 1968] and prefix [Nonretroactive as of January 1, 1986]. (Also see

G-S.1. Identification.) Modules without “intelligence” on a modular system (e.g., printer, keyboard module, cash 

drawer, and secondary display in a point-of-sale system) are not required to have serial numbers.

17. The accuracy class of a device shall be marked on the device with the appropriate designation as I, II, III, III L, or 

IIII. 

[Nonretroactive as of January 1, 1986]

18. The nominal capacity shall be conspicuously marked as follows:

(a) on any scale equipped with unit weights or weight ranges; 

(b) on any scale with which counterpoise or equal-arm weights are intended to be used;

(c) on any automatic-indicating or recording scale so constructed that the capacity of the indicating or recording 

element, or elements, is not immediately apparent;

(d) on any scale with a nominal capacity less than the sum of the reading elements; and

(e) on the load-receiving element (weighbridge) of vehicle, axle-load, and livestock scales.*

[*Nonretroactive as of January 1, 1989]

(Amended 1992)

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Table S.6.3.b.

Notes for Table S.6.3.a. Marking Requirements

19. For weighing and load-receiving elements not permanently attached to indicating element or covered by a separate 

CC.

[Nonretroactive as of January, 1, 1988]

(Amended 1992)

20. Combination vehicle/railway track scales must be marked with both the nominal capacity and CLC for vehicle 

weighing and the nominal capacity and section capacity for railway weighing. All other requirements relating to 

these markings will apply.

[Nonretroactive as of January 1, 2000]

(Added 1999)

21. The value of the load cell verification interval (vmin) must be stated in mass units. In addition to this information, a 

device may be marked with supplemental representations of vmin.

[Nonretroactive as of January 1, 2001]

(Added 1999)

22. Combination vehicle/livestock scales must be marked with both the CLC for vehicle weighing and the section capacity 

for livestock weighing. All other requirements relative to these markings will apply. 

[Nonretroactive as of January 1, 2003]

(Added 2002) (Amended 2003)

Note: The marked section capacity for livestock weighing may be less than the marked CLC for vehicle weighing.

(Amended 2003)

23. Required only if a CC has been issued for the device or equipment. 

[Nonretroactive as of January 1, 2003]

(G-S.1. Identification (e) Added 2001)

24. The section capacity shall be prefaced by the words “Section Capacity” or an abbreviation of that term. 

Abbreviations shall be “Sec Cap” or “Sec C.” All capital letters and periods may be used.

[Nonretroactive as of January 1, 2005]

(Added 2004)

S.6.4. Railway Track Scales. – A railway track scale shall be marked with the maximum capacity of each 

section of the load-receiving element of the scale. Such marking shall be accurately and conspicuously 

presented on, or adjacent to, the identification or nomenclature plate that is attached to the indicating element of 

the scale. The nominal capacity marking shall satisfy the following:

(a) For scales manufactured from January 1, 2002, through December 31, 2013:

(1) the nominal capacity of a scale with more than two sections shall not exceed twice its rated section 

capacity; and

(2) the nominal capacity of a two section scale shall not exceed its rated section capacity.

(b) For scales manufactured on or after January 1, 2014, the nominal scale capacity shall not exceed the 

lesser of:

(1) the sum of the Weigh Module Capacities as shown in Table S.6.4.M. and Table S.6.4.; or

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(2) the Rated Section Capacity (RSC) multiplied by the Number of Sections (Ns) minus the Number 

of Dead Spaces (Nd) minus 0.5. As a formula this is stated as: 

RSC × (Ns – Nd – 0.5); or

(3) 290 300 kg (640 000 lb).

(Amended 1988, 2001, 2002, and 2013) 

Table S.6.4.M.

Railway Track Scale – Weigh Module Capacity

Weigh Module Length

(meters)

Weigh Module Capacity

(kilograms)

< 1.5 36 300

1.5 to < 3.0 72 600

3.0 to < 4.5 108 900

4.5 to < 7.0 145 100

7.0 to < 9.0 168 700

9.0 to < 10.5 192 300

10.5 to < 12.0 234 100

12.0 to < 17.0 257 600

Note: The capacity of a particular module is based on its length as shown above. To determine the “sum of 

the weigh module capacities” referenced in paragraph S.6.4.(b)(1): (1) determine the length of each 

individual weigh module in the scale; (2) find its corresponding “weigh module capacity” in the table above; 

and (3) add all of the individual weigh module capacities.”

(Table Added 2013)

Table S.6.4. 

Railway Track Scale – Weigh Module Capacity

Weigh Module Length

(feet)

Weigh Module Capacity

(pounds)

< 5 80 000

5 to < 10 160 000

10 to < 15 240 000

15 to < 23 320 000

23 to < 29 372 000

29 to < 35 424 000

35 to < 40 516 000

40 to < 56 568 000

Note: The capacity of a particular module is based on its length as shown above. To determine the “sum of 

the weigh module capacities” referenced in paragraph S.6.4.(b)(1): (1) determine the length of each 

individual weigh module in the scale; (2) find its corresponding “weigh module capacity” in the table above; 

and (3) add all of the individual weigh module capacities.”

(Table Added 2013)

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S.6.5. Livestock Scales. – A livestock scale manufactured prior to January 1, 1989, or after January 1, 2003, 

shall be marked with the maximum capacity of each section of the load-receiving element of the scale. 

Livestock scales manufactured between January 1, 1989, and January 1, 2003, shall be marked with either the 

Concentrated Load Capacity (CLC) or the Section Capacity. Such marking shall be accurately and 

conspicuously presented on, or adjacent to the identification or nomenclature plate that is attached to the 

indicating element of the scale. The nominal capacity of a scale with more than two sections shall not exceed 

twice its rated section capacity. The nominal capacity of a two-section scale shall not exceed its rated section 

capacity.* 

[*Nonretroactive as of January 1, 2003]

(Added 2002)

Also see Note 14 in Table S.6.3.b. Notes for Table S.6.3.a.

S.6.6. Counting Feature, Minimum Individual Piece Weight, and Minimum Sample Piece Count. – A 

Class I or Class II prescription scale with an operational counting feature shall be marked with the minimum 

individual piece weight and minimum number of pieces used in the sample to establish an individual piece 

weight.

(Added 2003)

N. Notes

N.1. Test Procedures.

N.1.1. Increasing-Load Test. – The increasing-load test shall be conducted on all scales with the test loads

approximately centered on the load-receiving element of the scale, except on a scale having a nominal capacity

greater than the total available known test load. When the total test load is less than the nominal capacity, the 

test load is used to greatest advantage by concentrating it, within prescribed load limits, over the main load 

supports of the scale.

N.1.2. Decreasing-Load Test (Automatic Indicating Scales). – The decreasing-load test shall be conducted 

with the test load approximately centered on the load-receiving element of the scale.

N.1.2.1. Scales Marked I, II, III, or IIII. – Except for portable wheel load weighers, decreasing-load 

tests shall be conducted on scales marked I, II, III or IIII and with “n” equal to or greater than 1000 with 

test loads equal to the maximum test load at each tolerance value. For example, on a Class III scale, at test 

loads equal to 4000 d, 2000 d, and 500 d; for scales with n less than 1000, the test load shall be equal to 

one-half of the maximum load applied in the increasing-load test. (Also see Table 6. Maintenance 

Tolerances.) 

(Amended 1998)

N.1.2.2. All Other Scales. – On all other scales, except for portable wheel load weighers, the 

decreasing-load test shall be conducted with a test load equal to one-half of the maximum load applied in 

the increasing-load test.

(Amended 1998)

N.1.3. Shift Test.

N.1.3.1. Dairy-Product Test Scales. – A shift test shall be conducted with a test load of 18 g 

successively positioned at all points on which a weight might reasonably be placed in the course of normal 

use of the scale.

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N.1.3.2. Equal-Arm Scales. – A shift test shall be conducted with a half-capacity test load centered 

successively at four points positioned equidistance between the center and the front, left, back, and right 

edges of each pan as shown in the diagrams below. An equal test load shall be centered on the other pan.

N.1.3.3. Vehicle Scales, Axle-Load Scales, and Livestock Scales.

N.1.3.3.1. Vehicle Scales, Axle-Load Scales, and Combination Vehicle/Livestock Scales.

(a) Minimum Shift Test. – At least one shift test shall be conducted with a minimum test load of 

12.5 % of scale capacity, which may be performed anywhere on the load-receiving element 

using the prescribed test patterns and maximum test loads specified below. (Combination 

Vehicle/Livestock Scales shall also be tested consistent with N.1.3.3.2. Prescribed Test 

Pattern and Test Loads for Livestock Scales with More Than Two Sections and Combination 

Vehicle/Livestock Scales.)

(Amended 1991, 2000, and 2003)

(b) Prescribed Test Pattern and Loading for Vehicle Scales, Axle-Load Scales, and 

Combination Vehicle/Livestock Scales. – The normal prescribed test pattern shall be an area 

of 1.2 m (4 ft) in length and 3.0 m (10 ft) in width or the width of the scale platform, 

whichever is less. Multiple test patterns may be utilized when loaded in accordance with 

paragraph (c), (d), or (e) as applicable. An example of a possible test pattern is shown in the 

diagram below.

(Amended 1997, 2001, and 2003)

4’ 4’ 4’ 4’ 4’

Section

1

Midway between 

sections 1 and 2

Section

2

Midway between 

sections 2 and 3

Section 

3

(c) Loading Precautions for Vehicle Scales, Axle-Load Scales, and Combination 

Vehicle/Livestock Scales. – When loading the scale for testing, one side of the test pattern

shall be loaded to no more than half of the concentrated load capacity or test load before 

loading the other side. The area covered by the test load may be less than 1.2 m (4 ft) × 3.0 m 

(10 ft) or the width of the scale platform, whichever is less; for test patterns less than 1.2 m 

(4 ft) in length the maximum loading shall meet the formula: [(wheel base of test cart or 

length of test load divided by 48 in) × 0.9 × CLC]. The maximum test load applied to each 

test pattern shall not exceed the concentrated load capacity of the scale. When the test pattern 

exceeds 1.2 m (4 ft), the maximum test load applied shall not exceed the concentrated load 

capacity times the largest “r” factor in Table UR.3.2.1. Span Maximum Load for the length of 

the area covered by the test load. For load-receiving elements installed prior to 

January 1, 1989, the rated section capacity may be substituted for concentrated load capacity 

to determine maximum loading. An example of a possible test pattern is shown above.

(Amended 1997 and 2003)

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(d) Multiple Pattern Loading. – To test to the nominal capacity, multiple patterns may be 

simultaneously loaded in a manner consistent with the method of use.

(e) Other Designs. – Special design scales and those that are wider than 3.7 m (12 ft) shall be 

tested in a manner consistent with the method of use but following the principles described 

above.

(Amended 1988, 1991, 1997, 2000, 2001, and 2003)

(Amended 2003)

N.1.3.3.2. Prescribed Test Pattern and Test Loads for Livestock Scales with More Than Two 

Sections and Combination Vehicle/Livestock Scales. – A minimum test load of 5 000 kg (10 000 lb) 

or one-half of the rated section capacity, whichever is less, shall be placed, as nearly as possible, 

successively over each main load support as shown in the diagram below. For livestock scales

manufactured between January 1, 1989, and January 1, 2003, the required loading shall be no greater 

than one-half CLC. (Two-section livestock scales shall be tested consistent with N.1.3.7. All Other 

Scales Except Crane Scales, Hanging Scales, Hopper Scales, Wheel-Load Weighers, and Portable 

Axle-Load Weighers.)



Position 1



Position 2



Position 3

 

Position 6



Position 5



Position 4



 = Load Bearing Point

(Added 2003)

N.1.3.3.3. Prescribed Test Patterns and Test Loads for Two-Section Livestock Scales. – A shift 

test shall be conducted using the following prescribed test loads and test patterns, provided the shift 

test load does not exceed one-half the rated section capacity or one-half the rated concentrated load 

capacity whichever is applicable, using either:

(a) A one-half nominal capacity test load centered as nearly as possible, successively at the center 

of each quarter of the load-receiving element as shown in N.1.3.7. All Other Scales Except 

Crane Scales, Hanging Scales, Hopper Scales, Wheel-Load Weighers, and Portable 

Axle-Load Weighers Figure 1; or

(b) A one-quarter nominal capacity test load centered as nearly as possible, successively over 

each main load support as shown in N.1.3.7. All Other Scales Except Crane Scales, Hanging 

Scales, Hopper Scales, Wheel-Load Weighers, and Portable Axle-Load Weighers Figure 2.

(Added 2007)

N.1.3.4. Railway Track Scales Weighing Individual Cars in Single Drafts. – A shift test shall be 

conducted with at least two different test loads, if available, distributed over, to the right and left of, each 

pair of main levers or other weighing elements supporting each section of the scale.

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N.1.3.5. Monorail Scales, Static Test. – A shift test shall be conducted with a test load equal to the 

largest load that can be anticipated to be weighed in a given installation, but never less than one-half scale 

capacity. The load shall be placed successively on the right end, the left end, and the center of the live rail.

(Added 1985)

N.1.3.5.1. Dynamic Monorail Weighing Systems. – Dynamic tests with livestock carcasses or 

portions of carcasses shall be conducted during normal plant production. No less than 20 test loads 

using carcasses or portions of carcasses of the type normally weighed shall be used in the dynamic test. 

If the plant conveyor chain does not space or prevent the carcasses or portions of carcasses from 

touching one another, dynamic tests shall not be conducted until this condition has been corrected.

All carcasses or portions of carcasses shall be individually weighed statically on either the same scale 

being tested dynamically or another monorail scale with the same or smaller divisions and in close 

proximity. (The scale selected for static weighing of the carcasses or portions of carcasses shall first 

be tested statically with certified test weights that have been properly protected from the harsh 

environment of the packing plant to ensure they maintain accuracy.)

If the scale being tested is used for weighing freshly slaughtered animals (often referred to as a “hot 

scale”), care must be taken to get a static weighment as quickly as possible before or following the 

dynamic weighment to avoid loss due to shrink. If multiple dynamic tests are conducted using the 

same carcasses or portions of carcasses, static weights shall be obtained before and after multiple 

dynamic tests. If the carcass or portion of a carcass changes weight between static tests, the amount of 

weight change shall be taken into account, or the carcass or portion of a carcass shall be disregarded 

for tolerance purposes.

Note: For a dynamic monorail test, the reference scale shall comply with the principles in the Fundamental 

Considerations paragraph 3.2. Tolerances for Standards. 

(Added 1996) (Amended 1999 and 2007)

N.1.3.6. Vehicle On-Board Weighing Systems. – The shift test for a vehicle on-board weighing system

shall be conducted in a manner consistent with its normal use. For systems that weigh as part of the lifting 

cycle, the center of gravity of the load may be shifted in the vertical direction as well as from side to side. 

In other cases, the center of gravity may be moved to the extremes of the load-receiving element using 

loads of a magnitude that reflect normal use (i.e., the load for the shift test may exceed one-half scale 

capacity), and may, in some cases, be equal to the capacity of the scale. The shift test may be conducted 

when the weighing system is out of level to the extent that the weighing system remains operational.

(Added 1992)

N.1.3.7. All Other Scales Except Crane Scales, Hanging Scales, Hopper Scales, Wheel-Load 

Weighers, and Portable Axle-Load Weighers. – A shift test shall be conducted using the following 

prescribed test loads and test patterns. A single field standard weight used as the prescribed test load shall 

be applied centrally in the prescribed test pattern. When multiple field standard weights are used as the 

prescribed test load, the load shall be applied in a consistent pattern in the shift test positions throughout the 

test and applied in a manner that does not concentrate the load in a test pattern that is less than when that 

same load is a single field standard weight on the load-receiving element.

(a) For scales with a nominal capacity of 500 kg (1000 lb) or less, a shift test shall be conducted using 

a one-third nominal capacity test load (defined as test weights in amounts of at least 30 % of scale 

capacity, but not to exceed 35 % of scale capacity) centered as nearly as possible at the center of 

each quadrant of the load-receiving element using the prescribed test pattern as shown in Figure 1.

(b) For scales with a nominal capacity greater than 500 kg (1000 lb), a shift test may be conducted by 

either using a one-third nominal capacity test load (defined as test weights in amounts of at least 

30 % of scale capacity, but not to exceed 35 % of scale capacity) centered as nearly as possible at 

the center of each quadrant of the load-receiving element using the prescribed test pattern as 

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shown in Figure 1, or by using a one-quarter nominal capacity test load centered as nearly as 

possible, successively, over each corner of the load-receiving element using the prescribed test 

pattern as shown in Figure 2.

Figure 1 Figure 2

Position 

1

Position 

2 Position 

1 

Position 

2

Position 

4

Position 

3 Position 

4

Position 

3

(Added 2003)

(Amended 1987, 2003, and 2007)

N.1.4. Sensitivity Test. – A sensitivity test shall be conducted on nonautomatic-indicating (weighbeam) 

scales only, with the weighing device in equilibrium at zero-load and at maximum test load. The test shall be 

conducted by increasing or decreasing the test load in an amount equal to the applicable value specified in 

T.2. Sensitivity Requirement (SR) or T.N.6. Sensitivity.

N.1.5. Discrimination Test. – A discrimination test shall be conducted on all automatic indicating scales with 

the weighing device in equilibrium at or near zero load and at or near maximum test load, and under controlled 

conditions in which environmental factors are reduced to the extent that they will not affect the results obtained. 

For scales equipped with an Automatic Zero-Tracking Mechanism (AZT), the discrimination test may be 

conducted at a range outside of the AZT range.

[Nonretroactive as of January 1, 1986]

(Added 1985) (Amended 2004)

N.1.5.1. Digital Device. – On a digital device, this test is conducted from just below the lower edge of 

the zone of uncertainty for increasing load tests, or from just above the upper edge of the zone of 

uncertainty for decreasing-load tests.

N.1.6. RFI Susceptibility Tests, Field Evaluation. – An RFI test shall be conducted at a given installation 

when the presence of RFI has been verified and characterized if those conditions are considered “usual and 

customary.”

(Added 1986)

N.1.7. Ratio Test. – A ratio test shall be conducted on all scales employing counterpoise weights and on 

nonautomatic-indicating equal-arm scales.

N.1.8. Material Tests. – A material test shall be conducted on all customer-operated bulk weighing systems 

for recycled materials using bulk material for which the device is used. Insert into the device, in a normal 

manner, several accurately pre-weighed samples (free of foreign material) in varying amounts approximating 

average drafts.

N.1.9. Zero-Load Balance Change. – A zero-load balance change test shall be conducted on all scales after 

the removal of any test load. The zero-load balance should not change by more than the minimum tolerance 

applicable. (Also see G-UR.4.2. Abnormal Performance.) 

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N.1.10. Counting Feature Test. – A test of the counting function shall be conducted on all Class I and Class II 

prescription scales having an active counting feature used in “legal for trade” applications. The test should 

verify that the scale will not accept a sample with less than either the minimum sample piece count or the 

minimum sample weight of 30 e. Counting feature accuracy should be verified at a minimum of two test loads. 

Verification of the count calculations shall be based upon the weight indication of the test load.

Note:

(1) The minimum sample weight is equal to the marked minimum individual piece weight times the marked minimum 

sample piece count.

(2) Test load as used in this section refers to actual calibration test weights selected from an appropriate test weight class.

(Added 2003)

N.1.11. Substitution Test. – In the substitution test procedure, material or objects are substituted for known 

test weights, or a combination of known test weights and previously quantified material or objects, using the 

scale under test as a comparator. Additional test weights or other known test loads may be added to the known 

test load to evaluate higher weight ranges on the scale.

(Added 2003)

N.1.12. Strain-Load Test. – In the strain-load test procedure, an unknown quantity of material or objects are 

used to establish a reference load or tare to which test weights or substitution test loads are added.

(Added 2003)

N.2. Verification (Testing) Standards. – Field standard weights used in verifying weighing devices shall comply 

with requirements of NIST Handbook 105-Series standards (or other suitable and designated standards) or the 

tolerances expressed in Fundamental Considerations, paragraph 3.2. (i.e., one-third of the smallest tolerance 

applied).

(Amended 1986)

N.3. Minimum Test Weights and Test Loads. – The minimum test weights and test loads for in-service tests 

(except railway track scales) are shown in Table 4. (Also see Footnote 2 in Table 4. Minimum Test Weights and 

Test Loads.)

(Added 1984) (Amended 1988)

N.3.1. Minimum Test-Weight Load and Tests for Railway Track Scales.

(Amended 1990 and 2012) 

N.3.1.1. Initial and Subsequent Tests. – The test-weight load shall be not less than 35 000 kg 

(80 000 lb). A strain-load test conducted up to the used capacity of the weighing system is recommended.

(Added 1990) (Amended 2012)

N.3.1.2. Interim Test. – An Interim Test may be used to return a railway track scale into temporary 

service following repairs that could affect the accuracy of the weighing system providing all of the 

following conditions are met:

(a) a test weight load of not less than 13 500 kg (30 000 lb) shall be used;

(b) a shift (section) test shall be conducted using a test-weight load of not less than 13 500 kg 

(30 000 lb);

(c) a strain-load test shall be conducted up to at least 25 % of scale capacity; 

(d) all test results shall be within applicable tolerances; and 

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(e) the official with statutory authority shall be immediately notified when scales are repaired and 

placed in temporary service with an Interim Test. The length of temporary service following 

repair is at the discretion of the official with statutory authority.

 (Added 1990) (Amended 2012)

N.3.1.3. Enforcement Action for Inaccuracy. – To take enforcement action on a scale that is found to 

be inaccurate, a minimum test load of 13 500 kg (30 000 lb) must be used.

(Added 1990)

Table 4.

Minimum Test Weights and Test Loads1

Devices in Metric Units Devices in U.S. Customary Units

Device Capacity

(kg)

Minimums 

(in terms of device capacity) Device Capacity

(lb)

Minimums 

(in terms of device capacity)

Test Weights 

(greater of)

Test 

Loads2

Test Weights 

(greater of)

Test 

Loads2

0 to 150 kg 100 % 0 to 300 lb 100 %

151 to 1 500 kg 25 % or 150 kg 75 % 301 to 3 000 lb 25 % or 300 lb 75 %

1 501 to 20 000 kg 12.5 % or 500 kg 50 % 3001 to 40 000 lb 12.5 % or 1 000 lb 50 %

20 001 kg+ 12.5 % or 5 000 kg 25 %3 40 001 lb+ 12.5 % or 10 000 lb 25 %3

Where practicable:

• Test weights to dial face capacity, 1000 d, or test load to used capacity, if greater than minimums specified. 

• During initial verification, a scale should be tested to capacity.

1 If the amount of test weight in Table 4 combined with the load on the scale would result in an unsafe condition, 

then the appropriate load will be determined by the official with statutory authority.

2 The term “test load” means the sum of the combination of field standard test weights and any other applied load 

used in the conduct of a test using substitution test methods. Not more than three substitutions shall be used during 

substitution testing, after which the tolerances for strain load tests shall be applied to each set of test loads. 

3 The scale shall be tested from zero to at least 12.5 % of scale capacity using known test weights and then to at least 

25 % of scale capacity using either a substitution or strain load test that utilizes known test weights of at least 12.5 % 

of scale capacity. Whenever practical, a strain load test should be conducted to the used capacity of the scale. When 

a strain load test is conducted, the tolerances apply only to the test weights or substitution test loads.

(Amended 1988, 1989, 1994, and 2003)

Note: GIPSA requires devices subject to their inspection to be tested to at least “used capacity,” which is calculated 

based on the platform area of the scale and a weight factor assigned to the species of animal weighed on the scale. 

“Used capacity” is calculated using the formula:

Used Scale Capacity = Scale Platform Area x Species Weight Factor

Where species weight factor = 540 kg/m2 (110 lb/ft2

) for cattle, 340 kg/m2 (70 lb/ft2) for calves and hogs, and 

240 kg/m2 (50 lb/ft2) for sheep and lambs.

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N.3.2. Field Standard Weight Carts. – Field Standard Weight Carts that comply with the tolerances 

expressed in Fundamental Considerations, paragraph 3.2. (i.e., one-third of the smallest tolerance applied) may 

be included as part of the minimum required test load (Also see Table 4. Minimum Test Weights and Test 

Loads.) for shift tests and other test procedures.

(Added 2004)

N.4. Coupled-in-Motion Railroad Weighing Systems.

3

N.4.1. Weighing Systems Used to Weigh Trains of Less Than Ten Cars. – These weighing systems shall 

be tested using a consecutive-car test train consisting of the number of cars weighed in the normal operation run 

over the weighing system a minimum of five times in each mode of operation following the final calibration.

(Added 1990) (Amended 1992)

N.4.2. Weighing Systems Placed in Service Prior to January 1, 1991, and Used to Weigh Trains of Ten 

or More Cars. – The minimum test train shall be a consecutive-car test train of no less than ten cars run over 

the scale a minimum of five times in each mode of operation following final calibration.

(Added 1990) (Amended 1992)

N.4.3. Weighing Systems Placed in Service on or After January 1, 1991, and Used to Weigh Trains of 

Ten or More Cars.

(a) These weighing systems shall be tested using a consecutive-car test train of no less than ten cars run 

over the scale a minimum of five times in each mode of operation following final calibration; or

(b) if the official with statutory authority determines it necessary, the As-Used Test Procedures outlined in 

N.4.3.1. shall be used.

(Added 1990) (Amended 1992)

N.4.3.1. As-Used Test Procedures – A weighing system shall be tested in a manner that represents the 

normal method of operation and length(s) of trains normally weighed. The weighing systems may be tested 

using either a: 

(a) consecutive-car test train of a length typical of train(s) normally weighed; or

(b) distributed-car test train of a length typical of train(s) normally weighed.

However, a consecutive-car test train of a shorter length may be used, provided that initial verification test 

results for the shorter consecutive-car test train agree with the test results for the distributed-car or 

full-length consecutive-car test train as specified in N.4.3.1.1. Initial Verification.

The official with statutory authority shall be responsible for determining the minimum test train length to 

be used on subsequent tests.

(Added 1990) (Amended 1992)

N.4.3.1.1. Initial Verification. – Initial verification tests should be performed on any new weighing 

system and whenever either the track structure or the operating procedure changes. If a 

consecutive-car test train of length shorter than trains normally weighed is to be used for subsequent 

verification, the shorter consecutive-car test train results shall be compared either to a distributed-car 

or to a consecutive-car test train of length(s) typical of train(s) normally weighed.

 

3 A test weight car that is representative of one of the types of cars typically weighed on the scale under test may be 

used wherever reference weight cars are specified.

(Added 1991)

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The difference between the total train weight of the train(s) representing the normal method of 

operation and the weight of the shorter consecutive-car test train shall not exceed 0.15 %. If the 

difference in test results exceeds 0.15 %, the length of the shorter consecutive-car test train shall be 

increased until agreement within 0.15 % is achieved. Any adjustments to the weighing system based 

upon the use of a shorter consecutive-car test train shall be offset to correct the bias that was observed 

between the full-length train test and the shorter consecutive-car test train.

(Added 1990) (Amended 1992 and 1993)

N.4.3.1.2. Subsequent Verification. – The test train may consist of either a consecutive-car test

train with a length not less than that used in initial verification, or a distributed-car test train 

representing the number of cars used in the normal operation.

(Added 1990)

N.4.3.1.3. Distributed-Car Test Trains.

(a) The length of the train shall be typical of trains that are normally weighed.

(b) The reference weight cars shall be split into three groups, each group consisting of ten cars or 

10 % of the train length, whichever is less.

(Amended 1991)

(c) The test groups shall be placed near the front, around the middle, and near the end of the train.

(d) Following the final adjustment, the distributed-car test train shall be run over the scale at least 

three times or shall produce 50 weight values, whichever is greater.

(e) The weighing system shall be tested in each mode of operation.

(Added 1990) (Amended 1992)

N.4.3.1.4. Consecutive-Car Test Trains.

(a) A consecutive-car test train shall consist of at least ten cars.

(b) If the consecutive-car test train consists of between ten and twenty cars, inclusive, it shall be 

run over the scale a minimum of five times in each mode of operation following the final 

calibration.

(c) If the consecutive-car test train consists of more than twenty cars, it shall be run over the scale 

a minimum of three times in each mode of operation.

(Added 1990) (Amended 1992)

N.5. Uncoupled-in-Motion Railroad Weighing System. – An uncoupled-in-motion scale shall be tested statically 

before being tested in motion by passing railroad reference weight cars over the scale. When an uncoupled-in-motion 

railroad weighing system is tested, the car speed and the direction of travel shall be the same as when the scale is in 

normal use. The minimum in-motion test shall be three reference weight cars passed over the scale three times. The 

cars shall be selected to cover the range of weights that are normally weighed on the system and to reflect the types of 

cars normally weighed.

(Added 1993)

N.6. Nominal Capacity of Prescription Scales. – The nominal capacity of a prescription scale shall be assumed 

to be one-half apothecary ounce, unless otherwise marked. (Applicable only to scales not marked with an accuracy

class.)

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T. Tolerances Applicable to Devices not Marked I, II, III, III L, or IIII

T.1. Tolerance Values.

T.1.1. General. – The tolerances applicable to devices not marked with an accuracy class shall have the 

tolerances applied as specified in Table T.1.1. Tolerances for Unmarked Scales.

(Amended 1990)

T.1.2. Postal and Parcel Post Scales. – The tolerances for postal and parcel post scales are given in 

Table T.1.1. Tolerances for Unmarked Scales and Table 5. Maintenance and Acceptance Tolerances for 

Unmarked Postal and Parcel Post Scales.

(Amended 1990)

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(Table Added 1990; Amended 1992, 1993, and 2012) 

Table T.1.1. Tolerances for Unmarked Scales

Type of Device Subcategory Minimum 

Tolerance

Acceptance 

Tolerance

Maintenance 

Tolerance

Decreasing-Load

Multiplier1

Other Applicable 

Requirements

Vehicle, axle-load, livestock, railway 

track (weighing statically), crane, and 

hopper (other than grain hopper)

Class III L, T.N.3.1 (Table 6) and T.N.3.2. 1.0

T.N.2., T.N.3., T.N.4.1., 

T.N.4.2., T.N.4.3., T.N.4.4., 

T.N.5., T.N.7.2., T.N.8.1.4.4

, 

T.N.9.

Grain test scales n ≤ 10 000

n > 10 000

Class III, T.N.3.1. (Table 6) and T.N.3.2.

Class II, T.N.3.1. (Table 6) and T.N.3.2. 1.0 T.N.8.1.4.4

, T.N.9.

Railway track scales weighing in 

motion

T.N.3.6. except that for T.N.3.6.2. (a), no single error shall 

exceed four times the maintenance tolerance. 1.0 T.N.8.1.4.4

, T.N.9.

Monorail scales, in-motion T.N.3.8. 1.0 T.N.8.1.4.4, T.N.9.

Customer-operated bulk-weighing 

systems for recycled materials

± 5 % of applied material test load.

Average error on 10 or more test loads ≤ 2.5 %. 1.0 T.N.8.1.4.4

, T.N.9.

Wheel-load weighers and portable 

axle-load scales

Tested 

individually or 

in pairs2

0.5 d or 50 lb, 

whichever is greater 1 % of test load 2 % of test load 1.53 T.N.8.1.4.4

, T.N.9.

Prescription scales 0.1 grain (6 mg) 0.1 % of test load 0.1 % of test load 1.5 T.N.8.1.4.4, T.N.9.

Jewelers’ scales Graduated 0.5 d

0.05 % of test load 0.05 % of test load

1.5

Ungraduated

Sensitivity or 

smallest weight, 

whichever is less

T.N.8.1.4.4, T.N.9.

Dairy-product test scale Loads < 18 g

18 g load

0.2 grain

0.2 grain

0.2 grain

0.3 grain

0.2 grain

0.5 grain 1.5 T.N.8.1.4.4

, T.N.9.

Postal and parcel post scales

designed/used to weigh

loads < 2 lb

Loads < 2 lb 15 grain, 1 g, 1

/32 oz, 

0.03 oz, or 0.002 lb

15 grain, 

1 g, 1/32 oz, 

0.03 oz, or 

0.002 lb

15 grain, 1 g, 1/32 oz, 

0.03 oz, or 0.002 lb 1.5 T.N.8.1.4.4

, T.N.9.

Loads ≤ 2 lb Table 5 Table 5 Table 5

Other postal and parcel post scales Table 5 Table 5 Table 5 1.5 T.N.8.1.4.4, T.N.9.

All other scales (including grain 

hopper)

n > 5000

0.5 d or 0.05 % of 

scale capacity,

whichever is less

0.05 % of test load 0.1 % of test load 1.5

T.N.2.5., T.N.4.1., T.N.4.2., 

T.N.4.3., T.N.5., T.N.7.2., 

T.N.8.1.4.4, T.N.9.

n ≤ 5000 Class III, T.N.3.1., Table 6 and T.N.3.2. 1.0

T.N.2., T.N.3., T.N.4.1., 

T.N.4.2., T.N.4.3., T.N.5., 

T.N.7.2., T.N.8.1.4.4, T.N.9.

1 The decreasing load test applies only to automatic indicating scales. 2 If marked and tested as a pair, the tolerance shall be applied to the sum of the 

indication.

3 The decreasing load test does not apply to portable wheel load weighers. 4 T.N.8.1.4. Operating Temperature. is nonretroactive and effective for unmarked 

devices manufactured as of January 1, 1981.

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T.2. Sensitivity Requirement (SR).

T.2.1. Application. – The sensitivity requirement (SR) is applicable to all nonautomatic-indicating scales not 

marked I, II, III, III L, or IIII, and is the same whether acceptance or maintenance tolerances apply.

T.2.2. General. – Except for scales specified in paragraphs T.2.3. Prescription Scales through T.2.8. Railway 

Track Scales: 2 d, 0.2 % of the scale capacity, or 40 lb, whichever is least.

T.2.3. Prescription Scales. 6 mg (0.1 grain).

T.2.4. Jewelers’ Scales.

T.2.4.1. With One-Half Ounce Capacity or Less. – 6 mg (0.1 grain).

T.2.4.2. With More Than One-Half Ounce Capacity. – 1 d or 0.05 % of the scale capacity, whichever is 

less.

T.2.5. Dairy-Product Test Scales.

T.2.5.1. Used in Determining Butterfat Content. – 32 mg (0.5 grain).

T.2.5.2. Used in Determining Moisture Content. – 19 mg (0.3 grain).

T.2.6. Grain Test Scales. – The sensitivity shall be as stated in T.N.6. Sensitivity.

(Amended 1987)

T.2.7. Vehicle, Axle-Load, Livestock, and Animal Scales.

T.2.7.1. Equipped With Balance Indicators. – 1 d.

T.2.7.2. Not Equipped With Balance Indicators. – 2 d or 0.2 % of the scale capacity, whichever is less.

T.2.8. Railway Track Scales. – 3 d or 100 lb, whichever is less.

Table 5.

Maintenance and Acceptance Tolerances for Unmarked

Postal and Parcel Post Scales

Scale Capacity Test Loads Maintenance Tolerance

(±)

Acceptance Tolerance

(±)

(lb) (lb) (oz) (lb) (oz) (lb)

0 to 4, inclusive* 0 to 1, inclusive 1/32 0.002 1/32 0.002

over 1 1/8 0.008 1/16 0.004

over 4* 0 to 7, inclusive 3/16 0.012 3/16 0.012

7+ to 24, inclusive 3/8 0.024 3/16 0.012

24+ to 30, inclusive 1⁄2 0.030 1⁄4 0.015

over 30 0.1 % of Test Load 0.05 % of Test Load

*Also see Table T.1.1. Tolerances for Unmarked Scales for scales designed and/or used to weigh loads less than 2 lb.

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T.3.Sensitivity Requirement, Equilibrium Change Required.

The minimum change in equilibrium with test loads equal to the values specified in T.2. Sensitivity Requirements (SR) 

shall be as follows:

(a) Scale with a Trig Loop but without a Balance Indicator. – The position of rest of the weighbeam shall change 

from the center of the trig loop to the top or bottom, as the case may be.

(b) Scale with a Single Balance Indicator and Having a Nominal Capacity of Less Than 250 kg (500 lb). – The 

position of rest of the indicator shall change 1.0 mm (0.04 in) or one division on the graduated scale, whichever 

is greater.

(c) Scale with a Single Balance Indicator and Having a Nominal Capacity of 250 kg (500 lb) or Greater. – The 

position of rest of the indicator shall change 6.4 mm (0.25 in) or one division on the graduated scale or the width 

of the central target area, whichever is greater. However, the indicator on a batching scale shall change 3.2 mm 

(0.125 in) or one division on the graduated scale, whichever is greater.

(d) Scale with Two Opposite-Moving Balance Indicators. – The position of rest of the two indicators moving in 

opposite directions shall change 1.0 mm (0.04 in) with respect to each other.

(e) Scale with Neither a Trig Loop nor a Balance Indicator. – The position of rest of the weighbeam or lever 

system shall change from the horizontal, or midway between limiting stops, to either limit of motion.

T.N. Tolerances Applicable to Devices Marked I, II, III, III L, and IIII.

T.N.1. Principles.

T.N.1.1. Design. – The tolerance for a weighing device is a performance requirement independent of the design 

principle used.

T.N.1.2. Accuracy Classes. – Weighing devices are divided into accuracy classes according to the number of scale 

divisions (n) and the value of the scale division (d).

T.N.1.3. Scale Division. – The tolerance for a weighing device is related to the value of the scale division (d) or 

the value of the verification scale division (e) and is generally expressed in terms of d or e.

T.N.2. Tolerance Application.

T.N.2.1. General. – The tolerance values are positive (+) and negative (−) with the weighing device adjusted to 

zero at no load. When tare is in use, the tolerance values are applied from the tare zero reference (zero net weight 

indication); the tolerance values apply to the net weight indication for any possible tare load using certified test loads. 

(Amended 2008)

T.N.2.2. Type Evaluation Examinations. – For type evaluation examinations, the tolerance values apply to 

increasing and decreasing load tests within the temperature, power supply, and barometric pressure limits specified 

in T.N.8.

T.N.2.3. Subsequent Verification Examinations. – For subsequent verification examinations, the tolerance 

values apply regardless of the influence factors in effect at the time of the conduct of the examination. (Also see

G-N.2. Testing with Nonassociated Equipment.)

T.N.2.4. Multi-Interval and Multiple Range (Variable Division-Value) Scales. – For multi-interval and 

multiple range scales, the tolerance values are based on the value of the scale division of the range in use.

T.N.2.5. Ratio Tests. – For ratio tests, the tolerance values are 0.75 of the applicable tolerances. 

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T.N.3. Tolerance Values.

T.N.3.1. Maintenance Tolerance Values. – The maintenance tolerance values are as specified in Table 6. 

Maintenance Tolerances.

T.N.3.2. Acceptance Tolerance Values. – The acceptance tolerance values shall be one-half the maintenance

tolerance values.

T.N.3.3. Wheel-Load Weighers and Portable Axle-Load Weighers of Class IIII. – The tolerance values are two 

times the values specified in T.N.3.1. Maintenance Tolerance Values and T.N.3.2. Acceptance Tolerance Values.

(Amended 1986)

T.N.3.4. Crane and Hopper (Other than Grain Hopper) Scales. – The maintenance and acceptance tolerances

shall be as specified in T.N.3.1. Maintenance Tolerance Values and T.N.3.2. Acceptance Tolerance Values for 

Class III L, except that the tolerance for crane and construction materials hopper scales shall not be less than 1 d or 

0.1 % of the scale capacity, whichever is less.

(Amended 1986)

Table 6.

Maintenance Tolerances

(All values in this table are in scale divisions)

Tolerance in Scale Divisions

1 2 3 5 

Class Test Load

I 0 - 50 000 50 001 - 200 000 200 001 +

II 0 - 5 000 5 001 - 20 000 20 001 +

III 0 - 500 501 - 2 000 2 001 - 4 000 4 001 +

IIII 0 - 50 51 - 200 201 - 400 401 +

III L 0 - 500 501 - 1 000 (Add 1 d for each additional 500 d or fraction thereof)

T.N.3.5. Separate Main Elements: Load Transmitting Element, Indicating Element, Etc. – If a main element 

separate from a complete weighing device is submitted for laboratory type evaluation, the tolerance for the main 

element is 0.7 that for the complete weighing device. This fraction includes the tolerance attributable to the testing 

devices used.

(Amended 2015)

T.N.3.6. Coupled-In-Motion Railroad Weighing Systems. – The maintenance and acceptance tolerance values 

for the group of weight values appropriate to the application must satisfy the following conditions:

(Amended 1990 and 1992)

T.N.3.6.1. – For any group of weight values, the difference in the sum of the individual in-motion car weights of 

the group as compared to the sum of the individual static weights shall not exceed 0.2 %.

(Amended 1990)

T.N.3.6.2. – If a weighing system is used to weigh trains of five or more cars, and if the individual car weights 

are used, any single weight value within the group must meet the following criteria:

(a) no single error may exceed three times the static maintenance tolerance; 

(b) not more than 5 % of the errors may exceed two times the static maintenance tolerance; and

(c) not more than 35 % of the errors may exceed the static maintenance tolerance. 

(Amended 1990 and 1992)

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T.N.3.6.3. – For any group of weight values wherein the sole purpose is to determine the sum of the group, 

T.N.3.6.1. alone applies.

(Amended 1990)

T.N.3.6.4. – For a weighing system used to weigh trains of less than five cars, no single car weight within the 

group may exceed the static maintenance tolerance. 

(Amended 1990 and 1992)

T.N.3.7. Uncoupled-in-Motion Railroad Weighing Systems. – The maintenance and acceptance tolerance values 

for any single weighment within a group of non-interactive (i.e., uncoupled) loads, the weighment error shall not 

exceed the static maintenance tolerance.

(Amended 1992)

T.N.3.8. Dynamic Monorail Weighing System. – Acceptance tolerance shall be the same as the maintenance

tolerance shown in Table 6. Maintenance Tolerances. On a dynamic test of twenty or more individual test loads, 

10 % of the individual test loads may be in error, each not to exceed two times the tolerance. The error on the total of 

the individual test loads shall not exceed ± 0.2 %. (Also see Note in N.1.3.5.1. Dynamic Monorail Weighing 

Systems.) For equipment undergoing type evaluation, a tolerance equal to one-half the maintenance tolerance 

values shown in Table 6. Maintenance Tolerances shall apply.

[Nonretroactive January 1, 2002]

(Added 1986) (Amended 1999 and 2001)

T.N.3.9. Materials Test on Customer-Operated Bulk Weighing Systems for Recycled Materials. – The 

maintenance and acceptance tolerance shall be ± 5 % of the applied materials test load except that the average error 

on ten or more test materials test loads shall not exceed ± 2.5 %.

(Added 1986)

T.N.3.10. Prescription Scales with a Counting Feature. – In addition to Table 6. Maintenance Tolerances (for 

weight), the indicated piece count value computed by a Class I or Class II prescription scale counting feature shall 

comply with the tolerances in Table T.N.3.10. Maintenance and Acceptance Tolerances in Excess and in Deficiency 

for Count.

Table T.N.3.10.

Maintenance and Acceptance Tolerances

in Excess and in Deficiency for Count

Indication of Count Tolerance

(piece count)

0 to 100 0

101 to 200 1

201 or more 0.5 %

(Added 2003)

T.N.3.11. Tolerances for Substitution Test. – Tolerances are applied to the scale based on the substitution test 

load.

(Added 2003)

T.N.3.12. Tolerances for Strain-Load Test. – Tolerances apply only to the test weights or substitution test loads.

(Added 2003)

T.N.4. Agreement of Indications.

T.N.4.1. Multiple Indicating/Recording Elements. – In the case of a scale or weighing system equipped with 

more than one indicating element or indicating element and recording element combination, where the indicators or 

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indicator/recorder combination are intended to be used independently of one another, tolerances shall be applied 

independently to each indicator or indicator/recorder combination.

(Amended 1986)

T.N.4.2. Single Indicating/Recording Element. – In the case of a scale or weighing system with a single 

indicating element or an indicating/recording element combination, and equipped with component parts such as unit 

weights, weighbeam and weights, or multiple weighbeams that can be used in combination to indicate a weight, the 

difference in the weight value indications of any load shall not be greater than the absolute value of the applicable 

tolerance for that load, and shall be within tolerance limits.

(Amended 1986)

T.N.4.3. Single Indicating Element/Multiple Indications. – In the case of an analog indicating element equipped 

with two or more indicating means within the same element, the difference in the weight indications for any load 

other than zero shall not be greater than one-half the value of the scale division (d) and be within tolerance limits.

(Amended 1986)

T.N.4.4. Shift or Section Tests. – The range of the results obtained during the conduct of a shift test or a section 

test shall not exceed the absolute value of the maintenance tolerance applicable and each test result shall be within 

applicable tolerances. 

(Added 1986)

T.N.4.5. Time Dependence. – A time dependence test shall be conducted during type evaluation and may be 

conducted during field verification, provided test conditions remain constant.

(Amended 1989 and 2005)

T.N.4.5.1. Time Dependence: Class II, III, and IIII Non-automatic Weighing Instruments. – A 

non-automatic weighing instrument of Classes II, III, and IIII shall meet the following requirements at constant 

test conditions. During type evaluation, this test shall be conducted at 20 °C ± 2 °C (68 °F ± 4 °F):

(a) When any load is kept on an instrument, the difference between the indication obtained immediately 

after placing the load and the indication observed during the following 30 minutes shall not exceed 

0.5 e. However, the difference between the indication obtained at 15 minutes and the indication 

obtained at 30 minutes shall not exceed 0.2 e.

(b) If the conditions in (a) are not met, the difference between the indication obtained immediately after 

placing the load on the instrument and the indication observed during the following four hours shall not 

exceed the absolute value of the maximum permissible error at the load applied.

(Added 2005) (Amended 2006 and 2010)

T.N.4.5.2. Time Dependence: Class III L Non-automatic Weighing Instruments. – A non-automatic 

weighing instrument of Class III L shall meet the following requirements:

(a) When any load is kept on an instrument, the difference between the indication obtained immediately 

after placing the load and the indication observed during the following 30 minutes shall not 

exceed 1.5 e. However, the difference between the indication obtained at 15 minutes and the indication 

obtained at 30 minutes shall not exceed 0.6 e.

(b) If the conditions in (a) are not met, the difference between the indication obtained immediately after 

placing the load on the instrument and the indication observed during the following four hours shall not 

exceed the absolute value of the maximum permissible error at the load applied.

(Added 2005) (Amended 2010)

T.N.4.5.3. Zero Load Return: Non-automatic Weighing Instruments. – A non-automatic weighing 

instrument shall meet the following requirements at constant test conditions. During type evaluation, this test 

shall be conducted at 20 °C ± 2 °C (68 °F ± 4 °F). The deviation on returning to zero as soon as the indication 

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has stabilized, after the removal of any load which has remained on the instrument for 30 minutes shall not 

exceed: 

(a) 0.5 e for Class II and IIII devices,

(b) 0.5 e for Class III devices with 4000 or fewer divisions,

(c) 0.83 e for Class III devices with more than 4000 divisions, or

(d) one-half of the absolute value of the applicable tolerance for the applied load for Class III L devices.

For a multi-interval instrument, the deviation shall not exceed 0.83 e1 (where e1 is the interval of the first 

weighing segment of the scale).

On a multiple range instrument, the deviation on returning to zero from Maxi (load in the applicable weighing 

range) shall not exceed 0.83 ei (interval of the weighing range). Furthermore, after returning to zero from any 

load greater than Max1 (capacity of the first weighing range) and immediately after switching to the lowest 

weighing range, the indication near zero shall not vary by more than e1 (interval of the first weighing range) 

during the following five minutes.

(Added 2010) 

T.N.4.6. Time Dependence (Creep) for Load Cells during Type Evaluation. – A load cell (force transducer) 

marked with an accuracy class shall meet the following requirements at constant test conditions:

(a) Permissible Variations of Readings. – With a constant maximum load for the measuring range (Dmax) 

between 90 % and 100 % of maximum capacity (Emax), applied to the load cell, the difference between 

the initial reading and any reading obtained during the next 30 minutes shall not exceed the absolute 

value of the maximum permissible error (mpe) for the applied load. (Also see Table T.N.4.6. Maximum 

Permissible Error (mpe) for Load Cells During Type Evaluation.) The difference between the reading 

obtained at 20 minutes and the reading obtained at 30 minutes shall not exceed 0.15 times the absolute 

value of the mpe. (Also see Table T.N.4.6. Maximum Permissible Error (mpe) for Load Cells During 

Type Evaluation)

(b) Apportionment Factors. – The mpe for creep shall be determined from Table T.N.4.6. Maximum 

Permissible Error (mpe) for Load Cells During Type Evaluation using the following apportionment 

factors (pLC):

pLC = 0.7 for load cells marked with S (single load cell applications),

pLC = 1.0 for load cells marked with M (multiple load cell applications), and

pLC = 0.5 for Class III L load cells marked with S or M.

(Added 2005, Amended 2006) 

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Table T.N.4.6.

Maximum Permissible Error (mpe)* for Load Cells During Type Evaluation

mpe in Load Cell Verifications Divisions (v) = pLC x Basic Tolerance in v

Class pLC x 0.5 v pLC x 1.0 v pLC x 1.5 v

I 0 - 50 000 v 50 001 v - 200 000 v 200 001 v +

II 0 - 5 000 v 5 001 v - 20 000 v 20 001 v +

III 0 - 500 v 501 v - 2 000 v 2 001 v +

IIII 0 - 50 v 51 v - 200 v 201 v +

III L 0 - 500 v 501 v - 1 000 v (Add 0.5 v to the basic tolerance for each additional 500 v 

or fraction thereof up to a maximum load of 10 000 v)

v represents the load cell verification interval

pLC represents the apportionment factors applied to the basic tolerance

pLC = 0.7 for load cells marked with S (single load cell applications)

pLC = 1.0 for load cells marked with M (multiple load cell applications)

pLC = 0.5 for Class III L load cells marked with S or M

* mpe = pLC × Basic Tolerance in load cell verifications divisions (v)

(Table Added 2005) (Amended 2006)

T.N.4.7. Creep Recovery for Load Cells During Type Evaluation. – The difference between the initial reading 

of the minimum load of the measuring range (Dmin) and the reading after returning to minimum load subsequent to 

the maximum load (Dmax) having been applied for 30 minutes shall not exceed:

(a) 0.5 times the value of the load cell verification interval (0.5 v) for Class II and IIII load cells; 

(b) 0.5 times the value of the load cell verification interval (0.5 v) for Class III load cells with 4000 or fewer 

divisions; 

(c) 0.83 times the value of the load cell verification interval (0.83 v) for Class III load cells with more than 

4000 divisions; or

(d) 2.5 times the value of the load cell verification interval (2.5 v) for Class III L load cells.

(Added 2006) (Amended 2009 and 2011) 

T.N.5. Repeatability. – The results obtained from several weighings of the same load under reasonably static test 

conditions shall agree within the absolute value of the maintenance tolerance for that load, and shall be within applicable 

tolerances. 

T.N.6. Sensitivity. – This section is applicable to all nonautomatic-indicating scales marked I, II, III, III L, or IIII. 

T.N.6.1. Test Load.

(a) The test load for sensitivity for nonautomatic-indicating vehicle, axle-load, livestock, and animal scales shall 

be 1 d for scales equipped with balance indicator, and 2 d or 0.2 % of the scale capacity, whichever is less, 

for scales not equipped with balance indicators.

(b) For all other nonautomatic-indicating scales, the test load for sensitivity shall be 1 d at zero and 2 d at 

maximum test load.

T.N.6.2. Minimum Change of Indications. – The addition or removal of the test load for sensitivity shall cause a 

minimum permanent change as follows:

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(a) for a scale with trig loop but without a balance indicator, the position of the weighbeam shall change from 

the center to the outer limit of the trig loop;

(b) for a scale with balance indicator, the position of the indicator shall change one division on the graduated 

scale, the width of the central target area, or the applicable value as shown below, whichever is greater:

Scale of Class I or II: 1 mm (0.04 in),

Scale of Class III or IIII with a maximum capacity of 30 kg (70 lb) or less: 2 mm (0.08 in),

Scale of Class III, III L, or IIII with a maximum capacity of more than 30 kg (70 lb): 5 mm (0.20 in);

(c) for a scale without a trig loop or balance indicator, the position of rest of the weighbeam or lever system 

shall change from the horizontal or midway between limiting stops to either limit of motion.

(Amended 1987)

T.N.7. Discrimination.

T.N.7.1. Analog Automatic Indicating (i.e., Weighing Device with Dial, Drum, Fan, etc.). – A test load 

equivalent to 1.4 d shall cause a change in the indication of at least 1.0 d. (Also see N.1.5. Discrimination Test.) 

T.N.7.2. Digital Automatic Indicating. – A test load equivalent to 1.4 d shall cause a change in the indicated or 

recorded value of at least 2.0 d. This requires the zone of uncertainty to be not greater than three-tenths of the value 

of the scale division. (Also see N.1.5.1. Digital Device.) 

T.N.8. Influence Factors. – The following factors are applicable to tests conducted under controlled conditions only, 

provided that:

(a) types of devices approved prior to January 1, 1986, and manufactured prior to January 1, 1988, need not meet the 

requirements of this section; 

(b) new types of devices submitted for approval after January 1, 1986, shall comply with the requirements of this 

section; and

(c) all devices manufactured after January 1, 1988, shall comply with the requirements of this section.

(Amended 1985)

T.N.8.1. Temperature. – Devices shall satisfy the tolerance requirements under the following temperature

conditions:

T.N.8.1.1. If not specified in the operating instructions for Class I or II scales, or if not marked on the device 

for Class III, III L, or IIII scales, the temperature limits shall be: − 10 °C to 40 °C (14 °F to 104 °F).

T.N.8.1.2. If temperature limits are specified for the device, the range shall be at least that specified in 

Table T.N.8.1.2. Temperature Range by Class.

Table T.N.8.1.2.

Temperature Range by Class

Class Temperature Range

I 5 oC (9 °F)

II 15 oC (27 °F)

III, III L, and IIII 30 oC (54 °F)

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T.N.8.1.3. Temperature Effect on Zero-Load Balance. – The zero-load indication shall not vary by more 

than:

(a) three divisions per 5 °C (9 °F) change in temperature for Class III L devices; or

(b) one division per 5 °C (9 °F) change in temperature for all other devices.

(Amended 1990)

T.N.8.1.4. Operating Temperature. – Except for Class I and II devices, an indicating or recording element 

shall not display nor record any usable values until the operating temperature necessary for accurate weighing 

and a stable zero balance condition have been attained.

T.N.8.2. Barometric Pressure. – Except for Class I scales, the zero indication shall not vary by more than one 

scale division for a change in barometric pressure of 1 kPa over the total barometric pressure range of 95 kPa to 

105 kPa (28 in to 31 in of Hg).

T.N.8.3. Electric Power Supply.

T.N.8.3.1. Power Supply, Voltage and Frequency.

(a) Weighing devices that operate using alternating current must perform within the conditions defined in 

paragraphs T.N.3. Tolerance Values through T.N.7. Discrimination, inclusive, when tested over the 

range of − 15 % to + 10 % of the marked nominal line voltage(s) at 60 Hz, or the voltage range marked 

by the manufacturer, at 60 Hz.

(Amended 2003)

(b) Battery operated instruments shall not indicate nor record values outside the applicable tolerance limits 

when battery power output is excessive or deficient.

T.N.8.3.2. Power Interruption. – A power interruption shall not cause an indicating or recording element to 

display or record any values outside the applicable tolerance limits.

T.N.9. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility. – The 

difference between the weight indication due to the disturbance and the weight indication without the disturbance shall 

not exceed one scale division (d); or the equipment shall:

(a) blank the indication; or

(b) provide an error message; or

(c) the indication shall be so completely unstable that it cannot be interpreted, or transmitted into memory or to a 

recording element, as a correct measurement value.

The tolerance in T.N.9. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility is to 

be applied independently of other tolerances. For example, if indications are at allowable basic tolerance error limits 

when the disturbance occurs, then it is acceptable for the indication to exceed the applicable basic tolerances during the 

disturbance. 

(Amended 1997)

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UR. User Requirements

UR.1. Selection Requirements. – Equipment shall be suitable for the service in which it is used with respect to 

elements of its design, including but not limited to, its capacity, number of scale divisions, value of the scale division or 

verification scale division, minimum capacity, and computing capability.4

UR.1.1. General.

(a) For devices marked with a class designation, the typical class or type of device for particular weighing 

applications is shown in Table 7a. Typical Class or Type of Device for Weighing Applications.

(b) For devices not marked with a class designation, Table 7b. Applicable to Devices not Marked with a Class 

Designation applies.

Table 7a.

Typical Class or Type of Device for Weighing Applications

Class Weighing Application or Scale Type

I Precision laboratory weighing

II Laboratory weighing, precious metals and gem weighing, grain test scales

III

All commercial weighing not otherwise specified, grain test scales, retail precious metals and semi-precious 

gem weighing, grain-hopper scales, animal scales, postal scales, vehicle on-board weighing systems with a 

capacity less than or equal to 30 000 lb, and scales used to determine laundry charges

III L Vehicle scales, vehicle on-board weighing systems with a capacity greater than 30 000 lb, axle-load scales, 

livestock scales, railway track scales, crane scales, and hopper (other than grain hopper) scales

IIII Wheel-load weighers and portable axle-load weighers used for highway weight enforcement

Note: A scale with a higher accuracy class than that specified as “typical” may be used.

(Amended 1985, 1986, 1987, 1988, 1992, 1995, and 2012)

 

4 Purchasers and users of scales such as railway track, hopper, and vehicle scales should be aware of possible additional 

requirements for the design and installation of such devices.

(Footnote Added 1995)

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Table 7b.

Applicable to Devices not Marked with a Class Designation

Scale Type or Design Maximum Value of d

Retail Food Scales, 50 lb capacity and less 1 oz

Animal Scales 1 lb

Grain Hopper Scales

Capacity up to and including 50 000 lb

Capacity over 50 000 lb

10 lb (not greater than 0.05 % of capacity)

20 lb

Crane Scales not greater than 0.2 % of capacity

Vehicle and Axle-Load Scales Used in Combination

Capacity up to and including 200 000 lb

Capacity over 200 000 lb

20 lb

50 lb

Railway Track Scales

With weighbeam

Automatic indicating

20 lb

100 lb

Scales with capacities greater than 500 lb except 

otherwise specified 0.1 % capacity (but not greater than 50 lb)

Wheel-Load Weighers 0.25 % capacity (but not greater than 50 lb)

Note: For scales not specified in this table, G-UR.1.1. and UR.1. apply.

(Added 1985) (Amended 1989)

UR.1.2. Grain Hopper Scales. – Hopper scales manufactured as of January 1, 1986, that are used to weigh grain 

shall be Class III and have a minimum of 2000 scale divisions.

(Amended 2012)

UR.1.3. Value of the Indicated and Recorded Scale Division. – The value of the scale division as recorded shall 

be the same as the division value indicated.

[Nonretroactive as of January 1, 1986]

(Added 1985) (Amended 1999)

UR.1.3.1. Exceptions. – The provisions of UR.1.3. Value of the Indicated and Recorded Scale Division shall 

not apply to:

(a) Class I scales, or

(b) Dynamic monorail weighing systems when the value of d is less than the value of e.

(Added 1999)

UR.1.4. Grain-Test Scales: Value of the Scale Divisions. – The scale division for grain-test scales shall not 

exceed 0.2 g for loads through 500 g, and shall not exceed 1 g for loads above 500 g through 1000 g.

(Added 1992)

UR.1.5. Recording Element, Class III L Railway Track Scales. – Class III L Railway Track Scales must be 

equipped with a recording element.

[Nonretroactive as of January 1, 1996]

(Added 1995)

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UR.2. Installation Requirements.

UR.2.1. Supports. – A scale that is portable and that is being used on a counter, table, or the floor shall be so 

positioned that it is firmly and securely supported.

UR.2.2. Suspension of Hanging Scale. – A hanging scale shall be freely suspended from a fixed support when in 

use.

UR.2.3. Protection From Environmental Factors. – The indicating elements, the lever system or load cells, and 

the load-receiving element of a permanently installed scale, and the indicating elements of a scale not intended to be 

permanently installed, shall be adequately protected from environmental factors such as wind, weather, and RFI that

may adversely affect the operation or performance of the device.

UR.2.4. Foundation, Supports, and Clearance. – The foundation and supports of any scale installed in a fixed 

location shall be such as to provide strength, rigidity, and permanence of all components, and clearance shall be 

provided around all live parts to the extent that no contacts may result when the load-receiving element is empty, nor 

throughout the weighing range of the scale. An in-motion railway track scale is not required to provide clearance 

using rail gaps to separate the live rail portion of the weighing/load-receiving element from that which is not live if 

the scale is designed to be installed and operated using continuous rail. On vehicle and livestock scales, the 

clearance between the load-receiving elements and the coping at the bottom edge of the platform shall be greater 

than at the top edge of the platform.* 

[*Nonretroactive as of January 1, 1973]

(Amended 2014)

UR.2.5. Access to Weighing Elements. – Adequate provision shall be made for ready access to the pit of a 

vehicle, livestock, animal, axle-load, or railway track scale for the purpose of inspection and maintenance. Any of 

these scales without a pit shall be installed with adequate means for inspection and maintenance of the weighing 

elements. 

(Amended 1985)

UR.2.6. Approaches.

UR.2.6.1. Vehicle Scales. – On the entrance and exit end(s) of a vehicle scale, there shall be a straight 

approach as follows:

(a) the width at least the width of the platform,

(b) the length at least one-half the length of the platform but not required to be more than 12 m (40 ft), and

(c) not less than 3 m (10 ft) of any approach adjacent to the platform shall be in the same plane as the 

platform. Any slope in the remaining portion of the approach shall ensure (1) ease of vehicle access, 

(2) ease for testing purposes, and (3) drainage away from the scale.

In addition to (a), (b), and (c), scales installed in any one location for a period of six months or more shall have 

not less than 3 m (10 ft) of any approach adjacent to the platform constructed of concrete or similar durable 

material to ensure that this portion remains smooth and level and in the same plane as the platform; however, 

grating of sufficient strength to withstand all loads equal to the concentrated load capacity of the scale may be 

installed in this portion.

[Nonretroactive as of January 1, 1976]

(Amended 1977, 1983, 1993, 2006, and 2010) 

UR.2.6.2. Axle-Load Scales. – At each end of an axle-load scale there shall be a straight paved approach in 

the same plane as the platform. The approaches shall be the same width as the platform and of sufficient length 

to insure the level positioning of vehicles during weight determinations.

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UR.2.7. Stock Racks. – A livestock or animal scale shall be equipped with a suitable stock rack, with gates as 

required, which shall be securely mounted on the scale platform. Adequate clearances shall be maintained around the 

outside of the rack.

UR.2.8. Hoists. – On vehicle scales equipped with means for raising the load-receiving element from the weighing 

element for vehicle unloading, means shall be provided so that it is readily apparent to the scale operator when the 

load-receiving element is in its designed weighing position.

UR.2.9. Provision for Testing Dynamic Monorail Weighing Systems. – Provisions shall be made at the time of 

installation of a dynamic monorail weighing systems for testing in accordance with N.1.3.5.1. Dynamic Monorail 

Weighing Systems (a rail around or other means for returning the test carcasses to the scale being tested).

[Nonretroactive as of January 1, 1998]

(Added 1997) (Amended 1999)

UR.3. Use Requirements.

UR.3.1. Recommended Minimum Load. – A recommended minimum load is specified in Table 8 since the use 

of a device to weigh light loads is likely to result in relatively large errors.

Table 8.

Recommended Minimum Load

Class Value of Scale Division

(d or e*)

Recommended Minimum Load

(d or e*)

I equal to or greater than 0.001 g 100

II 0.001 g to 0.05 g, inclusive 20

equal to or greater than 0.1 g 50

III All** 20

 III L All 50

IIII All 10

*For Class I and II devices equipped with auxiliary reading means (i.e., a rider, a vernier, or a least 

significant decimal differentiated by size, shape or color), the value of the verification scale division “e” is 

the value of the scale division immediately preceding the auxiliary means. For Class III and IIII devices the 

value of “e” is specified by the manufacturer as marked on the device; “e” must be less than or equal to “d.”

**A minimum load of 10 d is recommended for a weight classifier marked in accordance with a statement 

identifying its use for special applications.

(Amended 1990)

UR.3.1.1. Minimum Load, Grain Dockage Determination. – When determining the quantity of foreign 

material (dockage) in grain, the weight of the sample shall be equal to or greater than 500 scale divisions.

(Added 1985)

UR.3.2. Maximum Load. – A scale shall not be used to weigh a load of more than the nominal capacity of the 

scale.

UR.3.2.1. Maximum Loading for Vehicle Scales. – A vehicle scale shall not be used to weigh loads 

exceeding the maximum load capacity of its span as specified in Table UR.3.2.1. Span Maximum Load.

(Added 1996)

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Table UR.3.2.1.

Span Maximum Load

Distance in Feet 

Between the 

Extremes of any 

Two or More 

Consecutive Axles

Ratio of CLC to Maximum Load (“r” factor) Carried on Any

Group of Two or More Consecutive Axles.

2 axles 3 axles 4 axles 5 axles 6 axles 7 axles 8 axles 9 axles

41 1.000 INSTRUCTIONS:

1. Determine the scale’s CLC. 

2. Count the number of axles on the vehicle in a given span and determine 

the distance in feet between the first and last axle in the span.

3. Multiply the CLC by the corresponding multiplier in the table.* 

4. The resulting number is the scale’s maximum concentrated load for a 

single span based on the vehicle configuration.

* note and formula on next page.

51 1.000

61 1.000

71 1.000

8 and less1 1.000 1.000

More than 81 1.118 1.235

9 1.147 1.257

10 1.176 1.279

11 1.206 1.301

12 1.235 1.324 1.471 1.632

13 1.265 1.346 1.490 1.651

14 1.294 1.368 1.510 1.669

15 1.324 1.390 1.529 1.688 1.853

16 1.353 1.412 1.549 1.706 1.871

17 1.382 1.434 1.569 1.724 1.888

18 1.412 1.456 1.588 1.743 1.906

19 1.441 1.478 1.608 1.761 1.924

20 1.471 1.500 1.627 1.779 1.941

21 1.500 1.522 1.647 1.798 1.959

22 1.529 1.544 1.667 1.816 1.976

23 1.559 1.566 1.686 1.835 1.994

24 1.588 1.588 1.706 1.853 2.012 2.176

25 1.618 1.610 1.725 1.871 2.029 2.194

26 1.632 1.745 1.890 2.047 2.211

27 1.654 1.765 1.908 2.065 2.228

28 1.676 1.784 1.926 2.082 2.245 2.412

29 1.699 1.804 1.945 2.100 2.262 2.429

30 1.721 1.824 1.963 2.118 2.279 2.445

31 1.743 1.843 1.982 2.135 2.297 2.462

32 1.765 1.863 2.000 2.153 2.314 2.479 2.647

33 1.882 2.018 2.171 2.331 2.496 2.664

34 1.902 2.037 2.188 2.348 2.513 2.680

35 1.922 2.055 2.206 2.365 2.529 2.697

36 2.0002 2.074 2.224 2.382 2.546 2.713

37 2.0002 2.092 2.241 2.400 2.563 2.730

38 2.0002 2.110 2.259 2.417 2.580 2.746

39 2.000 2.129 2.276 2.434 2.597 2.763

40 2.020 2.147 2.294 2.451 2.613 2.779

41 2.039 2.165 2.312 2.468 2.630 2.796

42 2.059 2.184 2.329 2.485 2.647 2.813

43 2.078 2.202 2.347 2.502 2.664 2.829

44 2.098 2.221 2.365 2.520 2.681 2.846

45 2.118 2.239 2.382 2.537 2.697 2.862

46 2.137 2.257 2.400 2.554 2.714 2.879

47 2.157 2.276 2.418 2.571 2.731 2.895

48 2.176 2.294 2.435 2.588 2.748 2.912

49 2.196 2.313 2.453 2.605 2.765 2.928

50 2.216 2.331 2.471 2.623 2.782 2.945

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Table UR.3.2.1.

Span Maximum Load

Distance in Feet 

Between the 

Extremes of any 

Two or More 

Consecutive Axles

Ratio of CLC to Maximum Load (“r” factor) Carried on Any

Group of Two or More Consecutive Axles.

2 axles 3 axles 4 axles 5 axles 6 axles 7 axles 8 axles 9 axles

51 2.235 2.349 2.488 2.640 2.798 2.961

52 2.255 2.368 2.506 2.657 2.815 2.978

53 2.275 2.386 2.524 2.674 2.832 2.994

54 2.294 2.404 2.541 2.691 2.849 3.011

55 2.314 2.423 2.559 2.708 2.866 3.028

56 2.333 2.441 2.576 2.725 2.882 3.044

57 2.3533 2.460 2.594 2.742 2.899 3.061

58 2.478 2.612 2.760 2.916 3.077

59 2.496 2.629 2.777 2.933 3.094

60 2.515 2.647 2.794 2.950 3.110

*Note: This table was developed based upon the following formula. Values may be rounded in some cases for ease of 

use.

 



 



  ++ 

 





− ×= 36 12 1

 500 N

N

LN rW

1 Tandem Axle Weight.

2 Exception – These values in the third column correspond to the maximum loads in which the inner bridge dimensions of 

36, 37, and 38 ft are considered to be equivalent to 39 ft. This allows a weight of 68 000 lb on axles 2 through 5. 3 Corresponds to the Interstate Gross Weight Limit.

UR.3.3. Single-Draft Vehicle Weighing. – A vehicle or a coupled-vehicle combination shall be commercially 

weighed on a vehicle scale only as a single draft. That is, the total weight of such a vehicle or combination shall not 

be determined by adding together the results obtained by separately and not simultaneously weighing each end of 

such vehicle or individual elements of such coupled combination. However, the weight of: 

(a) a coupled combination may be determined by uncoupling the various elements (tractor, semitrailer, trailer), 

weighing each unit separately as a single draft, and adding together the results; or

(b) a vehicle or coupled-vehicle combination may be determined by adding together the weights obtained while 

all individual elements are resting simultaneously on more than one scale platform.

Note: This paragraph does not apply to highway-law-enforcement scales and scales used for the collection of statistical data.

(Added 1992)

UR.3.4. Wheel-Load Weighing.

UR.3.4.1. Use in Pairs. – When wheel-load weighers or portable axle-load weighers are to be regularly used 

in pairs, both weighers of each such pair shall be appropriately marked to identify them as weighers intended to 

be used in combination.

UR.3.4.2. Level Condition. – A vehicle of which either an axle-load determination or a gross-load 

determination is being made utilizing wheel-load weighers or portable axle-load weighers, shall be in a 

reasonably level position at the time of such determination.

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UR.3.5. Special Designs. – A scale designed and marked for a special application (such as a prepackaging scale or 

prescription scale with a counting feature) shall not be used for other than its intended purpose5

. 

(Amended 2003)

UR.3.6. Wet Commodities. – Wet commodities not in watertight containers shall be weighed only on a scale 

having a pan or platform that will drain properly.

(Amended 1988)

UR.3.7. Minimum Load on a Vehicle Scale. – A vehicle scale shall not be used to weigh net loads smaller than:

(a) 10 d when weighing scrap material for recycling or weighing refuse materials at landfills and transfer 

stations; and

(b) 50 d for all other weighing.

As used in this paragraph, scrap materials for recycling shall be limited to ferrous metals, paper (including 

cardboard), textiles, plastic, and glass.

(Amended 1988, 1992, and 2006)

UR.3.8. Minimum Load for Weighing Livestock. – A scale with scale divisions greater than 2 kg (5 lb) shall not 

be used for weighing net loads smaller than 500 d.

(Amended 1989)

UR.3.9. Use of Manual Weight Entries. – Manual gross or net weight entries are permitted for use in the 

following applications only when:

(a) a point-of-sale system interfaced with a scale is giving credit for a weighed item;

(b) an item is pre-weighed on a legal for trade scale and marked with the correct net weight;

(c) a device or system is generating labels for standard weight packages;

(d) postal scales or weight classifiers are generating manifests for packages to be picked up at a later time; or

(e) livestock and vehicle scale systems generate weight tickets to correct erroneous tickets.

(Added 1992) (Amended 2000 and 2004)

UR.3.10. Dynamic Monorail Weighing Systems. – When the value of d is different from the value of e, the 

commercial transaction must be based on e.

(Added 1999)

 

5 Prepackaging scales and prescription scales with a counting feature (and other commercial devices) used for putting up 

packages in advance of sale are acceptable for use in commerce only if all appropriate provisions of NIST Handbook 44 

are met. Users of such devices must be alert to the legal requirements relating to the declaration of quantity on a package. 

Such requirements are to the effect that, on the average, the contents of the individual packages of a particular commodity 

comprising a lot, shipment, or delivery must contain at least the quantity declared on the label. The fact that a 

prepackaging scale may overregister, but within established tolerances, and is approved for commercial service is not a 

legal justification for packages to contain, on the average, less than the labeled quantity.

(Amended 2003)

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UR.3.11. Minimum Count. – A prescription scale with an operational counting feature shall not be used to count 

a quantity of less than 30 pieces weighing a minimum of 90 e.

(Added 2003)

Note: The minimum count as defined in this paragraph refers to the use of the device in the filling of prescriptions and is different 

from the minimum sample piece count as defined in S.1.2.3. and as required to be marked on the scale by S.6.6.

(Note Added 2004) 

UR.3.12. Correct Stored Piece Weight. – For prescription scales with a counting feature, the user is responsible 

for maintaining the correct stored piece weight. This is especially critical when a medicine has been reformulated or 

comes from different lots.

(Added 2003)

UR.4. Maintenance Requirements.

UR.4.1. Balance Condition. – The zero-load adjustment of a scale shall be maintained so that, with no load on the 

load-receiving element and with all load-counterbalancing elements of the scale (such as poises, drop weights, or 

counterbalance weights) set to zero, the scale shall indicate or record a zero balance condition. A scale not equipped 

to indicate or record a zero-load balance shall be maintained in balance under any no-load condition.

UR.4.2. Level Condition. – If a scale is equipped with a level-condition indicator, the scale shall be maintained in 

level.

UR.4.3. Scale Modification. – The dimensions (e.g., length, width, thickness, etc.) of the load receiving element 

of a scale shall not be changed beyond the manufacturer’s specifications, nor shall the capacity of a scale be 

increased beyond its design capacity by replacing or modifying the original primary indicating or recording element 

with one of a higher capacity, except when the modification has been approved by a competent engineering authority, 

preferably that of the engineering department of the manufacturer of the scale, and by the weights and measures 

authority having jurisdiction over the scale.

(Amended 1996)

UR.5. Coupled-in-Motion Railroad Weighing Systems. – A coupled-in-motion weighing system placed in service on 

or after January 1, 1991, should be tested in the manner in which it is operated, with the locomotive either pushing or 

pulling the cars at the designed speed and in the proper direction. The cars used in the test train should represent the 

range of gross weights that will be used during the normal operation of the weighing system. Except as provided in 

N.4.2. Weighing Systems Placed in Service Prior to January 1, 1991, and Used to Weigh Trains of Ten or More Cars and 

N.4.3.(a) Weighing Systems Placed in Service on or After January 1, 1991, and Used to Weigh Trains of Ten or More 

Cars, normal operating procedures should be simulated as nearly as practical. Approach conditions for a train length in 

each direction of the scale site are more critical for a weighing system used for individual car weights than for a unittrain-weights-only facility, and should be considered prior to installation.

(Added 1990) (Amended 1992)

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Scales Code Index

“r” factor................................................................................51

Acceptance ..........................................................17, 38, 40, 41

Acceptance tolerance...........................................17, 38, 40, 41

Accuracy...............15, 17, 18, 19, 20, 22, 23, 24, 35, 36, 39, 47

Accuracy class..................15, 18, 19, 20, 22, 23, 35, 36, 39, 47

Adjustable components....................................................13, 18

Adjustment .................................................... 13, 15, 18, 35, 54

Apportionment factor ......................................................43, 44

Approaches............................................................................49

Audit trail ..............................................................................13

Automatic zero-tracking mechanism.........................15, 19, 31

Balance condition ............................................ 7, 14, 16, 46, 54

Balance indicator........................... 7, 16, 17, 18, 38, 39, 44, 45

Balance position ....................................................................10

Barometric pressure.........................................................39, 46

Capacity...10, 11, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 27, 

28, 29, 30, 32, 33, 35, 37, 38, 40, 44, 45, 47, 48, 49, 50, 54

Capacity indication................................................................11

Center-of-zero ......................................................................... 7 

Certificate of Conformance ...................................................19

Class....8, 13, 15, 16, 17, 18, 20, 22, 23, 24, 27, 32, 37, 40, 42, 

45, 46, 47, 48, 50

Class I..8, 13, 15, 16, 17, 18, 20, 23, 24, 27, 36, 37, 38, 39, 40, 

44, 45, 46, 47, 48, 50

Class II. 8, 15, 16, 17, 18, 20, 23, 24, 27, 36, 37, 38, 39, 40, 42,

44, 45, 46, 47, 50

Class III8, 15, 18, 20, 23, 24, 27, 36, 37, 38, 39, 40, 42, 44, 45, 

47, 48, 50

Class III L15, 18, 20, 23, 24, 36, 37, 38, 39, 40, 42, 44, 45, 46, 

47, 48, 50

Class IIII....8, 18, 20, 23, 24, 27, 36, 38, 39, 40, 42, 44, 45, 47, 

50

CLC......................................................... 21, 22, 24, 25, 28, 51

Clearance.....................................................................9, 16, 49

Concentrated load capacity....................................................22

Consecutive-car test.........................................................34, 35

Counting feature ............................ 9, 17, 24, 27, 32, 41, 53, 54

Crane and hopper...................................................................40

Crane and hopper (other than grain hopper)..........................20

Creep .....................................................................................43

Dairy-product test..........................................16, 17, 27, 37, 38

Damping means.....................................................................17

Decreasing load test.........................................................37, 39

Direct sales.................................................... 10, 12, 15, 16, 18

Discrimination test................................................................. 31

Distributed-car test ..........................................................34, 35

Electric power supply............................................................46

Environmental factors .....................................................31, 49

Field standard ............................................................32, 33, 34

Foundation.............................................................................49

Graduations ..................................................... 9, 10, 11, 12, 16

Grain-test.........................................................................16, 48

Hoists.....................................................................................50

Index of an indicator................................................................ 9 

Indicating element . 7, 17, 21, 22, 23, 24, 25, 27, 40, 41, 42, 49

Indicator .................. 7, 9, 11, 13, 16, 17, 20, 23, 39, 42, 45, 54

Influence factors..............................................................39, 45

Initial verification ......................................................33, 34, 35

Initial zero-setting mechanism.........................................11, 16

Installation requirements....................................................... 49

Level ....................................................... 14, 17, 30, 49, 52, 54

Level condition.......................................................... 17, 52, 54

Level-indicating means ......................................................... 17

Load cell...................................... 19, 21, 22, 23, 24, 25, 43, 49

Load cell verification interval ................................... 19, 25, 44

Main elements................................................................. 21, 40

Maintenance ................................ 37, 38, 40, 41, 42, 44, 49, 54

Maintenance requirements .................................................... 54

Maintenance tolerance............................. 37, 38, 40, 41, 42, 44

Manual weight entries..................................................... 14, 53

Marking requirements..................................................... 21, 22

Material test.....................................................................31, 37

Maximum permissible error (mpe).................................. 43, 44

Minimum load................................................................. 50, 53

Minimum test weights..................................................... 32, 33

Money-value computation..................................................... 12

Money-value graduations................................................ 11, 12

Multi-interval ...................................................... 19, 20, 23, 39

Multiple range ................................................................. 19, 39

No-load reference value .......................................................... 7 

Nominal capacity .......10, 21, 22, 23, 24, 25, 27, 29, 35, 39, 50

Non-automatic....................................................................... 42

On-board ............................................................. 14, 17, 30, 47

Operating temperature ........................................................... 46

Parallax ................................................................................... 9 

Piece............................................................................ 9, 41, 54

Point-of-sale .................................................................... 12, 53

Poise................................................................................ 10, 11

Portable axle-load weighers ............................ 7, 30, 40, 47, 52

Power interruption................................................................. 46

Prescription ..........16, 17, 20, 24, 27, 32, 35, 37, 38, 41, 53, 54

Ratio test ......................................................................... 31, 39

Readability ............................................................................ 10

Recorded representations .................................................. 7, 12

Recording elements..................................................... 7, 17, 41

Repeatability ......................................................................... 44

RFI ............................................................................ 31, 46, 49

Scale modification................................................................. 54

Scales

Automatic indicating.............................................27, 31, 37

Axle load............................. 7, 17, 24, 28, 37, 44, 47, 48, 49

Belt-conveyor ..................................................................... 7 

Computing .................................................................. 11, 12

Crane ........................................................................... 30, 48

Dairy-product test ....................................................... 17, 27

Gem weighing................................................................... 47

Grain test.....................................................................37, 47

Hanging ...................................................................... 30, 49

Hopper............................................................ 30, 40, 47, 48

Jewelers’ .....................................................................17, 37

Livestock .........15, 17, 21, 24, 25, 27, 28, 29, 44, 47, 49, 53

Monorail ..................................................... 8, 15, 16, 30, 37

Parcel post.............................................................36, 37, 38

Postal ........................................ 8, 11, 24, 36, 37, 38, 47, 53

Prepackaging............................................................... 13, 53

Prescription............................................... 17, 32, 37, 41, 54

Railway track .............. 15, 17, 24, 25, 29, 32, 37, 38, 47, 48

Vehicle...................15, 17, 21, 24, 25, 28, 44, 47, 49, 50, 53

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Sealing.............................................................................13, 14

Security seal ..........................................................................13

Sensitivity requirement....................................................38, 39

Sensitivity test .......................................................................31

Shift test................................................... 27, 28, 29, 30, 34, 42

Single-draft............................................................................52

Stock racks ............................................................................50

Strain-load test................................................................. 32, 41

Subsequent verification .............................................34, 35, 39

Substitution................................................................32, 33, 41

Supports...........................................................................27, 49

Symmetry ................................................................................ 9 

Tare ...........................................................................14, 16, 39

Temperature............................................. 19, 22, 23, 39, 45, 46

Test loads...........................................27, 29, 32, 33, 37, 39, 41

Test pattern......................................................................28, 29

Time dependence...................................................................42

Tolerances ......16, 17, 32, 33, 36, 37, 38, 39, 40, 42, 44, 46, 53

Travel .................................................................. 10, 17, 18, 35

Type evaluation................................. 21, 39, 40, 41, 42, 43, 44

Unit prices....................................................................... 11, 12

Unit weights.............................................................. 11, 24, 42

Use requirements................................................................... 50

Vehicle on-board weighing system ..................... 14, 17, 30, 47

Verification scale interval ................................................. 8, 19

Weighing elements........................................ 18, 19, 28, 29, 49

Weighing systems

Coupled-in-motion................................................ 34, 40, 54

Uncoupled-in-motion......................................................... 35

Weight classifier............................................ 11, 12, 24, 50, 53

Weight ranges.................................................................. 11, 24

Weight units............................................................................ 8 

Wheel-load weighers................................. 7, 17, 30, 40, 48, 52

Zero indication .................................................................. 7, 46

Zero-load adjustment....................................................... 14, 54

Zero-load balance.............................. 13, 14, 15, 16, 31, 46, 54

Zero-tracking mechanism.............See Automatic zero-tracking 

mechanism 

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Table of Contents

Section 2.21. Belt-Conveyor Scale Systems .................................................................... 2-59

A. Application ...................................................................................................................................................2-59

A.1. General................................................................................................................................................2-59

A.2. Exceptions...........................................................................................................................................2-59

A.3. Additional Code Requirements...........................................................................................................2-59

S. Specifications................................................................................................................................................2-59

S.1. Design of Indicating and Recording Elements....................................................................................2-59

S.1.1. General..................................................................................................................................2-59

S.1.2. Units......................................................................................................................................2-59

S.1.3. Value of the Scale Division. .................................................................................................2-59

S.1.4. Recording Elements and Recorded Representations. ...........................................................2-60

S.1.5. Rate of Flow Indicators and Recorders. ...............................................................................2-60

S.1.6. Advancement of Primary Indicating or Recording Elements. ..............................................2-60

S.1.7. Master Weight Totalizer. ......................................................................................................2-60

S.1.8. Power Loss............................................................................................................................2-60

S.1.9. Zero-Ready Indicator............................................................................................................2-60

S.2. Design of Weighing Elements. ...........................................................................................................2-60

S.2.1. Speed Measurement..............................................................................................................2-60

S.2.2. Adjustable Components. .......................................................................................................2-61

S.2.3. Overload Protection. .............................................................................................................2-61

S.3. Zero Setting.........................................................................................................................................2-61

S.3.1. Design of Zero-Setting Mechanism. .....................................................................................2-61

S.3.2. Sensitivity at Zero Load (For Type Evaluation)....................................................................2-61

S.4. Marking Requirements........................................................................................................................2-61

S.5. Provision for Sealing. .........................................................................................................................2-61

N. Notes..............................................................................................................................................................2-62

N.1. General................................................................................................................................................2-62

N.1.1. Official Test. .........................................................................................................................2-62

N.1.2. Simulated Test. .....................................................................................................................2-62

N.2. Conditions of Tests. ............................................................................................................................2-62

N.2.1. Initial Verification.................................................................................................................2-63

N.2.2. Subsequent Verification........................................................................................................2-63

N.2.3. Minimum Test Load. ............................................................................................................2-64

N.3. Test Procedures...................................................................................................................................2-64

N.3.1. Zero-Load Tests....................................................................................................................2-64

N.3.2. Material Tests. ......................................................................................................................2-65

N.3.3. Simulated Load Tests............................................................................................................2-66

T. Tolerances.....................................................................................................................................................2-66

T.1. Tolerance Values. ...............................................................................................................................2-66

T.1.1. Tolerance Values – Test of Zero Stability. ...........................................................................2-66

T.2. Tolerance Values, Repeatability Tests................................................................................................2-67

T.3. Influence Factors.................................................................................................................................2-67

T.3.1. Temperature..........................................................................................................................2-67

T.3.2. Power Supply, Voltage, and Frequency................................................................................2-67

UR. User Requirements ......................................................................................................................................2-67

UR.1. Installation Requirements. ..................................................................................................................2-67

UR.1.1. Protection from Environmental Factors................................................................................2-67

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UR.1.2. Conveyor Installation............................................................................................................2-67

UR.1.3. Material Test.........................................................................................................................2-69

UR.1.4. Belt Travel (Speed or Velocity). ...........................................................................................2-69

UR.2. Use Requirements. ..............................................................................................................................2-69

UR.2.1. Rate of Operation..................................................................................................................2-69

UR.2.2. Minimum Totalized Load. ....................................................................................................2-69

UR.2.3. Security Means. ....................................................................................................................2-69

UR.2.4. Loading. ................................................................................................................................2-69

UR.2.5. Diversion or Loss of Measured Product................................................................................2-69

UR.2.6. Retention of Maintenance, Test, and Analog or Digital Recorder Information. ...................2-69

UR.3. Maintenance Requirements – Scale and Conveyor Maintenance. ......................................................2-69

UR.4. Compliance. ........................................................................................................................................2-71

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Section 2.21. Belt-Conveyor Scale Systems

A. Application

A.1. General. – This code applies to belt-conveyor scale systems and weigh-belt systems used for the weighing of 

bulk materials.

(Amended 2015)

A.2. Exceptions. – The code does not apply to:

(a) devices used for discrete weighing while moving on conveyors;

(b) devices that measure quantity on a time basis;

(c) checkweighers; or 

(d) controllers or other auxiliary devices except as they may affect the weighing performance of the 

belt-conveyor scale.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Belt-Conveyor Scale Systems 

shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements.

S.1.1. General. – A belt-conveyor scale shall be equipped with a primary indicating element in the form of a 

master weight totalizer and shall also be equipped with a recording element, and a rate of flow indicator and 

recorder (which may be analog).* An auxiliary indicator shall not be considered part of the master weight 

totalizer.

[*Nonretroactive as of January 1, 1986]

(Amended 1986)

S.1.2. Units. – A belt-conveyor scale shall indicate and record weight units in terms of pounds, tons, long tons, 

metric tons, or kilograms. The value of a scale division (d) expressed in a unit of weight shall be equal to:

(a) 1, 2, or 5; or

(b) a decimal multiple or submultiples of 1, 2, or 5.

S.1.3. Value of the Scale Division.

S.1.3.1. For Scales Installed After January 1, 1986. – The value of the scale division shall not be greater 

than 0.125 % ( 1 /800) of the minimum totalized load.

[Nonretroactive as of January 1, 1986]

(Added 1985)(Amended 2009)

S.1.3.2. For Scales Installed Before January 1, 1986. – The value of the scale division shall not be 

greater than 1

/1200 of the rated capacity of the device. However, provision shall be made so that compliance 

with the requirements of the zero-load test as prescribed in N.3.1. Zero Load Tests may be readily and 

accurately determined in 20 minutes of operation.

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S.1.4. Recording Elements and Recorded Representations. – The value of the scale division of the recording 

element shall be the same as that of the indicating element.

a) The belt-conveyor scale system shall record the unit of measurement (i.e., kilograms, tonnes, pounds, 

tons, etc.), the date, and the time.

b) The belt-conveyor scale system shall record the initial indication and the final indication of the master 

weight totalizer and the quantity.*

All of the information in (a) and (b) must be recorded for each delivery.*

[Nonretroactive as of January 1, 1986]

[*Nonretroactive as of January 1, 1994]

(Amended 1993)

S.1.4.1. The belt-conveyor scale system shall be capable of recording the results of automatic or semiautomatic zero load tests.**

[**Nonretroactive as of January 1, 2004]

(Added 2002)

S.1.5. Rate of Flow Indicators and Recorders. - A belt-conveyor scale shall be equipped with a rate of flow 

indicator and an analog or digital recorder. Permanent means shall be provided to produce an audio or visual 

signal when the rate of flow is equal to or less than 20 % and when the rate of flow is equal to or greater than 

100 % of the rated capacity of the scale. The type of alarm (audio or visual) shall be determined by the individual 

installation.

[Nonretroactive as of January 1, 1986]

(Amended 1989 and 2004)

S.1.6. Advancement of Primary Indicating or Recording Elements. – The master weight totalizer shall 

advance only when the belt conveyor is in operation and under load.

(Amended 1989)

S.1.7. Master Weight Totalizer. – The master weight totalizer shall not be resettable without breaking a 

security means.

[Nonretroactive as of January 1, 1986]

S.1.8. Power Loss. – In the event of a power failure of up to 24 hours, the accumulated measured quantity on 

the master weight totalizer of an electronic digital indicator shall be retained in memory during the power loss.

[Nonretroactive as of January 1, 1986]

(Amended 1989)

S.1.9. Zero-Ready Indicator. – A belt-conveyor scale shall be equipped with a zero-ready indicator that 

produces an audio or visual signal when the zero balance is within ± 0.12 % of the rated capacity of the scale 

during an unloaded belt condition. The type of indication (audio or visual) shall be determined by the individual 

installation.

[Nonretroactive as of January 1, 2014] 

(Added 2012)

S.2. Design of Weighing Elements. – A belt-conveyor scale system shall be designed to combine automatically 

belt travel with belt load to provide a determination of the weight of the material that has passed over the scale.

S.2.1. Speed Measurement. – A belt-conveyor scale shall be equipped with a belt speed or travel sensor that 

will accurately sense the belt speed or travel whether the belt is empty or loaded.

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S.2.2. Adjustable Components. – An adjustable component that can affect the performance of the device 

(except as prescribed in S.3.1. Design of Zero-Setting Mechanism) shall be held securely in adjustment.

(Amended 1998)

S.2.3. Overload Protection. – The load-receiving elements shall be equipped with means for overload 

protection of not less than 150 % of rated capacity. The accuracy of the scale in its normal loading range shall 

not be affected by overloading.

S.3. Zero Setting.

S.3.1. Design of Zero-Setting Mechanism. – Automatic and semiautomatic zero-setting mechanisms shall be 

so constructed that the resetting operation is carried out only after a whole number of belt revolutions and the 

completion of the setting or the whole operation is indicated. An audio or visual signal shall be given when the 

automatic and semiautomatic zero-setting mechanisms reach the limit of adjustment of the zero-setting 

mechanism.*

(Amended 1999 and 2002)

Except for systems that record the zero load reference at the beginning and end of a delivery, the range of the 

zero-setting mechanism shall not be greater than ± 2 % of the rated capacity of the scale without breaking the 

security means. For systems that record the zero-load reference at the beginning and end of a delivery, the range 

of zero-setting mechanism shall not be greater than ± 5 % without breaking the security means.**

[*Nonretroactive as of January 1, 1990]

[**Nonretroactive as of January 1, 2004]

(Amended 1989 and 2002)

S.3.1.1. Automatic Zero-Setting Mechanism. – The automatic zero-setting mechanism shall indicate or 

record any change in the zero reference.

[Nonretroactive as of January 1, 2010]

(Added 2009)

S.3.2. Sensitivity at Zero Load (For Type Evaluation). – When a system is operated for a time period equal to 

the time required to deliver the minimum test load and with a test load calculated to indicate two scale divisions 

applied directly to the weighing element, the totalizer shall advance not less than one or more than three scale 

divisions. An alternative test of equivalent sensitivity, as specified by the manufacturer, shall also be acceptable.

[Nonretroactive as of January 1, 1986]

S.4. Marking Requirements. – Belt-conveyor scale systems and weigh-belt systems shall be marked with the 

following: (Also see also G-S.1. Identification.) 

(a) the rated capacity in units of weight per hour (minimum and maximum);

(b) the value of the scale division;

(c) the belt speed in terms of feet (or meters) per minute at which the belt will deliver the rated capacity, or the 

maximum and minimum belt speeds at which the conveyor system will be operated for variable speed belts;

(d) the load in terms of pounds per foot or kilograms per meter (determined by material tests); and

(e) the operational temperature range if other than − 10 °C to 40 °C (14 °F to 104 °F).

[Nonretroactive as of January 1, 1986]

(Amended 2015)

S.5. Provision for Sealing. – A device shall be designed using the format set forth in Table S.5. with provision(s) 

for applying a security seal that must be broken, or for using other approved means of providing security (e.g. data 

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change audit trail available at the time of inspection), before any change that affects the metrological integrity of the 

device can be made to any electronic mechanism.

[Nonretroactive as of January 1, 1999]

(Added 1998)

Table S.5. 

Categories of Device and Methods of Sealing

Categories of Devices Methods of Sealing

Category 1: No remote configuration 

capability.

Seal by physical seal or two event counters: one for calibration 

parameters and one for configuration parameters.

Category 3: Remote configuration 

capability.

An event logger is required in the device; it must include an event 

counter (000 to 999), the parameter ID, the date and time of the 

change, and the new value of the parameter. A printed copy of 

the information must be available through the device or through 

another on-site device. The event logger shall have a capacity to 

retain records equal to 10 times the number of sealable 

parameters in the device, but not more than 1000 records are 

required. (Note: Does not require 1000 changes to be stored for 

each parameter.)

[Nonretroactive as of January 1, 1999]

(Table Added 1998)

N. Notes

N.1. General. – Belt-conveyor scales are capable of weighing bulk material accurately. (Also see Tolerances.) 

However, their performance can be detrimentally affected by the conditions of the installation. (Also see User 

Requirements.) The performance of the equipment is not to be determined by averaging the results of the individual 

tests. The results of all tests shall be within the tolerance limits.

(Amended 2002)

N.1.1. Official Test. – An official test of a belt-conveyor scale system shall include tests specified in 

N.3.1. Zero Load Tests, N.3.2. Material Tests, and, if applicable, N.3.3. Simulated Load Tests.

(Amended 2006)

N.1.2. Simulated Test. – Simulated loading conditions as recommended by the manufacturer and approved by 

the official with statutory authority may be used to properly monitor the system operational performance between 

official tests, but shall not be used for official certification.

(Amended 1991)

N.2. Conditions of Tests. – A belt-conveyor scale shall be tested after it is installed on the conveyor system with 

which it is to be used and under such environmental conditions as may normally be expected. Each test shall be 

conducted with test loads no less than the minimum test load. Before each test run, the inspector shall check the zero 

setting and adjust as necessary.

(Amended 1986, 2004, and 2009)

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N.2.1. Initial Verification. – A belt-conveyor scale system or a weigh-belt system shall be tested using a 

minimum of two test runs as indicated in Table N.2.1. Initial Verification.

Results of the individual test runs in each pair of tests shall not differ by more than the absolute value of the 

tolerance as specified in T.2. Tolerance Values, Repeatability Tests. All tests shall be within the tolerance as 

specified in T.1. Tolerance Values.

Test runs may also be conducted at any other rate of flow that may be used at the installation. A minimum of 

four test runs may be conducted at only one flow rate if evidence is provided that the system is used at a constant 

speed/constant loading setting and that rate does not vary in either direction by an amount more than 10 % of the 

normal flow rate that can be developed at the installation for at least 80 % of the time.

(Added 2004) (Amended 2009 and 2015) 

N.2.2. Subsequent Verification. – Subsequent testing shall include testing at the normal use flow rate and 

other flow rates used at the installation. The official with statutory authority may determine that testing only at 

the normal use flow rate is necessary for subsequent verifications if evidence is provided that the system is used 

to operate:

(a) at no less than 70 % of the maximum rated capacity for at least 80 % of the time (excluding time that the 

belt is unloaded); or

(b) with a normal use flow rate that does not vary by more than 10 % of the maximum rated capacity.

Example: If a belt-conveyor scale system has a maximum rated capacity of 200 tons per hour (tph), and the 

normal use flow rate is 150 tph (75 % of the maximum rated capacity), no testing at additional flow rates is 

Table N.2.1. 

Initial Verification

Device Configuration Minimum of Two Test Runs at Each of the Following Settings Total Tests 

(Minimum)

Constant Belt Speed and

Variable Loading

- Belt Loading: high (normal)

- Belt Loading: medium (intermediate)

- Belt Loading: low (35 %)

6 

Variable Belt Speed and

Constant Loading

- Belt Speed: maximum

- Belt Speed: medium

- Belt Speed: minimum

6 

Variable Belt Speed and

Variable Loading

- Belt Speed: maximum; Belt Loading: high (normal)

- Belt Speed: maximum; Belt Loading: medium (intermediate)

- Belt Speed: maximum; Belt Loading: low (35 %)

- Belt Speed: minimum; Belt Loading: high (normal)

- Belt Speed: minimum; Belt Loading: medium (intermediate)

- Belt Speed: minimum; Belt Loading: low (35 %)

12

1. Use the device configurations in the left-hand column to identify the scale being tested. 

2. Perform two test runs (minimum) at each of the settings shown in the center column.

3. The following terminology applies to “Belt Loading”: 

• Low: 35 % of the maximum rated capacity of the system.

• Medium: an intermediate rate between the high and low settings. 

• High: maximum (normal use) operational rate.

(Table Added 2015)

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required provided the flow rates remain above 140 tph for more than 80 % of the time. If the same device were 

operating with a normal use flow rate of 130 tph, it is operating at 65 % of the maximum rated capacity. In this 

case, testing at flow rates in addition to the normal use flow rate would be required if the normal use flow rate 

varies by more than 20 tph (10 % of the maximum rated capacity).

(Added 2004)

N.2.3. Minimum Test Load. 

N.2.3.1. Minimum Test Load, Weigh-Belt Systems. – The minimum test load shall not be less than the 

largest of the following values: 

(a) 800 scale divisions;

(b) the load obtained at maximum flow rate in one revolution of the belt; or

(c) at least one minute of operation.

(Amended 2015)

N.2.3.2. Minimum Test Load, All Other Belt-Conveyor Scale Systems. – Except for applications where 

a normal weighment is less than 10 minutes, the minimum test load shall not be less than the largest of the 

following values: 

(a) 800 scale divisions;

(b) the load obtained at maximum flow rate in one revolution of the belt; or

(c) at least 10 minutes of operation.

For applications where a normal weighment is less than 10 minutes (e.g., belt-conveyor scale systems used 

exclusively to issue net weights for material conveyed by individual vehicles and railway track cars) the 

minimum test load shall be the normal weighment that also complies with N.2.3.2.(a) and (b).

The official with statutory authority may determine that a smaller minimum totalized load down to 2 % of 

the load totalized in one hour at the maximum flow rate may be used for subsequent tests, provided that:

1. the smaller minimum totalized load is greater than the quantities specified in N.2.3.2.(a) and (b); 

and

2. consecutive official testing with the minimum totalized loads described in N.2.3.2.(a), (b), or (c) 

and the smaller minimum test load has been conducted that demonstrates the system complies with 

applicable tolerances for repeatability, acceptance, and maintenance.

(Added 2004) (Amended 2008 and 2015) 

N.3. Test Procedures.

N.3.1. Zero-Load Tests. – A zero-load test shall be conducted to establish that the belt scale system (including 

the conveyor) is capable of holding a stable, in-service zero.

(Amended 1989 and 2002)

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N.3.1.1. Determination of Zero. – A zero-load test is a determination of the error in zero, expressed as 

an internal reference, a percentage of the full-scale capacity, or a change in a totalized load over a whole 

number of complete belt revolutions. A zero-load test shall be performed as follows:

(a) For belt-conveyor scales with electronic integrators, the test must be performed over a period of at 

least three minutes and with a whole number of complete belt revolutions. 

(b) For belt-conveyor scales with mechanical integrators, the test shall be performed with no less than 

three complete revolutions or 10 minutes of operation, whichever is greater.

(c) For weigh belt systems, the test must be performed over a period of at least one minute and at least 

one complete revolution of the belt.

(Added 2002) (Amended 2015) 

N.3.1.2. Test of Zero Stability. – The conveyor system shall be operated to warm up the belt and the belt 

scale shall be zero adjusted as required. A series of zero-load tests shall be carried out immediately before 

conducting the simulated load or materials test until the three consecutive zero-load tests each indicate an 

error which does not exceed ± 0.06 % of the totalized load at full scale capacity for the duration of the test. 

No adjustments can be made during the three consecutive zero-load test readings.

(Added 2002) (Amended 2004 and 2009)

N.3.1.3. Check for Consistency of the Conveyor Belt along Its Entire Length. – During a zero-load 

test with any operational low-flow lock-out disabled, the absolute value of the difference between the 

maximum and minimum totalizer readings indicated on the totalizer during any complete revolution of the 

belt shall not exceed 0.12 % of the minimum test load.

Note: The end value of the zero-load test must meet the ± 0.06 % requirement referenced in the “Test for Zero Stability.” 

(Added 2002) (Amended 2004 and 2011)

N.3.2. Material Tests. – Material tests should be conducted using actual belt loading conditions. These belt 

loading conditions shall include, but are not limited to conducting materials tests using different belt loading 

points, all types and sizes of products weighed on the scale, at least one other belt speed, and in both directions 

of weighing.

On subsequent verifications, at least two individual tests shall be conducted. The results of all these tests shall be 

within the tolerance limits.

Either pass a quantity of pre-weighed material over the belt-conveyor scale in a manner as similar as feasible to 

actual loading conditions, or weigh all material that has passed over the belt-conveyor scale. Means for weighing 

the material test load will depend on the capacity of the belt-conveyor scale and availability of a suitable scale for 

the test. To assure that the test load is accurately weighed and determined, the following precautions shall be 

observed:

(a) The containers, whether railroad cars, trucks, or boxes, must not leak, and shall not be overloaded to the 

point that material will be lost.

(b) The actual empty or tare weight of the containers shall be determined at the time of the test. Stenciled 

tare weight of railway cars or trucks shall not be used. Gross and tare weights shall be determined on 

the same scale.

(c) When a pre-weighed test load is passed over the scale, the belt-loading hopper shall be examined before 

and after the test to assure that the hopper is empty and that only the material of the test load has passed 

over the scale.

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(d) Where practicable, a reference scale should be tested within 24 hours preceding the determination of the 

weight of the test load used for a belt-conveyor scale material test.

A reference scale which is not “as found” within maintenance tolerance should have its accuracy 

re-verified after the belt-conveyor test with a suitable known weight load if the “as found” error of the 

belt-conveyor scale material test exceeds maintenance tolerance values.*

(e) If any suitable known weight load other than a certified test weight load is used for re-verification of the 

reference scale accuracy, its weight shall be determined on the reference scale after the reference scale 

certification and before commencing the belt scale material test.*

(f) The test shall not be conducted if the weight of the test load has been affected by environmental 

conditions.

*Note: Even if the reference scale is within maintenance tolerance it may require adjusting to be able to meet 

paragraph N.3.2.1. Accuracy of Material.

(Amended 1986, 1989, 1998, 2000, 2002, and 2009)

N.3.2.1. Accuracy of Material. – The quantity of material used to conduct a material test shall be weighed 

on a reference scale to an accuracy within 0.1 %. Scales typically used for this purpose include Class III and 

III L scales or a scale without a class designation as described in Handbook 44, Section 2.20., Table T.1.1. 

Tolerances for Unmarked Scales.

(Added 1989) (Amended 1991, 1993, 1998 and 2000)

N.3.3. Simulated Load Tests.

(a) As required by the official with statutory authority, simulated load tests as recommended by the 

manufacturer are to be conducted between material tests to monitor the system’s operational 

performance, but shall not be used for official certification.

(Amended 1991)

(b) A simulated load test consisting of at least three consecutive test runs shall be conducted as soon as 

possible, but not more than 12 hours after the completion of the material test, to establish the factor to 

relate the results of the simulated load test to the results of the material tests.

(Added 1990)

(c) The results of the simulated load test shall repeat within 0.1 %.

(Added 1990) 

(Amended 1989 and 1990)

T. Tolerances

T.1. Tolerance Values.1

 – Maintenance and acceptance tolerances on materials tests, relative to the weight of the 

material, shall be ± 0.25 % of the test load.

(Amended 1993)

T.1.1. Tolerance Values – Test of Zero Stability. – Immediately after material has been weighed over the 

belt-conveyor scale during the conduct of any material test run, the zero-load test shall be repeated. The change 

 

1 The variables and uncertainties included in the relative tolerance represent only part of the variables that affect the 

accuracy of the material weighed on belt-conveyor scales. If this tolerance was based on an error analysis beginning 

with mass standards through all of the test processes and following the principle expressed in Section 3.2. of the 

Fundamental Considerations in Appendix A, the tolerance would be 0.5 %.

(Added 1993)

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in the accumulated or subtracted weight during the zero-load test shall not exceed 0.12 % of the totalized load at 

full scale capacity for the duration of that test. If the range of zero adjustments during a complete (official) 

verification test exceeds 0.18 % of the totalized load at full scale capacity for the duration of the zero-load test, 

the official with statutory authority may establish an interval for zero-load testing during normal operation.

(Added 2004) (Amended 2009)

T.2. Tolerance Values, Repeatability Tests. – The variation in the values obtained during the conduct of materials 

tests shall not be greater than 0.25 % (1

/400).

T.3. Influence Factors. – The following factors are applicable to tests conducted under controlled conditions only, 

provided that:

(a) types of devices approved prior to January 1, 1986, and manufactured prior to January 1, 1988, need not meet 

the requirements of this section; 

(b) new types of devices submitted for approval after January 1, 1986, shall comply with the requirements of the 

section; and

(c) all devices manufactured after January 1, 1988, shall comply with the requirements of this section.

T.3.1. Temperature. – Devices shall satisfy the tolerance requirements at temperatures from − 10 °C to 40 °C 

(14 °F to 104 °F).

T.3.1.1. Effect on Zero-Load Balance. – The zero-load indication shall not change by more than 0.035 % 

of the rated capacity of the scale (without the belt) for a change in temperature of 10 °C (18 °F) at a rate not 

to exceed 5 °C (9 °F) per hour.

(Amended 2004)

T.3.1.2. Temperature Limits. – If a temperature range other than − 10 °C to 40 °C (14 °F to 104 °F) is 

specified for the device, the range shall be at least 30 °C (54 °F).

[Nonretroactive as of January 1, 1990]

(Added 1989)

T.3.2. Power Supply, Voltage, and Frequency. – A belt-conveyor scale system shall satisfy the tolerance 

requirements over a range of 100 V to 130 V or 200 V to 250 V as appropriate and over a frequency range of 

59.5 Hz to 60.5 Hz.

UR. User Requirements

UR.1. Installation Requirements. 

UR.1.1. Protection from Environmental Factors. – The indicating elements, the lever system or load cells, 

and the load-receiving element of a belt-conveyor scale shall be adequately protected from environmental factors 

such as wind, moisture, dust, weather, and radio frequency interference (RFI) and electromagnetic interference 

(EMI) that may adversely affect the operation or performance of the device.

UR.1.2. Conveyor Installation. – The design and installation of the conveyor leading to and from the 

belt-conveyor scale is critical with respect to scale performance. Installation shall be in accordance with the scale 

manufacturer’s instructions and the following:

(a) Installation - General. – A belt-conveyor scale shall be so installed that neither its performance nor 

operation will be adversely affected by any characteristic of the installation, including but not limited to, 

the foundation, supports, covers, or any other equipment.

(Amended 2002)

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(b) Live Portions of Scale. – All live portions of the scale shall be protected with appropriate guard devices 

and clearances, as recommended by the scale manufacturer, to prevent accidental interference with the 

weighing operation. (Also see UR.3.1. Scale and Conveyor Maintenance.) 

(Amended 2004)

(c) Storage of Simulated Load Equipment. – Suitable protection shall be provided for storage of any 

simulated load equipment.

(d) Take-up Device. – Any take-up device shall provide constant and consistent tension for the belt under 

all operating conditions.

(Amended 2014)

(e) Scale Location and Training Idlers. – The scale shall be so installed that the first weigh idler of the 

scale is at least 6 m (20 ft) or five idler spaces, whichever is greater, from loading point, skirting, head 

or tail pulley, or convex curve in the conveyor. Any training idler shall be located at least 18 m (60 ft) 

from the centerline of the weigh span of the scale. Training idlers shall not be restrained at any time in 

order to force belt alignment.

(Amended 1998)

(f) Concave Curve. – If there is a concave curve in the conveyor, before or after the scale, the scale shall 

be installed so that the belt is in contact with all the idler rollers at all times for at least 6 m (20 ft) or five 

idler spaces, whichever is greater, before and after the scale.2

 A concave curve shall start no closer than 

12 m (40 ft) from the scale to the tangent point of the concave curve.

(Amended 1998)

(g) Tripper and Movable Pulleys. – There shall be no tripper or movable head pulleys in the conveyor.

(h) Conveyor Orientation. – The conveyor may be horizontal or inclined, but, if inclined, the angle shall 

be such that slippage of material along the belt does not occur.

 

(i) Conveyor Stringers. – Conveyor stringers at the scale and for not less than 6 m (20 ft) before and 

beyond the scale shall be continuous or securely joined and of sufficient size and so supported as to 

eliminate relative deflection between the scale and adjacent idlers when under load. The conveyor 

stringers should be so designed that the deflection between any two adjacent idlers within the weigh area 

does not exceed 0.6 mm (0.025 in) under load.

(j) Identification of Scale Area. – The scale area and five idlers on both ends of the scale shall be of a 

contrasting color, or other suitable means shall be used to distinguish the scale from the remainder of the 

conveyor installation, and the scale shall be readily accessible.

(Amended 1998)

(k) Belt Composition and Maintenance. – In a loaded or unloaded condition, the belt shall make constant 

contact with horizontal and wing rollers of the idlers in the scale area. Splices shall not cause any undue 

disturbance in scale operation. (Also see N.3. Test Procedures.) 

(Amended 1998, 2000, 2001, and 2015) 

 

2 Installing the belt scale five-idler spaces from the tail pulley or the infeed skirting will be in the area of least belt 

tension on the conveyor and should produce the best accuracy. The performance of a belt-conveyor scale may be 

adversely affected by a concave curve in the conveyor that is located between the loading point and the scale. 

Therefore, whenever possible, a belt-conveyor scale should not be installed with a concave curve in the conveyor 

between the loading point and the scale.

(Amended 1995 and 1998)

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(l) Uniformity of Belt Loading and Flow. – The conveyor loading mechanism shall be designed to provide 

uniform belt loading. The distance from the loading point to the scale shall allow for adequate settling 

time of the material on the belt before it is weighed. Feeding mechanisms shall have a positive closing 

or stopping action so that material leakage does not occur. Feeders shall provide an even flow over the 

scale through the full range of scale operation. Sufficient impact idlers shall be provided in the conveyor 

under each loading point to prevent deflection of the belt during the time material is being loaded.

(m) Belt Alignment. – The belt shall not extend beyond the edge of the outermost roller of any carry side 

(top) roller in any area of the conveyor nor touch the conveyor structure on the return (bottom) side of 

the conveyor.

(Amended 1998 and 2008)

(Amended 2002, 2012, 2013, 2014, and 2015)

UR.1.3. Material Test. – A belt-conveyor scale shall be installed so that a material test can be conveniently 

conducted.

[Nonretroactive as of January 1, 1981]

UR.1.4. Belt Travel (Speed or Velocity). – The belt travel sensor shall be so positioned that it accurately 

represents the travel of the belt over the scale for all flow rates between the maximum and minimum values. The 

belt travel sensor shall be so designed and installed that there is no slip.

(Amended 2012)

UR.2. Use Requirements.

UR.2.1. Rate of Operation. – A belt-conveyor scale system shall be operated between 20 % and 100 % of its 

rated capacity.

(Amended 2004)

UR.2.2. Minimum Totalized Load. – Delivered quantities of less than the minimum test load shall not be 

considered a valid weighment.

UR.2.3. Security Means. – When a security means has been broken, it shall be reported to the official with 

statutory authority.

(Amended 1991)

UR.2.4. Loading. – The feed of material to the scale shall be controlled to assure that, during normal operation, 

the material flow is in accordance with the manufacturer’s recommendation for rated capacity. 

UR.2.5. Diversion or Loss of Measured Product. – There shall be no operation(s) or condition(s) of use that 

result in loss or diversion that adversely affects the quantity of measured product.

(Added 2005)

UR.2.6. Retention of Maintenance, Test, and Analog or Digital Recorder Information. – Records of 

calibration and maintenance, including conveyor alignment, analog or digital recorder, zero-load test, and material 

test data shall be maintained on site for at least the three concurrent years as a history of scale performance. 

Copies of any report as a result of a test or repair shall be mailed to the official with statutory authority as required. 

The current date and correction factor(s) for simulated load equipment shall be recorded and maintained in the 

scale cabinet.

(Added 2002) 

(Amended 2012)

UR.3. Maintenance Requirements – Scale and Conveyor Maintenance. – Weighing systems and idlers shall be 

maintained and serviced in accordance with manufacturer’s instructions and the following: 

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(a) Zero Balance. – The zero balance condition of a belt-conveyor scale shall be maintained such that, prior 

to beginning any commercial transaction, with no load on the belt, the zero balance condition is within 

± 0.12 % of the scale’s rated capacity. 

(Added 2012)

(b) Scale Clearance. – The scale and area surrounding the scale shall be kept clean of debris or other foreign 

material that can detrimentally affect the performance of the system.

(c) Weighed Material. – There shall be provisions to ensure that weighed material does not adhere to the 

belt and return to the scale system area.

(Added 2004)

(d) Simulated and Zero-Load Test Intervals. – Zero-load tests and simulated load or material tests shall 

be conducted at periodic intervals between official tests and after a repair or mechanical adjustment to 

the conveyor system in order to provide reasonable assurance that the device is performing correctly. 

The minimum interval for periodic zero-load tests and simulated load tests shall be established by the 

official with statutory authority or according to manufacturer recommendations.

The actions to be taken as a result of the zero-load test are shown in the following table.

Change in Zero (∆ 0) Actions to be Taken

If the change in zero is less than ± 0.25 % 

(∆ 0 < 0.25 %)

Perform zero adjustment and proceed to simulated load test.

If the change in zero is ± 0.25 % to ± 0.5 % 

(0.25 % ≤ ∆ 0 ≤ 0.5 %)

Inspect the conveyor and weighing area for compliance with 

UR.1. Installation Requirements and repeat the zero-load 

test.

If the change in zero is greater than ± 0.5 % 

(∆ 0 > 0.5 %)

Inspect the conveyor and weighing area for compliance with 

UR.1. Installation Requirements, repeat the zero-load test, 

and reduce the interval between zero-load tests.

The action to be taken as a result of the simulated load or material tests is shown in the following 

table.

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Change in Factor (Reference) Established in 

N.3.3.(b)

[∆ N.3.3.(b)]

Action to be Taken

If the error is less than 0.25 %

(∆ N.3.3.(b) < 0.25 %) No Action

If the error is at least 0.25 % but not more than 

0.6 % 

(0.25 % ≤ ∆ N.3.3.(b) ≤ 0.6 %)

Inspect the conveyor and weighing area for compliance with 

UR.1. Installation Requirements and, after compliance is 

verified, repeat the test.

If the result of that test remains greater than ± 0.25 %, a span 

correction shall be made and the official with statutory 

authority notified.

(Amended 1991)

If the error is greater than 0.6 % but does not 

exceed 0.75 % 

(0.6 % < ∆ N.3.3.(b) ≤ 0.75 %)

Inspect the conveyor and weighing area for compliance with 

UR.1. Installation Requirements and, after compliance is 

verified, repeat the test.

If the result of that test remains greater than ± 0.25 %, a span 

correction shall be made, the official with statutory authority 

shall be notified, and an official test shall be conducted.

(Amended 1991)

If the error is greater than 0.75 % 

(∆ N.3.3.(b) > 0.75 %)

An official test is required.

(Amended 1987)

(Amended 2002 and 2009)

(e) Scale Alignment. – Alignment checks shall be conducted in accordance with the manufacturer’s

recommendation. A material test is required after any realignment.

(Amended 1986, 2000, and 2015) 

(f) Simulated Load Equipment. – Simulated load equipment shall be clean and properly maintained.

(g) Zero Load Reference Information. – When zero load reference information is recorded for a delivery, 

the information must be based upon zero load tests performed as a minimum both immediately before 

and immediately after the totalized load.

(Added 2002)

(Amended 1986, 2000, 2002, 2004, 2009, 2012, and 2015) 

UR.4. Compliance. – Prior to initial verification, the scale manufacturer or installer shall certify to the owner that 

the scale meets code requirements. Prior to initial verification and each subsequent verification, the scale owner or 

his agent shall notify the official with statutory authority in writing that the belt-conveyor scale system is in compliance 

with this specification and ready for material testing.

(Amended 1991)

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Table of Contents

Section 2.22.Automatic Bulk Weighing Systems ................................................................... 2-75

A. Application ...................................................................................................................................................2-75

A.1. General................................................................................................................................................2-75

A.2. Additional Code Requirements...........................................................................................................2-75

S. Specifications................................................................................................................................................2-75

S.1. Design of Indicating and Recording Elements and Recorded Representations. .................................2-75

S.1.1. Zero Indication......................................................................................................................2-75

S.1.2. Value of Scale Division (d). ..................................................................................................2-75

S.1.3. Capacity Indication and Recorded Representation. ..............................................................2-75

S.1.4. Weighing Sequence. .............................................................................................................2-75

S.1.5. Recording Sequence..............................................................................................................2-75

S.1.6. Provision for Sealing Adjustable Components on Electronic Devices. ................................2-76

S.2. Design of Balance and Damping Mechanism.....................................................................................2-76

S.2.1. Zero-Load Adjustment..........................................................................................................2-76

S.2.2. Damping Means....................................................................................................................2-76

S.3. Interlocks and Gate Control. ...............................................................................................................2-76

S.3.1. Gate Position.........................................................................................................................2-76

S.3.2. Interlocks. .............................................................................................................................2-76

S.3.3. Overfill Sensor......................................................................................................................2-76

S.4. Design of Weighing Elements. ...........................................................................................................2-77

S.4.1. Antifriction Means................................................................................................................2-77

S.4.2. Adjustable Components. .......................................................................................................2-77

S.4.3. Multiple Load-Receiving Elements. .....................................................................................2-77

S.4.4. Venting. ................................................................................................................................2-77

S.5. Marking Requirements........................................................................................................................2-77

S.5.1. Capacity and Value of the Scale Division.............................................................................2-77

S.5.2. Weighing Elements...............................................................................................................2-77

S.5.3. Temperature Limits...............................................................................................................2-77

S.5.4. Accuracy Class. ....................................................................................................................2-77

N. Notes..............................................................................................................................................................2-78

N.1. Testing Procedures..............................................................................................................................2-78

N.1.1. Test Weights. ........................................................................................................................2-78

N.1.2. Increasing-Load Test. ...........................................................................................................2-78

N.1.3. Decreasing-Load Test. ..........................................................................................................2-78

N.1.4. Zero-Balance or No-Load Reference Value Change Test.....................................................2-78

N.1.5. Discrimination Test...............................................................................................................2-78

N.2. Verification (Testing) Standards.........................................................................................................2-78

T. Tolerances.....................................................................................................................................................2-78

T.1. Tolerance Application.........................................................................................................................2-78

T.1.1. To Errors of Underregistration and Overregistration............................................................2-78

T.1.2. To Increasing-Load Tests. ....................................................................................................2-78

T.1.3. To Decreasing-Load Tests. ...................................................................................................2-78

T.1.4. To Tests Involving Digital Indications or Representations...................................................2-78

T.2. Minimum Tolerance Values................................................................................................................2-79

T.2.1. For Systems Used to Weigh Construction Materials. ...........................................................2-79

T.3. Basic Tolerance Values.......................................................................................................................2-79

T.3.1. Acceptance Tolerance...........................................................................................................2-79

T.3.2. For Systems Used to Weigh Grain........................................................................................2-79

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T.3.3. For All Other Systems. .........................................................................................................2-79

T.4. Time Dependence................................................................................................................................2-79

T.5. Repeatability. ......................................................................................................................................2-79

T.6. Discrimination, Digital Automatic Indicating Scales. ........................................................................2-79

T.7. Influence .............................................................................................................................................2-79

T.7.1. Temperature..........................................................................................................................2-79

T.7.2. Barometric Pressure. ............................................................................................................2-80

T.7.3. Electric Power Supply...........................................................................................................2-80

UR. User Requirements ......................................................................................................................................2-80

UR.1. Selection Requirements. .....................................................................................................................2-80

UR.1.1. For Systems used to Weigh Grain.........................................................................................2-80

U.R.1.2. For Systems used to Weigh Commodities other than Grain. ................................................2-80

UR.2. Installation Requirements. ..................................................................................................................2-80

UR.2.1. Protection from Environmental Factors................................................................................2-80

UR.2.2. Foundation, Supports, and Clearance....................................................................................2-80

UR.3. Loading Requirements. .......................................................................................................................2-81

UR.3.1. For Systems Used to Weigh Grain........................................................................................2-81

UR.3.2. For Systems Used to Weigh Commodities Other than Grain................................................2-81

UR.4. System Modification...........................................................................................................................2-81

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Section 2.22. Automatic Bulk Weighing Systems1

A. Application

A.1. General. – This code applies to automatic bulk weighing systems, that is, weighing systems adapted to the 

automatic weighing of a commodity in successive drafts of predetermined amounts automatically recording the 

no-load and loaded weight values and accumulating the net weight of each draft.

(Amended 1987)

A.2. Additional Code Requirements. – In addition to the requirements of this code, Automatic Bulk Weighing 

Systems shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and Recorded Representations.

S.1.1. Zero Indication. – Provisions shall be made to indicate and record a no-load reference value and, if the 

no-load reference value is a zero value indication, to indicate and record an out-of-balance condition on both sides 

of zero.

S.1.1.1. Digital Zero Indication. – A digital zero indication shall represent a balance condition that is 

within ± 1⁄2 the value of the scale division.

S.1.2. Value of Scale Division (d). – The value of the scale division (d), expressed in a unit of weight, shall be 

equal to:

(a) 1, 2, or 5; or

(b) a decimal multiple or submultiple of 1, 2, or 5; or

(c) a binary submultiple of a unit of weight.

Examples: Scale divisions may be 0.01, 0.02, or 0.05; 0.1, 0.2, or 0.5; 1, 2, or 5; 10, 20, or 50; or 1⁄2, 1⁄4, 

1⁄8, 1/16, etc.

[Nonretroactive as of January 1, 1986]

(Amended 1987)

S.1.3. Capacity Indication and Recorded Representation. – An indicating or recording element shall not 

indicate or record any values when the gross load is in excess of 105 % of the capacity of the system.

S.1.4. Weighing Sequence. – For systems used to receive (weigh in), the no-load reference value shall be 

determined and recorded only at the beginning of each weighing cycle. For systems used to deliver (weigh out), 

the no-load reference value shall be determined and recorded only after the gross load reference value for each 

weighing cycle has been indicated and recorded.

S.1.5. Recording Sequence. – Provision shall be made so that all weight values are indicated until the 

completion of the recording of the indicated value.

 

1 (Title amended 1986)

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S.1.6. Provision for Sealing Adjustable Components on Electronic Devices. – Provision shall be made for 

applying a security seal in a manner that requires the security seal to be broken before an adjustment can be made 

to any component affecting the performance of the device.

S.2. Design of Balance and Damping Mechanism.

S.2.1. Zero-Load Adjustment. – The weighing system shall be equipped with manual or semiautomatic means 

by which the zero-load balance or no-load reference value indication may be adjusted. Automatic zero-tracking 

and automatic zero-setting mechanisms are prohibited.

(Amended 2010)

S.2.1.1. Manual. – A manual zero-load or no-load reference value setting mechanism shall be operable 

or accessible only by a tool outside of or entirely separate from this mechanism or enclosed in a cabinet.

S.2.1.2. Semiautomatic. – A semiautomatic zero-load or no-load reference value setting mechanism shall 

meet the provisions of S.2.1.1. or shall be operable only when:

(a) the indication is stable within ± 3 scale divisions; and

(b) cannot be operated during a weighing operation.

S.2.2. Damping Means. – A system shall be equipped with effective means necessary to bring the indications 

quickly to a readable, stable equilibrium. Effective means shall also be provided to permit the recording of weight 

values only when the indication is stable within plus or minus three scale divisions for devices with 10 000 scale 

divisions, or plus or minus one division for devices with less than 10 000 scale divisions.

S.3. Interlocks and Gate Control.

S.3.1. Gate Position. – Provision shall be made to clearly indicate to the operator the position of the gates 

leading directly to and from the weigh hopper.

S.3.2. Interlocks. – Each automatic bulk weighing system shall have operating interlocks to provide for the 

following:

(a) Product cannot be cycled and weighed if the weight recording element is disconnected or subjected to a 

power loss.

(b) The recording element cannot print a weight if either of the gates leading directly to or from the weigh 

hopper is open.

(c) A “low paper” sensor, when provided, is activated.

(d) The system will operate only in the proper sequence in all modes of operation.

(e) When an overfill alarm is activated, the system shall indicate and record an overfill condition.

(Amended 1993)

S.3.3. Overfill Sensor.

(a) The weigh hopper shall be equipped with an overfill sensor which will cause the feed gate to close, 

activate an alarm, and inhibit weighing until the overfill condition has been corrected.

(Added 1993)

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(b) If the system is equipped with a lower garner or surge bin, that garner shall also be equipped with an 

overfill sensor which will cause the gate of the weigh hopper to remain open, activate an alarm, and 

inhibit weighing until the overfill condition has been corrected.

[Nonretroactive as of January 1, 1998]

(Amended 1997)

S.4. Design of Weighing Elements.

S.4.1. Antifriction Means. – At all points at which a live part of the mechanism may come into contact with 

another part in the course of normal usage, frictional effects shall be reduced to a minimum by means of suitable 

antifriction means, opposing surfaces and points being properly shaped, finished, and hardened.

S.4.2. Adjustable Components. – An adjustable component, such as a potentiometer, shall be held securely 

in adjustment and, except for a component for adjusting level or a no-load reference value, shall not be adjustable 

from the outside of the device.

S.4.3. Multiple Load-Receiving Elements. – A system with a single indicating or recording element, or a 

combination indicating recording element, that is coupled to two or more load-receiving elements with 

independent weighing systems, shall be provided with means to prohibit the activation of any load-receiving 

element (or elements) not in use, and shall be provided with automatic means to indicate clearly and definitely 

which load-receiving element (or elements) is in use.

S.4.4. Venting. – All weighing systems shall be vented so that any internal or external pressure will not affect 

the accuracy or operation of the system.

S.5. Marking Requirements. (Also see Section 1.10. General Code paragraph G-S.1. Identification.) 

S.5.1. Capacity and Value of the Scale Division. – The capacity of the weighing system and the value of the 

scale division shall be clearly and conspicuously marked on the indicating element near the weight value 

indications.

S.5.2. Weighing Elements. – On a weighing element not permanently attached to an indicating element, there 

shall be clearly and permanently marked for the purposes of identification, the name, initials, or trademark of the 

manufacturer, the manufacturer’s designation that positively identifies the pattern or design, and the nominal 

capacity.

S.5.3. Temperature Limits. – Unless the temperature range is − 10 °C to + 40 °C (14 °F to 104 °F), the 

temperature range shall be marked on the device.

[Nonretroactive as of January 1, 1986]

(Added 1985)

S.5.4. Accuracy Class.

(a) All systems used to weigh grain shall be marked Class III.*

(b) All other systems shall be marked either Class III or III L.*

(*Also see Section 2.20. Scales Code for the parameters for these accuracy classes for scales. The specific 

requirements for automatic bulk weighing systems apply to these devices when there is a conflict between the 

Scales Code and the Automatic Bulk Weighing Systems Code.)

[Nonretroactive as of January 1, 1986]

(Added 1985) (Amended 1992)

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N. Notes

N.1. Testing Procedures.

N.1.1. Test Weights. – The increasing load test shall be conducted using test weights equal to at least 10 % of 

the capacity of the system:

(a) on automatic grain bulk-weighing systems installed after January 1, 1984; and

(b) on other automatic bulk-weighing systems installed after January 1, 1986.

(Amended 1987)

N.1.2. Increasing-Load Test. – An increasing-load test consisting of substitution and strain-load tests shall be 

conducted up to the used capacity of the weighing system.

(Amended 1987)

N.1.3. Decreasing-Load Test. – A decreasing-load test shall be conducted on devices used to weigh out.

(Added 1986)

N.1.4. Zero-Balance or No-Load Reference Value Change Test. – A test for change of zero-balance or

no-load reference value shall be conducted on all scales after the removal of any test load. The change shall not 

be more than the minimum tolerance applicable. 

N.1.5. Discrimination Test. – A discrimination test shall be conducted on all automatic indicating scales with 

the weighing device in equilibrium at zero-load and at maximum test load, and under controlled conditions in 

which environmental factors are reduced to the extent that they will not affect the results obtained.

[Nonretroactive as of January 1, 1986]

N.1.5.1. Digital Device. – On a digital device, this test is conducted from just below the lower edge of the 

zone of uncertainty for increasing-load tests, or from just above the upper edge of the zone of uncertainty for 

decreasing-load tests.

(Added 1987)

N.2. Verification (Testing) Standards. – Standard weights and masses used in verifying weighing devices shall 

comply with requirements of NIST Handbook 105-1 (Class F) or the tolerances expressed in Appendix A, 

Fundamental Considerations, paragraph 3.2. (i.e., one-third of the smallest tolerance applied).

T. Tolerances

T.1. Tolerance Application. – Tolerance values shall be applied to all indications and recorded representations of 

a weighing system.

T.1.1. To Errors of Underregistration and Overregistration. – The tolerances hereinafter prescribed shall 

be applied equally to errors of underregistration and errors of overregistration. 

T.1.2. To Increasing-Load Tests. – Basic tolerances shall be applied.

T.1.3. To Decreasing-Load Tests. – Basic tolerances shall be applied to systems used to weigh out.

(Added 1986)

T.1.4. To Tests Involving Digital Indications or Representations. – To the tolerances that would otherwise 

be applied, there shall be added an amount equal to one-half the value of the scale division. This does not apply 

to digital indications or recorded representations that have been corrected for rounding using error weights.

(Added 1986)

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T.2. Minimum Tolerance Values. – The minimum tolerance value shall not be less than half the value of the scale 

division.

T.2.1. For Systems Used to Weigh Construction Materials. – The minimum maintenance and acceptance 

tolerance shall be 0.1 % of the weighing capacity of the system, or the value of the scale division, whichever is 

less.

(Added 1986)

T.3. Basic Tolerance Values.

T.3.1. Acceptance Tolerance. – The basic acceptance tolerance shall be one-half the basic maintenance 

tolerance.

T.3.2. For Systems Used to Weigh Grain. – The basic maintenance tolerance shall be 0.1 % of test load. 

T.3.3. For All Other Systems. – The basic maintenance tolerance shall be 0.2 % of test load. 

(Amended 1986)

T.4. Time Dependence. – At constant test conditions, the indication 20 seconds after the application of a load and 

the indication after one hour shall not differ by more than the absolute value of the applicable tolerance for the applied 

load.

[Nonretroactive and enforceable as of January 1, 1987]

(Added 1986)

T.5. Repeatability. – The results obtained by several weighings of the same load under reasonably static test 

conditions shall agree within the absolute value of the maintenance tolerance for that load, and shall be within 

applicable tolerances.

(Added 1986)

T.6. Discrimination, Digital Automatic Indicating Scales. – A test load equivalent to 1.4 d shall cause a change 

in the indicated or recorded value of at least 2.0 d. This requires the zone of uncertainty to be not greater than 0.3 times 

the value of the scale division.

(Added 1985)

T.7. Influence Factors. – The following factors are applicable to tests conducted under controlled conditions only, 

provided that:

(a) types of devices approved prior to January 1, 1986, and manufactured prior to January 1, 1988, need not 

meet the requirements of this section; and

(b) new types of devices submitted for approval after January 1, 1986, shall comply with the requirements of this 

section; and 

(c) all devices manufactured after January 1, 1988, shall comply with the requirements of this section.

[Nonretroactive as of January 1, 1986]

T.7.1. Temperature. – Devices shall satisfy the tolerance requirements under the following temperature 

conditions:

T.7.1.1. If not marked on the device, the temperature limits shall be: − 10 °C to 40 °C (14 °F to 104 °F). 

T.7.1.2. If temperature limits are specified for the device, the range shall be at least 30 °C (54 °F).

T.7.1.3. Temperature Effect on Zero-Load Balance. – The zero-load indicator shall not vary by more 

than one division per 5 °C (9 °F) change in temperature. 

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T.7.1.4. Operating Temperature. – An indicating or recording element shall not display or record any 

usable values until the operating temperature necessary for accurate weighing and a stable zero-balance 

condition has been attained.

[Nonretroactive as of January 1, 1986]

T.7.2. Barometric Pressure. – The zero indication shall not vary by more than one scale division for a change 

in barometric pressure of 1 kPa over the total barometric range of 95 kPa to 105 kPa (28 in to 31 in of mercury).

[Nonretroactive as of January 1, 1986]

T.7.3. Electric Power Supply.

T.7.3.1. Power Supply, Voltage, and Frequency.

(a) Weighing devices that operate using alternating current must perform within the conditions defined 

in paragraphs T.2. through T.7., inclusive over the line voltage range of 100 V to 130 V or 200 V 

to 250 V rms as appropriate and over the frequency range of 59.5 Hz to 60.5 Hz.

(b) Battery-operated instruments shall not indicate nor record values outside the applicable tolerance 

limits when battery power output is excessive or deficient.

T.7.3.2. Power Interruption. – A power interruption shall not cause an indicating or recording element 

to display or record any values outside the applicable tolerance limits.

[Nonretroactive as of January 1, 1986]

(Added 1985)

UR. User Requirements

UR.1. Selection Requirements.

UR.1.1. For Systems used to Weigh Grain. – The number of scale divisions of a weighing system shall not be 

less than 2 000 nor greater than 10 000 divisions.

[Nonretroactive as of January 1, 1984]

(Amended 1986 and 1992)

U.R.1.2. For Systems used to Weigh Commodities other than Grain. – The number of scale divisions shall not 

be less than 500 nor greater than 10 000.

[Nonretroactive as of January 1, 1987]

(Added 1986)

UR.2. Installation Requirements.

UR.2.1. Protection from Environmental Factors. – The indicating elements, the lever system or load cells, 

the load-receiving element, and any permanently installed test weights shall be adequately protected from 

environmental factors such as wind, weather, and RFI that may adversely affect the operation or performance of 

the system.

UR.2.2. Foundation, Supports, and Clearance. – The foundation and supports of any system shall be such 

as to provide strength, rigidity, and permanence of all components, and clearance shall be provided around all 

live parts so that no contact can result before or during operation of the system.

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UR.3. Loading Requirements.

UR.3.1. For Systems Used to Weigh Grain. – A system shall not be used to weigh drafts less than 40 % of 

the weighing capacity of the system except for a final partial draft. Loads shall not normally be retained on the 

weighing element for a period longer than a normal weighing cycle.

(Amended 1986)

UR.3.2. For Systems Used to Weigh Commodities Other than Grain. – A system shall not be used to weigh 

drafts less than 20 % of the weighing capacity of the system except for a final partial draft. Loads shall not 

normally be retained on the weighing element for a period longer than a normal weighing cycle.

[Nonretroactive as of January 1, 1987]

(Added 1986)

UR.4. System Modification. – The weighing system shall not be modified except when the modification has been 

approved by a competent engineering authority, preferably that of the engineering department of the manufacturer of 

the scale, and the official with statutory authority having jurisdiction over the scale.

(Amended 1991)

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Table of Contents

Section 2.23. Weights........................................................................................................... 2-85

A. Application .................................................................................................................................................. 2-85

A.1. General................................................................................................................................................2-85

A.2. Exceptions...........................................................................................................................................2-85

A.3. Additional Code Requirements...........................................................................................................2-85

S. Specifications............................................................................................................................................... 2-85

S.1. Material...............................................................................................................................................2-85

S.2. Design. ................................................................................................................................................2-85

S.2.1. Surface......................................................................................................................................2-85

S.2.2. Ring..........................................................................................................................................2-85

S.3. Adjusting Material. .............................................................................................................................2-85

S.4. Marking Requirements........................................................................................................................2-85

S.4.1. General. ....................................................................................................................................2-85

S.4.2. Apothecaries’ Weights. ............................................................................................................2-85

S.4.3. Troy Weights............................................................................................................................2-85

S.4.4. Metric Weights.........................................................................................................................2-85

S.4.5. Carat Weights...........................................................................................................................2-85

S.4.6. Counterpoise Weight................................................................................................................2-85

N. Notes............................................................................................................................................................. 2-86

N.1. Testing Procedures..............................................................................................................................2-86

T. Tolerances.................................................................................................................................................... 2-86

T.1. In Excess and in Deficiency................................................................................................................2-86

T.2. On Avoirdupois Weights. ...................................................................................................................2-86

T.3. On Metric Weights..............................................................................................................................2-88

T.4. On Carat Weights................................................................................................................................2-88

T.5. On Apothecaries and Troy Weights....................................................................................................2-88

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Section 2.23. Weights 

A. Application

A.1. General. – This code applies to commercial weights; that is, weights used in connection with commercial 

weighing devices.

A.2. Exceptions. – This code does not apply to test weights or to other “standards” of mass.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Weights shall meet the 

requirements of Section 1.10. General Code.

S. Specifications

S.1. Material. – The material used for weights shall be as follows:

(a) Weights of 6 g or 100 gr and larger shall be made of a metal, or a metal alloy, not softer than brass.

(b) Weights of less than 6 g or 100 gr may be made of aluminum, but shall not be made of iron or of unplated 

steel, except stainless steel.

S.2. Design.

S.2.1. Surface. – The surface of a weight shall be smooth and shall not be coated with thick, soft, or brittle 

material. A weight of more than 2 g or 30 gr or shall not have sharp edges, points, or corners.

S.2.2. Ring. – A ring on a weight shall not be split or removable.

S.3. Adjusting Material. – Adjusting material shall be securely positioned and shall not project beyond the surface 

of the weight.

S.4. Marking Requirements.

S.4.1. General. – A weight shall be marked to show clearly its nominal value, which shall include identification 

of the unit; however, the nominal value of a weight of 30 gr or 2 g, or less, may be designated by dots, lines, 

figures, distinctive shape, or other appropriate means.

S.4.2. Apothecaries’ Weights. – On apothecaries’ dram, ounce, and pound weights, the letters “ap” shall be 

used in combination with the nominal value and the appropriate abbreviation of or symbol for the unit.

S.4.3. Troy Weights. – On troy ounce and pound weights, the letter “t” shall be used in combination with the 

nominal value and the appropriate symbol of the unit.

S.4.4. Metric Weights. – On metric weights, the symbols “kg,” “g,” and “mg” shall be used in combination 

with the nominal value of kilograms, grams, and milligrams, respectively.

S.4.5. Carat Weights. – On carat weights, the letter “c” shall be used in combination with the nominal value.

S.4.6. Counterpoise Weight. – A counterpoise weight shall be marked to show clearly both its nominal value 

and the value it represents when used on the multiplying-lever scale for which it is intended.

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N. Notes

N.1. Testing Procedures. – Commercial weights should be tested on a precision balance using standard weights, 

the errors of which, when used without correction, do not exceed 1

/3 of the smallest tolerance to be applied. (Also see 

Appendix A, Fundamental Considerations, paragraphs 3.2. Tolerance for Standars and 3.3. Accuracy of Standards.) 

T. Tolerances

T.1. In Excess and In Deficiency. – The tolerances hereinafter prescribed shall be applied equally to errors in 

excess and errors in deficiency.

T.2. On Avoirdupois Weights. – The maintenance tolerances shall be as shown in Table 1. Maintenance Tolerance 

for Avoirdupois Weights. Acceptance tolerances shall be one-half the maintenance tolerances.

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Table 1.

Maintenance Tolerance for Avoirdupois Weights

Maintenance Tolerance

Nominal 

Value

Equal-Arm

Weights

Counterpoise Weights

For scales with multiples of 

less than 1000

For scales with multiples of 

1000 or over

oz Grains mg grains mg grains mg

1

/64 0.1 6

1

/32 0.3 19

1

/16 0.4 26

1

/8 0.5 32

1⁄4 1.0 65

1⁄2 1.5 97 1.0 65

1 1.7 110 1.0 65

2 2.0 130 1.0 65

3 2.0 130 1.5 97

4 3.0 190 1.5 97 1.0 65

5 3.5 230 1.5 97 1.0 65

6 3.5 230 1.5 97

8 4.0 260 2.0 130 1.5 97

10 4.0 260 2.5 160 2.0 130

12 5.0 320 2.5 160 2.0 130

Lb Grains mg grains mg grains mg

1 5.0 320 3.0 190 2.5 160

2 7.0 450 6.0 390 4.0 260

3 9.0 580 9.0 580 5.0 320

4 11.0 710 11.0 710 6.0 390

5 15.0 970 12.0 780 6.5 420

6 17.0 1190

7 19.0 1200

8 21.0 1400 15.0 970 9.0 580

9 23.0 1500

10 25.0 1600 18.0 1160 10.0 650

15 28.0 1800

20 30.0 1900

25 35.0 2300

30 40.0 2600

40 45.0 2900

50 50.0 3200

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T.3. On Metric Weights. – The maintenance tolerances shall be as shown in Table 2. Maintenance Tolerances for 

Metric Weights. Acceptance tolerances shall be one-half the maintenance tolerances.

T.4. On Carat Weights. – The maintenance tolerances shall be as shown in Table 2. Maintenance Tolerances for 

Metric Weights. Acceptance tolerances shall be one-half the maintenance tolerances.

Table 2.

Maintenance Tolerances for Metric Weights

Nominal

Value

(mg)

Maintenance

Tolerance

(mg)

Nominal

Value

(g)

Maintenance

Tolerance

(mg)

5 or less

10

20

30

50

100

200

300

500

0.1

0.3

0.4

0.6

0.8

1.0

1.5

2.0

3.0

1

2 

3 

5 

10

20

30

50

100

200

300

500

4

6 

8 

10

15

20

30

40

70

100

150

175

Nominal

Value

(kg)

Maintenance

Tolerance

(mg)

Nominal

Value

(carats)

Maintenance

Tolerance

(mg)

1

2 

3 

5 

10

20

250

400

500

800

 1000

1500

0.25*

0.5**

1.0

2.0

3.0

5.0

10.0

20.0

30.0

50.0

100.0

0.6

1.0

1.5

2.0

3.0

4.0

6.0

10.0

12.0

15.0

25.0

*25 points or less

**50 points

T.5. On Apothecaries and Troy Weights. – The maintenance tolerances shall be as shown in Table 3. Maintenance 

Tolerances for Apothecaries’ and Troy Weights. Acceptance tolerances shall be one-half the maintenance tolerances.

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Table 3.

Maintenance Tolerances for Apothecaries’ and Troy Weights

Nominal

Value Maintenance Tolerance Nominal

Value Maintenance Tolerance

grains grains mg oz grains mg

1

2 

3 

5 

10

20

0.01

0.02

0.03

0.03

0.04

0.06

0.6

1.3

2.0

2.0

2.5

4.0

1

2 

3 

4 

5 

0.4

0.6

1.0

1.5

1.6

25.0

40.0

65.0

100.0

105.0

scruples grains mg oz grains mg

1

2 

0.06

0.10

4.0

6.5

6

7 

8 

9 

10

1.8

1.9

2.0

2.1

2.2

115.0

125.0

130.0

135.0

145.0

dr grains mg oz grains mg

0.5

1.0

2.0

3.0

4.0

5.0

6.0

0.07

0.10

0.20

0.30

0.40

0.50

0.60

4.5

6.5

13.0

20.0

25.0

30.0

40.0

11

12

20

30

50

2.4

2.5

2.9

3.7

5.4

155.0

160.0

190.0

240.0

350.0

dwt grains mg oz grains mg

1

2 

3 

4 

5 

10

0.06

0.10

0.15

0.20

0.30

0.40

4.0

6.5

10.0

13.0

20.0

25.0

100

200

300

500

1 000

7.7

12.3

15.4

23.1

38.6

500.0

800.0

1 000.0

1 500.0

2 500.0

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Table of Contents

Section 2.24. Automatic Weighing Systems ......................................................................... 2-93

A. Application ...................................................................................................................................................2-93

A.1. General................................................................................................................................................2-93

A.2. Exceptions...........................................................................................................................................2-93

A.3. Additional Code Requirements...........................................................................................................2-94

S. Specifications................................................................................................................................................2-94

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................2-94

S.1.1. Zero Indication......................................................................................................................2-94

S.1.2. Value of Division Units. .......................................................................................................2-94

S.1.3. Provision for Sealing.............................................................................................................2-95

S.1.4. Automatic Calibration...........................................................................................................2-95

S.1.5. Adjustable Components. .......................................................................................................2-95

S.2. Design of Zero and Tare Mechanisms. ...............................................................................................2-96

S.2.1. Zero Load Adjustment. .........................................................................................................2-96

S.2.2. Tare.......................................................................................................................................2-96

S.3. Verification Scale Interval. .................................................................................................................2-96

S.3.1. Multiple Range and Multi-Interval Automatic Weighing System. .......................................2-96

S.3.2. Load Cell Verification Interval Value...................................................................................2-96

S.4. Weight Indicators, Weight Displays, Reports, and Labels..................................................................2-96

S.4.1. Additional Digits in Displays................................................................................................2-96

S.4.2. Damping. ..............................................................................................................................2-97

S.4.3. Over Capacity Indication. .....................................................................................................2-97

S.4.4. Label Printer. ........................................................................................................................2-97

S.5. Accuracy Class. ..................................................................................................................................2-97

S.5.1. Marking.................................................................................................................................2-97

S.6. Parameters for Accuracy Classes........................................................................................................2-97

S.7. Marking Requirements........................................................................................................................2-97

S.7.1. Location of Marking Information. ........................................................................................2-97

S.7.2. Marking Required on Components of Automatic Weighing Systems. ............................... 2-100

N. Notes............................................................................................................................................................ 2-100

N.1. Test Requirements for Automatic Weighing Systems. ..................................................................... 2-100

N.1.1. Test Pucks and Packages. ................................................................................................... 2-100

N.1.2. Accuracy of Test Pucks or Packages. ................................................................................. 2-100

N.1.3. Verification (Testing) Standards......................................................................................... 2-100

N.1.4. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility, 

Field Evaluation.................................................................................................................. 2-100

N.1.5. Tests Loads. ........................................................................................................................ 2-100

N.1.6. Influence Factor Testing. .................................................................................................... 2-101

N.2. Test Procedures - Weigh-Labelers.................................................................................................... 2-101

N.2.1. Non-Automatic Tests.......................................................................................................... 2-101

N.2.2. Automatic Test Procedures. ................................................................................................ 2-101

N.3. Test Procedures - Automatic Checkweigher..................................................................................... 2-101

N.3.1. Tests Non-Automatic.......................................................................................................... 2-101

N.3.2. Automatic Tests. ................................................................................................................. 2-101

T. Tolerances................................................................................................................................................... 2-102

T.1. Principles. ......................................................................................................................................... 2-102

T.1.1. Design. ................................................................................................................................ 2-102

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T.1.2. Scale Division. .................................................................................................................... 2-102

T.2. Tolerance Application....................................................................................................................... 2-102

T.2.1. General................................................................................................................................ 2-102

T.2.2. Type Evaluation Examinations. .......................................................................................... 2-102

T.2.3. Subsequent Verification Examinations............................................................................... 2-102

T.2.4. Multiple Range and Multi-Interval Automatic Weighing System. ..................................... 2-102

T.3. Tolerance Values. ............................................................................................................................. 2-103

T.3.1. Tolerance Values – Class III Weigh-Labeler...................................................................... 2-103

T.3.2. Tolerance Values - Class IIIS Weigh-labelers in Package Shipping Applications. ............ 2-103

T.3.3. Tolerance Values. ............................................................................................................... 2-103

T.4. Agreement of Indications.................................................................................................................. 2-105

T.5. Repeatability. .................................................................................................................................... 2-105

T.6. Discrimination. ................................................................................................................................. 2-105

T.7. Influence Factors............................................................................................................................... 2-105

T.7.1. Temperature........................................................................................................................ 2-105

T.7.2. Electric Power Supply......................................................................................................... 2-105

T.8. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility. ......... 2-106

UR. User Requirements .................................................................................................................................... 2-106

UR.1. Selection Requirements. ................................................................................................................... 2-106

UR.1.1. General................................................................................................................................ 2-106

UR.1.2. Value of the Indicated and Recorded Scale Division.......................................................... 2-106

UR.2. Installation Requirements. ................................................................................................................ 2-106

UR.2.1. Protection from Environmental Factors.............................................................................. 2-106

UR.2.2. Foundation, Supports, and Clearance.................................................................................. 2-106

UR.2.3. Entry and Departure from Weighing Area.......................................................................... 2-106

UR.3. Use Requirements. ............................................................................................................................ 2-106

UR.3.1. Minimum Load. .................................................................................................................. 2-106

UR.3.2. Maximum Load................................................................................................................... 2-107

UR.3.3. Special Designs................................................................................................................... 2-107

UR.3.4. Use of Manual Gross Weight Entries. ................................................................................ 2-107

UR.4. Maintenance Requirements............................................................................................................... 2-107

UR.4.1. Balance Condition............................................................................................................... 2-107

UR.4.2. Level Condition. ................................................................................................................. 2-107

UR.4.3. Automatic Weighing System Modification. ....................................................................... 2-107

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Section 2.24. Automatic Weighing Systems

A. Application

A.1. General. – This code applies to devices used to automatically weigh pre-assembled discrete loads or single 

loads or loose materials in applications where automatic weighing systems1 are used or employed in the determination 

of quantities, things, produce, or articles for distribution, for purchase, offered or submitted for sale, for distribution, 

purchase, or in computing any basic charge or payment for services rendered on the basis of weight, and in packaging 

plants subject to regulation by the USDA. Some weigh-labelers and checkweighers may also include a scale that is 

incorporated in a conveyor system that weighs packages in a static or non-automatic weighing mode2

. 

This includes:

(a) Automatic weigh-labelers;

(b) Combination automatic and non-automatic weigh-labelers;

(c) Automatic checkweighers;

(d) Combination automatic and non-automatic checkweighers; and

(e) Automatic gravimetric filling machines that weigh discrete loads or single loads of loose materials and 

determine package and production lot compliance with net content representations.

(Amended 1997 and 2004)

A.2. Exceptions. - This code does not apply to:

(a) Belt-Conveyor Scale Systems;

(b) Railway Track Scales;

(c) Monorail Scales;

(d) Automatic Bulk-Weighing Systems;

(e) Devices that measure quantity on a time basis;

(f) Controllers or other auxiliary devices except as they may affect the weighing performance; or

 

1 An automatic weighing system does not require the intervention of an operator during the weighing process. The 

necessity to give instructions to start a process or to release a load or the function of the instrument (static, dynamic, 

set-up, etc.) is not relevant in deciding the category of automatic or non-automatic instruments.

(Added 2004)

2 Prepackaging scales (and other commercial devices) used for putting up packages in advance of sale are acceptable 

for use in commerce if all appropriate provisions of Handbook 44 are met. Users of such devices must be alert to the 

legal requirements relating to the declaration of quantity on a package. Such requirements are to the effect that, on 

the average, the contents of the individual packages of a particular commodity comprising a lot, shipment, or delivery 

must contain at least the quantity declared on the label. The fact that a scale or other commercial device may 

overregister, but within established tolerances, and is approved for commercial service is not a legal justification for 

packages to contain, on the average, less than the labeled quantity.

(Added 2004)

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(g) Automatic gravimetric filling machines and other automatic weighing systems employed in determining the 

weight of a commodity in a plant or business with a separate quantity control program (e.g., a system of 

statistical process control) using suitable weighing instruments and measurement standards traceable to 

national standards to determine production lot compliance with net content representations.

3

(Added 2004)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Automatic Weighing Systems 

shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Zero Indication.

(a) A weigh-labeler shall be equipped with an indicating or recording element. Additionally, a weigh-labeler

equipped with an indicating or recording element shall either indicate or record a zero-balance condition 

and an out-of-balance condition on both sides of zero.

(Amended 2004)

(b) An automatic checkweigher may be equipped with an indicating or recording element.

(c) A zero-balance condition may be indicated by other than a continuous digital zero indication, provided 

that effective automatic means is provided to inhibit a weighing operation or to return to a continuous 

digital indication when the device is in an out-of-balance condition.

S.1.1.1. Digital Indicating Elements.

(a) A digital zero indication shall represent a balance condition that is within ± 1⁄2 scale division.

(b) A digital indicating device shall either automatically maintain a “center of zero” condition to 

± 1⁄4 scale division or less, or have an auxiliary or supplemental “center-of-zero” indicator that 

defines a zero-balance condition to ± 1⁄4 scale division or less.

(c) Verification of the accuracy of the center of zero indication to ± 1⁄4 scale division or less during 

automatic operation is not required on automatic checkweighers. 

(Amended 2004)

S.1.2. Value of Division Units. – The value of a division d expressed in a unit of weight shall be equal to:

(a) 1, 2, or 5; or

(b) a decimal multiple or submultiple of 1, 2, or 5.

The requirement that the value of the scale division be expressed only as 1, 2, or 5, or a decimal multiple or 

submultiple of only 1, 2, or 5 does not apply to net weight indications and recorded representations that are 

calculated from gross and tare weight indications where the scale division of the gross weight is different from 

the scale division of the tare weight(s) on multi-interval or multiple range scales. For example, a multiple range 

or multi-interval scale may indicate and record tare weights in a lower weighing range (WR) or weighing segment 

(WS), gross weights in the higher weighing range or weighing segment, and net weights as follows:

 

3 See NIST Handbook 130, “Uniform Laws and Regulations in the Area of Legal Metrology and Engine Fuel Quality,” 

Interpretations and Guidelines, paragraph 2.6.11. Good Quantity Control Practices.

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55 kg Gross Weight (WR2 d = 5 kg) 10.05 lb Gross Weight (WS2 d = 0.05 lb)

– 4 kg Tare Weight (WR1 d = 2 kg) – 0.06 lb Tare Weight (WS1 d = 0.02 lb)

= 51 kg Net Weight (Mathematically Correct) = 9.99 lb Net Weight (Mathematically Correct)

(Amended 2008)

S.1.2.1. Weight Units. – Except for postal scales, indicating and recording elements for shipping and 

postal applications, and scales used to print standard pack labels, a device shall indicate weight values using 

only a single unit of measure.

(Amended 2004)

S.1.3. Provision for Sealing.

(a) Automatic Weighing Systems, Except Automatic Checkweighers. – A device shall be designed with 

provision(s) as specified in Table S.1.3. Categories of Device and Methods of Sealing for applying a 

security seal that must be broken, or for using other approved means of providing security (e.g., data 

change audit trail available at the time of inspection), before any change that detrimentally affects the 

metrological integrity of the device can be made to any electronic mechanism.

(b) For Automatic Checkweighers. – Security seals are not required in applications where it would prohibit 

an authorized user from having access to the calibration functions of a device.

Table S.1.3.

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No Remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but 

access is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable 

of printing in this mode.

The hardware enabling access for remote 

communication must be at the device and sealed using 

a physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 3: Remote configuration capability access 

may be unlimited or controlled through a software 

switch (e.g., password).

An event logger is required in the device; it must 

include an event counter (000 to 999), the parameter 

ID, the date and time of the change, and the new value 

of the parameter. A printed copy of the information 

must be available through the device or through 

another on-site device. The event logger shall have a 

capacity to retain records equal to 10 times the number 

of sealable parameters in the device, but not more than 

1000 records are required. (Note: Does not require 

1000 changes to be stored for each parameter.)

S.1.4. Automatic Calibration. – A device may be fitted with an automatic or a semi-automatic calibration 

mechanism. This mechanism shall be incorporated inside the device. After sealing, neither the mechanism nor 

the calibration process shall facilitate fraud.

S.1.5. Adjustable Components. – Adjustable components shall be held securely in adjustment and, except for 

a zero-load balance mechanism, shall be located within the housing of the element.

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S.2. Design of Zero and Tare Mechanisms.

S.2.1. Zero Load Adjustment.

S.2.1.1. Automatic Zero-Tracking Mechanism. – Except for automatic checkweighers, under normal 

operating conditions the maximum load that can be “rezeroed,” when either placed on or removed from the 

platform all at once, shall be 1.0 scale division.

Except for an initial zero-setting mechanism, an automatic zero adjustment outside these limits is prohibited.

(Amended 2004 and 2010)

S.2.1.2. Initial Zero-Setting Mechanism. – Except for automatic checkweighers, an initial zero-setting 

mechanism shall not zero a load in excess of 20 % of the maximum capacity of the automatic weighing 

system unless tests show that the scale meets all applicable tolerances for any amount of initial load 

compensated by this device within the specified range.

S.2.2. Tare. – On any automatic weighing system (except for multi-interval scales or multiple range scales 

when the value of tare is determined in a lower weighing range or weighing segment) the value of the tare division 

shall be equal to the value of the scale division. The tare mechanism shall operate only in a backward direction 

(i.e., in a direction of underregistration) with respect to the zero-load balance condition of the automatic weighing 

system. A device designed to automatically clear any tare value shall also be designed to prevent the automatic 

clearing of tare until a complete transaction has been indicated.

(Amended 2008)

Note: On a computing automatic weighing system, this requires the input of a unit price, the display of the unit price, and a 

computed positive total price at a readable equilibrium. Other devices require that a transaction or lot run be completed.

(Note Amended 2004)

S.3. Verification Scale Interval.

S.3.1. Multiple Range and Multi-Interval Automatic Weighing System. – The value of e shall be equal to 

the value of d.

S.3.2. Load Cell Verification Interval Value. – The relationship of the value for the load cell verification 

scale interval, vmin, to the scale division d for a specific scale installation shall be:

 , where N is the number of load cells in the scale.

Note: When the value of the scale division d differs from the verification scale division e for the scale, the value of e must be 

used in the formula above.

S.3.3. – For automatic checkweighers, the value of e shall be specified by the manufacturer and may be larger 

than d, but in no case can e be more than ten times the value of d.

S.4. Weight Indicators, Weight Displays, Reports, and Labels.

S.4.1. Additional Digits in Displays. – Auxiliary digital displays that provide additional digits for use during 

performance evaluation may be included on automatic checkweighers. However, in cases where these indications 

are not valid for determining the actual weight of a package (e.g., only appropriate for use in statistical process 

control programs by users) they shall be clearly and distinctly differentiated from valid weight displays by 

indicating them to the user.

For example, the additional digits may be differentiated by color, partially covered by placing crosshatch overlays 

on the display, or made visible only after the operator presses a button or turns a key to set the device in a mode 

which enables the additional digits.

N

d

vmin ≤

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S.4.2. Damping. – An indicating element equipped with other than automatic recording elements shall be 

equipped with effective means to permit the recording of weight values only when the indication is stable within 

plus or minus one scale division. The values recorded shall be within applicable tolerances.

S.4.3. Over Capacity Indication. – An indicating or recording element shall not display nor record any values 

when the scale capacity is exceeded by nine scale divisions.

S.4.4. Label Printer. – A device that produces a printed ticket to be used as the label for a package shall print 

all values digitally and of such size, style of type, and color as to be clear and conspicuous on the label.

S.4.4.1. Label Printing. – If an automatic checkweigher prints a label containing weight information that 

will be used in a commercial transaction, it must conform to all of the requirements specified for weighlabelers so that the printed ticket meets appropriate requirements.

S.5. Accuracy Class.

S.5.1. Marking. – Weigh-labelers and automatic checkweighers shall be Class III devices and shall be marked 

accordingly, except that a weigh-labeler marked Class IIIS may be used in package shipping applications.

(Amended 1997)

S.6. Parameters for Accuracy Classes. – The number of divisions for device capacity is designated by the 

manufacturer and shall comply with parameters shown in Table S.6. Parameters for Accuracy Classes.

Table S.6.

Parameters for Accuracy Classes

Number of Divisions (n)

Class Value of the Verification Division (e) Minimum Maximum

SI Units

III 0.1 to 2 g, inclusive 100 10 000

equal to or greater than 5 g 500 10 000

U.S. Customary Units

III

0.0002 lb to 0.005 lb, inclusive 100 10 000

0.005 oz to 0.125 oz, inclusive 100 10 000

equal to or greater than 0.01 lb 500 10 000

equal to or greater than 0.25 oz 500 10 000

IIIS greater than 0.01 lb 100 1 000

greater than 0.25 oz 100 1 000

For Class III devices, the value of e is specified by the manufacturer as marked on the device; d shall not be smaller 

than 0.1 e. e shall be differentiated from d by size, shape, or color.

(Amended 2004)

S.7. Marking Requirements. [Also see G-S.1. Identification, G-S.4. Interchange or Reversal of Parts, 

G-S.6. Marking Operational Controls, Indications, and Features, G-S.7. Lettering, G-UR.2.1.1. Visibility of 

Identification, and UR.3.3. Special Designs]

S.7.1. Location of Marking Information. – Automatic weighing systems which are not permanently attached 

to an indicating element, and for which the load-receiving element is the only part of the weighing/load-receiving 

element visible after installation, may have the marking information required in Section 1.10. General Code, 

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G-S.1. Identification, and Section 2.24. Automatic Weighing Systems Code, Table S.7.a. Marking Requirements 

and Table S.7.b. Notes for Table S.7.a. located in an area that is accessible only through the use of a tool; provided 

that the information is easily accessible (e.g., the information may appear on the junction box under an access 

plate). The identification information for these automatic weighing systems shall be located on the weighbridge 

(load-receiving element) near the point where the signal leaves the weighing element, or beneath the nearest 

access cover.

Table S.7.a. Marking Requirements

To Be

Marked With ⇓

Weighing Equipment

Weighing, loadreceiving, and 

indicating element 

in same housing

Indicating element 

not permanently 

attached to 

weighing and 

load-receiving 

element

Weighing and 

load-receiving 

element not 

permanently 

attached to 

indicating element

Load 

cell 

with 

CC 

(10)

Other 

equipment 

or device 

(9)

Manufacturer’s ID (1) x x x x x

Model Designation (1) x x x x x 

Serial Number and Prefix (2) x x x x x (13)

Certificate of Conformance

(CC) Number (16) x x x x x (16)

Accuracy Class (14) x x (8) x x

Nominal Capacity (3)(15) x x x 

Value of Division, d (3) x x

Value of e (4) x x 

Temperature Limits (5) x x x x

Special Application (11) x x x 

Maximum Number of 

Scale Divisions, nmax (6) x (8) x x 

Minimum Verification

Division, (emin) x 

“S” or “M” (7) x 

Direction of Loading (12) x

Minimum Dead Load x 

Maximum Capacity (Max) x x

Minimum Capacity (Min) x

Safe Load Limit x 

Load Cell Verification

Interval (vmin) x 

Maximum Belt Speed

(m/sec or m/min) x x 

Note: Also see Table S.7.b. for applicable parenthetical notes.

(Amended 1999)

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Table S.7.b.

Notes for Table S.7.a.

1. Manufacturer’s identification and model designation. (Also see G-S.1. Identification)

2. Serial number and prefix. Also see G-S.1. Identification)

3. The nominal capacity and value of the automatic weighing system division shall be shown together 

(e.g., 50 000 × 5 kg, or 30 × 0.01 lb) adjacent to the weight display when the nominal capacity and value of the 

automatic weighing system division are not immediately apparent. Each division value or weight unit shall be marked 

on variable-division value or division-unit automatic weighing systems.

4. Required only if different from d.

5. Required only on automatic weighing systems if the temperature range on the NTEP CC is narrower than and within 

– 10 oC to 40 oC (14 oF to 104 oF).

(Amended 2007)

6. This value may be stated on load cells in units of 1000; (e.g., nmax 10 is 10 000 divisions.)

7. Denotes compliance for single or multiple load cell applications.

8. An indicating element not permanently attached to a weighing element shall be clearly and permanently marked with 

the accuracy Class III, or IIIS and the maximum number of divisions, nmax. 

9. Necessary to the weighing system but having no metrological effect (e.g., auxiliary remote display, keyboard, etc.).

10. The markings may be either on the load cell or in an accompanying document; except that, if an accompanying 

document is provided, the serial number shall appear both on the load cell and in the document. The manufacturer’s 

name or trademark, the model designation, and identifying symbol for the serial number shall also be marked both on 

the load cell and in any accompanying document.

11. An automatic weighing system designed for a special application rather than general use shall be conspicuously marked 

with suitable words visible to the operator and customer restricting its use to that application.

12. Required if the direction of loading the load cell is not obvious.

13. Serial number and prefix (Also see G-S.1. Identification) modules without “intelligence” on a modular system 

(e.g., printer, keyboard module, cash drawer, and secondary display in a point-of-sale system) are not required to have 

serial numbers.

14. The accuracy class of a device shall be marked on the device with the appropriate designation.

15. The nominal capacity shall be conspicuously marked on any automatic-indicating or recording automatic weighing system 

so constructed that the capacity of the indicating or recording element, or elements, is not immediately apparent.

16. Required only if a CC has been issued for the equipment.

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S.7.2. Marking Required on Components of Automatic Weighing Systems. – The following components 

of automatic weighing systems shall be marked as specified in Tables S.7.a. Marking Requirements and 

S.7.b. Notes for Table S.7.2.a.:

(a) Main elements and components when not contained in a single enclosure for the entire automatic weighing 

system;

(b) Load cells for which Certificates of Conformance (CC) have been issued under the National Type 

Evaluation Program; and

(c) Other equipment necessary to a weighing system but having no metrological effect on the weighing 

system.

N. Notes

N.1. Test Requirements for Automatic Weighing Systems.

N.1.1. Test Pucks and Packages.

(a) Test pucks and packages shall be:

(1) representative of the type, size, and weight ranges to be weighed on a device; and

(2) stable while in motion, hence the length and width of a puck or package should be greater than its 

height.

(b) For type evaluation the manufacturer shall supply the test pucks or packages for each range of test loads.

(Amended 1997)

N.1.2. Accuracy of Test Pucks or Packages. – The error in any test puck or package shall not exceed 

one-fourth (1⁄4) of the acceptance tolerance. If packages are used to conduct field tests on automatic weighing 

systems, the package weights shall be determined on a reference scale or balance with an inaccuracy that does 

not exceed one-fifth (1

/5) of the smallest tolerance that can be applied to the device under test.

N.1.3. Verification (Testing) Standards. – Field standard weights shall comply with requirements of NIST 

Handbook 105-1, “Specifications and Tolerances for Field Standard Weights (Class F)” or the tolerances 

expressed in Fundamental Considerations, paragraph 3.2. (i.e., one-third of the smallest tolerance applied).

N.1.4. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility, Field 

Evaluation. – An RFI test shall be conducted at a given installation when the presence of RFI has been verified 

and characterized if those conditions are considered “usual and customary.”

(Added 2004)

N.1.5. Tests Loads. – A performance test shall consist of four separate test runs conducted at different test 

loads according to Table N.1.5. Test Loads.

Table N.1.5. 

Test Loads

At or near minimum capacity

At or near maximum capacity

At two (2) critical points between minimum and maximum capacity

Test may be conducted at other loads if the device is intended for use at other specific capacities

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N.1.6. Influence Factor Testing. – Influence factor testing shall be conducted statically.

N.2. Test Procedures - Weigh-Labelers. – If the device is designed for use in a non-automatic weighing mode, it 

shall be tested in the non-automatic mode according to NIST Handbook 44, Section 2.20. Scales Code.

Note: If the device is designed for only automatic weighing, it shall only be tested in the automatic weighing mode.

(Amended 2004)

N.2.1. Non-Automatic Tests.

N.2.1.1. Increasing-Load Test. – The increasing-load test shall be conducted with the test loads 

approximately centered on the load-receiving element of the scale.

N.2.1.2. Decreasing-Load Test. – The decreasing-load test shall be conducted with the test loads 

approximately centered on the load-receiving element of the scale.

N.2.1.3. Shift Test. – To determine the effect of off-center loading, a test load equal to one-half (1⁄2) 

maximum capacity shall be placed in the center of each of the four points equidistant between the center and 

front, left, back, and right edges of the load receiver.

N.2.1.4. Discrimination Test. – A discrimination test shall be conducted with the weighing device in 

equilibrium at zero-load and at maximum test load, and under controlled conditions in which environmental 

factors are reduced to the extent that they will not affect the results obtained. This test is conducted from just 

below the lower edge of the zone of uncertainty for increasing-load tests, or from just above the upper edge 

of the zone of uncertainty for decreasing-load tests.

N.2.1.5. Zero-Load Balance Change. – A zero-load balance change test shall be conducted on all 

automatic weighing systems after the removal of any test load. The zero-load balance should not change by 

more than the minimum tolerance applicable. (Also see G-UR.4.2. Abnormal Performance)

(Amended 2004)

N.2.2. Automatic Test Procedures.

N.2.2.1. Tests Non-Automatic. – If the automatic weighing system is designed to operate 

non-automatically, and is used in that manner, during normal use operation, it shall be tested 

non-automatically using mass standards. The device shall not be tested non-automatically if it is used only 

in the automatic mode.

N.2.2.2. Automatic Tests. – The device shall be tested at the normal operating speed using packages. Test 

runs should be conducted using at least two test loads distributed over its normal weighing range (e.g., near 

the lowest and highest ranges in which the device is typically operated.) Each test load should be run a 

minimum of ten consecutive times.

(Amended 2004)

N.3. Test Procedures - Automatic Checkweigher.

N.3.1. Tests Non-Automatic. – If the scale is designed to operate non-automatically during normal user 

operation, it shall be tested non-automatically according to paragraphs N.2.1.1. Increasing Load Test through 

N.2.1.5. Zero-Balance Change.

(Amended 2004)

N.3.2. Automatic Tests. – The device shall be tested at the highest speed in each weight range using 

standardized test pucks or packages. Test runs shall be conducted using two test loads. The number of 

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consecutive test weighments shall be as specified in Table N.3.2. Number of Sample Weights per Test for 

Automatic Checkweighers.

(Amended 2004)

Table N.3.2. 

Number of Sample Weights per Test for Automatic Checkweighers

Weighing Range

m = mass of test load

Number of Sample Weights per Test

Field

Type 

Evaluation

20 divisions < m < 10 kg

20 divisions < m < 22 lb 30 60

10 kg < m < 25 kg

22 lb < m < 55 lb 16 32

25 kg < m < 100 kg

55 lb < m < 220 lb 10 20

100 kg (220 lb) < m 10 10

T. Tolerances

T.1. Principles.

T.1.1. Design. – The tolerance for a weighing device is a performance requirement independent of the design 

principle used.

T.1.2. Scale Division. – The tolerance for a weighing device is related to the value of the scale division (d) or 

the value of the verification scale division (e) and is generally expressed in terms of d or e. The random tolerance 

for automatic checkweighers is expressed in terms of Maximum Allowable Variance (MAV).

T.2. Tolerance Application.

T.2.1. General. – The tolerance values are positive (+) and negative (−) with the weighing device adjusted to 

zero at no load. When tare is in use, the tolerance values are applied from the tare zero reference (zero net weight 

indication); the tolerance values apply to the net weight indication for any possible tare load using certified test 

loads.

(Amended 2008)

T.2.2. Type Evaluation Examinations. – For type evaluation examinations, the tolerance values apply to 

increasing and decreasing load tests within the temperature and power supply limits specified in T.7. Influence 

Factors.

(Amended 2004)

T.2.3. Subsequent Verification Examinations. – For subsequent verification examinations, the tolerance 

values apply regardless of the influence factors in effect at the time of the conduct of the examination. (Also see 

G-N.2. Testing with Nonassociated Equipment.) 

(Added 2007)

T.2.4. Multiple Range and Multi-Interval Automatic Weighing System. – For multiple range and 

multi-interval devices, the tolerance values are based on the value of the scale division of the range in use.

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T.3. Tolerance Values.

Table T.3. 

Class III - Tolerance in Divisions (e)

Test Load in Divisions Tolerance in Divisions

Class III Acceptance Maintenance

0 - 500 ± 0.5 ± 1

501 - 2000 ± 1.0 ± 2

2001 - 4000 ± 1.5 ± 3

4001 + ± 2.5 ± 5

T.3.1. Tolerance Values – Class III Weigh-Labeler. (Also see Section T.3.2. Class IIIS Weigh-Labelers.) 

T.3.1.1. Non-automatic Tests. – Tolerance values shall be as specified in Table T.3. Class III - Tolerance 

in Divisions (e).

(Amended 2004)

T.3.1.2. Automatic Tests. – Acceptance tolerance values shall be the same as maintenance tolerance 

values specified in Table T.3. Class III - Tolerance in Divisions (e).

(Amended 2004)

T.3.2. Tolerance Values - Class IIIS Weigh-labelers in Package Shipping Applications.

(Added 1997)

T.3.2.1. Non-automatic Tests. – Tolerance values shall be as specified in Table T.3.2.1. Non-automatic 

Tolerances for Class IIIS Weigh-labelers.

(Amended 2004)

T.3.2.2. Automatic Tests. – Tolerance values specified in Table T.3.2.2. Automatic Tolerances for 

Class IIIS Weigh-labelers shall be applied.

(Amended 2004)

Table T.3.2.1. 

Non-automatic Tolerances

for Class IIIS Weigh-labelers

Table T.3.2.2. 

Automatic Tolerances

for Class IIIS Weigh-labelers

Test Load in 

Divisions Tolerance in Divisions Test Load in Divisions Tolerance in Divisions

Class IIIS Acceptance Maintenance Class IIIS Acceptance Maintenance

0 - 50 ± 0.5 ± 1 0 - 50 ± 1.5 ± 2

51 - 200 ± 1.0 ± 2 51 - 200 ± 2.0 ± 3

201 - 1000 ± 1.5 ± 3 201 - 1000 ± 2.5 ± 4

(Added 1997) (Amended 2004) (Added 1997) (Amended 2004)

T.3.3. Tolerance Values. – Automatic Checkweighers.

T.3.3.1. Laboratory Tests for Automatic Checkweighers.

T.3.3.1.1. Non-Automatic Tests. – The acceptance tolerance values specified in 

Table T.3. Class III - Tolerance in Divisions (e), shall be applied.

(Amended 2004)

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T.3.3.1.2. Automatic Tests.

(a) The systematic error for each test run shall be within the acceptance tolerances specified in 

Table T.3. Class III - Tolerance in Divisions (e) for the test loads specified in Table N.1.5. Test 

Loads.

(Amended 2004)

(b) The standard deviation of the results shall not exceed one-ninth (1

/9) of the MAV for specific 

package weights (which means that three standard deviations cannot exceed one-third (1

/3) of 

the MAV value) as required in the latest edition of NIST Handbook 133, “Checking the Net 

Contents of Packaged Goods.” This value does not change regardless of whether acceptance 

or maintenance tolerances are being applied to the device under test.

(Amended 2004)

(1) For U.S. Department of Agriculture (USDA) inspected meat and poultry products 

packaged at a plant subject to inspection by the USDA Food Safety and Inspection Service, 

use NIST Handbook 133, Appendix A. Tables, Table 2-9, U.S. Department of Agriculture, 

Meat and Poultry, Groups and Lower Limits for Individual Packages; 

(2) for all other packages with a labeled net quantity in terms of weight, use NIST 

Handbook 133, Appendix A. Tables, Table 2-5, Maximum Allowable Variations (MAVs) 

for Packages Labeled by Weight; or

(3) for all packages with a labeled net quantity in terms of liquid or dry volume use NIST 

Handbook 133, Appendix A. Tables, Table 2-6, Maximum Allowable Variations (MAVs) 

for Packages Labeled by Liquid or Dry Volume.

(Amended 2004)

T.3.3.2. Field Tests for Automatic Checkweighers.

T.3.3.2.1. Non-Automatic Test. – The tolerance values shall be as specified in 

Table T.3. Class III – Tolerance in Divisions (e).

(Amended 2004)

T.3.3.2.2. Automatic Test.

(a) The systematic error requirement is not applied in a field test.

(b) The standard deviation of the test results shall not exceed one-ninth (1

/9) of the MAV for specific 

package weights (which means that three standard deviations cannot exceed one-third (1

/3) of 

the MAV value) as required in the latest Edition of NIST Handbook 133. This value does not 

change regardless of whether acceptance or maintenance tolerances are being applied to the 

device under test.

(Amended 2004)

(1) For USDA inspected meat and poultry products packaged at a plant subject to inspection 

by the USDA Food Safety and Inspection Service, use NIST Handbook 133, Appendix A, 

Tables, Table 2-9, U.S. Department of Agriculture, Meat and Poultry, Groups and Lower

Limits for Individual Packages;

(2) for all other packages with a labeled net quantity in terms of weight, use NIST 

Handbook 133, Appendix A. Tables, Table 2-5, Maximum Allowable Variations (MAVs)

for Packages Labeled by Weight; or

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(3) for all packages with a labeled net quantity in terms of liquid or dry volume use NIST 

Handbook 133, Appendix A. Tables, Table 2-6. Maximum Allowable Variations (MAVs) 

for Packages Labeled by Liquid or Dry Volume.

T.4. Agreement of Indications. – In the case of a weighing system equipped with more than one indicating element 

or indicating element and recording element combination, the difference in the weight value indications of any load 

shall not be greater than the absolute value of the applicable tolerance for that load, and shall be within tolerance 

limits.

T.5. Repeatability. – The results obtained from several weighings of the same load under reasonably constant test 

conditions shall agree within the absolute value of the maintenance tolerance for that load, and shall be within 

applicable tolerances.

(Amended 2004)

T.6. Discrimination. – A test load equivalent to 1.4 d shall cause a change in the indicated or recorded value of at 

least 2.0 d. This requires the zone of uncertainty to be not greater than 0.3 d (See N.2.1.4. Discrimination Test).

(Amended 2004)

T.7. Influence Factors. – The following factors are applicable to tests conducted under controlled conditions only.

T.7.1. Temperature. – Devices shall satisfy the tolerance requirements under the following temperature 

conditions:

T.7.1.1. if not specified in the operating instructions or if not marked on the device, the temperature limits 

shall be: − 10 °C to 40 °C (14 °F to 104 °F).

T.7.1.2. if temperature limits are specified for the device, the range shall be at least 30 °C (54 °F).

T.7.1.3. Temperature Effect on Zero-Load Balance. – The zero-load indication shall not vary by more 

than one division per 5 °C (9 °F) change in temperature.

T.7.1.4. Operating Temperature. – The indicating or recording element shall not display nor record any 

usable values until the operating temperature necessary for accurate weighing and a stable zero balance 

condition have been attained.

T.7.2. Electric Power Supply.

T.7.2.1. Range of Voltages.

(a) Automatic weighing systems that operate using alternating current must perform within the 

conditions defined in paragraphs T.3. Tolerance Values through T.6. Discrimination, inclusive, 

when tested over the range of − 15 % to + 10 % of the marked nominal line voltage(s) at 60 Hz, or 

the voltage range marked by the manufacturer, at 60 Hz.

(b) Automatic weighing systems that operate using DC current must perform within the conditions 

defined in paragraphs T.3. Tolerance Values through T.6. Discrimination, inclusive, when tested 

over the range from minimum operating voltage4 to + 20 % of the voltage marked on the instrument 

(nominal voltage).

(c) Battery-operated electronic automatic weighing systems with external or plug-in power supply (AC 

or DC) shall either continue to function correctly or not indicate any weight values if the voltage is 

 

4 The minimum operating voltage is defined as the lowest possible operating voltage before the automatic weighing 

system no longer indicates nor records weight values.

(Added 2004)

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below the manufacturer’s specified value, the latter being larger than or equal to the minimum 

operating voltage.4

Note: This requirement applies only to metrologically significant voltage supplies.

(Amended 2001)

(Amended 2004)

T.7.2.2. Power Interruption. – A power interruption shall not cause an indicating or recording element 

to display or record any values outside the applicable tolerance limits.

T.8. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility. – The 

difference between the weight indication with the disturbance and the weight indication without the disturbance (also 

see N.1.4. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility, Field 

Evaluation) shall not exceed one scale division (d) or the equipment shall:

(a) blank the indication; 

(b) provide an error message; or

(c) the indication shall be so completely unstable that it could not be interpreted, or transmitted into memory or 

to a recording element, as a correct measurement value.

(Amended 2004)

UR. User Requirements

UR.1. Selection Requirements. – Equipment shall be suitable for the service in which it is used with respect to 

elements of its design, including but not limited to, its capacity, number of scale divisions, value of the scale division 

or verification scale division, minimum capacity, and computing capability.

UR.1.1. General. – Automatic Weighing Systems shall be designated by the manufacturer for that service.

UR.1.2. Value of the Indicated and Recorded Scale Division. – The value of the division as recorded shall 

be the same as the division value indicated.

UR.2. Installation Requirements.

UR.2.1. Protection from Environmental Factors. – The indicating elements, the lever system or load cells, 

and the load-receiving element of a permanently installed scale, and the indicating elements of a scale not intended 

to be permanently installed, shall be adequately protected from environmental factors such as wind, weather, and 

RFI that may adversely affect the operation or performance of the device.

UR.2.2. Foundation, Supports, and Clearance. – The foundation and supports of any scale installed in a 

fixed location shall be such as to provide strength, rigidity, and permanence of all components, and clearance 

shall be provided around all live parts to the extent that no contacts may result when the load-receiving element 

is empty, nor throughout the weighing range of the scale.

UR.2.3. Entry and Departure from Weighing Area. – The belt or other conveyance that introduces the 

weighed load to the weighing zone and that carries the weighed load away from the weighing zone shall be 

maintained per the manufacturer’s recommendations.

UR.3. Use Requirements.

UR.3.1. Minimum Load. – The minimum load shall be as specified by the manufacturer, but not less than 

twenty divisions since the use of a device to weigh light loads is likely to result in relatively large errors.

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UR.3.1.1. Minimum Load for Class IIIS Weigh-Labelers. – The minimum load shall be as specified 

by the manufacturer, but not less than ten divisions since the use of a device to weigh light loads is likely to 

result in relatively large errors.

(Added 1997)

UR.3.2. Maximum Load. – An automatic weighing system shall not be used to weigh a load of more than its 

maximum capacity.

(Amended 2004)

UR.3.3. Special Designs. – An automatic weighing system designed and marked for a special application shall 

not be used for other than its intended purpose.

UR.3.4. Use of Manual Gross Weight Entries. – Manual entries are permitted only when a device or system 

is generating labels for standard weight packages.

UR.4. Maintenance Requirements.

UR.4.1. Balance Condition. – If an automatic weighing system is equipped with a zero-load display, the 

zero-load adjustment of an automatic weighing system shall be maintained so that the device indicates or records 

a zero balance condition.

UR.4.2. Level Condition. – If an automatic weighing system is equipped with a level-condition indicator, the 

automatic weighing system shall be maintained in level.

UR.4.3. Automatic Weighing System Modification. – The length or the width of the load-receiving element 

of an automatic weighing system shall not be increased beyond the manufacturer’s design dimension, nor shall 

the capacity of an automatic weighing system be increased beyond its design capacity by replacing or modifying 

the original primary indicating or recording element with one of a higher capacity, except when the modification 

has been approved by competent engineering authority, preferably that of the engineering department of the 

manufacturer of the automatic weighing system, and by the weights and measures authority having jurisdiction 

over the automatic weighing system.

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Table of Contents

Section 2.25. Weigh-In-Motion Systems Used for Vehicle Enforcement Screening – 

Tentative Code ................................................................................................................. 2-111

A. Application ................................................................................................................................................. 2-111

A.1. General. ............................................................................................................................................ 2-111

A.2. Exception. ......................................................................................................................................... 2-111

A.3. Additional Code Requirements......................................................................................................... 2-111

S. Specifications.............................................................................................................................................. 2-111

S.1. Design of Indicating and Recording Elements and of Recorded Representations. ........................... 2-111

S.1.1. Ready Indication. ................................................................................................................ 2-111

S.1.2. Value of System Division Units.......................................................................................... 2-111

S.1.3. Maximum Value of Division. ............................................................................................. 2-111

S.1.4. Value of Other Units of Measure........................................................................................ 2-111

S.1.5. Capacity Indication. ............................................................................................................ 2-112

S.1.6. Identification of a Fault....................................................................................................... 2-112

S.1.7. Recorded Representations................................................................................................... 2-112

S.1.8. Value of the Indicated and Recorded System Division....................................................... 2-112

S.2. System Design Requirements. .......................................................................................................... 2-112

S.2.1. Violation Parameters........................................................................................................... 2-112

S.3. Design of Weighing Elements. ......................................................................................................... 2-113

S.3.1. Multiple Load-Receiving Elements.................................................................................... 2-113

S.4. Design of Weighing Devices, Accuracy Class. ................................................................................ 2-113

S.4.1. Designation of Accuracy..................................................................................................... 2-113

S.5. Marking Requirements...................................................................................................................... 2-113

S.5.1. Location of Marking Information ....................................................................................... 2-114

N. Notes............................................................................................................................................................ 2-114

N.1. Test Procedures................................................................................................................................. 2-114

N.1.1. Selection of Test Vehicles. ................................................................................................. 2-114

N.1.2. Test Loads........................................................................................................................... 2-114

N.1.3. Reference Scale................................................................................................................... 2-114

N.1.4. Test Speeds. ........................................................................................................................ 2-115

N.1.5. Test Procedures................................................................................................................... 2-115

T. Tolerances................................................................................................................................................... 2-115

T.1. Principles. ......................................................................................................................................... 2-115

T.1.1. Design. ................................................................................................................................ 2-115

T.2. Tolerance Values for Accuracy Class A. .......................................................................................... 2-115

T.2.2. Tolerance Values for Dynamic Load Test .......................................................................... 2-115

T.2.3. Tolerance Value for Vehicle Position Test ......................................................................... 2-116

T.2.4. Tolerance Value for Axle Spacing...................................................................................... 2-116

T.3. Influence Factors............................................................................................................................... 2-116

T.3.1. Temperature ........................................................................................................................ 2-116

T.4. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility. ......... 2-116

UR. User Requirements .................................................................................................................................... 2-116

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UR.1. Selection Requirements .................................................................................................................... 2-116

UR.1.1. General................................................................................................................................ 2-116

UR.2. User Location Conditions and Maintenance. .................................................................................... 2-116

UR.2.1. System Modification........................................................................................................... 2-116

UR.2.2. Foundation, Supports, and Clearance.................................................................................. 2-117

UR.2.3. Access to Weighing Elements............................................................................................. 2-117

UR.3. Maximum Load................................................................................................................................. 2-117

Appendix D. Definitions...................................................................................................................................... 2-117

axle. .......................................................................................................................................................... 2-117

axle-group load. ........................................................................................................................................... 2-117

axle load....................................................................................................................................................... 2-117

axle spacing ................................................................................................................................................. 2-117

single-axle load............................................................................................................................................ 2-117

tandem-axle load.......................................................................................................................................... 2-117

triple-axle load............................................................................................................................................. 2-117

weigh-in-motion (WIM). ............................................................................................................................. 2-117

weigh-in-motion screening scale ................................................................................................................. 2-117

wheel weight................................................................................................................................................ 2-118

WIM System................................................................................................................................................ 2-118

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Section 2.25. Weigh-In-Motion Systems

Used for Vehicle Enforcement Screening – Tentative Code

This tentative code has a trial or experimental status and is not intended to be enforced. The requirements are designed 

for study prior to the development and adoption of a final code. Officials wanting to conduct an official examination 

of a device or system are advised to see paragraph G-A.3. Special and Unclassified Equipment.

(Tentative Code Added 2015)

A. Application

A.1. General. – This code applies to systems used to weigh vehicles, while in motion, for the purpose of screening 

and sorting the vehicles based on the vehicle weight to determine if a static weighment is necessary.

A.2. Exception. – This code does not apply to weighing systems intended for the collection of statistical traffic data.

A.3. Additional Code Requirements. – In addition to the requirements of this code, weigh-in-motion screening 

systems shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Ready Indication. – The system shall provide a means of verifying that the system is operational and 

ready for use.

S.1.2. Value of System Division Units. – The value of a system division “d” expressed in a unit of weight 

shall be equal to:

(a) 1, 2, or 5; or

 

(b) a decimal multiple or submultiple of 1, 2, or 5.

Examples: divisions may be 10, 20, 50, 100; or 0.01, 0.02, 0.05; or 0.1, 0.2, 0.5, etc.

S.1.2.1. Units of Measure. – The system shall indicate weight values using only a single unit of measure. 

S.1.3. Maximum Value of Division. – The value of the system division “d” for a Class A, weight-in-motion 

system shall not be greater than 50 kg (100 lb).

S.1.4. Value of Other Units of Measure.

S.1.4.1. Speed. – Vehicle speeds shall be measured in miles per hour or kilometers per hour.

S.1.4.2. Axle-Spacing (Length). – The center-to-center distance between any two successive axles shall 

be measured in:

(a) meters and decimal submultiples of a meter;

(b) feet and inches; or

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(c) feet and decimal submultiples of a foot.

S.1.4.3. Vehicle Length. – If the system is capable of measuring the overall length of the vehicle, the 

length of the vehicle shall be measured in feet and/or inches, or meters.

S.1.5. Capacity Indication. – An indicating or recording element shall not display nor record any values 

greater than 105 % of the specified capacity of the load receiving element.

S.1.6. Identification of a Fault. – Fault conditions shall be presented to the operator in a clear and 

unambiguous means. The following fault conditions shall be identified:

(a) Vehicle speed is below the minimum or above the maximum speed as specified.

(b) The maximum number of vehicle axles as specified has been exceeded.

(c) A change in vehicle speed greater than that specified has been detected. 

S.1.7. Recorded Representations.

S.1.7.1. Values to be Recorded. – At a minimum, the following values shall be printed and/or stored 

electronically for each vehicle weighment:

(a) transaction identification number;

(b) lane identification (required if more than one lane at the site has the ability to weigh a vehicle in

motion);

(c) vehicle speed;

(d) number of axles;

(e) weight of each axle;

(f) identification and weight of axle groups;

(g) axle spacing;

(h) total vehicle weight;

(i) all fault conditions that occurred during the weighing of the vehicle;

(j) violations, as identified in paragraph S.2.1. Violation Parameters, which occurred during the 

weighing of the vehicle; and

(k) time and date.

S.1.8. Value of the Indicated and Recorded System Division. – The value of the system’s division “(d),” as 

recorded, shall be the same as the division value indicated.

S.2. System Design Requirements. 

S.2.1. Violation Parameters. – The instrument shall be capable of accepting user-entered violation parameters 

for the following items:

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(a) single axle weight limit;

(b) axle group weight limit;

(c) gross vehicle weight limit; and

(d) bridge formula maximum.

The instrument shall display and/or record violation conditions when these parameters have been exceeded.

S.3. Design of Weighing Elements.

S.3.1. Multiple Load-Receiving Elements. –An instrument with a single indicating or recording element, or 

a combination indicating-recording element, that is coupled to two or more load-receiving elements with 

independent weighing systems, shall be provided with means to prohibit the activation of any load-receiving 

element (or elements) not in use, and shall be provided with automatic means to indicate clearly and definitely 

which load receiving element (or elements) is in use.

S.4. Design of Weighing Devices, Accuracy Class.

S.4.1. Designation of Accuracy. – Weigh-in-motion systems meeting the requirements of this code shall be 

designated as accuracy Class A. 

Note: This does not preclude higher accuracy classes from being proposed and added to this Code in the future when it can 

be demonstrated that weigh-in-motion systems grouped within those accuracy classes can achieve the higher level of 

accuracy specified for those devices.

S.5. Marking Requirements. – In addition to the marking requirements in G-S.1. Identification (except G.S.1.(e)), 

the system shall be marked with the following information:

(a) accuracy class;

(b) value of the system division “d”;

(c) operational temperature limits;

(d) number of instrumented lanes (not required if only one lane is instrumented);

(e) minimum and maximum vehicle speed;

(f) maximum number of axles per vehicle;

(g) maximum change in vehicle speed during weighment; and 

(h) minimum and maximum load.

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S.5.1. Location of Marking Information. – The marking information required in Section 1.10. General Code,

G-S.1. Identification and Section 2.25. Weigh-in-Motion Systems, S.5. Marking Requirements shall be visible 

after installation. The information shall be marked on the system or recalled from an information screen.

N. Notes

N.1. Test Procedures. 

N.1.1. Selection of Test Vehicles. – All dynamic testing associated with the procedures described in each of 

the subparagraphs of N.1.5 shall be performed with a minimum of two test vehicles. 

(a) The first test vehicle may be a two-axle, six-tire, single-unit truck; that is, a vehicle with two axles with 

the rear axle having dual wheels. The vehicle shall have a maximum gross vehicle weight of 10 000 lb.

(b) The second test vehicle shall be a five-axle, single-trailer truck with a maximum gross vehicle weight 

of 80 000 lb.

Note: Consideration should be made for testing the systems using vehicles which are typical to the system’s daily 

operation.

N.1.1.1. Weighing of Test Vehicles. – All test vehicles shall be weighed on a reference scale before being 

used to conduct the dynamic tests.

N.1.1.2. Determining Reference Weights for Axle, Axle Groups, and Gross Vehicle Weight. – The 

reference weights shall be the average weight value of a minimum of three static weighments of all single 

axles, axle groups, and gross vehicle weight.

Note: The axles within an axle group are not considered single axles. 

N.1.2. Test Loads. 

N.1.2.1. Static Test Loads. – All static test loads shall use certified test weights.

N.1.2.2. Dynamic Test Loads. – Test vehicles used for dynamic testing shall be loaded to 85 to 95% of 

their legal maximum Gross Vehicle Weight. The “load” shall be non-shifting and shall be positioned to 

present as close as possible, an equal side-to-side load.

N.1.3. Reference Scale. – Each reference vehicle shall be weighed statically on a multiple platform vehicle 

scale comprised of three individual weighing/load-receiving elements, each an independent scale. The three 

individual weighing/load receiving elements shall be of such dimension and spacing to facilitate: 

 

(a) the single-draft weighing of all reference test vehicles; 

(b) the simultaneous weighing of each single axle and axle group of the reference test vehicles on different 

individual elements of the scale; and

(c) gross vehicle weight determined by summing the values of the different reference axle and reference 

axle groups of a test vehicle. 

The scale shall be tested immediately prior to using it to establish reference test loads and in no case more than 

24 hours prior. To qualify for use as a suitable reference scale, it must meet NIST Handbook 44, Class III L 

maintenance tolerances. 

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N.1.3.1. Location of a Reference Scale. – The location of the reference scale must be considered since 

vehicle weights will change due to fuel consumption.

N.1.4. Test Speeds. – All dynamic tests shall be conducted within 20 % below or at the posted speed limit.

N.1.5. Test Procedures. 

N.1.5.1. Dynamic Load Test. – The dynamic test shall be conducted using the test vehicles defined in 

N.1.1. Selection of Test Vehicles. The test shall consist of a minimum of 20 runs for each test vehicle at the 

speed as stated in N.1.4. Test Speeds.

At the conclusion of the dynamic test there will be a minimum of 20 weight readings for each single axle, 

axle group, and gross vehicle weight of the test vehicle. The tolerance for each weight reading shall be based 

on the percentage values specified in Table T.2.2. Tolerances for Accuracy Class A. 

N.1.5.2. Vehicle Position Test. – During the conduct of the dynamic testing, ensure the vehicle stays 

within the defined roadway along the width of the sensor. The test shall be conducted with 10 runs with the 

vehicle centered along the width of the sensor; 5 runs with the vehicle on the right side along the width of 

the sensor; and 5 runs with the vehicle on the left side along the width of the sensor. Only gross vehicle 

weight is used for this test and the tolerance for each weighment shall be based on the tolerance value 

specified in T.2.3. Tolerance Value for Vehicle Position Test.

N.1.5.3. Axle Spacing Test. – The axle spacing test is a review of the displayed and/or recorded axle 

spacing distance of the test vehicles. The tolerance value for each distance shall be based on the tolerance 

value specified in T.2.4. Tolerance Value for Axle Spacing. 

T. Tolerances

T.1. Principles.

T.1.1. Design. – The tolerance for a weigh-in-motion system is a performance requirement independent of the 

design principle used. 

T.2. Tolerance Values for Accuracy Class A.

T.2.1. Tests Involving Digital Indications or Representations – To the tolerances that would otherwise be 

applied in paragraphs T.2.2. Tolerance Value for Dynamic Load Test and T.2.3. Tolerance Value for Vehicle 

Position Test, there shall be added an amount equal to one-half the value of the scale division to account for the 

uncertainty of digital rounding.

T.2.2. Tolerance Values for Dynamic Load Test. – The tolerance values applicable during dynamic load 

testing are as specified in Table T.2.2. 

Table T.2.2.

Tolerances for Accuracy Class A

Load Description* Tolerance as a Percentage of Applied Test Load

Axle Load ± 20 %

Axle Group Load ± 15 %

Gross Vehicle Weight ± 10 %

* No more than 5 % of the weighments in each of the load description subgroups shown in this table shall 

exceed the applicable tolerance.

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T.2.3. Tolerance Value for Vehicle Position Test. – The tolerance value applied to each gross vehicle 

weighment is ± 10 % of the applied test load.

T.2.4. Tolerance Value for Axle Spacing. – The tolerance value applied to each axle spacing measurement 

shall be ± 0.15 m (0.5 ft).

T.3. Influence Factors. – The following factor is applicable to tests conducted under controlled conditions only.

T.3.1. Temperature. – Systems shall satisfy the tolerance requirements under all operating temperature unless 

a limited operating temperature range is specified by the manufacturer.

T.4. Radio Frequency Interference (RFI) and Other Electromagnetic Interference Susceptibility. – The 

difference between the weight indication due to the disturbance and the weight indication without the disturbance shall 

not exceed the tolerance value as stated in Table T.2.2. Tolerances for Accuracy Class A.

UR. User Requirements

UR.1. Selection Requirements. – Equipment shall be suitable for the service in which it is used with respect to 

elements of its design, including but not limited to, its capacity, number of scale divisions, value of the scale division, 

or verification scale division and minimum capacity. 

UR.1.1. General. – The typical class or type of device for particular weighing applications is shown in Table 1. 

Typical Class or Type of Device for Weighing Applications.

Table 1.

Typical Class or Type of Device for Weighing Applications

Class Weighing Application

A Screening and sorting of vehicles based on axle, axle group, and gross vehicle weight.

Note: A WIM system with a higher accuracy class than that specified as “typical” may be used.

UR.2. User Location Conditions and Maintenance. – The system shall be installed and maintained as defined in 

the manufacturer’s recommendation. 

UR.2.1. System Modification. – The dimensions (e.g., length, width, thickness, etc.) of the load receiving 

element of a system shall not be changed beyond the manufacturer’s specifications, nor shall the capacity of a 

scale be increased beyond its design capacity by replacing or modifying the original primary indicating or 

recording element with one of a higher capacity, except when the modification has been approved by a competent 

engineering authority, preferably that of the engineering department of the manufacturer of the system, and by 

the weights and measures authority having jurisdiction over the system.

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UR.2.2. Foundation, Supports, and Clearance. – The foundation and supports shall be such as to provide 

strength, rigidity, and permanence of all components. 

 

On load-receiving elements, which use moving parts for determining the load value, clearance shall be provided 

around all live parts to the extent that no contacts may result when the load-receiving element is empty, nor 

throughout the weighing range of the system. 

UR.2.3. Access to Weighing Elements. – If necessary, adequate provision shall be made for inspection and 

maintenance of the weighing elements.

UR.3. Maximum Load. – A system shall not be used to weigh a load of more than the marked maximum load of 

the system.

Appendix D. Definitions

The specific code to which the definition applies is shown in the [brackets] at the end of the definition. Definitions 

for the General Code [1.10] apply to all codes in NIST Handbook 44.

A 

axle. – The axis oriented transversely to the nominal direction of vehicle motion, and extending the full width of the 

vehicle, about which the wheel(s) at both ends rotate. [2.25]

axle-group load. – The sum of all tire loads of the wheels on a group of adjacent axles; a portion of the gross-vehicle 

weight. [2.25]

axle load. – The sum of all tire loads of the wheels on an axle; a portion of the gross-vehicle weight. [2.25]

axle spacing. – The distance between the centers of any two axles. When specifying axle spacing, the axels used also 

need to be identified. [2.25]

S 

single-axle load. – The load transmitted to the road surface by the tires lying on the same longitudinal axis (that axis 

transverse to the movement of the vehicle and about which the wheels rotate). [2.25]

T 

tandem-axle load. – The load transmitted to the road surface by the tires of two single-axles lying on the same 

longitudinal axis (that axis transverse to the movement of the vehicle and about which the wheels rotate). [2.25]

triple-axle load. – The load transmitted to the road surface by the tires of three single-axles lying on the same 

longitudinal axis (that axis transverse to the movement of the vehicle and about which the wheels rotate). [2.25]

W 

weigh-in-motion (WIM). – A process of estimating a moving vehicle’s gross weight and the portion of that weight 

that is carried by each wheel, axle, or axle group, or combination thereof, by measurement and analysis of dynamic 

vehicle tire forces. [2.25]

weigh-in-motion screening scale. – A weigh-in-motion system used to identify potentially overweight vehicles. 

[2.25]

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wheel weight. – The weight value of any single or set of wheels on one side of a vehicle on a single axle. [2.25]

WIM System. – A set of sensors and supporting instruments that measure the presence of a moving vehicle and the 

related dynamic tire forces at specified locations with respect to time; estimate tire loads; calculate speed, axle spacing, 

vehicle class according to axle arrangement, and other parameters concerning the vehicle; and process, display, store, 

and transmit this information. This standard applies only to highway vehicles. [2.25]

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Handbook 44 – 2016 Section 3

3-1

Section 3

Table of Contents

Page

3.30. Liquid-Measuring Devices............................................................................................... 3-3 

3.31. Vehicle-Tank Meters ..................................................................................................... 3-29 

3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices ......................................... 3-45 

3.33. Hydrocarbon Gas Vapor-Measuring Devices................................................................ 3-59 

3.34. Cryogenic Liquid-Measuring Devices........................................................................... 3-71 

3.35. Milk Meters.................................................................................................................... 3-83 

3.36. Water Meters.................................................................................................................. 3-93 

3.37. Mass Flow Meters........................................................................................................ 3-101 

3.38. Carbon Dioxide Liquid-Measuring Devices................................................................ 3-115 

3.39. Hydrogen Gas-Measuring Devices – Tentative Code ................................................. 3-131 

3.40. Electric Vehicle Fueling Systems – Tentative Code .................................................... 3-145 

Note: In this section of Handbook 44, the reference temperature for the temperature compensation of refined petroleum products 

is shown as “15 °C (60 °F).” Although these values are not exact equivalents, they reflect industry usage when the SI and U.S. 

customary units are used in measurements.

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3-2 

THIS PAGE INTENTIONALLY LEFT BLANK

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Table of Contents

Section 3.30. Liquid-Measuring Devices ................................................................................ 3-5

A. Application .................................................................................................................................................... 3-5

A.1. General. .................................................................................................................................................3-5

A.2. Exceptions.............................................................................................................................................3-5

A.3. Additional Code Requirements.............................................................................................................3-5

S. Specifications................................................................................................................................................. 3-5

S.1. Indicating and Recording Elements and Recorded Representations.....................................................3-5

S.1.1. General....................................................................................................................................3-5

S.1.2. Units........................................................................................................................................3-5

S.1.3. Advancement of Indicating and Recording Elements.............................................................3-6

S.1.4. Graduations.............................................................................................................................3-6

S.1.5. Indicators. ...............................................................................................................................3-6

S.1.6. Additional Operating Requirements, Retail Devices (Except Slow-flow Meters)..................3-7

S.1.7. Additional Operating Requirements, Wholesale Devices Only............................................3-12

S.2. Measuring Elements............................................................................................................................3-12

S.2.1. Vapor Elimination.................................................................................................................3-12

S.2.2. Provision for Sealing.............................................................................................................3-12

S.2.3. Directional Flow Valves. ......................................................................................................3-13

S.2.4. Stop Mechanism. ..................................................................................................................3-13

S.2.5. Zero-Set-Back Interlock, Retail Motor-Fuel Devices. ..........................................................3-14

S.2.6. Temperature Determination – Wholesale Devices................................................................3-14

S.2.7. Wholesale Devices Equipped with Automatic Temperature Compensators.........................3-14

S.2.8. Exhaustion of Supply, Lubricant Devices Other than Meter Types......................................3-15

S.3. Discharge Lines and Valves................................................................................................................3-15

S.3.1. Diversion of Measured Liquid. .............................................................................................3-15

S.3.2. Exceptions.............................................................................................................................3-15

S.3.3. Pump-Discharge Unit............................................................................................................3-15

S.3.4. Gravity-Discharge Unit.........................................................................................................3-15

S.3.5. Discharge Hose, Reinforcement. ..........................................................................................3-16

S.3.6. Discharge Valve....................................................................................................................3-16

S.3.7. Anti-drain Means. .................................................................................................................3-16

S.4. Marking Requirements........................................................................................................................3-16

S.4.1. Limitation on Use. ................................................................................................................3-16

S.4.2. Air Pressure...........................................................................................................................3-16

S.4.3. Wholesale Devices................................................................................................................3-16

S.4.4. Retail Devices. ......................................................................................................................3-16

S.5. Totalizers for Retail Motor-Fuel Dispensers. .....................................................................................3-17

N. Notes............................................................................................................................................................. 3-17

N.1. Test Liquid..........................................................................................................................................3-17

N.1.1. Type of Liquid. .....................................................................................................................3-17

N.1.2. Labeling. ...............................................................................................................................3-17

N.2. Volume Change. .................................................................................................................................3-17

N.3. Test Drafts...........................................................................................................................................3-17

N.3.1. Retail Piston-Type and Visible-Type Devices......................................................................3-17

N.3.2. Slow-flow Meters. ................................................................................................................3-17

N.3.3. Lubricant Devices. ................................................................................................................3-17

N.3.4. Other Retail Devices.............................................................................................................3-17

N.3.5. Wholesale Devices................................................................................................................3-18

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N.4. Testing Procedures..............................................................................................................................3-18

N.4.1. Normal Tests.........................................................................................................................3-18

N.4.2. Special Tests. ........................................................................................................................3-18

N.4.3. Money-Value Computation Tests. ........................................................................................3-19

N.4.4. Pour and Drain Times. ..........................................................................................................3-19

N.5. Temperature Correction on Wholesale Devices..................................................................................3-20

T. Tolerances.................................................................................................................................................... 3-20

T.1. Application to Underregistration and to Overregistration...................................................................3-20

T.2. Tolerance Values. ...............................................................................................................................3-20

T.3. Repeatability. ......................................................................................................................................3-21

T.4. Automatic Temperature-Compensating Systems.................................................................................3-21

UR. User Requirements ..................................................................................................................................... 3-22

UR.1. Selection Requirements. .....................................................................................................................3-22

UR.1.1. Discharge Hose. ....................................................................................................................3-22

UR.2. Installation Requirements. ..................................................................................................................3-22

UR.2.1. Manufacturer’s Instructions. .................................................................................................3-22

UR.2.2. Discharge Rate......................................................................................................................3-22

UR.2.3. Suction Head.........................................................................................................................3-22

UR.2.4. Diversion of Liquid Flow......................................................................................................3-22

UR.2.5. Product Storage Identification. .............................................................................................3-23

UR.3. Use of Device......................................................................................................................................3-23

UR.3.1. Return of Indicating and Recording Elements to Zero. ........................................................3-23

UR.3.2. Unit Price and Product Identity.............................................................................................3-23

UR.3.3. Computing Device. ...............................................................................................................3-23

UR.3.4. Printed Ticket........................................................................................................................3-24

UR.3.5. Steps after Dispensing...........................................................................................................3-24

UR.3.6. Temperature Compensation, Wholesale. ..............................................................................3-25

Liquid-Measuring Device Code Index ................................................................................................................. 3-27

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Section 3.30. Liquid-Measuring Devices

A. Application

A.1. General. – This code applies to:

(a) devices used for the measurement of liquids, including liquid fuels and lubricants; and

(b) wholesale devices used for the measurement and delivery of agri-chemical liquids such as fertilizers, feeds, 

herbicides, pesticides, insecticides, fungicides, and defoliants.

(Added 1985)

A.2. Exceptions. – This code does not apply to:

(a) meters mounted on vehicle tanks (Also see Section 3.31. Code for Vehicle-Tank Meters.);

(b) devices used for dispensing liquefied petroleum gases (Also see Section 3.32. Code for Liquefied Petroleum 

Gas and Anhydrous Ammonia Liquid-Measuring Devices.);

(c) devices used for dispensing other liquids that do not remain in a liquid state at atmospheric pressures and 

temperatures;

(d) water meters;

(e) devices used solely for dispensing a product in connection with operations in which the amount dispensed 

does not affect customer charges; or

(f) mass flow meters. (Also see Section 3.37. Code for Mass Flow Meters.) 

(Added 1994)

A.3. Additional Code Requirements. – In addition to the requirements of this code, liquid-measuring devices shall 

meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Indicating and Recording Elements and Recorded Representations.

S.1.1. General. – A liquid-measuring device:

(a) shall be equipped with a primary indicating element; and

(b) may be equipped with a primary recording element.

S.1.2. Units. – A liquid-measuring device shall indicate, and record if the device is equipped to record, its 

deliveries in liters, gallons, quarts, pints, fluid ounces, or binary-submultiples or decimal subdivisions of the liter 

or gallon.

(Amended 1987, 1994, and 2006)

S.1.2.1. Retail Motor-Fuel Devices. – Deliveries shall be indicated and recorded, if the device is equipped 

to record, in liters or gallons and decimal subdivisions or fractional equivalents thereof.

(Added 1979)

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S.1.2.2. Agri-Chemical Liquid Devices.

S.1.2.2.1. Liquid Measure. – Deliveries shall be indicated and recorded in liters or gallons and 

decimal subdivisions or fractional equivalents thereof.

S.1.2.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded 

delivery if the device is equipped to record, shall not exceed the equivalent of:

(a) 0.5 L (0.1 gal) on devices with a maximum rated flow rate of 750 L/min (200 gal/min) or less;

(b) 5 L (1 gal) on devices with a maximum rated flow of more than 750 L/min (200 gal/min); or

(c) 5 L (1 gal) on meters with a rated maximum flow rate of 375 L/min (100 gal/min) or more used for 

jet fuel aviation refueling systems.

(Added 2007)

This requirement does not apply to manually operated devices equipped with stops or stroke-limiting means.

(Amended 1983, 1986, and 2007)

S.1.3. Advancement of Indicating and Recording Elements. – It shall not be possible to advance primary 

indicating and recording elements except by the mechanical operation of the device. Clearing a device by 

advancing its elements to zero is permitted, but only if:

(a) once started, the advancement movement cannot be stopped until zero is reached; and

(b) in the case of indicating elements only, such elements are automatically obscured until the elements 

reach the correct zero position.

S.1.4. Graduations.

S.1.4.1. Length. – Graduations shall be varied in length so that they may be conveniently read.

S.1.4.2. Width. – In a series of graduations, the width of:

(a) every graduation shall be at least 0.2 mm (0.008 in) but not greater than the minimum clear interval

between graduations; and

(b) main graduations shall be not more than 50 % greater than the width of subordinate graduations. 

S.1.4.3. Clear Interval Between Graduations. – The clear interval between graduations shall be not less 

than 1.0 mm (0.04 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of movement of the tip of the index of the indicator as it passes over the graduations; 

or

(b) if the indicator extends over the entire length of the graduations, at the point of widest separation of 

the graduations.

S.1.5. Indicators.

S.1.5.1. Symmetry. – The portion of the index of an indicator associated with the graduations shall be 

symmetrical with respect to the graduations.

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S.1.5.2. Length.

(a) If the indicator and the graduations are in different planes, the index of the indicator shall extend to 

each graduation with which it is to be used.

(b) If the indicator is in the same plane as the graduations, the distance between the index of the indicator 

and the ends of the graduations, measured along the line of the graduations, shall be not more than 

1.0 mm (0.04 in).

S.1.5.3. Width.

(a) The index of an indicator shall not be wider than the width of the narrowest graduation.

[Nonretroactive as of January 1, 2002]

(Amended 2000)

(b) If the index of an indicator extends over the entire length of a graduation, it shall be of uniform 

width throughout the portion that coincides with the graduation.

S.1.5.4. Clearance. – If the indicator and the graduations are in different planes, the clearance between 

the index of an indicator and the plane of the graduations shall be no greater than 1.5 mm (0.06 in).

S.1.5.5. Parallax. – Parallax effects shall be reduced to the practical minimum.

S.1.6. Additional Operating Requirements, Retail Devices (Except Slow-flow Meters).

S.1.6.1. Indication of Delivery. – The device shall automatically show on its face the initial zero condition 

and the quantity delivered (up to the nominal capacity). However, the following requirements shall apply:

For electronic devices manufactured prior to January 1, 2006, the first 0.03 L (or 0.009 gal) of a delivery and 

its associated total sales price need not be indicated.

For electronic devices manufactured on or after January 1, 2006, the measurement, indication of delivered

quantity, and the indication of total sales price shall be inhibited until the fueling position reaches conditions 

necessary to ensure that the delivery starts at zero.

[Nonretroactive as of January 1, 2006]

(Added 2005)

(Amended 1982 and 2005)

S.1.6.2. Provisions for Power Loss.

S.1.6.2.1. Transaction Information. – In the event of a power loss, the information needed to 

complete any transaction in progress at the time of the power loss (such as the quantity and unit price, 

or sales price) shall be determinable for at least 15 minutes at the dispenser or at the console if the 

console is accessible to the customer.

[Nonretroactive as of January 1, 1983]

S.1.6.2.2. User Information. – The device memory shall retain information on the quantity of fuel 

dispensed and the sales price totals during power loss.

[Nonretroactive as of January 1, 1983]

S.1.6.3. Return to Zero.

(a) The primary indicating elements, and primary recording elements if the device is equipped to record, 

shall be readily returnable to a definite zero indication. However, a key-lock operated or other 

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self-operated device may be equipped with cumulative indicating or recording elements, provided 

that it is also equipped with a zero-return indicating element.

(b) It shall not be possible to return primary indicating elements, or primary recording elements beyond 

the correct zero position.

(Amended 1972)

S.1.6.4. Display of Unit Price and Product Identity.

S.1.6.4.1. Unit Price.

(a) A computing or money-operated device shall be able to display on each face the unit price at 

which the device is set to compute or to dispense.

(b) Except for dispensers used exclusively for fleet sales, other price contract sales, and truck 

refueling (e.g., truck stop dispensers used only to refuel trucks), whenever a grade, brand, 

blend, or mixture is offered for sale from a device at more than one unit price, then all of the 

unit prices at which that product is offered for sale shall meet the following conditions:

(1) For a system that applies a discount prior to the delivery, all unit prices shall be displayed 

or shall be capable of being displayed on the dispenser through a deliberate action of the 

customer prior to the delivery of the product. It is not necessary that all of the unit prices 

for all grades, brands, blends, or mixtures be simultaneously displayed prior to the delivery 

of the product. 

[Effective and Nonretroactive as of January 1, 1991]

(2) For a system that offers post-delivery discounts on fuel sales, display of pre-delivery unit 

price information is exempt from (b)(1), provided the system complies with 

S.1.6.8. Recorded Representations for Transactions Where a Post-Delivery Discount(s) is 

Provided.

(Added 2012)

Note: When a product is offered at more than one unit price, display of the unit price information may be 

through the deliberate action of the customer: 1) using controls on the device; 2) through the customer’s 

use of personal or vehicle-mounted electronic equipment communicating with the system; or 3) verbal 

instructions by the customer.

(Added 2012)

(Amended 1989, 1997, and 2012) 

S.1.6.4.2. Product Identity.

(a) A device shall be able to conspicuously display on each side the identity of the product being 

dispensed.

(b) A device designed to dispense more than one grade, brand, blend, or mixture of product also 

shall be able to display on each side the identity of the grade, brand, blend, or mixture being 

dispensed.

S.1.6.5. Money-Value Computations.

(a) A computing device shall compute the total sales price at any single-purchase unit price

(i.e., excluding fleet sales, other price contract sales, and truck stop dispensers used only to refuel 

trucks) for which the product being measured is offered for sale at any delivery possible within 

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either the measurement range of the device or the range of the computing elements, whichever is 

less.

[Effective and Nonretroactive as of January 1, 1991]

(b) The analog sales price indicated for any delivered quantity shall not differ from a mathematically 

computed price (quantity × unit price = total sales price) by an amount greater than the value in 

Table 1. Money-Value Divisions and Maximum Allowable Variations for Money-Value 

Computations on Mechanical Analog Computers. 

(Amended 1984, 1989, and 1993)

S.1.6.5.1. Money-Value Divisions, Analog. – The values of the graduated intervals representing 

money values on a computing type device shall be no greater than those in Table 1. Money-Value 

Divisions and Maximum Allowable Variations for Money-Value Computations on Mechanical Analog 

Computers.

(Amended 1991)

Table 1.

Money-Value Divisions and

Maximum Allowable Variations for Money-Value

Computations on Mechanical Analog Computers

Unit Price

Money-Value

Division

Maximum

Allowable Variation

From To and including Design

Test

Field

Test

 0 $0.25/liter or

$1.00/gallon 1¢ ± 1¢ ± 1¢

$0.25/liter or

$1.00/gallon

$0.75/liter or

$3.00/gallon 1¢ or 2¢ ± 1¢ ± 2¢

$0.75/liter or

$3.00/gallon

$2.50/liter or

$10.00/gallon 1¢ or 2¢ ± 1¢ ± 2¢

 $0.75/liter or

$3.00/gallon

$2.50/liter or

$10.00/gallon 5¢ ± 21⁄2¢ ± 5¢

S.1.6.5.2. Money-Value Divisions, Digital. – A computing type device with digital indications shall 

comply with the requirements of paragraph G.S.5.5. Money-Values, Mathematical Agreement, and the 

total price computation shall be based on quantities not exceeding 0.05 L for devices indicating in metric 

units and 0.01 gal intervals for devices indicating in U.S. customary units.

(Added 1980)

S.1.6.5.3. Auxiliary Elements. – If a system is equipped with auxiliary indications, all indicated 

money-value divisions of the auxiliary element shall be identical with those of the primary element.

[Nonretroactive and Enforceable as of January 1, 1985]

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S.1.6.5.4. Selection of Unit Price. – A system shall not permit a change to the unit price during 

delivery of product. When a product or grade is offered for sale at more than one unit price through a 

computing device, the following conditions shall be met: 

(a) Except for a system only capable of applying a post-delivery discount(s), the selection of the 

unit price shall be made prior to delivery through a deliberate action of the customer to select 

the unit price for the fuel delivery. 

 [Nonretroactive as of January 1, 1991]

(b) For a system only capable of applying a post-delivery discount(s), the selection of the unit price 

shall be made through a deliberate action of the customer to select the unit price for the fuel 

delivery. 

(Added 2012)

Note: When a product is offered at more than one unit price, selection of the unit price may be through the deliberate 

action of the customer: 1) using controls on the device; 2) through the customer’s use of personal or vehiclemounted electronic equipment communicating with the system; or 3) verbal instructions by the customer. 

 (Added 2012)

The provisions in (a) and (b) do not apply to dispensers used exclusively for fleet sales, other price 

contract sales, and truck refueling (e.g., truck stop dispensers used only to refuel trucks).

(Added 1989) (Amended 1991, 1992, 1993, 1996, and 2012)

S.1.6.5.5. Display of Quantity and Total Price. – Except for aviation refueling applications, when a 

delivery is completed, the total price and quantity for that transaction shall be displayed on the face of 

the dispenser for at least five minutes or until the next transaction is initiated by using controls on the 

device or other customer-activated controls.

[Nonretroactive as of January 1, 1994]

(Added 1992) (Amended 1996 and 2007)

S.1.6.5.6. Display of Quantity and Total Price, Aviation Refueling Applications.

(a) The quantity shall be displayed throughout the transaction.

(b) The total price shall also be displayed under one of the following conditions:

(1) The total price can appear on the face of the dispenser or through a controller adjacent to 

the device.

(2) If a device is designed to continuously compute and display the total price, then the total 

price shall be computed and displayed throughout the transaction for the quantity delivered.

(c) The total price and quantity shall be displayed for at least five minutes or until the next 

transaction is initiated by using controls on the device or other customer-activated controls.

(d) A printed receipt shall be available and shall include, at a minimum, the total price, quantity, 

and unit price.

[Nonretroactive as of January 1, 2008]

(Added 2007)

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S.1.6.6. Agreement Between Indications. 

(a) When a quantity value indicated or recorded by an auxiliary element is a derived or computed value 

based on data received from a retail motor fuel dispenser, the value may differ from the quantity 

value displayed on the dispenser, provided the following conditions are met:

(1) all total money-values for an individual sale that are indicated or recorded by the system 

agree; and

(2) within each element, the values indicated or recorded meet the formula (quantity × unit price = 

total sales price) to the closest cent.

[Nonretroactive as of January 1, 1988]

(b) When a system applies a post-delivery discount(s) to a fuel’s unit price through an auxiliary element, 

the following conditions shall apply for computed values: 

(1) the total volume of the delivery shall be in agreement between all elements in the system.

(Added 2012)

(Added 1985) (Amended 1987, 1988, and 2012) 

S.1.6.7. Recorded Representations. – Except for fleet sales and other price contract sales and for 

transactions where a post-delivery discount is provided, a printed receipt providing the following information 

shall be available through a built-in or separate recording element for all transactions conducted with pointof-sale systems or devices activated by debit cards, credit cards, and/or cash:

(a) the total volume of the delivery;

(b) the unit price;

(c) the total computed price; and

(d) the product identity by name, symbol, abbreviation, or code number.

[Nonretroactive as of January 1, 1986]

(Added 1985) (Amended 1997, 2012, and 2014) 

S.1.6.8. Recorded Representations for Transactions Where a Post-Delivery Discount(s) is Provided.

– Except for fleet sales and other price contract sales, a printed receipt providing the following information 

shall be available through a built-in or separate recording element that is part of the system for transactions 

involving a post-delivery discount:

(a) the product identity by name, symbol, abbreviation, or code number;

(b) transaction information as shown on the dispenser at the end of the delivery and prior to any postdelivery discount(s), including the: 

(1) total volume of the delivery; 

(2) unit price; and 

(3) total computed price of the fuel sale. 

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(c) an itemization of the post-delivery discounts to the unit price; and

(d) the final total price of the fuel sale after all post-delivery discounts are applied.

(Added 2012) (Amended 2014)

S.1.6.9. Lubricant Devices, Travel of Indicator. – The indicator shall move at least 2.5 cm (1 in) in 

relation to the graduations, if provided, for a delivery of 0.5 L (1 pt). 

S.1.7. Additional Operating Requirements, Wholesale Devices Only.

S.1.7.1. Travel of Indicator. – A wholesale device shall be readily operable to deliver accurately any 

quantity from 200 L (50 gal) to the capacity of the device. If the most sensitive element of the indicating 

system utilizes an indicator and graduations, the relative movement of these parts corresponding to a delivery 

of 4 L (1 gal) shall be not less than 5 mm (0.20 in).

(Amended 1987)

S.1.7.2. Money-Values – Mathematical Agreement. – Any digital money-value indication and any 

recorded money-value on a computing-type device shall be in mathematical agreement with its associated 

quantity indication or representation to within 1 cent of money-value.

S.2. Measuring Elements.

S.2.1. Vapor Elimination.

(a) A liquid-measuring device shall be equipped with a vapor or air eliminator or other automatic means to 

prevent the passage of vapor and air through the meter.

(b) Vent lines from the air or vapor eliminator shall be made of metal tubing or other rigid material.

(Amended 1975)

S.2.1.1. Vapor Elimination on Loading Rack Metering Systems.

(a) A loading rack metering system shall be equipped with a vapor or air eliminator or other automatic

means to prevent the passage of vapor and air through the meter unless the system is designed or 

operationally controlled by a method, approved by the weights and measures jurisdiction having 

control over the device, such that air and/or vapor cannot enter the system.

(b) Vent lines from the air or vapor eliminator (if present) shall be made of metal tubing or other rigid 

material.

(Added 1994)

S.2.2. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or for physically applying a security seal in such a manner that requires the security seal to be 

broken before an adjustment or interchange can be made of:

(a) any measuring or indicating element;

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries; and

(c) any metrological parameter that will affect the metrological integrity of the device or system.

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When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal. 

[Audit trails shall use the format set forth in Table S.2.2.]* 

[*Nonretroactive and Enforceable as of January 1, 1995]

(Amended 1991, 1993, 1995, and 2006)

Table S.2.2. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for 

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but access 

is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

[The hardware enabling access for remote communication 

must be on-site. The hardware must be sealed using a 

physical seal or an event counter for calibration 

parameters and an event counter for configuration 

parameters. The event counters may be located either at 

the individual measuring device or at the system 

controller; however, an adequate number of counters must 

be provided to monitor the calibration and configuration 

parameters of the individual devices at a location. If the 

counters are located in the system controller rather than 

at the individual device, means must be provided to 

generate a hard copy of the information through an onsite device.]*

[*Nonretroactive as of January 1, 1996]

Category 3: Remote configuration capability access may 

be unlimited or controlled through a software switch (e.g., 

password). 

[Nonretroactive as of January 1, 1995]

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

[Nonretroactive as of January 1, 2001]

An event logger is required in the device; it must include 

an event counter (000 to 999), the parameter ID, the date 

and time of the change, and the new value of the 

parameter. A printed copy of the information must be 

available on demand through the device or through 

another on-site device. The information may also be 

available electronically. The event logger shall have a 

capacity to retain records equal to 10 times the number of 

sealable parameters in the device, but not more than 1000 

records are required. (Note: Does not require 1000 

changes to be stored for each parameter.)

[Nonretroactive as of January 1, 1995]

(Table Added 1993) (Amended 1995, 1998, 1999, 2006, and 2015)

S.2.3. Directional Flow Valves. – Valves intended to prevent reversal of flow shall be automatic in operation.

S.2.4. Stop Mechanism.

S.2.4.1. Indication. – The delivery for which the device is set shall be conspicuously indicated.

(Amended 1983)

S.2.4.2. Stroke Limiting Elements. – Stops or other stroke limiting elements subject to direct pressure or 

impact shall be:

(a) made secure by positive, nonfrictional engagement of these elements; and

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(b) adjustable to provide for deliveries within tolerances.

(Amended 1983)

S.2.4.3. Setting. – If two or more stops or other elements may be selectively brought into operation to 

permit predetermined quantities of deliveries:

(a) the position for the proper setting of each such element shall be accurately defined; and

(b) any inadvertent displacement from the proper setting shall be obstructed.

(Amended 1983)

S.2.5. Zero-Set-Back Interlock, Retail Motor-Fuel Devices. – A device shall be constructed so that:

(a) after a delivery cycle has been completed by moving the starting lever to any position that shuts off the 

device, an automatic interlock prevents a subsequent delivery until the indicating elements, and 

recording elements if the device is equipped and activated to record, have been returned to their zero 

positions;

(b) the discharge nozzle cannot be returned to its designed hanging position (that is, any position where the 

tip of the nozzle is placed in its designed receptacle and the lock can be inserted) until the starting lever 

is in its designed shut-off position and the zero-set-back interlock has been engaged; and

(c) in a system with more than one dispenser supplied by a single pump, an effective automatic control valve 

in each dispenser prevents product from being delivered until the indicating elements on that dispenser 

are in a correct zero position.

(Amended 1981 and 1985)

S.2.6. Temperature Determination – Wholesale Devices. – For test purposes, means shall be provided 

(e.g., thermometer well) to determine the temperature of the liquid either:

(a) in the liquid chamber of the meter; or

(b) in the meter inlet or discharge line immediately adjacent to the meter.

[Nonretroactive as of January 1, 1985]

(Added 1984) (Amended 1986)

S.2.7. Wholesale Devices Equipped with Automatic Temperature Compensators. 

S.2.7.1. Automatic Temperature Compensation. – A device may be equipped with an automatic means 

for adjusting the indication and registration of the measured volume of product to the volume at 15 °C (60 °F).

S.2.7.2. Provision for Deactivating. – On a device equipped with an automatic temperaturecompensating mechanism that will indicate or record only in terms of gallons compensated to 15 °C (60 °F), 

provision shall be made for deactivating the automatic temperature-compensating mechanism so that the 

meter can indicate and record, if it is equipped to record, in terms of the uncompensated volume.

(Amended 1972)

S.2.7.3. Provision for Sealing Automatic Temperature-Compensating Systems. – Provision shall be 

made for applying security seals in such a manner that an automatic temperature-compensating system cannot 

be disconnected and that no adjustment may be made to the system without breaking the seal.

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S.2.7.4. Temperature Determination with Automatic Temperature-Compensation. – For test 

purposes, means shall be provided (e.g., thermometer well) to determine the temperature of the liquid either:

(a) in the liquid chamber of the meter; or

(b) immediately adjacent to the meter in the meter inlet or discharge line.

(Amended 1987)

S.2.8. Exhaustion of Supply, Lubricant Devices Other than Meter Types. – When the level of the supply 

of lubricant becomes so low as to compromise the accuracy of measurement, the device shall:

(a) automatically become inoperable; or

(b) give a conspicuous and distinct warning.

S.3. Discharge Lines and Valves.

S.3.1. Diversion of Measured Liquid. – No means shall be provided by which any measured liquid can be 

diverted from the measuring chamber of the meter or its discharge line. Two or more delivery outlets may be 

installed only if automatic means are provided to ensure that:

(a) liquid can flow from only one outlet at a time; and

(b) the direction of flow for which the mechanism may be set at any time is clearly and conspicuously 

indicated. 

An outlet that may be opened for purging or draining the measuring system or for recirculating, if recirculation is 

required in order to maintain the product in a deliverable state, shall be permitted only when the system is 

measuring food products, agri-chemicals, biodiesel, or biodiesel blends. Effective automatic means shall be 

provided to prevent passage of liquid through any such outlet during normal operation of the measuring system 

and to inhibit meter indications (or advancement of indications) and recorded representations while the outlet is 

in operation.

(Amended 1991, 1995, 1996, and 2007)

S.3.2. Exceptions. – The provisions of S.3.1. Diversion of Measured Liquid shall not apply to truck refueling

devices when diversion of flow to other than the receiving vehicle cannot readily be accomplished and is readily 

apparent. Allowable deterrents include, but are not limited to, physical barriers to adjacent driveways, visible 

valves, or lighting systems that indicate which outlets are in operation, and explanatory signs.

(Amended 1982, 1990, 1991, and 2002)

S.3.3. Pump-Discharge Unit. – A pump-discharge unit equipped with a flexible discharge hose shall be of the 

wet-hose type.

S.3.4. Gravity-Discharge Unit. – On a gravity-discharge unit: 

(a) the discharge hose or equivalent pipe shall be of the dry-hose type with no shutoff valve at its outlet end 

unless the hose or pipe drains to the same level under all conditions of use;

(b) the dry-hose shall be sufficiently stiff and only as long as necessary to facilitate drainage;

(c) an automatic vacuum breaker, or equivalent mechanism, shall be incorporated to prevent siphoning and 

to ensure rapid and complete drainage; and

(d) the inlet end of the hose or outlet pipe shall be high enough to ensure complete drainage.

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S.3.5. Discharge Hose, Reinforcement. – A discharge hose shall be reinforced so that the performance of the 

device is not affected by the expansion or contraction of the hose.

S.3.6. Discharge Valve. – A discharge valve may be installed in the discharge line only if the device is of the 

wet-hose type. Any other shutoff valve on the discharge side of the meter shall be of the automatic or 

semiautomatic predetermined-stop type or shall be operable only:

(a) by means of a tool (but not a pin) entirely separate from the device; or

(b) by mutilation of a security seal with which the valve is sealed open.

S.3.7. Anti-drain Means. – In a wet-hose pressure-type device, means shall be incorporated to prevent the 

drainage of the discharge hose. 

(Amended 1990)

S.4. Marking Requirements.

S.4.1. Limitation on Use. – The limitations on its use shall be clearly and permanently marked on any device 

intended to measure accurately only:

(a) products having particular properties; 

(b) under specific installation or operating conditions; or

(c) when used in conjunction with specific accessory equipment.

S.4.2. Air Pressure. – If a device is operated by air pressure, the air pressure gauge shall show by special 

graduations or other means the maximum and minimum working pressures recommended by the manufacturer.

S.4.3. Wholesale Devices.

S.4.3.1. Discharge Rates. – A wholesale device shall be marked to show its designed maximum and 

minimum discharge rates. However, the minimum discharge rate shall not exceed 20 % of the maximum 

discharge rate.

S.4.3.2. Temperature Compensation. – If a device is equipped with an automatic temperature 

compensation, the primary indicating elements, recording elements, and recorded representation shall be 

clearly and conspicuously marked to show that the volume delivered has been adjusted to the volume at 15 °C 

(60 °F).

S.4.4. Retail Devices.

S.4.4.1. Discharge Rates. – On a retail device with a designed maximum discharge rate of 115 L (30 gal) 

per minute or greater, the maximum and minimum discharge rates shall be marked in accordance with 

S.4.4.2. Location of Marking Information; Retail Motor-Fuel Dispensers. The marked minimum discharge 

rate shall not exceed 20 % of the marked maximum discharge rate.

[Nonretroactive as of January 1, 1985]

(Added 1984) (Amended 2003)

Example: With a marked maximum discharge rate of 230 L/min (60 gpm), the marked minimum discharge 

rate shall be 45 L/min (12 gpm) or less (e.g., 40 L/min [10 gpm] is acceptable). A marked minimum 

discharge rate greater than 45 L/min (12 gpm) (e.g., 60 L/min [15 gpm]) is not acceptable.

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S.4.4.2. Location of Marking Information; Retail Motor-Fuel Dispensers. – The marking information 

required in the General Code, paragraph G-S.1. Identification shall appear as follows:

(a) within 60 cm (24 in) to 150 cm (60 in) from the base of the dispenser;

(b) either internally and/or externally provided the information is permanent and easily read; and

(c) on a portion of the device that cannot be readily removed or interchanged (i.e., not on a service 

access panel).

Note: The use of a dispenser key or tool to access internal marking information is permitted for retail liquidmeasuring devices.

[Nonretroactive as of January 1, 2003]

(Added 2002) (Amended 2004)

S.5. Totalizers for Retail Motor-Fuel Dispensers. – Retail motor-fuel dispensers shall be equipped with a nonresettable totalizer for the quantity delivered through the metering device.

[Nonretroactive as of January 1, 1995]

(Added 1993) (Amended 1994)

N. Notes

N.1. Test Liquid.

N.1.1. Type of Liquid. – The liquid used for testing a liquid-measuring device shall be the type the device is 

used to measure, or another liquid with the same general physical characteristics.

N.1.2. Labeling. – Following the completion of a successful examination of a wholesale device, the weights 

and measures official should attach a label or tag indicating the type of liquid used during the test.

N.2. Volume Change. – Care shall be taken to minimize changes in volume of the test liquid due to temperature 

changes and evaporation losses.

N.3. Test Drafts.

N.3.1. Retail Piston-Type and Visible-Type Devices. – Test drafts shall include the full capacity delivery and 

each intermediate delivery for which the device is designed.

N.3.2. Slow-flow Meters. – Test drafts shall be equal to at least four times the minimum volume that can be 

measured and indicated through either a visible indication or an audible signal.

N.3.3. Lubricant Devices. – Test drafts shall be 1 L (1 qt). Additional test drafts may include 0.5 L (1 pt), 4 L 

(4 qt), and 6 L (6 qt).

N.3.4. Other Retail Devices. – On devices with a designed maximum discharge rate of:

(a) less than 80 L (20 gal) per minute, tests shall include drafts of one or more amounts, including a draft of 

at least 19 L (5 gal).

(b) 80 L (20 gal) per minute or greater, tests shall include drafts of one or more amounts, including a draft 

of at least the amount delivered by the device in one minute at the maximum flow rate of the installation.

(Amended 1984)

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N.3.5. Wholesale Devices. – The delivered quantity should be equal to at least the amount delivered by the 

device in one minute at its maximum discharge rate, and shall in no case be less than 200 L (50 gal).

(Amended 1987 and 1996)

N.4. Testing Procedures.

N.4.1. Normal Tests. – The “normal” test of a device shall be made at the maximum discharge flow rate 

developed under the conditions of installation. Any additional tests conducted at flow rates down to and including 

one-half of the sum of the maximum discharge flow rate and the rated minimum discharge flow rate shall be 

considered normal tests.

(Amended 1991)

N.4.1.1. Wholesale Devices Equipped with Automatic Temperature-Compensating Systems. – On 

wholesale devices equipped with automatic temperature-compensating systems, normal tests shall be 

conducted:

(a) by comparing the compensated volume indicated or recorded to the actual delivered volume 

corrected to 15 °C (60 °F); and

(b) with the temperature-compensating system deactivated, comparing the uncompensated volume 

indicated or recorded to the actual delivered volume.

The first test shall be performed with the automatic temperature-compensating system operating in the “as 

found” condition.

On devices that indicate or record both the compensated and uncompensated volume for each delivery, the 

tests in (a) and (b) may be performed as a single test.

(Amended 1987)

N.4.1.2. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2001)

N.4.2. Special Tests. – “Special” tests shall be made to develop the operating characteristics of a device and 

any special elements and accessories attached to or associated with the device. Any test except as set forth in 

N.4.1. Normal Tests shall be considered a special test.

N.4.2.1. Slow-Flow Meters. – A “special” test shall be made at a flow rate:

(a) not larger than twice the actual minimum flow rate; and

(b) not smaller than the actual minimum flow rate of the installation.

N.4.2.2. Retail Motor-Fuel Devices.

(a) Devices without a marked minimum flow-rate shall have a “special” test performed at the slower of 

the following rates:

(1) 19 L (5 gal) per minute; or

(2) the minimum discharge rate at which the device will deliver when equipped with an automatic

discharge nozzle set at its slowest setting.

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(b) Devices with a marked minimum flow-rate shall have a “special” test performed at or near the 

marked minimum flow rate.

(Added 1984) (Amended 2005)

N.4.2.3. Other Retail Devices. – “Special” tests of other retail devices shall be made at the slower of the 

following rates:

(a) 50 % of the maximum discharge rate developed under the conditions of installation; or

(b) the minimum discharge rate marked on the device.

N.4.2.4. Wholesale Devices. – “Special” tests shall be made to develop the operating characteristics of a 

measuring system and any special associated or attached elements and accessories. “Special” tests shall 

include a test at or slightly above the slower of the following rates:

(a) 20 % of the marked maximum discharge rate; or

(b) the minimum discharge rate marked on the device.

In no case shall the test be performed at a flow rate less than the minimum discharge rate marked on the 

device.

(Amended 2014)

N.4.3. Money-Value Computation Tests.

N.4.3.1. Laboratory Tests. – When testing the device in the laboratory:

(a) compliance with paragraph S.1.6.5. Money-Value Computations, shall be determined by using the 

cone gear as a reference for the total quantity delivered;

(b) the indicated quantity shall agree with the cone gear representation with the index of the indicator 

within the width of the graduation; and

(c) the maximum allowable variation of the indicated sales price shall be as shown in Table 1. MoneyValue Divisions and Maximum Allowable Variations for Money-Value Computations on 

Mechanical Analog Computers.

(Amended 1984)

N.4.3.2. Field Tests. – In the conduct of field tests to determine compliance with 

paragraph S.1.6.5. Money-Value Computations, the maximum allowable variation in the indicated sales price 

shall be as shown in Table 1. Money-Value Divisions and Maximum Allowable Variations for Money-Value 

Computations on Mechanical Analog Computers. 

(Added 1982) (Amended 1984)

N.4.4. Pour and Drain Times.

N.4.4.1. Pour and Drain Times for Hand-held Test Measures. – Hand-held test measures require a 

30-second (± 5 seconds) pour followed by a 10-second drain with the measure held at a 10-degree to 

15-degree angle from vertical.

N.4.4.2. Drain Times for Bottom Drain Test Measures or Provers. – Bottom drain field standard 

provers require a 30-second drain time after main flow cessation.

(Added 2009)

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N.5. Temperature Correction on Wholesale Devices. – Corrections shall be made for any changes in volume 

resulting from the differences in liquid temperatures between time of passage through the meter and time of volumetric 

determination in the prover. When adjustments are necessary, appropriate petroleum measurement tables should be 

used.

(Amended 1974)

T. Tolerances

T.1. Application to Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be 

applied to errors of underregistration and errors of overregistration, whether or not a device is equipped with an 

automatic temperature compensator.

T.2. Tolerance Values. – Maintenance, acceptance, and special test tolerances shall be as shown in 

Table T.2. Accuracy Classes and Tolerances for Liquid Measuring Devices Covered in NIST Handbook 44, 

Section 3.30.

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Table T.2. 

Accuracy Classes and Tolerances for Liquid Measuring Devices Covered in

NIST Handbook 44, Section 3.30.

Accuracy 

Class Application

Acceptance

Tolerance

Maintenance

Tolerance

Special Test 

Tolerance1 

0.3

- Petroleum products delivered from large capacity 

(flow rates greater than 115 L/min or 30 gpm)** 

devices, including motor-fuel devices

- Heated products (other than asphalt) at temperatures 

greater than 50 °C (122 °F)

- Asphalt at temperatures equal to or below 50 °C

(122 °F)

- All other liquids not shown in the table where the 

typical delivery is over 200 L (50 gal)

0.2 % 0.3 % 0.5 %

0.3A - Asphalt at temperatures greater than 50 °C (122 °F) 0.3 % 0.3 % 0.5 %

0.5*

- Petroleum products delivered from small capacity 

(at 4 L/min (1 gpm) through 115 L/min or 

30 gpm)** motor-fuel devices

- Agri-chemical liquids

- All other applications not shown in the table where 

the typical delivery is ≤ 200 L (50 gal)

0.3 % 0.5 % 0.5 %

1.1

- Petroleum products and other normal liquids from 

devices with flow rates** less than 1 gpm.

- Devices designed to deliver less than 1 gal

0.75 % 1.0 % 1.25 %

* For test drafts ≤ 40 L or 10 gal, the tolerances specified for Accuracy Class 0.5 in the table above do not apply. 

For these test drafts, the following applies:

(a) Maintenance tolerances on normal and special tests shall be 20 mL plus 4 mL per indicated liter or 1 in3 plus 

1 in3 per indicated gallon.

(b) Acceptance tolerances on normal and special tests shall be one-half the maintenance tolerance values.

1 Special test tolerances are not applicable to retail motor fuel dispensers.

** Flow rate refers to designed or marked maximum flow rate.

(Added 2002) (Amended 2006 and 2013)

T.3. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within the applicable tolerance. This tolerance does not apply to the test of the 

automatic temperature-compensating system. (Also see N.4.1.2. Repeatability Tests.) 

(Added 1992) (Amended 2001 and 2002)

T.4. Automatic Temperature-Compensating Systems. – The difference between the meter error (expressed as a 

percentage) for results determined with and without the automatic temperature-compensating system activated shall 

not exceed:

(a) 0.2 % for mechanical automatic temperature-compensating systems; and

(b) 0.1 % for electronic automatic temperature-compensating systems.

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The delivered quantities for each test shall be approximately the same size. The results of each test shall be within 

the applicable acceptance or maintenance tolerance.

[Nonretroactive as of January 1, 1988]

(Added 1987) (Amended 1992, 1996, and 2002)

UR. User Requirements

UR.1. Selection Requirements.

UR.1.1. Discharge Hose.

UR.1.1.1. Length. – The length of the discharge hose on a retail motor-fuel device:

(a) shall be measured from its housing or outlet of the discharge line to the inlet of the discharge nozzle;

(b) shall be measured with the hose fully extended if it is coiled or otherwise retained or connected 

inside a housing; and

(c) shall not exceed 5.5 m (18 ft) unless it can be demonstrated that a longer hose is essential to permit 

deliveries to be made to receiving vehicles or vessels.

An unnecessarily remote location of a device shall not be accepted as justification for an abnormally long 

hose.

(Amended 1972 and 1987)

UR.1.1.2. Marinas and Airports.

UR.1.1.2.1. Length. – The length of the discharge hose shall be as short as practicable, and shall not 

exceed 15 m (50 ft) unless it can be demonstrated that a longer hose is essential.

UR.1.1.2.2. Protection. – Discharge hoses exceeding 8 m (26 ft) in length shall be adequately 

protected from weather and other environmental factors when not in use.

(Made retroactive 1974 and Amended 1984)

UR.2. Installation Requirements.

UR.2.1. Manufacturer’s Instructions. – A device shall be installed in accordance with the manufacturer’s 

instructions, and the installation shall be sufficiently secure and rigid to maintain this condition.

(Added 1987)

UR.2.2. Discharge Rate. – A device shall be installed so that the actual maximum discharge rate will not 

exceed the rated maximum discharge rate. Automatic means for flow regulation shall be incorporated in the 

installation if necessary.

UR.2.3. Suction Head. – A piston-type device shall be installed so that the total effective suction head will 

not be great enough to cause vaporization of the liquid being dispensed under the highest temperature and lowest 

barometric pressure likely to occur.

UR.2.4. Diversion of Liquid Flow. – A motor-fuel device equipped with two delivery outlets used exclusively 

in the fueling of trucks shall be so installed that any diversion of flow to other than the receiving vehicle cannot be 

readily accomplished and is readily apparent. Allowable deterrents include, but are not limited to, physical barriers 

to adjacent driveways, visible valves, or lighting systems that indicate which outlets are in operation, and explanatory 

signs.

(Amended 1991)

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UR.2.5. Product Storage Identification.

(a) The fill connection for any petroleum product storage tank or vessel supplying motor-fuel devices shall 

be permanently, plainly, and visibly marked as to product contained.

(b) When the fill connection device is marked by means of a color code, the color code key shall be 

conspicuously displayed at the place of business.

(Added 1975) (Amended 1976)

UR.3. Use of Device.

UR.3.1. Return of Indicating and Recording Elements to Zero. – On any dispenser used in making retail 

deliveries, the primary indicating element, and recording element if so equipped, shall be returned to zero before 

each delivery.

Exceptions to this requirement are totalizers on key-lock-operated or other self-operated dispensers and the 

primary recording element if the device is equipped to record.

UR.3.2. Unit Price and Product Identity.

(a) The following information shall be conspicuously displayed or posted on the face of a retail dispenser 

used in direct sale:

(1) except for unit prices resulting from any post-delivery discount and dispensers used exclusively for 

fleet sales, other price contract sales, and truck refueling (e.g., truck stop dispensers used only to 

refuel trucks), all of the unit prices at which the product is offered for sale; and

(2) in the case of a computing type or money-operated type, the unit price at which the dispenser is set 

to compute. 

Provided that the dispenser complies with S.1.6.4.1. Display of Unit Price, it is not necessary that all the unit 

prices for all grades, brands, blends, or mixtures be simultaneously displayed or posted.

(b) The following information shall be conspicuously displayed or posted on each side of a retail dispenser 

used in direct sale:

(1) the identity of the product in descriptive commercial terms; and

(2) the identity of the grade, brand, blend, or mixture that a multi-product dispenser is set to deliver.

(Amended 1972, 1983, 1987, 1989, 1992, 1993, and 2012) 

UR.3.3. Computing Device. – Any computing device used in an application where a product or grade is 

offered for sale at one or more unit prices shall be used only for sales for which the device computes and displays 

the sales price for the selected transaction.

(Became retroactive 1999)

(Added 1989) (Amended 1992)

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The following exceptions apply:

(a) Fleet sales and other price contract sales are exempt from this requirement.

(b) A truck stop dispenser used exclusively for refueling trucks is exempt from this requirement provided 

that:

(1) all purchases of fuel are accompanied by a printed receipt of the transaction containing the 

applicable price per gallon, the total gallons delivered, and the total price of the sale; and

(Added 1993)

(2) unless a dispenser complies with S.1.6.4.1. Display of Unit Price, the price posted on the dispenser 

and the price at which the dispenser is set to compute shall be the highest price for any transaction 

which may be conducted.

(Added 1993)

(c) A dispenser used in an application where a price per unit discount is offered following the delivery is 

exempt from this requirement, provided the following conditions are satisfied:

(1) the unit price posted on the dispenser and the unit price at which the dispenser is set to compute 

prior to the application of any discount shall be the highest unit price for any transaction; 

(Amended 2014)

(2) all purchases of fuel are accompanied by a receipt recorded by the system. The receipt shall contain:

a. the product identity by name, symbol, abbreviation, or code number; 

b. transaction information as shown on the dispenser at the end of the delivery and prior to any 

post-delivery discount including the:

1. total volume of the delivery; 

2. unit price; and 

3. total computed price of the fuel sale prior to post-delivery discounts being applied. 

c. an itemization of the post-delivery discounts to the unit price; and 

d. the final total price of the fuel sale.

(Added 2012) (Amended 2014)

(Added 1989) (Amended 1992, 1993, 2012, and 2014) 

UR.3.4. Printed Ticket. – The total price, the total volume of the delivery, and the price per liter or gallon 

shall be shown, either printed by the device or in clear hand script, on any printed ticket issued by a device and 

containing any one of these values.

(Amended 2001)

UR.3.5. Steps after Dispensing. – After delivery to a customer from a retail motor-fuel device: 

(a) the starting lever shall be returned to its shutoff position and the zero-set-back interlock engaged; and

(b) the discharge nozzle shall be returned to its designed hanging position unless the primary indicating 

elements, and recording elements, if the device is equipped and activated to record, have been returned 

to a definite zero indication.

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UR.3.6. Temperature Compensation, Wholesale.

UR.3.6.1. Automatic.

UR.3.6.1.1. When to be Used. – If a device is equipped with a mechanical automatic temperature 

compensator, it shall be connected, operable, and in use at all times. An electronic or mechanical 

automatic temperature-compensating system may not be removed, nor may a compensated device be 

replaced with an uncompensated device, without the written approval of the responsible weights and 

measures jurisdiction.

Note: This requirement does not specify the method of sale for product measured through a meter.

(Amended 1989)

UR.3.6.1.2. Invoices.

(a) A written invoice based on a reading of a device that is equipped with an automatic temperature 

compensator shall show that the volume delivered has been adjusted to the volume at 15 °C 

(60 °F).

(b) The invoice issued from an electronic wholesale device equipped with an automatic

temperature-compensating system shall also indicate: 

(1) the API gravity, specific gravity or coefficient of expansion for the product; 

(2) product temperature; and 

(3) gross reading.

(Amended 1987)

UR.3.6.2. Nonautomatic.

UR.3.6.2.1. Temperature Determination. – If the volume of the product delivered is adjusted to the 

volume at 15 °C (60 °F), the product temperature shall be taken during the delivery in:

(a) the liquid chamber of the meter; or

(b) the meter inlet or discharge line adjacent to the meter; or

(c) the compartment of the receiving vehicle at the time it is loaded.

UR.3.6.2.2. Invoices. – The accompanying invoice shall indicate that the volume of the product has 

been adjusted for temperature variations to a volume at 15 °C (60 °F) and shall also state the product 

temperature used in making the adjustment.

UR.3.6.3. Period of Use. – When fuel is bought or sold on an automatic or non-automatic

temperature-compensated basis, it shall be bought or sold using this method over at least a consecutive 

12-month period, unless otherwise agreed to by both the buyer and seller in writing.

(Added 2003)

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Liquid-Measuring Device Code Index

Acceptance ..................................................20, 21, 22

Adjustable element ..................................................12

Advancement............................................................. 6 

Agreement .....................................................9, 11, 12

Agri-chemical ..................................................5, 6, 21

Antidrain means.......................................................16

Automatic .......... 12, 13, 14, 15, 16, 18, 20, 21, 22, 25

Automatic temperature compensation ...............14, 15

Automatic temperature compensators .........14, 16, 25

Automatic temperature-compensating systems 14, 18, 

21

Auxiliary elements..................................................... 9 

Blend ................................................................... 8, 23

Clear interval ............................................................. 6 

Clearance ................................................................... 7 

Computing device..........................................8, 10, 23

Directional flow valves............................................13

Discharge hose.............................................15, 16, 22

Discharge lines ........................................................15

Discharge rate..................................16, 17, 18, 19, 22

Diversion ................................................................. 22

Dry-hose ..................................................................15

Fleet sales ................................................8, 10, 11, 23

Grade ............................................................. 8, 10, 23

Graduations................................................ 6, 7, 12, 16

Gravity-discharge unit .............................................15

Index of an indicator..............................................6, 7

Indicating element ...........................................6, 8, 14

Indicators................................................................... 6 

Installation requirements .........................................22

Interlock...................................................................14

Invoices....................................................................25

Key-lock ..............................................................7, 23

Lubricant devices.........................................12, 15, 17

Maintenance ................................................20, 21, 22

Marking requirements..............................................16

Mass........................................................................... 5 

Mass flow meters....................................................... 5

Measuring element ..................................................12

Money value computation .......................................19

Money value divisions............................................... 9 

Money values - mathematical agreement ................12

Money-value computation................................... 8, 19

Money-value divisions .............................................. 9 

Motor-fuel device ........................................21, 22, 23

Nonautomatic ..........................................................25

Normal tests.............................................................18

Operating requirements ....................................... 7, 12

Parallax...................................................................... 7 

Power loss.................................................................. 7 

Price contract sales ..................................8, 10, 11, 23

Primary indicating element..............5, 7, 8, 16, 23, 24

Printed ticket............................................................24

Product identity ............................................. 8, 11, 23

Pump-discharge unit................................................15

Quantity ...................................7, 9, 11, 12, 17, 18, 19

Recording element...........5, 6, 7, 8, 11, 14, 16, 23, 24

Repeatability......................................................18, 21

Retail devices........................................... 7, 16, 17, 19

Retail motor-fuel device .................... 5, 14, 18, 22, 24

Retail motor-fuel dispensers....................................17

Seal ..............................................................13, 14, 16

Sealing .........................................................12, 13, 14

Security..................................................12, 13, 14, 16

Slow-flow meters........................................... 7, 17, 18

Special tests.............................................................18

Stop mechanism.......................................................13

Temperature compensation................................15, 16

Temperature compensators..........................14, 16, 25

Temperature correction............................................20

Temperature determination..........................14, 15, 25

Temperature-compensating systems............14, 18, 21

Test drafts....................................................17, 18, 21

Tolerances..........................................................14, 20

Total price............................................................9, 24

Totalizers...........................................................17, 23

Truck refueling ............................................10, 15, 23

Unit price ................................... 7, 8, 9, 10, 11, 23, 24

User information........................................................ 7 

Valves..........................................................13, 15, 22

Vapor elimination....................................................12

Wet-hose............................................................15, 16

Wholesale devices ...........5, 12, 14, 16, 18, 19, 20, 25

Zero-set-back interlock......................................14, 24

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Table of Contents

Section 3.31. Vehicle-Tank Meters ....................................................................................... 3-31

A. Application .................................................................................................................................................. 3-31

A.1. General................................................................................................................................................3-31

A.2. Exceptions...........................................................................................................................................3-31

A.3. Additional Code Requirements...........................................................................................................3-31

S. Specifications............................................................................................................................................... 3-31

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-31

S.1.1. Primary Elements..................................................................................................................3-31

S.1.2. Graduations...........................................................................................................................3-32

S.1.3. Indicators. .............................................................................................................................3-32

S.1.4. Computing-Type Device.......................................................................................................3-33

S.2. Design of Measuring Elements...........................................................................................................3-34

S.2.1. Vapor Elimination.................................................................................................................3-34

S.2.2. Provision for Sealing.............................................................................................................3-34

S.2.3. Directional Flow Valves. ......................................................................................................3-35

S.2.4. Zero-Set-Back Interlock, Vehicle-Tank Meters, Electronic. .................................................3-35

S.2.5. Automatic Temperature Compensation for Refined Petroleum Products.............................3-35

S.2.6. Thermometer Well, Temperature Determination..................................................................3-36

S.3. Design of Discharge Lines and Discharge Line Valves......................................................................3-36

S.3.1. Diversion of Measured Liquid. .............................................................................................3-36

S.3.2. Pump-Discharge Unit............................................................................................................3-36

S.3.3. Gravity-Discharge Unit.........................................................................................................3-37

S.3.4. Discharge Hose. ....................................................................................................................3-37

S.3.5. Discharge Valve....................................................................................................................3-37

S.3.6. Antidrain Valve.....................................................................................................................3-37

S.4. Design of Intake Lines (for Milk-Metering Systems).........................................................................3-37

S.4.1. Diversion of Liquid to be Measured. ....................................................................................3-37

S.4.2. Intake Hose. ..........................................................................................................................3-37

S.5. Marking Requirements........................................................................................................................3-37

S.5.1. Limitation of Use. .................................................................................................................3-37

S.5.2. Discharge Rates. ...................................................................................................................3-37

S.5.3. Measuring Components, Milk-Metering System. .................................................................3-37

S.5.4. Flood Volume, Milk-Metering System.................................................................................3-38

S.5.5. Conversion Factor.................................................................................................................3-38

S.5.6. Temperature Compensation for Refined Petroleum Products...............................................3-38

S.5.7. Meter Size. ............................................................................................................................3-38

N. Notes............................................................................................................................................................. 3-38

N.1. Test Liquid..........................................................................................................................................3-38

N.2. Evaporation and Volume Change. ......................................................................................................3-38

N.3. Test Drafts...........................................................................................................................................3-38

N.4. Testing Procedures..............................................................................................................................3-38

N.4.1. Normal Tests.........................................................................................................................3-38

N.4.2. Special Tests (Except Milk-Measuring Systems). ................................................................3-39

N.4.3. Antidrain Valve Test.............................................................................................................3-39

N.4.4. System Capacity. ..................................................................................................................3-39

N.4.5. Product Depletion Test. ........................................................................................................3-39

N.5. Temperature Correction for Refined Petroleum Products...................................................................3-39

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T. Tolerances.................................................................................................................................................... 3-40

T.1. Application..........................................................................................................................................3-40

T.1.1. To Underregistration and to Overregistration. ......................................................................3-40

T.2. Tolerance Values. ...............................................................................................................................3-40

T.2.1. Automatic Temperature-Compensating Systems..................................................................3-41

T.3. Repeatability. ......................................................................................................................................3-41

T.4. Product Depletion Test. ......................................................................................................................3-41

UR. User Requirements ..................................................................................................................................... 3-41

UR.1. Installation Requirements. ..................................................................................................................3-41

UR.1.1. Discharge Rate......................................................................................................................3-41

UR.1.2. Unit Price. .............................................................................................................................3-41

UR.1.3. Intake Hose. ..........................................................................................................................3-42

UR.1.4. Liquid Measured. ..................................................................................................................3-42

UR.2. Use Requirements. ..............................................................................................................................3-42

UR.2.1. Return of Indicating and Recording Elements to Zero. ........................................................3-42

UR.2.2. Ticket Printer, Customer Ticket............................................................................................3-42

UR.2.3. Ticket in Printing Device. .....................................................................................................3-42

UR.2.4. Credit for Flood Volume.......................................................................................................3-42

UR.2.5. Automatic Temperature Compensation for Refined Petroleum Products.............................3-42

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Section 3.31. Vehicle-Tank Meters

A. Application

A.1. General. – This code applies to meters mounted on vehicle tanks including those used for the measurement 

and delivery of petroleum products or agri-chemical liquids such as fertilizers, feeds, pesticides, defoliants, and bulk 

deliveries of water.

(Amended 1985 and 1995)

A.2. Exceptions. – This code does not apply to the following devices:

(a) Devices used for dispensing liquefied petroleum gases, or other liquids that do not remain in a liquid state at 

atmospheric pressures and temperatures. (Also see Section 3.32. Code for Liquefied Petroleum Gas and 

Anhydrous Ammonia Liquid-Measuring Devices.) 

(b) Devices used solely for dispensing a product in connection with operations in which the amount dispensed 

does not affect customer charges.

(c) Vehicle tanks used as measures. (Also see Section 4.40. Code for Vehicle Tanks Used as Measures.) 

(d) Mass flow meters. (Also see Section 3.37. Code for Mass Flow Meters.) 

(Added 1994)

(e) Devices used to measure cryogenic liquids. (Also see Section 3.34. Code for Cryogenic Liquid-Measuring 

Devices.) 

(f) Devices used to measure carbon dioxide liquids. (Also see Section 3.38. Code for Carbon Dioxide 

Liquid-Measuring Devices.) 

A.3. Additional Code Requirements. – In addition to the requirements of this code, Vehicle-Tank Meters shall 

meet the requirements of 1.10. General Code requirements.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A meter shall be equipped with a primary indicating element and may also be equipped 

with a primary recording element.

Note: Except for systems used solely for the sale of aviation fuel into aircraft and for aircraft-related operations, vehicletank meters shall be equipped with a primary recording element as required by paragraph UR.2.2. Ticket Printer; 

Customer Ticket.

(Amended 1993)

S.1.1.2. Units.

(a) A meter shall indicate, and record if the meter is equipped to record, its deliveries in terms of liters 

or gallons. Fractional parts of the liter or gallon shall be in terms of either decimal or binary 

subdivisions.

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(b) When it is an industry practice to purchase and sell milk by weight based upon 1.03 kg/L (8.6 lb/gal), 

the primary indicating element may indicate in kilograms or pounds and decimal kilograms or 

pounds. The weight value division shall be a decimal multiple or submultiple of 1, 2, or 5. (Also 

see Section S.5.5. Conversion Factor.) 

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded 

delivery if the meter is equipped to record, shall not exceed the equivalent of:

(a) 0.5 L (0.1 gal) or 0.5 kg (1 lb) on milk-metering systems;

(b) 0.5 L (0.1 gal) on meters with a rated maximum flow rate of 750 L/min (200 gal/min) or less;

(c) 5 L (1 gal) on meters with a rated maximum flow of 375 L/min (100 gal/min) or more used for jet 

fuel aviation refueling systems; or

 (Added 2006)

(d) 5 L (1 gal) on other meters. 

(Amended 1989, 1994 and 2006) 

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only by the mechanical operation of the meter. However, a 

meter may be cleared by advancing its elements to zero, but only if:

(a) the advancing movement, once started, cannot be stopped until zero is reached; or

(b) in the case of indicating elements only, such elements are automatically obscured until the elements 

reach the correct zero position.

S.1.1.5. Return to Zero. – Primary indicating elements shall be readily returnable to a definite zero 

indication. Means shall be provided to prevent the return of primary indicating elements, and of primary 

recording elements if these are returnable to zero, beyond their correct zero position.

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) wide.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall be not less than 2.5 mm 

(0.10 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

(Amended 1986)

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations at 

least throughout that portion of its length associated with the graduations.

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S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than:

(a) the width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) the width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.1.3.6. Travel of Indicator. – If the most sensitive element of the primary indicating element utilizes an 

indicator and graduations, the relative movement of these parts corresponding to the smallest indicated value 

shall not be less than 5 mm (0.20 in).

S.1.4. Computing-Type Device.

S.1.4.1. Display of Unit Price. – In a device of the computing type, means shall be provided for 

displaying, in a manner clear to the operator and an observer, the unit price at which the device is set to 

compute. The unit price is not required to be displayed continuously.

(Amended 1983 and 2005)

S.1.4.2. Printed Ticket. – If a computing-type device issues a printed ticket which displays the total 

computed price, the ticket shall also have printed clearly thereon the total quantity of the delivery, the 

appropriate fraction of the quantity, and the price per unit of quantity.

(Amended 1989)

S.1.4.3. Money-Value Computations. – Money-value computations shall be of the full-computing type 

in which the money-value at a single unit price, or at each of a series of unit prices, shall be computed for 

every delivery within either the range of measurement of the device or the range of the computing elements, 

whichever is less. Value graduations shall be supplied and shall be accurately positioned. The value of each 

graduated interval shall be one cent. On electronic devices with digital indications, the total price may be 

computed on the basis of the quantity indicated when the value of the smallest division indicated is equal to 

or less than 0.2 L (0.1 gal) or 0.2 kg (1 lb).

(Amended 1979 and 1989)

S.1.4.4. Money-Values, Mathematical Agreement. – Any digital money-value indication and any 

recorded money-value on a computing-type device shall be in mathematical agreement with its associated 

quantity indication or representation to within one cent of money-value.

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S.2. Design of Measuring Elements.

S.2.1. Vapor Elimination. – A metering system shall be equipped with an effective vapor or air eliminator or 

other automatic means to prevent the passage of vapor and air through the meter. Vent lines from the air or vapor 

eliminator shall be made of metal tubing or some other suitable rigid material.

(Amended 1993)

S.2.2. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or for physically applying a security seal in such a manner that requires the security seal to be 

broken before a change or an adjustment or interchange may be made of:

(a) any measuring or indicating element;

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries; and

(c) any metrological parameter that will affect the metrological integrity of the device or system.

When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

[Audit trails shall use the format set forth in Table S.2.2. Categories of Device and Methods Sealing.]* 

[*Nonretroactive as of January 1, 1995]

(Amended 2006)

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Table S.2.2. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but access 

is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

The hardware enabling access for remote communication 

must be on-site. The hardware must be sealed using a 

physical seal or an event counter for calibration 

parameters and an event counter for configuration 

parameters. The event counters may be located either at 

the individual measuring device or at the system 

controller; however, an adequate number of counters must 

be provided to monitor the calibration and configuration

parameters of the individual devices at a location. If the 

counters are located in the system controller rather than 

at the individual device, means must be provided to 

generate a hard copy of the information through an on-site 

device.

Category 3: Remote configuration capability access may 

be unlimited or controlled through a software switch (e.g., 

password). 

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

An event logger is required in the device; it must include 

an event counter (000 to 999), the parameter ID, the date 

and time of the change, and the new value of the 

parameter. A printed copy of the information must be 

available through the device or through another on-site 

device. The event logger shall have a capacity to retain 

records equal to 10 times the number of sealable

parameters in the device, but not more than 1000 records 

are required. (Note: Does not require 1000 changes to 

be stored for each parameter.)

[Nonretroactive as of January 1, 1995]

(Table Added 2006)

S.2.3. Directional Flow Valves. – Valves intended to prevent reversal of flow shall be automatic in operation. 

However, on equipment used exclusively for fueling aircraft, such valves may be manual in operation.

S.2.4. Zero-Set-Back Interlock, Vehicle-Tank Meters, Electronic. – Except for vehicle-mounted metering 

systems used solely for the delivery of aviation fuel, a device shall be so constructed that after an individual or 

multiple deliveries at one location have been completed, an automatic interlock system shall engage to prevent a 

subsequent delivery until the indicating and, if equipped, recording elements have been returned to their zero 

position. For individual deliveries, if there is no product flow for three minutes the transaction must be completed 

before additional product flow is allowed. The 3-minute timeout shall be a sealable feature on an indicator.

[Nonretroactive as of January 1, 2006]

(Added 2005)

S.2.5. Automatic Temperature Compensation for Refined Petroleum Products.

S.2.5.1. Automatic Temperature Compensation for Refined Petroleum Products. – A device may be 

equipped with an automatic means for adjusting the indication and registration of the measured volume of 

product to the volume at 15 °C for liters or the volume at 60 °F for gallons and decimal subdivisions or 

fractional equivalents thereof where not prohibited by state law.

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S.2.5.2. Provision for Deactivating. – On a device equipped with an automatic temperaturecompensating mechanism that will indicate or record only in terms of liters compensated to 15°C or gallons 

compensated to 60 °F, provision shall be made for deactivating the automatic temperature-compensating 

mechanism so the meter can indicate and record, if it is equipped to record, in terms of the uncompensated 

volume.

S.2.5.3. Gross and Net Indications. – A device equipped with automatic temperature compensation shall 

indicate or record, if equipped to record, both the gross (uncompensated) and net (compensated) volume for 

testing purposes. It is not necessary that both net and gross volume be displayed simultaneously.

S.2.5.4. Provision for Sealing Automatic Temperature-Compensating Systems. – Adequate provision 

shall be made for an approved means of security (e.g., data change audit trail) or physically applying security 

seals in such a manner that an automatic temperature-compensating system cannot be disconnected and no 

adjustment may be made to the system.

S.2.5.5. Temperature Determination with Automatic Temperature Compensation. – For test 

purposes, means shall be provided (e.g., thermometer well) to determine the temperature of the liquid either:

(a) in the liquid chamber of the meter; or

(b) immediately adjacent to the meter in the meter inlet or discharge line.

(Added 2007)

S.2.6. Thermometer Well, Temperature Determination. For test purposes, means shall be provided (e.g., 

thermometer well) to determine the temperature of the liquid either in the: 

(a) liquid chamber of the meter; or 

(b) meter inlet or discharge line immediately adjacent to the meter.

[Nonretroactive as of January 1, 2012)

(Added 2011)

S.3. Design of Discharge Lines and Discharge Line Valves.

(Not applicable to milk-metering systems.)

S.3.1. Diversion of Measured Liquid. – Except on equipment used exclusively for fueling aircraft, no means 

shall be provided by which any measured liquid can be diverted from the measuring chamber of the meter or the 

discharge line thereof. However, two or more delivery outlets may be installed if means is provided to insure 

that:

(a) liquid can flow from only one such outlet at one time; and

(b) the direction of flow for which the mechanism may be set at any time is definitely and conspicuously 

indicated.

S.3.2. Pump-Discharge Unit. – On a pump-discharge unit, the discharge hose shall be of the wet-hose type 

with a shutoff valve at its outlet end. However, a pump-discharge unit may be equipped also with a dry-hose 

without a shutoff valve at its outlet end, but only if:

(a) the dry-hose is as short as practicable; and

(b) there is incorporated in the discharge piping, immediately adjacent to the meter, effective means to insure 

that liquid can flow through only one of the discharge hoses at any one time and that the meter and the 

wet-hose remain full of liquid at all times.

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S.3.3. Gravity-Discharge Unit. – On a gravity-discharge unit, the discharge hose or equivalent pipe shall be 

of the dry-hose type with no shutoff valve at its outlet end. The dry-hose shall be of such stiffness and only of 

such length as to facilitate its drainage. The inlet end of the hose or of an equivalent outlet pipe shall be of such 

height as to provide for proper drainage of the hose or pipe. There shall be incorporated an automatic vacuum 

breaker or equivalent means to prevent siphoning and to ensure the rapid and complete drainage.

S.3.4. Discharge Hose. – A discharge hose shall be adequately reinforced.

S.3.5. Discharge Valve. – A discharge valve may be installed in the discharge line only if the device is of the 

wet-hose type, in which case such valve shall be at the discharge end of the line. Any other shutoff valve on the 

discharge side of the meter shall be of the automatic or semiautomatic predetermined-stop type or shall be 

operable only:

(a) by means of a tool (but not a pin) entirely separate from the device; or

(b) by mutilation of a security seal with which the valve is sealed open.

S.3.6. Antidrain Valve. – In a wet-hose, pressure-type device, an effective antidrain valve shall be 

incorporated in the discharge valve or immediately adjacent thereto. The antidrain valve shall function so as to 

prevent the drainage of the discharge hose. However, a device used exclusively for fueling and defueling aircraft 

may be of the pressure type without an antidrain valve.

S.4. Design of Intake Lines (for Milk-Metering Systems).

S.4.1. Diversion of Liquid to be Measured. – No means shall be provided by which any liquid can be diverted 

from the supply tank to the receiving tank without being measured by the device.

S.4.2. Intake Hose. – The intake hose shall be:

(a) of the dry-hose type;

(b) adequately reinforced;

(c) not more than 6 m (20 ft) in length, unless it can be demonstrated that a longer hose is essential to permit 

pickups from a supply tank; and

(d) connected to the pump at horizontal or above, to permit complete drainage of the hose.

S.5. Marking Requirements.

S.5.1. Limitation of Use. – If a meter is intended to measure accurately only liquids having particular 

properties, or to measure accurately only under specific installation or operating conditions, or to measure 

accurately only when used in conjunction with specific accessory equipment, these limitations shall be clearly 

and permanently stated on the meter.

S.5.2. Discharge Rates. – A meter shall be marked to show its designed maximum and minimum discharge 

rates. However, the minimum discharge rate shall not exceed 20 % of the maximum discharge rate.

Note: Also see example in Section 3.30. Liquid-Measuring Devices Code, paragraph S.4.4.1. Discharge Rates.

(Added 2003)

S.5.3. Measuring Components, Milk-Metering System. – All components that affect the measurement of 

milk that are disassembled for cleaning purposes shall be clearly and permanently identified with a common serial 

number.

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S.5.4. Flood Volume, Milk-Metering System. – When applicable, the volume of product necessary to flood 

the system when dry shall be clearly, conspicuously, and permanently marked on the air eliminator.

S.5.5. Conversion Factor. – When the conversion factor of 1.03 kg/L (8.6 lb/gal) is used to convert the volume 

of milk to weight, the conversion factor shall be clearly marked on the primary indicating element and recorded 

on the delivery ticket.

(Added 1989)

S.5.6. Temperature Compensation for Refined Petroleum Products. – If a device is equipped with an 

automatic temperature compensator, the primary indicating elements, recording elements, and recorded 

representations shall be clearly and conspicuously marked to show the volume delivered has been adjusted to the 

volume at 15 °C for liters or the volume at 60 °F for gallons and decimal subdivisions or fractional equivalents 

thereof.

(Added 2007)

S.5.7. Meter Size. – Except for milk meters, if the meter model identifier does not provide a link to the meter 

size (in terms of pipe diameter) on an NTEP Certificate of Conformance, the meter shall be marked to show meter 

size.

[Nonretroactive as of January 1, 2009]

(Added 2008)

N. Notes

N.1. Test Liquid.

(a) A measuring system shall be tested with the liquid to be commercially measured or with a liquid of the same 

general physical characteristics. Following a satisfactory examination, the weights and measures official 

should attach a seal or tag indicating the product used during the test.

(Amended 1975)

(b) A milk-measuring system shall be tested with the type of milk to be measured when the accuracy of the 

system is affected by the characteristics of milk (e.g., positive displacement meters).

(Added 1989)

(Amended 1975 and 1989)

N.2. Evaporation and Volume Change. – Care shall be exercised to reduce to a minimum, evaporation losses and 

volume changes resulting from changes in temperature of the test liquid.

N.3. Test Drafts. – Test drafts should be equal to at least the amount delivered by the device in 1 minute at its 

maximum discharge rate, and shall in no case be less than 180 L (50 gal) or 225 kg (500 lb).

(Amended 1989)

N.4. Testing Procedures.

N.4.1. Normal Tests. – The “normal” test of a measuring system shall be made at the maximum discharge rate 

that may be anticipated under the conditions of the installation. Any additional tests conducted at flow rates down 

to and including one-half of the sum of the maximum discharge flow rate and the rated minimum discharge flow 

rate shall be considered normal tests.

(Amended 1992)

N.4.1.1. Milk Measuring System. – The “normal” test shall include a determination of the effectiveness 

of the air elimination system.

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N.4.1.2. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2001)

N.4.1.3. Automatic Temperature-Compensating Systems for Refined Petroleum Products. – On 

devices equipped with automatic temperature-compensating systems, normal tests shall be conducted:

(a) by comparing the compensated volume indicated or recorded to the actual delivered volume 

corrected to 15 °C for liters or 60 °F for gallons and decimal subdivisions or fractional equivalents 

thereof; and

(b) with the temperature-compensating system deactivated, comparing the uncompensated volume 

indicated or recorded to the actual delivered volume.

The first test shall be performed with the automatic temperature-compensating system operating in the 

“as-found” condition. On devices that indicate or record both the compensated and uncompensated volume 

for each delivery, the tests in (a) and (b) may be performed as a single test.

(Added 2007)

N.4.2. Special Tests (Except Milk-Measuring Systems). – “Special” tests shall be made to develop the 

operating characteristics of a measuring system and any special elements and accessories attached to or associated 

with the device. Any test except as set forth in N.4.1. Normal Tests and N.4.5. Product Depletion Test shall be 

considered a special test. Special tests of a measuring system shall be made at a minimum discharge rate of 20 % 

of the marked maximum discharge rate or at the minimum discharge rate marked on the device, whichever is less.

(Amended 1978 and 2005)

N.4.3. Antidrain Valve Test. – The effectiveness of the antidrain valve shall be tested after the pump pressure 

in the measuring system has been released and a valve between the supply tank and the discharge valve is closed.

N.4.4. System Capacity. – The test of a milk-measuring system shall include the verification of the volume of 

product necessary to flood the system as marked on the air eliminator.

N.4.5. Product Depletion Test. – Except for vehicle-mounted metering systems used solely for the delivery of 

aviation fuel, the effectiveness of the vapor eliminator or vapor elimination means shall be tested by dispensing 

product at the normal flow rate until the product supply is depleted and continuing until the lack of fluid causes 

the meter indication to stop completely for at least 10 seconds. If the meter indication fails to stop completely for 

at least 10 seconds, continue to operate the system for 3 minutes. Finish the test by switching to another 

compartment with sufficient product to complete the test on a multi-compartment vehicle or by adding sufficient 

product to complete the test to a single compartment vehicle. When adding product to a single compartment 

vehicle, allow appropriate time for any entrapped vapor to disperse before continuing the test. Test drafts shall 

be of the same size and run at approximately the same flow rate.

(Added 2005)

N.5. Temperature Correction for Refined Petroleum Products. – Corrections shall be made for any changes in 

volume resulting from the differences in liquid temperatures between the time of passage through the meter and the 

time of volumetric determination in the prover. When adjustments are necessary, appropriate petroleum measurement 

tables should be used.

(Added 2007)

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T. Tolerances

T.1. Application.

T.1.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied 

to errors of underregistration and errors of overregistration.

T.2. Tolerance Values. – Tolerances shall be as shown in Table 1. Accuracy Classes and Tolerances for VehicleTank Meters and Table 2. Tolerances for Vehicle-Mounted Milk Meters.

(Amended 1995)

Table 1. 

Accuracy Classes and Tolerances for Vehicle-Tank Meters

Accuracy 

Class Application

Acceptance 

Tolerance

Maintenance 

Tolerance

Special Test 

Tolerance

0.3

- Petroleum products delivered from large capacity (flow 

rates over 115 L/min or 30 gpm)** devices, including 

motor-fuel devices

- Heated products (other than asphalt) at temperatures

greater than 50 °C (122 °F)

- Asphalt at temperatures equal to or below 50 °C (122 °F)

- All other liquids not shown in the table where the typical 

delivery is greater than 200 L (50 gal)

0.15 % 0.3 % 0.45 %

0.3A - Asphalt at temperatures greater than 50 °C (122 °F) 0.3 % 0.3 % 0.5 %

0.5*

- Petroleum products delivered from small capacity (at 

4 L/min (1 gpm) through 115 L/min or 30 gpm)** 

motor-fuel devices

- Agri-chemical liquids

- All other applications not shown in the table where the 

typical delivery is ≤ 200 L (50 gal)

0.3 % 0.5 % 0.5 %

1.1

- Petroleum products and other normal liquids from 

devices with flow rates** less than 4 L/min (1 gpm) and

- Devices designed to deliver less than 4 L (1 gal)

0.75 % 1.0 % 1.25 %

1.5 - Water

Overregistration 1.5 % 1.5 % 1.5 %

Underregistration 1.5 % 1.5 % 5.0 %

* For 5 gal and 10 gal test drafts, the tolerances specified for Accuracy Class 0.5 in the table above do not apply. For 

these test drafts, the maintenance tolerances on normal and special tests for 5 gal and 10 gal test drafts are 6 in3 and 

11 in3, respectively. Acceptance tolerances on normal and special tests are 3 in3 and 5.5 in3. 

** Flow rate refers to designed or marked maximum flow rate.

(Added 2002) (Amended 2013)

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Table 2. 

Tolerances for Vehicle-Mounted Milk Meters

Indication

(gallons)

Maintenance Tolerance

(gallons)

Acceptance Tolerance

(gallons)

100 0.5 0.3

200 0.7 0.4

300 0.9 0.5

400 1.1 0.6

500 1.3 0.7

Over 500 Add 0.002 gallon per indicated gallon 

over 500

Add 0.001 gallon per indicated gallon over 

500

(Added 1989)

T.2.1. Automatic Temperature-Compensating Systems. – The difference between the meter error (expressed 

as a percentage) for results determined with and without the automatic temperature-compensating system 

activated shall not exceed:

(a) 0.2 % for mechanical automatic temperature-compensating systems; and

(b) 0.1 % for electronic automatic temperature-compensating systems.

The delivered quantities for each test shall be approximately the same size. The results of each test shall be within 

the applicable acceptance or maintenance tolerance.

(Added 2007) (Amended 2010)

T.3. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within the applicable tolerance. (Also see N.4.1.2. Repeatability Tests.)

(Added 1992) (Amended 2001 and 2002)

T.4. Product Depletion Test. – The difference between the test result for any normal test and the product depletion 

test shall not exceed 0.5 % of the volume delivered in one minute at the maximum flow rate marked on the meter for 

meters rated higher than 380 Lpm (100 gpm) or 0.6 % of the volume delivered in one minute at the maximum flow 

rate marked on the meter for meters rated 380 Lpm (100 gpm) or lower. Test drafts shall be of the same size and run 

at approximately the same flow rate.

Note: The result of the product depletion test may fall outside of the applicable test tolerance as specified in Table 1. Accuracy 

Classes and Tolerances for Vehicle-Tank Meters.

(Amended 2013)

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Discharge Rate. – A meter shall be so installed that the actual maximum discharge rate will not exceed 

the rated maximum discharge rate. If necessary, means for flow regulation shall be incorporated in the 

installation, in which case this shall be fully effective and automatic in operation.

UR.1.2. Unit Price. – There shall be displayed on the face of a device of the computing type the unit price at 

which the device is set to compute.

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UR.1.3. Intake Hose. – The intake hose in a milk-metering system shall be installed to permit complete 

drainage and ensure that all available product is measured following each pickup.

UR.1.4. Liquid Measured. – A vehicle-tank meter shall continue to be used to measure the same liquid or one 

with the same general physical properties as that used for calibration and weights and measures approval unless 

the meter is recalibrated with a different product and tested by a registered service agency or a weights and 

measures official and approved by the weights and measures jurisdiction having statutory authority over the 

device.

(Added 2003)

UR.2. Use Requirements.

UR.2.1. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual), 

and the primary recording elements, when these are returnable to zero, shall be returned to zero immediately 

before each delivery is begun and after the pump has been activated and the product to be measured has been 

supplied to the measuring system.

(Amended 1981)

UR.2.2. Ticket Printer, Customer Ticket. – Vehicle-Mounted metering systems shall be equipped with a 

ticket printer which shall be used for all sales where product is delivered through the meter. A copy of the ticket 

issued by the device shall be left with the customer at the time of delivery or as otherwise specified by the 

customer.

(Added 1993) (Amended 1994)

UR.2.2.1. Exceptions for the Sale of Aviation Fuel. – The provisions of UR.2.2. Ticket Printer, 

Customer Ticket shall not apply to vehicle-mounted metering systems used solely for the delivery of aviation

fuel into aircraft and for aircraft-related operations.

(Added 1999)

UR.2.3. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket printer 

until immediately before a delivery is begun, and in no case shall a ticket be in the device when the vehicle is in 

motion while on a public street, highway, or thoroughfare.

UR.2.4. Credit for Flood Volume. – The volume of product necessary to flood the system as marked on the 

air eliminator shall be individually recorded on the pickup ticket of each seller affected.

UR.2.5. Automatic Temperature Compensation for Refined Petroleum Products.

UR.2.5.1. When to be Used. – In a state that does not prohibit, by law or regulation, the sale of 

temperature-compensated product, a device equipped with an activated automatic-temperature compensator 

shall be connected, operable, and in use at all times. An electronic or mechanical automatic 

temperature-compensating device or system may not be removed or deactivated, nor may a compensated 

device be replaced with an uncompensated device or system, without the written approval of the responsible 

weights and measures jurisdiction.

Note: This requirement does not specify the method of sale for products measured through a meter.

(Amended 2009)

UR.2.5.2. Period of Use. – When fuel is bought or sold on an automatic temperature compensation basis, 

it shall be bought or sold using this basis over at least a consecutive 12-month period unless otherwise agreed 

to by both the buyer and seller in writing.

(Added 2009)

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UR.2.5.3. Invoices. – An invoice based on a reading of a device that is equipped with an automatic 

temperature compensator shall show that the volume delivered has been adjusted to the volume at 15 °C for 

liters or the volume at 60 °F for gallons and decimal subdivisions or fractional equivalents thereof.

(Added 2007)

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Table of Contents

Section 3.32. Liquefied Petroleum Gas and Anhydrous Ammonia Liquid-Measuring 

Devices ............................................................................................................... 3-47

A. Application. ..................................................................................................................................................3-47

A.1. General................................................................................................................................................3-47

A.2. Devices Used to Measure Other Liquid Products not Covered in Specific Codes..............................3-47

A.3. Exceptions...........................................................................................................................................3-47

A.4. Additional Code Requirements...........................................................................................................3-47

S. Specifications................................................................................................................................................3-47

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-47

S.1.1. Primary Elements..................................................................................................................3-47

S.1.2. Graduations...........................................................................................................................3-48

S.1.3. Indicators. .............................................................................................................................3-48

S.1.4. For Retail Devices Only........................................................................................................3-49

S.1.5. For Stationary Retail Devices Only. .....................................................................................3-49

S.1.6. For Wholesale Devices Only. ...............................................................................................3-51

S.2. Design of Measuring Elements...........................................................................................................3-51

S.2.1. Vapor Elimination.................................................................................................................3-51

S.2.2. Provision for Sealing.............................................................................................................3-51

S.2.3. Directional Flow Valves. ......................................................................................................3-52

S.2.4. Maintenance of Liquid State.................................................................................................3-52

S.2.5. Thermometer Well................................................................................................................3-52

S.2.6. Automatic Temperature Compensation. ...............................................................................3-53

S.3. Design of Discharge Lines and Discharge Line Valves......................................................................3-53

S.3.1. Diversion of Measured Liquid. .............................................................................................3-53

S.3.2. Delivery Hose. ......................................................................................................................3-53

S.4. Marking Requirements........................................................................................................................3-53

S.4.1. Limitation of Use. .................................................................................................................3-53

S.4.2. Discharge Rates. ...................................................................................................................3-53

S.4.3. Location of Marking Information; Retail Motor-Fuel Dispensers........................................3-54

S.4.4. Temperature Compensation. .................................................................................................3-54

N. Notes..............................................................................................................................................................3-54

N.1. Test Liquid..........................................................................................................................................3-54

N.2. Vaporization and Volume Change......................................................................................................3-54

N.3. Test Drafts...........................................................................................................................................3-54

N.4. Testing Procedures..............................................................................................................................3-54

N.4.1. Normal Tests.........................................................................................................................3-54

N.4.2. Special Tests. ........................................................................................................................3-55

N.4.3. Money-Value Computation Tests. ........................................................................................3-55

N.5. Temperature Correction. .....................................................................................................................3-55

T. Tolerances.....................................................................................................................................................3-56

T.1. Application..........................................................................................................................................3-56

T.1.1. To Underregistration and to Overregistration. ......................................................................3-56

T.2. Tolerance Values. ...............................................................................................................................3-56

T.3. Repeatability. ......................................................................................................................................3-56

T.4. Automatic Temperature-Compensating Systems................................................................................3-56

UR. User Requirements ......................................................................................................................................3-56

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UR.1. Installation Requirements. ..................................................................................................................3-56

UR.1.1. Discharge Rate......................................................................................................................3-56

UR.1.2. Length of Discharge Hose. ...................................................................................................3-56

UR.2. Use Requirements. ..............................................................................................................................3-57

UR.2.1. Return of Indication and Recording Elements to Zero. ........................................................3-57

UR.2.2. Condition of Fill of Discharge Hose. ....................................................................................3-57

UR.2.3. Vapor-Return Line................................................................................................................3-57

UR.2.4. Temperature Compensation. .................................................................................................3-57

UR.2.5. Ticket in Printing Device. .....................................................................................................3-57

UR.2.6. Ticket Printer; Customer Ticket............................................................................................3-57

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Section 3.32. Liquefied Petroleum Gas and Anhydrous Ammonia 

Liquid-Measuring Devices1

A. Application.

A.1. General. – This code applies to devices used for the measurement of liquefied petroleum gas and anhydrous 

ammonia in the liquid state, whether such devices are installed in a permanent location or mounted on a vehicle.

A.2. Devices Used to Measure Other Liquid Products not Covered in Specific Codes. – Insofar as they are 

clearly appropriate, the requirements and provisions of the code may be applied to devices used for the measurement 

of other liquids that do not remain in a liquid state at atmospheric pressures and temperatures.

A.3. Exceptions. – This code does not apply to mass flow meters. (Also see Section 3.37. Code for Mass Flow 

Meters.) 

(Added 1994)

A.4. Additional Code Requirements. – In addition to the requirements of this code, LPG and Anhydrous Ammonia 

Liquid-Measuring Devices shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A device shall be equipped with a primary indicating element and may also be 

equipped with a primary recording element.

Note: Vehicle-mounted metering systems shall be equipped with a primary recording element as required by 

paragraph UR.2.6. Ticket Printer; Customer Ticket.

S.1.1.2. Units. – A device shall indicate, and record if the device is equipped to record, its deliveries in 

terms of liters, gallons, quarts, pints, or binary-submultiple or decimal subdivisions of the liter or gallon.

(Amended 1987)

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded 

delivery if the device is equipped to record, shall not exceed the equivalent of:

(a) 0.5 L (1 pt) on retail devices; or

(b) 5 L (1 gal) on wholesale devices.

(Amended 1987)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only by the mechanical operation of the device. However, a 

device may be cleared by advancing its elements to zero, but only if:

(a) the advancing movement, once started, cannot be stopped until zero is reached; or

 

1

Title amended 1986.

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(b) in the case of indicating elements only, such elements are automatically obscured until the elements 

reach the correct zero position.

S.1.1.5. Money-Values, Mathematical Agreement. – Any digital money-value indication and any 

recorded money-value on a computing-type device shall be in mathematical agreement with its associated 

quantity indication or representation to within 1 cent of money-value; except that a stationary retail 

computing-type device must compute and indicate to the nearest 1 cent of money-value. (Also see 

Section 1.10. General Code, G-S.5.5. Money-Values, Mathematical Agreement.) 

(Amended 1984 and 1988)

S.1.1.6. Printed Ticket. – Any printed ticket issued by a device of the computing type on which there is 

printed the total computed price, shall have printed clearly thereon the total volume of the delivery in terms 

of liters or gallons, and the appropriate decimal fraction of the liter or gallon, and the corresponding price per 

liter or gallon.

(Added 1979) (Amended 1987)

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations: 

(a) the width of a graduation shall in no case be greater than the width of the minimum clear interval 

between graduations; 

(b) the width of main graduations shall be not more than 50 % greater than the width of subordinate 

graduations; and

(c) graduations shall in no case be less than 0.2 mm (0.008 in) in width.

S.1.2.3. Clear Interval between Graduations. – The clear interval shall be not less than 1.0 mm 

(0.04 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of graduations, shall be not more than 

1.0 mm (0.04 in).

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S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than:

(a) the width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) the width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.1.4. For Retail Devices Only.

S.1.4.1. Indication of Delivery. – A retail device shall be constructed to show automatically its initial 

zero condition and the amounts delivered up to the nominal capacity of the device.

S.1.4.2. Return to Zero.

(a) Primary indicating elements shall be readily returnable to a definite zero indication.

(b) Primary recording elements on a stationary retail device shall be readily returnable to a definite zero 

indication if the device is equipped to record.

(c) Means shall be provided to prevent the return of primary indicating elements and of primary 

recording elements if these are returnable to zero, beyond their correct zero position.

(Amended 1990)

S.1.5. For Stationary Retail Devices Only.

S.1.5.1. Display of Unit Price and Product Identity. – In a device of the computing type, means shall 

be provided for displaying on each face of the device the unit price at which the device is set to compute or 

to deliver as the case may be, and there shall be conspicuously displayed on each side of the device the 

identity of the product that is being dispensed. If a device is so designed as to dispense more than one grade, 

brand, blend, or mixture of product, the identity of the grade, brand, blend, or mixture being dispensed shall 

also be displayed on each face of the device.

S.1.5.2. Money-Value Computations. – A computing device shall compute the total sales price at any 

single-purchase unit price (excluding fleet sales and other price contract sales) for which the product is 

offered for sale at any delivery possible within either the measurement range of the device or the range of the 

computing elements, whichever is less. The analog money-value indication shall not differ from the 

mathematically computed money-value (quantity × unit price = sales price), for any delivered quantity, by 

an amount greater than the values shown in Table 1. Money-Value Divisions and Maximum Allowable 

Variations for Money-Value Computations on Mechanical Analog Computers.

(Amended 1995)

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Table 1.

Money-Value Divisions and 

Maximum Allowable Variations for Money-Value

Computations on Mechanical Analog Computers

Unit Price MoneyValue

Division

Maximum

Allowable Variation

From To and Including Design

Test

Field

Test

0 $0.25/liter or

$1.00/gallon 1¢ ± 1¢ ± 1¢

$0.25/liter or

$1.00/gallon

$0.75/liter or

$3.00/gallon 1¢ or 2¢ ± 1¢ ± 2¢

$0.75/liter or

$3.00/gallon

 $2.50/liter or

 $10.00/gallon 1¢ or 2¢ ± 1¢ ± 2¢

$0.75/liter or

$3.00/gallon

 $2.50/liter or

 $10.00/gallon 5¢ ± 21⁄2¢ ± 5¢

S.1.5.2.1. Money-Value Divisions, Analog. – The value of the graduated intervals representing 

money-values on a computing-type device with analog indications shall be as follows:

(a) Not more than 1 cent at all unit prices up to and including $0.25 per liter or $1.00 per gallon.

(b) Not more than 2 cents at unit prices greater than $0.25 per liter or $1.00 per gallon up to and 

including $0.75 per liter or $3.00 per gallon.

(c) Not more than 5 cents at all unit prices greater than $0.75 per liter or $3.00 per gallon.

(Amended 1984)

S.1.5.2.2. Money-Value Divisions, Digital. – A computing-type device with digital indications shall 

comply with the requirements of paragraph G.-S.5.5. Money-Values, Mathematical Agreement, and the 

total price computation shall be based on quantities not exceeding 0.01 gal intervals for devices 

indicating in U.S. customary units and 0.05 L for devices indicating in metric units.

S.1.5.2.3. Money-Value Divisions, Auxiliary Indications. – In a system equipped with auxiliary 

indications, all indicated money-value divisions shall be identical.

[Nonretroactive as of January 1, 1985.]

S.1.5.3. Recorded Representations, Point-of-Sale Systems. – Except for fleet sales and other price 

contract sales, a printed receipt providing the following information shall be available through a built-in or 

separate recording element for all transactions conducted with point-of-sale systems or devices activated by 

debit cards, credit cards, and/or cash:

(a) the total volume of the delivery;

(b) the unit price;

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(c) the total computed price; and

(d) the product identity by name, symbol, abbreviation, or code number.

(Added 2014)

S.1.6. For Wholesale Devices Only.

S.1.6.1. Travel of Indicator. – A wholesale device shall be readily operable to deliver accurately any 

quantity from 180 L (50 gal) to the capacity of the device. If the most sensitive element of the indicating 

system uses an indicator and graduations, the relative movement of these parts corresponding to a delivery 

of 5 L (1 gal) shall be not less than 5 mm (0.20 in).

(Amended 1987)

S.2. Design of Measuring Elements.

S.2.1. Vapor Elimination. – A device shall be equipped with an effective vapor eliminator or other effective 

means to prevent the passage of vapor through the meter.

S.2.2. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or for physically applying a security seal in such a manner that requires the security seal to be 

broken before an adjustment or interchange may be made of:

(a) any measuring or indicating element;

(b) any adjustable element for controlling delivery rate, when such rate tends to affect the accuracy of 

deliveries; and

(c) any metrological parameter that will affect the metrological integrity of the device or system.

When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

[Audit trails shall use the format set forth in Table S.2.2. Categories of Device and Methods of Sealing.]*

[*Nonretroactive as of January 1, 1995]

(Amended 2006)

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Table S.2.2. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for 

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but access 

is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

The hardware enabling access for remote 

communication must be on-site. The hardware must be 

sealed using a physical seal or an event counter for 

calibration parameters and an event counter for 

configuration parameters. The event counters may be 

located either at the individual measuring device or at 

the system controller; however, an adequate number of 

counters must be provided to monitor the calibration 

and configuration parameters of the individual devices 

at a location. If the counters are located in the system 

controller rather than at the individual device, means 

must be provided to generate a hard copy of the 

information through an on-site device.

Category 3: Remote configuration capability access may 

be unlimited or controlled through a software switch (e.g., 

password). 

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

An event logger is required in the device; it must include 

an event counter (000 to 999), the parameter ID, the 

date and time of the change, and the new value of the 

parameter. A printed copy of the information must be 

available through the device or through another on-site 

device. The event logger shall have a capacity to retain 

records equal to 10 times the number of sealable 

parameters in the device, but not more than 

1000 records are required. (Note: Does not require 

1000 changes to be stored for each parameter.)

[Nonretroactive as of January 1, 1995]

(Table Added 2006)

S.2.3. Directional Flow Valves. – A measuring system shall be equipped with a valve or other effective means, 

automatic in operation and installed in or adjacent to the measuring element, to prevent reversal of flow of the 

product being measured.

(Amended 1982)

S.2.4. Maintenance of Liquid State. – A device shall be so designed and installed that the product being 

measured will remain in a liquid state during the passage through the meter.

S.2.5. Thermometer Well. – For test purposes, means shall be provided to determine the temperature of the 

liquid either:

(a) in the liquid chamber of the meter; or

(b) in the meter inlet or discharge line and immediately adjacent to the meter.

(Amended 1987)

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S.2.6. Automatic Temperature Compensation. – A device may be equipped with an adjustable automatic 

means for adjusting the indication and registration of the measured volume of product to the volume at 15 °C 

(60 °F).

S.2.6.1. Provision for Deactivating. – On a device equipped with an automatic temperaturecompensating mechanism that will indicate or record only in terms of liters or gallons adjusted to 15 °C 

(60 °F), provision shall be made to facilitate the deactivation of the automatic temperature-compensating 

mechanism so that the meter may indicate, and record if it is equipped to record, in terms of the 

uncompensated volume.

(Amended 1972)

S.2.6.2. Provision for Sealing. – Provision shall be made for applying security seals in such a manner 

that an automatic temperature-compensating system cannot be disconnected and that no adjustment may be 

made to the system.

S.3. Design of Discharge Lines and Discharge Line Valves.

S.3.1. Diversion of Measured Liquid. – No means shall be provided by which any measured liquid can be 

diverted from the measuring chamber of the meter or the discharge line therefrom. However, two or more delivery 

outlets may be permanently installed if means are provided to insure that:

(a) liquid can flow from only one such outlet at one time; and

(b) the direction of flow for which the mechanism may be set at any time is definitely and conspicuously 

indicated.

In addition, a manually controlled outlet that may be opened for the purpose of emptying a portion of the system 

to allow for repair and maintenance operations shall be permitted. Effective means shall be provided to prevent 

the passage of liquid through any such outlet during normal operation of the device and to indicate clearly and 

unmistakably when the valve controls are so set as to permit passage of liquid through such outlet.

(Amended 1975)

S.3.2. Delivery Hose. – The delivery hose of a retail device shall be of the wet-hose type with a shutoff valve 

at its outlet end.

S.4. Marking Requirements.

S.4.1. Limitation of Use. – If a device is intended to measure accurately only products having particular 

properties, or to measure accurately only under specific installation or operating conditions, or to measure 

accurately only when used in conjunction with specific accessory equipment, these limitations shall be clearly 

and permanently stated on the device.

S.4.2. Discharge Rates. – A device shall be marked to show its designed maximum and minimum discharge 

rates. The marked minimum discharge rate shall not exceed:

(a) 20 L (5 gal) per minute for stationary retail devices; or

(b) 20 % of the marked maximum discharge rate for other retail devices and for wholesale devices.

(Amended 1987)

Note: Also see example in Section 3.30. Liquid-Measuring Devices Code, paragraph S.4.4.1. Discharge Rates.

(Added 2003)

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S.4.3. Location of Marking Information; Retail Motor-Fuel Dispensers. – The marking information required 

in General Code, paragraph G-S.1. Identification shall appear as follows:

(a) within 60 cm (24 in) to 150 cm (60 in) from the base of the dispenser;

(b) either internally and/or externally provided the information is permanent and easily read; and

(c) on a portion of the device that cannot be readily removed or interchanged (i.e., not on a service access 

panel).

Note: The use of a dispenser key or tool to access internal marking information is permitted for retail motor-fuel dispensers.

[Nonretroactive as of January 1, 2003]

(Added 2006)

S.4.4. Temperature Compensation. – If a device is equipped with an automatic temperature compensator, the 

primary indicating elements, recording elements, and recorded representation shall be clearly and conspicuously 

marked to show that the volume delivered has been adjusted to the volume at 15 °C (60 °F).

N. Notes

N.1. Test Liquid. – A device shall be tested with the liquid to be commercially measured or with a liquid of the 

same general physical characteristics.

N.2. Vaporization and Volume Change. – Care shall be exercised to reduce to a minimum, vaporization and 

volume changes.

N.3. Test Drafts. – Test drafts should be equal to at least the amount delivered by the device in one minute at its 

normal discharge rate.

(Amended 1982)

N.4. Testing Procedures.

N.4.1. Normal Tests. – The “normal” test of a device shall be made at the maximum discharge flow rate 

developed under the conditions of the installation. Any additional tests conducted at flow rates down to and 

including one-half the sum of the maximum discharge flow rate and the rated minimum discharge flow rate shall 

be considered normal tests.

(Amended 1998)

N.4.1.1. Automatic Temperature Compensation. – On devices equipped with automatic 

temperature-compensating systems, normal tests shall be conducted as follows:

(a) by comparing the compensated volume indicated or recorded to the actual delivered volume adjusted 

to 15 °C (60 °F); and

(b) with the temperature-compensating system deactivated, comparing the uncompensated volume 

indicated or recorded to the actual delivered volume.

The first test shall be performed with the automatic temperature-compensating system operating in the “as 

found” condition. On devices that indicate or record both the compensated and uncompensated volume for 

each delivery, the tests in (a) and (b) may be performed as a single test.

(Amended 1987)

N.4.1.2. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

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factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2001)

N.4.2. Special Tests. – “Special” tests shall be made to develop the operating characteristics of a device and 

any special elements and accessories attached to or associated with the device. Any test except as set forth in 

N.4.1. Normal Tests shall be considered a special test.

N.4.2.1. For Motor-Fuel Devices. – A motor-fuel device shall be so tested at a minimum discharge rate 

of:

(a) 20 L (5 gal) per minute; or

(b) the minimum discharge rate marked on the device, whichever is less.

N.4.2.2. For Other Retail Devices. – A retail device other than a motor-fuel device shall be tested at a 

minimum discharge rate of the:

(a) minimum discharge rate that can be developed under the conditions of installation; or

(b) minimum discharge rate marked on the device, whichever is greater.

(Amended 1973)

N.4.2.3. For Wholesale Devices. – A wholesale device shall be so tested at a minimum discharge rate of:

(a) 40 L (10 gal) per minute for a device with a rated maximum discharge less than 180 L (50 gal) per 

minute.

(b) 20 % of the marked maximum discharge rate for a device with a rated maximum discharge of 180 L 

(50 gal) per minute or more, or

(c) the minimum discharge rate marked on the device, whichever is least.

(Amended 1987)

N.4.3. Money-Value Computation Tests.

N.4.3.1. Laboratory Design Evaluation Tests. – In the conduct of laboratory design evaluation tests, 

compliance with paragraph S.1.5.2. Money-Value Computations shall be determined by using the cone gear 

as a reference for the total quantity delivered. The indicated delivered quantity shall agree with the cone gear 

representation with the index of the indicator within the width of the graduation. The maximum allowable 

variation of the indicated sales price shall be as shown in Table 1. Money-Value Divisions and Maximum 

Allowable Variations for Money-Value Computations on Mechanical Analog Computers.

N.4.3.2. Field Tests. – In the conduct of field tests to determine compliance with 

paragraph S.1.5.2. Money-Value Computations the maximum allowable variation in the indicated sales price 

shall be as shown in Table 1. Money-Value Divisions and Maximum Allowable Variations for Money-Value 

Computations on Mechanical Analog Computers.

(Added 1984)

N.5. Temperature Correction. – Adjustments shall be made for any changes in volume resulting from the 

differences in liquid temperatures between time of passage through the meter and time of volumetric determination in 

the prover. When adjustments are necessary, appropriate petroleum measurement tables should be used.

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T. Tolerances

T.1. Application.

T.1.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied 

to errors of underregistration and errors of overregistration, whether or not a device is equipped with an automatic 

temperature compensator.

T.2. Tolerance Values. – The maintenance and acceptance tolerances for normal and special tests shall be as shown 

in Table T.2. Accuracy Classes and Tolerances for LPG and Anhydrous Ammonia Liquid-Measuring Devices.

(Amended 2003)

Table T.2.

Accuracy Classes and Tolerances for LPG and Anhydrous Ammonia Liquid-Measuring Devices

Accuracy 

Class

Application Acceptance 

Tolerance

Maintenance 

Tolerance

Special Test 

Tolerance

1.0 Anhydrous ammonia, LPG 

(including vehicle-mounted meters) 0.6 % 1.0 % 1.0 % 

(Added 2003)

T.3. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within applicable tolerance. This tolerance does not apply to the test of the automatic 

temperature-compensating system. (Also see N.4.1.2. Repeatability Tests). 

(Added 1992) (Amended 1997 and 2001)

T.4. Automatic Temperature-Compensating Systems. – The difference between the meter error (expressed as a 

percentage) for results determined with and without the automatic temperature-compensating system activated shall 

not exceed:

(a) 1.0 % for mechanical automatic temperature-compensating systems; and

(b) 0.5 % for electronic automatic temperature-compensating systems.

The delivered quantities for each test shall be approximately the same size. The results of each test shall be within 

the applicable acceptance or maintenance tolerance.

(Added 1991) (Amended 1992, 1996, and 1997)

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Discharge Rate. – A device shall be so installed that the actual maximum discharge rate will not 

exceed the rated maximum discharge rate. If necessary, means for flow regulation shall be incorporated in the 

installation, in which case this shall be fully effective and automatic in operation.

UR.1.2. Length of Discharge Hose. – The length of the discharge hose on a stationary motor-fuel device shall 

not exceed 5.5 m (18 ft), measured from the outside of the housing of the device to the inlet end of the discharge 

nozzle, unless it can be demonstrated that a longer hose is essential to permit deliveries to be made to receiving 

vehicles or vessels. Unnecessarily remote location of a device shall not be accepted as justification for an 

abnormally long hose.

(Amended 1991)

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UR.2. Use Requirements.

UR.2.1. Return of Indication and Recording Elements to Zero. – The primary indicating elements (visual), 

and the primary recording elements when these are returnable to zero, shall be returned to zero before each 

delivery.

UR.2.2. Condition of Fill of Discharge Hose. – The discharge hose shall be completely filled with liquid 

before the “zero” condition is established prior to the start of a commercial delivery, whether this condition is 

established by resetting the primary indicating elements to zero indication or by recording the indications of the 

primary indicating elements. (Also see UR.2.1. Return of Indication and Recording Elements to Zero.)

UR.2.3. Vapor-Return Line. – During any metered delivery of liquefied petroleum gas from a supplier’s tank 

to a receiving container, there shall be no vapor-return line from the receiving container to the supplier’s tank:

(a) in the case of any receiving container to which normal deliveries can be made without the use of such 

vapor-return line; or

(b) in the case of any new receiving container when the ambient temperature is below 90 °F.

UR.2.4. Temperature Compensation.

UR.2.4.1. Use of Automatic Temperature Compensators. – If a device is equipped with an automatic 

temperature compensator, this shall be connected, operable, and in use at all times. Such automatic 

temperature compensator may not be removed, nor may a compensated device be replaced with an 

uncompensated device, without the written approval of the weights and measures authority having 

jurisdiction over the device.

UR.2.4.2. Temperature Compensated Sale. – All sales of liquefied petroleum gas in a liquid state, when 

the quantity is determined by an approved measuring system equipped with a temperature-compensating 

mechanism, or by weight and converted to liters or gallons, or by a calibrated container, shall be in terms of 

liters or the U.S. gallon of 231 in3 at 15 °C (60 °F).

(Added 1984)

UR.2.4.3. Invoices. – Any invoice based on a reading of a device that is equipped with an automatic 

temperature compensator or based on a weight converted to gallons, or based on the volume of a calibrated 

container, shall have shown thereon that the volume delivered has been adjusted to the volume at 15 °C 

(60 °F).

(Amended 1984)

UR.2.4.4. Automated Temperature-Compensating Systems. – Means for determining the temperature 

of measured liquid in an automatic temperature-compensating system shall be so designed and located that, 

in any “usual and customary” use of the system, the resulting indications and/or recorded representations are 

within applicable tolerances.

(Added 1987)

UR.2.5. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket printer 

until immediately before a delivery is begun, and in no case shall a ticket be in the device when the vehicle is in 

motion while on a public street, highway, or thoroughfare.

UR.2.6. Ticket Printer; Customer Ticket. – Vehicle-mounted metering systems shall be equipped with a 

ticket printer. The ticket printer shall be used for all sales; a copy of the ticket issued by the device shall be left 

with the customer at the time of delivery or as otherwise specified by the customer.

(Added 1992)

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Table of Contents

Section 3.33. Hydrocarbon Gas Vapor-Measuring Devices ............................................ 3-61

A. Application .................................................................................................................................................. 3-61

A.1. General................................................................................................................................................3-61

A.2. Exceptions...........................................................................................................................................3-61

A.3. Additional Code Requirements...........................................................................................................3-61

S. Specifications............................................................................................................................................... 3-61

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-61

S.1.1. Primary Elements..................................................................................................................3-61

S.1.2. Graduations...........................................................................................................................3-62

S.1.3. Indicators. .............................................................................................................................3-62

S.2. Design of Measuring Elements...........................................................................................................3-63

S.2.1. Pressure Regulation. .............................................................................................................3-63

S.2.2. Provision for Sealing.............................................................................................................3-63

S.2.3. Maintenance of Vapor State..................................................................................................3-63

S.2.4. Automatic Temperature Compensation. ...............................................................................3-63

S.3. Design of Discharge Lines..................................................................................................................3-63

S.3.1. Diversion of Measured Vapor...............................................................................................3-63

S.4. Marking Requirements........................................................................................................................3-63

S.4.1. Limitations of Use. ...............................................................................................................3-63

S.4.2. Discharge Rates. ...................................................................................................................3-64

S.4.3. Temperature Compensation. .................................................................................................3-64

S.4.4. Badge. ...................................................................................................................................3-64

N. Notes............................................................................................................................................................. 3-64

N.1. Test Medium.......................................................................................................................................3-64

N.2. Temperature and Volume Change. .....................................................................................................3-64

N.3. Test Drafts...........................................................................................................................................3-64

N.4. Test Procedures...................................................................................................................................3-64

N.4.1. Normal Tests.........................................................................................................................3-64

N.4.2. Special Tests. ........................................................................................................................3-65

N.5. Temperature Correction. .....................................................................................................................3-65

N.6. Frequency of Test. ..............................................................................................................................3-65

T. Tolerances.................................................................................................................................................... 3-65

T.1. Tolerance Values on Normal Tests and on Special Tests Other Than Low-Flame Tests. ..................3-65

T.2. Repeatability. ......................................................................................................................................3-66

UR. User Requirements ..................................................................................................................................... 3-66

UR.1. Installation Requirements. ..................................................................................................................3-66

UR.1.1. Capacity Rate........................................................................................................................3-66

UR.1.2. Leakage.................................................................................................................................3-66

UR.2. Use Requirements. ..............................................................................................................................3-66

UR.2.1. Automatic Temperature Compensation. ...............................................................................3-66

UR.2.2. Invoices.................................................................................................................................3-66

UR.2.3. Correction for Elevation. ......................................................................................................3-67

UR.2.4. Valves and Test Tee. .............................................................................................................3-67

UR.2.5. Use of Auxiliary Heated Vaporizer Systems. .......................................................................3-67

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Section 3.33. Hydrocarbon Gas Vapor-Measuring Devices1

A. Application

A.1. General. – This code applies to devices used for the measurement of hydrocarbon gas in the vapor state, such 

as propane, propylene, butanes, butylenes, ethane, methane, natural gas, and any other hydrocarbon gas/air mix.

(Amended 1984, 1986, 1988, and 1991)

A.2. Exceptions. – This code does not apply to:

(a) Liquid-measuring devices used for dispensing liquefied petroleum gases in liquid form. (Also see 

Section 3.32. Code for Liquefied Petroleum Gas and Anhydrous Ammonia Liquid-Measuring Devices.)

(b) Natural, liquefied petroleum, and manufactured-gas-vapor meters when these are operated in a public utility 

system.

(c) Mass flow meters. (Also see Section 3.37. Code for Mass Flow Meters.) 

(Added 1994)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Hydrocarbon Gas VaporMeasuring Devices shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A device shall be equipped with a primary indicating element and may also be 

equipped with a primary recording element.

S.1.1.2. Units. – A volume-measuring device shall indicate, and record if equipped to record, its deliveries 

in terms of cubic meters or cubic feet, or multiple or decimal subdivisions of cubic meters or cubic feet.

(Amended 1972 and 1991)

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded 

delivery if the device is equipped to record, shall not exceed:

(a) 1 m3 (1000 dm3

) (100 ft3) when the maximum rated gas capacity is less than 280 m3/h (10 000 ft3/h);

(b) 10 m3 (1000 ft3

) when the maximum rated gas capacity is 280 m3/h (10 000 ft3/h) up to, but not 

including, 1700 m3

/h (60 000 ft3/h); and

(c) 100 m3 (10 000 ft3

) when the maximum rated gas capacity is 1700 m3/h (60 000 ft3/h) or more.

(Amended 1972, 1988, and 1991)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall advance digitally or continuously and be susceptible to advancement only by the mechanical 

operation of the device.

 

1

Title changed 1986.

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S.1.1.5. Proving Indicator. – Devices rated less than 280 m3

/h (10 000 ft3/h) gas capacity shall be 

equipped with a proving indicator measuring 0.025, 0.05, 0.1, 0.2, or 0.25 m3 per revolution, (1, 2, 5, or 10 ft3

per revolution) for testing the meter. Devices with larger capacities shall be equipped as follows:

(a) Devices rated 280 m3 (10 000 ft3

) up to but not including 1700 m3/h (60 000 ft3/h) gas capacity shall 

be equipped with a proving indicator measuring not greater than 1 m3 (100 ft3

) per revolution.

(b) Devices rated 1700 m3

/h (60 000 ft3/h) gas capacity or more shall be equipped with a proving 

indicator measuring not more than 10 m3 (1000 ft3

) per revolution.

The test circle of the proving indicator shall be divided into ten equal parts. Additional subdivisions of 

one or more of such equal parts may be made.

(Amended 1973 and 1988)

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and in no case should it exceed 1.0 mm 

(0.04 in) for indicating elements and 0.5 mm (0.02 in) for proving circles.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall be not less than 1.0 mm 

(0.04 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used.

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than the: 

(a) width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

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S.2. Design of Measuring Elements.

S.2.1. Pressure Regulation. – The vapor should be measured at a normal gauge pressure (psig) of:

(Amended 1991)

(a) 2740 Pa ± 685 Pa (11 in of water column (0.40 psig) ± 2.75 in of water column (0.10 psig)) for liquefied 

petroleum gas vapor; or

(b) 1744 Pa ± 436 Pa (7 in of water column (0.25 psig) ± 1.75 in of water column (0.06 psig)) for natural 

and manufactured gas.

When vapor is measured at a pressure other than what is specified above for the specific product, a volume 

multiplier shall be applied within the meter or to the billing invoice based on the following equation:

AAP + GP

VPM = AAP + NGP 

Where:

VPM = Volume pressure multiplier

AAP = Assumed atmospheric pressure in Pa or psia

GP = Gauge pressure in Pa or psig

NGP = Normal gauge pressure in Pa or psig

The assumed atmospheric pressure is to be taken from Tables 2 and 2M.

When liquefied petroleum gas vapor is measured at a pressure of 6900 Pa (1 psig) or more, the delivery pressure 

shall be maintained within ± 1725 Pa (± 0.25 psig). 

Pressure variations due to regulator lock off shall not increase the operating pressure by more than 25 %.

(Amended 1980, 1984, and 1991)

S.2.2. Provision for Sealing. – Adequate provision shall be made for applying security seals in such a manner 

that no adjustment or interchange may be made of any measurement element.

S.2.3. Maintenance of Vapor State. – A device shall be so designed and installed that the product being 

measured will remain in a vapor state during passage through the meter.

S.2.4. Automatic Temperature Compensation. – A device may be equipped with an adjustable automatic 

means for adjusting the indication and registration of the measured volume of vapor product to the volume at 

15 °C (60 °F).

S.3. Design of Discharge Lines.

S.3.1. Diversion of Measured Vapor. – No means shall be provided by which any measured vapor can be 

diverted from the measuring chamber of the meter or the discharge line therefrom.

S.4. Marking Requirements.

S.4.1. Limitations of Use. – If a device is intended to measure accurately only products having particular 

properties, or to measure accurately only under specific installation or operating conditions, or to measure 

accurately only when used in conjunction with specific accessory equipment, these limitations shall be clearly 

and permanently stated on the device.

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S.4.2. Discharge Rates. – A device shall be marked to show its rated gas capacity in cubic meters per hour or 

cubic feet per hour.

S.4.3. Temperature Compensation. – If a device is equipped with an automatic temperature compensator, 

this shall be indicated on the badge or immediately adjacent to the badge of the device and on the register.

S.4.4. Badge. – A badge affixed in a prominent position on the front of the device shall show the manufacturer’s 

name, serial number and model number of the device, and capacity rate of the device for the particular products 

that it was designed to meter as recommended by the manufacturer.

N. Notes

N.1. Test Medium. – The device shall be tested with air or the product to be measured.

(Amended 1991)

N.2. Temperature and Volume Change. – Care should be exercised to reduce to a minimum any volume changes. 

The temperature of the air, bell-prover oil, and the meters under test should be within 1 °C (2 °F) of one another. The 

devices should remain in the proving room for at least 16 hours before starting any proving operations to allow the 

device temperature to approximate the temperature of the proving device.

N.3. Test Drafts. – Except for low-flame tests, test drafts shall be at least equal to one complete revolution of the 

largest capacity proving indicator, and shall in no case be less than 0.05 m3 or 2 ft3

. All flow rates shall be controlled 

by suitable outlet orifices.

(Amended 1973 and 1991)

Table 1.

Capacity of Low-Flow Test Rate Orifices with Respect to Device Capacity

Metric Units U.S. Customary Units

Rated Capacity Low-Flow Test Rate Rated Capacity Low-Flow Test Rate

Up to and including 7 m3/h 0.007 m3/h Up to and including 250 ft3/h 0.25 ft3/h

Over 7 m3/h up to and including 

14 m3/h 0.014 m3

/h Over 250 ft3

/h up to and 

including 500 ft3/h 0.50 ft3

/h

Over 14 m3/h 0.1 % of capacity rate Over 500 ft3/h 0.1 % of capacity rate

N.4. Test Procedures. – If a device is equipped with an automatic temperature compensator, the proving device 

reading shall be corrected to 15 °C (60 °F), using an approved table.

(Amended 1972)

N.4.1. Normal Tests. – The normal test of a device shall be made at a rate not to exceed the capacity rate given 

on the badge of the meter.

(Amended 1988)

N.4.1.1. Automatic Temperature Compensation. – If a device is equipped with an automatic 

temperature compensator, the quantity of the test draft indication of the standard shall be corrected to 15 °C 

(60 °F).

N.4.1.2. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

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factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2002)

N.4.2. Special Tests. – “Special” tests shall be made to develop the operating characteristics of a device and 

any special elements and accessories attached to or associated with the device. Any test except as set forth in 

N.4.1. Normal Tests shall be considered a special test.

N.4.2.1. Slow Test. – The device shall be tested at a rate not less than 20 % of the marked capacity rate, 

or (at the check rate) not less than the minimum flow rate if marked on the device, whichever is less.

(Amended 1988)

N.4.2.2. Low-Flame Test. – The device shall be tested at an extremely low-flow rate as given in Table 1. 

The test shall consist of passing air at a pressure of 375 Pa (1.5 in water column) through the meter for not 

less than 60 minutes. The meter shall continue to advance at the conclusion of the test period.

(Amended 1990 and 1991)

N.4.2.3. Pressure Regulation Test. – On devices operating at a pressure of 6900 Pa (1 psig) or more, a 

pressure regulation test shall be made at both the minimum and maximum use load to determine the proper 

operation of the regulator and the proper sizing of the piping and dispensing equipment. These tests may 

include a test of 24 hours during which the pressure is recorded.

(Added 1984)

N.5. Temperature Correction. – Corrections shall be made for any changes in volume resulting from the difference 

in air temperatures between time of passage through the device and time of volumetric determination in the proving

device.

N.6. Frequency of Test. – A hydrocarbon gas vapor-measuring device shall be tested before installation and allowed 

to remain in service for 10 years from the time last tested without being retested, unless a test is requested by:

(a) the purchaser of the product being metered;

(b) the seller of the product being metered; or

(c) the weights and measures official.

T. Tolerances

T.1. Tolerance Values on Normal Tests and on Special Tests Other Than Low-Flame Tests. – Maintenance 

and acceptance tolerances for normal and special tests for hydrocarbon gas vapor-measuring devices shall be as shown 

in Table T.1. Accuracy Classes and Tolerances for Hydrocarbon Gas Vapor-Measuring Devices.

(Amended 1981 and 2003)

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Table T.1. 

Accuracy Classes and Tolerances for Hydrocarbon Gas Vapor-Measuring Devices

Accuracy Class Application Acceptance 

Tolerance

Maintenance 

Tolerance

3.0 Gases at low pressure

(for example, LPG vapor)

Overregistration 1.5 % 1.5 % 

Underregistration 3.0 % 3.0 % 

(Added 2003)

T.2. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 0.9 % and the results of each test shall be within the applicable 

tolerance. (Also see N.4.1.2. Repeatability Test.)

(Added 2002)

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Capacity Rate. – A device shall be so installed that the actual maximum flow rate will not exceed the 

capacity rate except for short durations. If necessary, means for flow regulation shall be incorporated in the 

installation, in which case this shall be fully effective and automatic in operation.

UR.1.2. Leakage. – The metering system shall be installed and maintained as a pressure-tight and leak-free 

system.

UR.2. Use Requirements.

UR.2.1. Automatic Temperature Compensation. – A compensated device may not be replaced with an 

uncompensated device without the written approval of the weights and measures authority having jurisdiction 

over the device.

UR.2.2. Invoices. – A customer purchasing hydrocarbon gas measured by a vapor meter shall receive from the 

seller an invoice for each billing period. The invoice shall clearly and separately show the following:

(a) The opening and closing meter readings and the dates of those readings.

(b) The altitude correction factor.

(c) The total cubic meters (cubic feet) billed, corrected for elevation.

(d) The charge per cubic meter (cubic foot) after correction for elevation.

(e) All periodic charges independent of the measured gas, such as meter charges, meter reading fees, service 

charges or a minimum charge for a minimum number of cubic meters (cubic feet).

(f) The total charge for the billing period.

If the vapor meter is equipped with an automatic temperature compensator, or any other means are used to 

compensate for temperature, the invoice shall show that the volume has been adjusted to the volume at 15 °C 

(60 °F).

(Amended 1988 and 1991)

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UR.2.3. Correction for Elevation. – The metered volume of gas shall be corrected for changes in the 

atmospheric pressure with respect to elevation to the standard pressure of 101.56 kPa (14.73 psia). The 

appropriate altitude correction factor from Table 2M. Corrections for Altitude, Metric Units 

or Table 2. Corrections for Altitude, U.S. Customary Units shall be used. (The table is modified from NIST 

Handbook 117.)

(Amended 1988)

Elevation correction factors (ACF) were obtained by using the following equation:

GP of gas + AAP

ACF = base pressure

Where:

GP = gauge pressure

AAP = assumed atmospheric pressure 

base pressure = 101.560 kPa = 14.73 psia

2740 Pa = 11 in of water column = 0.397 psig

1744 Pa = 7 in of water column = 0.253 psig

(Added 1988)

UR.2.4. Valves and Test Tee. – All gas meter installations shall be provided with a shut-off valve located 

adjacent to and on the inlet side of the meter. In the case of a single meter installation utilizing a liquefied 

petroleum gas tank, the tank service valve may be used in lieu of the shut-off valve. All gas meter installations 

shall be provided with a test tee located adjacent to and on the outlet side of the meter.

[Nonretroactive as of January 1, 1990]

(Added 1989)

UR.2.5. Use of Auxiliary Heated Vaporizer Systems. – Automatic temperature compensation shall be used 

on hydrocarbon gas vapor meters equipped with an auxiliary heated vaporizer system unless there is sufficient 

length of underground piping to provide gas at a uniform temperature to the meter inlet. When required by 

weights and measures officials, a thermometer well (appropriately protected against freezing) shall be installed 

immediately up-stream of the meter.

(Added 1990)

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Table 2M. 

Corrections for Altitude, Metric Units

Elevation

(meters)

Altitude

Correction

Factor

Assumed

Atmospheric

Pressure

Assumed Atmospheric

Pressure Plus

Gauge Pressure

2.74 kPa

Gauge

Pressure

1.74 kPa

Gauge

Pressure

(kPa)

2.74 kPa

Gauge

Pressure

1.74 kPa

Gauge

Pressure

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

− 50 to

120 to

300 to

470 to

650 to

830 to

1020 to

1210 to

1400 to

1590 to

1790 to

2000 to

2210 to

2420 to

2640 to

2860 to

3080 to

3320 to

3560 to

3800 to

4050 to

4310 to

120

300

470

650

830

1020

1210

1400

1590

1790

2000

2210

2420

2640

2860

3080

3320

3560

3800

4050

4310

4580

1.02

1.00

0.98

0.96

0.94

0.92

0.90

0.88

0.86

0.84

0.82

0.80

0.78

0.76

0.74

0.72

0.70

0.68

0.66

0.64

0.62

0.60

1.01

0.99

0.97

0.95

0.93

0.91

0.89

0.87

0.85

0.83

0.81

0.79

0.77

0.75

0.73

0.71

0.69

0.67

0.65

0.63

0.61

0.59

100.85

98.82

96.79

94.76

92.73

90.70

88.66

86.63

84.60

82.57

80.54

78.51

76.48

74.45

72.41

70.38

68.35

66.32

64.29

62.26

60.23

58.20

103.59

101.56

99.53

97.50

95.47

93.44

91.40

89.37

87.34

85.31

83.28

81.25

79.22

77.19

75.15

73.12

71.09

69.06

67.03

65.00

62.97

60.94

102.58

100.54

98.51

96.48

94.45

92.42

90.39

88.36

86.33

84.29

82.26

80.23

78.20

76.17

74.15

72.12

70.08

68.05

66.01

63.98

61.95

59.92

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Table 2. 

Corrections for Altitude, U.S. Customary Units

Elevation

(feet)

Altitude

Correction

Factor

Assumed

Atmospheric

Pressure

Assumed Atmospheric 

Pressure Plus Gauge 

Pressure

11 inch 

WC

7 inch 

WC (psia) 11 inch WC(psia)

7 inch WC

(psia)

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

above

− 150 to

400 to

950 to

1 550 to

2 100 to

2 700 to

3 300 to

3 950 to

4 550 to

5 200 to

5 850 to

6 500 to

7 200 to

7 900 to

8 600 to

9 350 to

10 100 to

10 850 to

11 650 to

12 450 to

13 250 to

14 100 to

400

950

1 550

2 100

2 700

3 300

3 950

4 550

5 200

5 850

6 500

7 200

7 900

8 600

9 350

10 100

10 850

11 650

12 450

13 250

14 100

14 950

1.02

1.00

0.98

0.96

0.94

0.92

0.90

0.88

0.86

0.84

0.82

0.80

0.78

0.76

0.74

0.72

0.70

0.68

0.66

0.64

0.62

0.60

1.01

0.99

0.97

0.95

0.93

0.91

0.89

0.87

0.85

0.83

0.81

0.79

0.77

0.75

0.73

0.71

0.69

0.67

0.65

0.63

0.61

0.59

14.64

14.35

14.05

13.76

13.46

13.17

12.87

12.58

12.28

11.99

11.69

11.40

11.10

10.81

10.51

10.22

9.92

9.63

9.33

9.04

8.75

8.45

15.04

14.74

14.45

14.15

13.86

13.56

13.27

12.97

12.68

12.38

12.09

11.79

11.50

11.20

10.91

10.61

10.32

10.03

9.73

9.44

9.14

8.85

14.89

14.60

14.30

14.01

13.71

13.42

13.12

12.83

12.53

12.24

11.94

11.65

11.35

11.06

10.76

10.47

10.17

9.88

9.58

9.29

9.00

8.70

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Table of Contents

Section 3.34. Cryogenic Liquid-Measuring Devices ......................................................... 3-73

A. Application ...................................................................................................................................................3-73

A.1. General................................................................................................................................................3-73

A.2. Exceptions...........................................................................................................................................3-73

A.3. Additional Code Requirements...........................................................................................................3-73

S. Specifications................................................................................................................................................3-73

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-73

S.1.1. Primary Elements..................................................................................................................3-73

S.1.2. Graduations...........................................................................................................................3-74

S.1.3. Indicators. .............................................................................................................................3-74

S.1.4. Computing-Type Device.......................................................................................................3-75

S.2. Design of Measuring Elements...........................................................................................................3-75

S.2.1. Vapor Elimination.................................................................................................................3-75

S.2.2. Directional Flow Valves. ......................................................................................................3-75

S.2.3. Maintenance of Liquid State.................................................................................................3-75

S.2.4. Automatic Temperature or Density Compensation...............................................................3-76

S.2.5. Provision for Sealing.............................................................................................................3-76

S.3. Design of Discharge Lines and Discharge Line Valves......................................................................3-77

S.3.1. Diversion of Measured Liquid. .............................................................................................3-77

S.3.2. Discharge Hose. ....................................................................................................................3-77

S.4. Marking Requirements........................................................................................................................3-77

S.4.1. Limitation of Use. .................................................................................................................3-77

S.4.2. Discharge Rates. ...................................................................................................................3-78

S.4.3. Temperature or Density Compensation. ...............................................................................3-78

N. Notes..............................................................................................................................................................3-78

N.1. Test Liquid..........................................................................................................................................3-78

N.2. Vaporization and Volume Change......................................................................................................3-78

N.3. Test Drafts...........................................................................................................................................3-78

N.3.1. Gravimetric Test. ..................................................................................................................3-78

N.3.2. Transfer Standard Test..........................................................................................................3-78

N.4. Density................................................................................................................................................3-78

N.5. Testing Procedures..............................................................................................................................3-79

N.5.1. Normal Tests.........................................................................................................................3-79

N.5.2. Special Tests. ........................................................................................................................3-79

N.6. Temperature Correction. .....................................................................................................................3-80

N.7. Automatic Temperature or Density Compensation.............................................................................3-80

T. Tolerances.....................................................................................................................................................3-80

T.1. Application..........................................................................................................................................3-80

T.1.1. To Underregistration and to Overregistration. ......................................................................3-80

T.2. Tolerance Values. ...............................................................................................................................3-80

T.3. On Tests Using Transfer Standards. ...................................................................................................3-80

T.4. Repeatability. ......................................................................................................................................3-80

UR. User Requirements ......................................................................................................................................3-80

UR.1. Installation Requirements. ..................................................................................................................3-80

UR.1.1. Discharge Rate......................................................................................................................3-80

UR.1.2. Length of Discharge Hose. ...................................................................................................3-80

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UR.1.3. Maintenance of Liquid State.................................................................................................3-81

UR.2. Use Requirements. ..............................................................................................................................3-81

UR.2.1. Return of Indicating and Recording Elements to Zero. ........................................................3-81

UR.2.2. Condition of Discharge System. ...........................................................................................3-81

UR.2.3. Vapor Return Line. ...............................................................................................................3-81

UR.2.4. Drainage of Discharge Line. .................................................................................................3-81

UR.2.5. Conversion Factors. ..............................................................................................................3-81

UR.2.6. Temperature or Density Compensation. ...............................................................................3-81

UR.2.7. Pressure of Tanks with Volumetric Metering Systems without Temperature 

Compensation. ......................................................................................................................3-82

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Section 3.34. Cryogenic Liquid-Measuring Devices

A. Application

A.1. General. – This code applies to devices used for the measurement of cryogenic liquids such as, but not limited 

to oxygen, nitrogen, hydrogen, and argon.

(Amended 1986 and 1995)

A.2. Exceptions. – This code does not apply to the following:

(a) Devices used for dispensing liquefied petroleum gases (for which see Section 3.32. Code for Liquefied 

Petroleum Gas and Anhydrous Ammonia Liquid-Measuring Devices).

(b) Devices used solely for dispensing a product in connection with operations in which the amount dispensed 

does not affect customer charges.

(c) Devices used solely for dispensing liquefied natural gas.

(d) Mass flow meters. (Also see Section 3.37. Code for Mass Flow Meters.) 

(Added 1994)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Cryogenic Liquid- Measuring 

Devices shall meet the requirements of Section 1.10. General Code. 

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A device shall be equipped with a primary indicating element and may also be 

equipped with a primary recording element.

S.1.1.2. Units. – A device shall indicate and record, if equipped to record, its deliveries in terms of: 

kilograms or pounds; liters or gallons of liquid at the normal boiling point of the specific cryogenic product; 

cubic meters (cubic feet) of gas at a normal temperature of 21 °C (70 °F) and an absolute pressure of 

101.325 kPa (14.696 psia); or decimal subdivisions or multiples of the measured units cited above.

(Amended 2002)

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded 

delivery, if the device is equipped to record, shall not exceed the equivalent of:

(a) for small delivery devices: 

(1) 1 L; 

(2) 0.1 gal; 

(3) 1 kg; 

(4) 1 lb; 

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(5) 0.1 m3 of gas; or

(6) 10 ft3 of gas. 

(b) for large delivery devices: 

(1) 10 L; 

(2) 1 gal; 

(3) 10 kg; 

(4) 10 lb; 

(5) 1 m3 of gas; or

(6) 100 ft3 of gas. 

(Amended 2002)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only by the normal operation of the device. However, a device 

may be cleared by advancing its elements to zero, but only if:

(a) the advancing movement, once started, cannot be stopped until zero is reached; or

(b) in the case of indicating elements only, such elements are automatically obscured until the elements 

reach the correct zero position.

S.1.1.5. Return to Zero. – Primary indicating and recording elements shall be readily returnable to a 

definite zero indication. Means shall be provided to prevent the return of primary indicating elements and of 

primary recording elements beyond their correct zero position.

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) in width.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall be no less than 1.0 mm (0.04 in). 

If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

(Also see S.1.3.6. Travel of Indicator.) 

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

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the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than the: 

(a) width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effect shall be reduced to the practicable minimum.

S.1.3.6. Travel of Indicator. – If the most sensitive element of the primary indicating element uses an 

indicator and graduations, the relative movement of these parts corresponding to the smallest indicated value 

shall be not less than 0.5 mm (0.20 in).

S.1.4. Computing-Type Device.

S.1.4.1. Printed Ticket. – Any printed ticket issued by a device of the computing type on which there is 

printed the total computed price shall have printed clearly thereon also the total quantity of the delivery and 

the price per unit.

S.1.4.2. Money-Value Computations. – Money-value computations shall be of the full-computing type 

in which the money-value at a single unit price, or at each of a series of unit prices, shall be computed for 

every delivery within either the range of measurement of the device or the range of the computing elements, 

whichever is less. Value graduations shall be supplied and shall be accurately positioned. The total price 

shall be computed on the basis of the quantity indicated when the value of the smallest division indicated is 

equal to or less than the values specified in S.1.1.3. Value of Smallest Unit.

S.1.4.3. Money-Values, Mathematical Agreement. – Any digital money-value indication and any

recorded money-value on a computing type device shall be in mathematical agreement with its associated 

quantity indication or representation to within 1 cent of money-value. 

S.2. Design of Measuring Elements.

S.2.1. Vapor Elimination. – A measuring system shall be equipped with an effective vapor eliminator or other 

effective means to prevent the measurement of vapor that will cause errors in excess of the applicable tolerances. 

(Also see Section T. Tolerances.) 

S.2.2. Directional Flow Valves. – A valve or valves or other effective means, automatic in operation, to 

prevent the reversal of flow shall be installed in or adjacent to the measuring device.

(Amended 1978)

S.2.3. Maintenance of Liquid State. – A device shall be so designed that the product being measured will 

remain in a liquid state during passage through the device.

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S.2.4. Automatic Temperature or Density Compensation. – A device shall be equipped with automatic 

means for adjusting the indication and/or recorded representation of the measured quantity of the product, to 

indicate and/or record in terms of: kilograms or pounds; or liters or gallons of liquid at the normal boiling point 

of the specific cryogenic product; or the equivalent cubic meters (cubic feet) of gas at a normal temperature of 

21 C (70 F) and an absolute pressure of 101.325 kPa (14.696 lb/in2 absolute). When a compensator system 

malfunctions, the indicating and recording elements may indicate and record in uncompensated volume if the 

mode of operation is clearly indicated, e.g., by a marked annunciator, recorded statement, or other obvious 

means.*

[*Nonretroactive as of January 1, 1992]

(Amended 1991 and 2002)

S.2.5. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or for physically applying a security seal in such a manner that requires the security seal to be 

broken before an adjustment or interchange may be made of:

(a) any measuring or indicating element; 

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries; 

(c) any automatic temperature or density compensating system; and

(d) any metrological parameter that will affect the metrological integrity of the device or system.

When applicable, any adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

[Audit trails shall use the format set forth in Table S.2.5. Categories of Device and Methods of Sealing]* 

[*Nonretroactive as of January 1, 1995]

(Amended 2006)

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Table S.2.5. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but access 

is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

The hardware enabling access for remote 

communication must be on-site. The hardware must be 

sealed using a physical seal or an event counter for 

calibration parameters and an event counter for 

configuration parameters. The event counters may be 

located either at the individual measuring device or at

the system controller; however, an adequate number of 

counters must be provided to monitor the calibration 

and configuration parameters of the individual devices 

at a location. If the counters are located in the system 

controller rather than at the individual device, means 

must be provided to generate a hard copy of the 

information through an on-site device.

Category 3: Remote configuration capability access may 

be unlimited or controlled through a software switch (e.g., 

password). 

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

An event logger is required in the device; it must 

include an event counter (000 to 999), the parameter 

ID, the date and time of the change, and the new value 

of the parameter. A printed copy of the information 

must be available through the device or through 

another on-site device. The event logger shall have a 

capacity to retain records equal to 10 times the number 

of sealable parameters in the device, but not more than

1000 records are required. (Note: Does not require 

1000 changes to be stored for each parameter.)

[Nonretroactive as of January 1, 1995] 

(Table Added 2006)

S.3. Design of Discharge Lines and Discharge Line Valves.

S.3.1. Diversion of Measured Liquid. – No means shall be provided by which any measured liquid can be 

diverted from the measuring chamber of the device or the discharge line therefrom, except that a manually 

controlled outlet that may be opened for purging or draining the measuring system shall be permitted. Effective 

means shall be provided to prevent the passage of liquid through any such outlet during normal operation of the 

device and to indicate clearly and unmistakably when the valve controls are so set as to permit passage of liquid 

through such outlet.

S.3.2. Discharge Hose. – The discharge hose of a measuring system shall be of the completely draining 

dry-hose type.

S.4. Marking Requirements.

S.4.1. Limitation of Use. – If a measuring system is intended to measure accurately only liquids having 

particular properties, or to measure accurately only under specific installation or operating conditions, or to 

measure accurately only when used in conjunction with specific accessory equipment, these limitations shall be 

clearly and permanently marked on the device.

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S.4.2. Discharge Rates. – A meter shall be marked to show its designed maximum and minimum discharge 

rates.

S.4.3. Temperature or Density Compensation. – Devices equipped with an automatic temperature or density 

compensator, shall be clearly and conspicuously marked on the primary indicating elements, recording elements, 

and recorded representations to show that the quantity delivered has been adjusted to the conditions specified in 

S.2.4. Automatic Temperature or Density Compensation.

N. Notes

N.1. Test Liquid. – A meter shall be tested with the liquid to be commercially measured except that, in a type 

evaluation examination, nitrogen may be used.

N.2. Vaporization and Volume Change. – Care shall be exercised to reduce to a minimum vaporization and volume 

changes. When testing by weight, the weigh tank and transfer systems shall be pre-cooled to liquid temperature prior 

to the start of the test to avoid the venting of vapor from the vessel being weighed.

N.3. Test Drafts.

N.3.1. Gravimetric Test. – Weight test drafts shall be equal to at least the amount delivered by the device in 

2 minutes at its maximum discharge rate, and shall in no case be less than 907 kg (2000 lb).

N.3.2. Transfer Standard Test. – When comparing a meter with a calibrated transfer standard, the test draft 

shall be equal to at least the amount delivered by the device in two minutes at its maximum discharge rate, and 

shall in no case be less than 180 L (50 gal) or equivalent thereof. When testing uncompensated volumetric meters 

in a continuous recycle mode, appropriate corrections shall be applied if product conditions are abnormally 

affected by this test mode.

(Amended 1976)

N.4. Density. – Temperature and pressure of the metered test liquid shall be measured during the test for the 

determination of density or volume correction factors when applicable. For Liquid Density and Volume Correction 

Factors (with respect to temperature and pressure) the publications shown in Table N.4. Density or Volume Correction 

Factors shall apply.

(Amended 1986 and 2004)

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Table N.4. 

Density or Volume Correction Factors

Cryogenic Liquid Publication

Argon

Tegeler, Ch., Span, R., Wagner, W. “A New Equation of State for Argon Covering the 

Fluid Region for Temperatures from the Melting Line to 700 K at Pressures up to 

1000 Mpa.” J. Phys. Chem. Ref. Data, 28(3):779-850, 1999.

Ethylene

Smukala, J., Span, R., Wagner, W. “New Equation of State for Ethylene Covering the 

Fluid Region for Temperatures from the Melting Line to 450 k at Pressures up to 

300 Mpa.” J. Phys. Chem. Ref. Data, 29(5):1053-1122, 2000.

Nitrogen 

Span, R., Lemmon, E.W., Jacobsen, R.T, Wagner, W., and Yokozeki, A. “A Reference 

Thermodynamic Property Formulation for Nitrogen.” J. Phys. Chem. Ref. Data, 

Volume 29, Number 6, pp. 1361-1433, 2000.

Oxygen Schmidt, R., Wagner, W. “A New Form of the Equation of State for Pure Substances 

and its Application to Oxygen.” Fluid Phase Equilib., 19:175-200, 1985

Hydrogen

Leachman, J. W., Jacobsen, R. T., Lemmon, E.W., and Penoncello, S.G. “Fundamental 

Equations of State for Parahydrogen, Normal Hydrogen, and Orthohydrogen” J. Phys. 

Chem. Ref. Data, Volume 38, Number 3, pp. 565, 2009.

Note: A complete database program containing all of the most recent equations for calculating density for various 

cryogenic liquids is available at www.nist.gov/srd/nist23.cfm. There is a fee for download of this database.

(Added 2004)

N.5. Testing Procedures.

N.5.1. Normal Tests. – The “normal” tests of a device shall be made over a range of discharge rates that may 

be anticipated under the conditions of installation.

N.5.1.1. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2001)

N.5.2. Special Tests. – Any test except as set forth in N.5.1. Normal Tests shall be considered a “special” test. 

Tests shall be conducted, if possible, to evaluate any special elements or accessories attached to or associated 

with the device. A device shall be tested at a minimum discharge rate of:

(a) 50 % of the maximum discharge rate developed under the conditions of installation, or the minimum 

discharge rate marked on the device, whichever is less; or

(b) the lowest discharge rate practicable under conditions of installation.

Special tests may be conducted to develop any characteristics of the device that are not normally anticipated under 

the conditions of installation.

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N.6. Temperature Correction. – Corrections shall be made for any changes in volume resulting from the 

differences in liquid temperature between time of passage through the meter and time of volumetric determination of 

test draft.

N.7. Automatic Temperature or Density Compensation. – When a device is equipped with an automatic 

temperature or density compensator, the compensator shall be tested by comparing the quantity indicated or recorded 

by the device (with the compensator connected and operating) with the actual delivered quantity corrected to the 

normal boiling point of the cryogenic product being measured or to the normal temperature and pressure as applicable.

T. Tolerances

T.1. Application.

T.1.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied 

to errors of underregistration and errors of overregistration.

T.2. Tolerance Values. – The maintenance and acceptance tolerances for normal and special tests shall be as shown 

in Table T.2. Accuracy Classes and Tolerances for Cryogenic Liquid-Measuring Devices.

(Amended 2003)

Table T.2. 

Accuracy Classes and Tolerances for Cryogenic Liquid-Measuring Devices

Accuracy 

Class Application

Acceptance 

Tolerance

Maintenance 

Tolerance

Special Test 

Tolerance

2.5 Cryogenic products; liquefied compressed gases 

other than liquid carbon dioxide 1.5 % 2.5 % 2.5 %

(Added 2003)

T.3. On Tests Using Transfer Standards. – To the basic tolerance values that would otherwise be applied, there 

shall be added an amount equal to two times the standard deviation of the applicable transfer standard when compared 

to a basic reference standard.

(Added 1976)

T.4. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within the applicable tolerance. Also see N.5.1.1. Repeatability Tests.

(Added 2001)

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Discharge Rate. – A device shall be so installed that the actual maximum discharge rate will not 

exceed the rated maximum discharge rate. If necessary, means for flow regulation shall be incorporated in the 

installation.

UR.1.2. Length of Discharge Hose. – The discharge hose shall be of such a length and design as to keep 

vaporization of the liquid to a minimum.

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UR.1.3. Maintenance of Liquid State. – A device shall be so installed and operated that the product being 

measured shall remain in the liquid state during passage through the meter.

UR.2. Use Requirements.

UR.2.1. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual) 

and the primary recording elements shall be returned to zero immediately before each delivery.

UR.2.2. Condition of Discharge System. – The discharge system, up to the measuring element, shall be 

precooled to liquid temperatures before a “zero” condition is established prior to the start of a commercial 

delivery.

UR.2.3. Vapor Return Line. – A vapor return line shall not be used during a metered delivery.

(Amended 1976)

UR.2.4. Drainage of Discharge Line. – On a dry-hose system, upon completion of a delivery, the vendor shall 

leave the discharge line connected to the receiving container with the valve adjacent to the meter in the closed 

position and the valve at the discharge line outlet in the open position for a period of at least: 

(a) 1 minute for small delivery devices; and

(b) 3 minutes for large delivery devices

to allow vaporization of some product in the discharge line to force the remainder of the product in the line to 

flow into the receiving container.

(Amended 1976)

UR.2.5. Conversion Factors. – Established conversion values (Also see references in Table N.4. Density or 

Volume Correction Factors.) shall be used whenever metered liquids are to be billed in terms of:

(a) kilograms or pounds based on a meter indication of liters, gallons, cubic meters of gas, or cubic feet of 

gas; 

(b) cubic meters or cubic feet of gas based on a meter indication of liters or gallons, kilograms, or pounds; 

or

(c) liters or gallons based on a meter indication of kilograms or pounds, cubic meters of gas or cubic feet of 

gas.

All sales of cryogenics shall be based on either kilograms or pounds, liters or gallons of liquid at NBP1

, cubic 

meters of gas or cubic feet of gas at NTP1

. 

(Amended 1986)

UR.2.6. Temperature or Density Compensation.

UR.2.6.1. Use of Automatic Temperature or Density Compensators. – If a device is equipped with an 

automatic temperature or density compensator, this shall be connected, operable, and in use at all times. Such 

automatic temperature or density compensator may not be removed, nor may a compensated device be 

replaced with an uncompensated device, without the written approval of the weights and measures authority 

having jurisdiction over the device.

UR.2.6.2. Tickets or Invoices. – Any written invoice or printed ticket based on a reading of a device that 

is equipped with an automatic temperature or density compensator shall have shown thereon that the quantity 

 

1 See Appendix D, Definitions.

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delivered has been adjusted to the quantity at the NBP of the specific cryogenic product or the equivalent 

volume of gas at NTP.

UR.2.6.3. Printed Ticket. – Any printed ticket issued by a device of the computing type on which there 

is printed the total computed price, the total quantity of the delivery, or the price per unit, shall also show the 

other two values (either printed or in clear hand script).

UR.2.6.4. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket 

printer until immediately before a delivery is begun, and in no case shall a ticket be in the device when the 

vehicle is in motion while on a public street, highway, or thoroughfare.

UR.2.7. Pressure of Tanks with Volumetric Metering Systems without Temperature Compensation. – 

When the saturation pressure of the product in the vendor’s tank exceeds 240 kPa (35 psia), a correction shall be 

applied to the written invoice or printed ticket using the appropriate tables as listed in Table N.4. Density or 

Volume Correction Factors; or the saturation pressure shall be reduced to 207 kPa (30 psia) (if this can be safely 

accomplished) prior to making a delivery.

(Added 1976)

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Table of Contents

Section 3.35. Milk Meters ................................................................................................... 3-85

A. Application .................................................................................................................................................. 3-85

A.1. General................................................................................................................................................3-85

A.2. Exceptions...........................................................................................................................................3-85

A.3. Additional Code Requirements...........................................................................................................3-85

S. Specifications............................................................................................................................................... 3-85

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-85

S.1.1. Primary Elements..................................................................................................................3-85

S.1.2. Graduations...........................................................................................................................3-86

S.1.3. Indicators. .............................................................................................................................3-86

S.1.4. Computing-Type Devices. ....................................................................................................3-87

S.2. Design of Measuring Elements...........................................................................................................3-87

S.2.1. Vapor Elimination.................................................................................................................3-87

S.2.2. Maintaining Flooded Condition............................................................................................3-87

S.2.3. Provision for Sealing.............................................................................................................3-87

S.2.4. Directional Flow Valves. ......................................................................................................3-88

S.3. Design of Intake Lines. .......................................................................................................................3-88

S.3.1. Diversion of Liquid to be Measured. ....................................................................................3-88

S.3.2. Intake Hose. ..........................................................................................................................3-88

S.4. Marking Requirements........................................................................................................................3-89

S.4.1. Limitation of Use. .................................................................................................................3-89

S.4.2. Discharge Rates. ...................................................................................................................3-89

S.4.3. Measuring Components. .......................................................................................................3-89

S.4.4. Flood Volume. ......................................................................................................................3-89

S.4.5. Conversion Factor.................................................................................................................3-89

N. Notes............................................................................................................................................................. 3-89

N.1. Test Liquid..........................................................................................................................................3-89

N.2. Evaporation and Volume Change. ......................................................................................................3-89

N.2.1. Temperature Correction. .......................................................................................................3-89

N.3. Test Drafts...........................................................................................................................................3-89

N.4. Testing Procedures..............................................................................................................................3-90

N.4.1. Normal Tests.........................................................................................................................3-90

N.4.2. Special Tests. ........................................................................................................................3-90

N.4.3. System Capacity. ..................................................................................................................3-90

T. Tolerances.................................................................................................................................................... 3-90

T.1. Application..........................................................................................................................................3-90

T.1.1. To Underregistration and to Overregistration. ......................................................................3-90

T.2. Tolerance Values. ...............................................................................................................................3-90

T.3. Repeatability. ......................................................................................................................................3-90

UR. User Requirements ..................................................................................................................................... 3-91

UR.1. Installation Requirements. ..................................................................................................................3-91

UR.1.1. Plumb and Level Condition. .................................................................................................3-91

UR.1.2. Discharge Rate......................................................................................................................3-91

UR.1.3. Unit Price. .............................................................................................................................3-91

UR.1.4. Intake Hose. ..........................................................................................................................3-91

UR.2. Use Requirements. ..............................................................................................................................3-91

UR.2.1. Return of Indicating and Recording Elements to Zero. ........................................................3-91

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UR.2.2. Printed Ticket........................................................................................................................3-91

UR.2.3. Ticket in Printing Device. .....................................................................................................3-91

UR.2.4. Credit for Flood Volume.......................................................................................................3-91

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Section 3.35. Milk Meters

A. Application

A.1. General. – This code applies to devices used for the measurement of milk; generally applicable to, but not 

limited to, meters used in dairies, milk processing plants, and cheese factories, to measure incoming bulk milk.

A.2. Exceptions. – This code does not apply to mass flow meters. (Also see Section 3.37. Code for Mass Flow 

Meters.) 

(Added 1994)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Milk Meters shall meet the 

requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A meter shall be equipped with a primary indicating element and may also be equipped 

with a primary recording element.

S.1.1.2. Units.

(a) A meter shall indicate, and record if the meter is equipped to record, its deliveries in terms of liters 

or gallons. Fractional parts of the liter shall be in terms of decimal subdivisions. Fractional parts 

of the gallon shall be in terms of either decimal or binary subdivisions.

(b) When it is an industry practice to purchase and sell milk by weight based upon 1.03 kg/L (8.6 lb/gal), 

the primary indicating element may indicate in kilograms or pounds. The weight value division 

shall be a decimal multiple or submultiple of 1, 2, or 5. Fractional parts of the kilogram or pound 

shall be in decimal subdivisions. (Also see S.4.5. Conversion Factor.) 

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated quantity and recorded 

quantity, if the meter is equipped to record, shall not exceed the equivalent of:

(a) 0.5 L or 0.5 kg (1 pt or 1 lb) when measuring quantities less than or equal to 4000 L or 4000 kg 

(1000 gal or 8600 lb); or

(b) 5 L or 5 kg (1 gal or 10 lb) when measuring quantities in excess of 4000 L or 4000 kg (1000 gal or 

8600 lb). 

(Amended 1989)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only by the mechanical operation of the meter. However, a 

meter may be cleared by advancing its elements to zero, but only if:

(a) the advancing movement, once started, cannot be stopped until zero is reached; or

(b) in the case of indicating elements only, such elements are automatically obscured until the elements 

reach the correct zero position.

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S.1.1.5. Return to Zero. – Primary indicating elements and primary recording elements, if the device is 

equipped to record, shall be readily returnable to a definite zero indication. Means shall be provided to 

prevent the return of the primary indicating elements and the primary recording elements, if the device is so 

equipped, beyond their correct zero position.

S.1.1.6. Indication of Measurement. – A meter shall be constructed to show automatically its initial zero 

condition and the volume measured up to the nominal capacity of the device.

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than

the width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) in width.

S.1.2.3. Clear Interval between Graduations. – The clear interval shall be not less than 1.0 mm 

(0.04 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of graduations, shall be not more than 

1.0 mm (0.04 in).

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than:

(a) the width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) the width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.1.3.6. Travel of Indicator. – If the most sensitive element of the primary indicating element utilizes an 

indicator and graduations, the relative movement of these parts corresponding to the smallest indicated value 

shall be not less than 5 mm (0.20 in).

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S.1.4. Computing-Type Devices.

S.1.4.1. Display of Unit Price. – In a device of the computing type, means shall be provided for displaying 

on the outside of the device, and in close proximity to the display of the total computed price, the price per 

unit at which the device is set to compute.

S.1.4.2. Printed Ticket. – If a computing-type device issues a printed ticket which displays the total 

computed price, the ticket also shall have printed clearly thereon the total quantity of the delivery, the 

appropriate fraction of the quantity, and the price per unit of quantity.

(Amended 1989)

S.1.4.3. Money-Value Computations. – Money-value computations shall be of the full-computing type 

in which the money-value at a single unit price, or at each of a series of unit prices, shall be computed for 

every delivery within either the range of measurement of the device or the range of the computing elements, 

whichever is less. Value graduations shall be supplied and shall be accurately positioned. The value of each 

graduated interval shall be 1 cent.

S.1.4.4. Money-Values, Mathematical Agreement. – Any digital money-value indication and any 

recorded money-value on a computing-type device shall be in mathematical agreement with its associated 

quantity indicating or representation to within 1 cent of money-value.

S.2. Design of Measuring Elements.

S.2.1. Vapor Elimination. – A metering system shall be equipped with an effective vapor eliminator or other 

effective means automatic in operation to prevent the passage of vapor and air through the meter. Vent lines from 

the air (or vapor) eliminator shall be made of metal tubing or some other suitably rigid material.

S.2.2. Maintaining Flooded Condition. – The vent on the vapor eliminator shall be positioned or installed in 

such a manner that the vapor eliminator cannot easily be emptied between uses.

S.2.3. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or for physically applying a security seal in such a manner that requires the security seal to be 

broken before an adjustment or interchange may be made of any: 

(a) measuring element or indicating element; 

(b) adjustable element for controlling delivery rate, when such rate tends to affect the accuracy of deliveries; 

and

(c) metrological parameter that will affect the metrological integrity of the device or system.

When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

[Audit trails shall use the format set forth in Table S.2.3. Categories of Device and Methods of Sealing]* 

[*Nonretroactive as of January 1, 1995]

(Amended 2006)

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Table S.2.3. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but access 

is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

The hardware enabling access for remote communication 

must be on-site. The hardware must be sealed using a 

physical seal or an event counter for calibration 

parameters and an event counter for configuration 

parameters. The event counters may be located either at 

the individual measuring device or at the system 

controller; however, an adequate number of counters must 

be provided to monitor the calibration and configuration 

parameters of the individual devices at a location. If the 

counters are located in the system controller rather than 

at the individual device, means must be provided to 

generate a hard copy of the information through an onsite device.

Category 3: Remote configuration capability access may 

be unlimited or controlled through a software switch (e.g., 

password). 

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable of 

printing in this mode or shall not operate while in this 

mode.

An event logger is required in the device; it must include 

an event counter (000 to 999), the parameter ID, the date 

and time of the change, and the new value of the 

parameter. A printed copy of the information must be 

available through the device or through another on-site 

device. The event logger shall have a capacity to retain 

records equal to 10 times the number of sealable

parameters in the device, but not more than 1000 records 

are required. (Note: Does not require 1000 changes to 

be stored for each parameter.)

[Nonretroactive as of January 1, 1995]

(Table Added 2006)

S.2.4. Directional Flow Valves. – Valves intended to prevent reversal of flow shall be automatic in operation.

S.3. Design of Intake Lines.

S.3.1. Diversion of Liquid to be Measured. – No means shall be provided by which any liquid can be diverted 

from the supply tank to the receiving tank without being measured by the device. A manually controlled outlet 

that may be opened for purging or draining the measuring system shall be permitted. Effective means shall be 

provided to prevent passage of liquid through any such outlet during normal operation of the measuring system.

(Amended 1994)

S.3.2. Intake Hose. – The intake hose shall be:

(a) of the dry-hose type; 

(b) adequately reinforced; 

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(c) not more than 6 m (20 ft) in length unless it can be demonstrated that a longer hose is essential to permit 

transfer from a supply tank; and

(d) connected to the pump at horizontal or above to permit complete drainage of the hose.

(Amended 1991)

S.4. Marking Requirements.

S.4.1. Limitation of Use. – If a meter is intended to measure accurately only liquids having particular 

properties, or to measure accurately only under specific installation or operating conditions, or to measure 

accurately only when used in conjunction with specific accessory equipment, these limitations shall be clearly 

and permanently stated on the meter.

S.4.2. Discharge Rates. – A meter shall be marked to show its designed maximum and minimum discharge 

rates. The marked minimum discharge rate shall not exceed 20 % of the marked maximum discharge rate.

Note: Also see example in Section 3.30. Liquid-Measuring Devices Code, paragraph S.4.4.1. Discharge Rates.

(Added 2003)

S.4.3. Measuring Components. – All components that affect the measurement of milk that are disassembled 

for cleaning purposes shall be clearly and permanently identified with a common serial number.

S.4.4. Flood Volume. – When applicable, the volume of product (to the nearest minimum division of the meter) 

necessary to flood the system when dry shall be clearly, conspicuously, and permanently marked on the air 

eliminator.

S.4.5. Conversion Factor. – When the conversion factor of 1.03 kg/L (8.6 lb/gal) is used to convert the volume 

of milk to weight, the conversion factor shall be clearly marked on the primary indicating element and recorded 

on the delivery ticket.

N. Notes

N.1. Test Liquid.

(a) A meter shall be tested with the liquid to be commercially measured or with a liquid of the same general 

physical characteristics. Following a satisfactory examination, the weights and measures official should 

attach a seal or tag indicating the product used during the test.

(Amended 1989)

(b) A milk measuring system shall be tested with the type of milk to be measured when the accuracy of the 

system is affected by the characteristics of milk (e.g., positive displacement meters).

(Added 1989)

N.2. Evaporation and Volume Change. – Care shall be exercised to reduce to a minimum, evaporation losses and 

volume changes resulting from changes in temperature of the test liquid.

N.2.1. Temperature Correction. – Corrections shall be made for any changes in volume resulting from the 

differences in liquid temperatures between time of passage through the meter and time of volumetric

determination in the test measure. When adjustments are necessary, appropriate tables should be used.

N.3. Test Drafts. – Test drafts should be equal to at least the amount delivered by the device in one minute at its 

maximum discharge rate, and shall in no case be less than 400 L or 400 kg (100 gal or 1 000 lb). 

(Amended 1989)

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N.4. Testing Procedures.

N.4.1. Normal Tests. – The “normal” test of a meter shall be made at the maximum discharge rate that may be 

anticipated under the conditions of the installation. The “normal” test shall include a determination of the 

effectiveness of the air elimination system.

N.4.1.1. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2002)

N.4.2. Special Tests. – “Special” tests shall be made to develop the operating characteristics of a device and 

any special elements and accessories attached to or associated with the device. Any test except as set forth in 

N.4.1. Normal Tests shall be considered a special test.

N.4.3. System Capacity. – The test of a milk-metering system shall include the verification of the volume of 

product necessary to flood the system as marked on the air eliminator.

T. Tolerances

T.1. Application.

T.1.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied 

to errors of underregistration and errors of overregistration. 

T.2. Tolerance Values. – Maintenance and acceptance tolerances shall be as shown in Table 1. Tolerances for Milk 

Meters. 

(Amended 1989)

Table 1. 

Tolerances for Milk Meters

Indication Maintenance Acceptance

gallons gallons gallons

100 0.5 0.3

200 0.7 0.4

300 0.9 0.5

400 1.1 0.6

500 1.3 0.7

Over 500 Add 0.002 gallon per indicated 

gallon over 500

Add 0.001 gallon per indicated 

gallon over 500

(Added 1989)

T.3. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within the applicable tolerance. (Also see N.4.1.1. Repeatability Tests.)

(Added 2002)

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UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Plumb and Level Condition. – A device installed in a fixed location shall be installed plumb and 

level, and the installation shall be sufficiently strong and rigid to maintain this condition.

UR.1.2. Discharge Rate. – A meter shall be so installed that the actual maximum discharge rate will not exceed 

the rated maximum discharge rate. If necessary, means for flow regulation shall be incorporated in the 

installation, in which case this shall be fully effective and automatic in operation.

UR.1.3. Unit Price. – There shall be displayed on the face of a device of the computing type the unit price at 

which the device is set to compute.

UR.1.4. Intake Hose. – The intake hose shall be so installed as to permit complete drainage and that all 

available product is measured following each transfer.

UR.2. Use Requirements.

UR.2.1. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual), 

and the primary recording elements when these are returnable to zero, shall be returned to zero before each 

transfer.

UR.2.2. Printed Ticket. – Any printed ticket issued by a device of the computing type on which there is printed 

the total computed price, the total quantity, or the price per unit of quantity, shall also show the other two values 

(either printed or in clear script).

(Amended 1989)

UR.2.3. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket printer 

until immediately before a transfer is begun. If the meter is mounted on a vehicle, in no case shall a ticket be in 

the device when the vehicle is in motion while on a public street, highway, or thoroughfare.

UR.2.4. Credit for Flood Volume. – The volume of product necessary to flood the system as marked on the 

air eliminator shall be individually recorded on the ticket of each transfer affected.

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Table of Contents

Section 3.36. Water Meters .................................................................................................... 3-95

A. Application ...................................................................................................................................................3-95

A.1. General................................................................................................................................................3-95

A.2. Exceptions...........................................................................................................................................3-95

A.3. Additional Code Requirements...........................................................................................................3-95

S. Specifications................................................................................................................................................3-95

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................3-95

S.1.1. Primary Elements..................................................................................................................3-95

S.1.2. Graduations...........................................................................................................................3-96

S.1.3. Indicators. .............................................................................................................................3-96

S.2. Design of Measuring Elements...........................................................................................................3-97

S.2.1. Provision for Sealing.............................................................................................................3-97

S.2.2. Batching Meters Only. ..........................................................................................................3-97

S.2.3. Multi-Jet Meter Identification...............................................................................................3-97

S.3. Markings.................................................................................................................................................3-97

S.3.1. Location of Marking Information; Utility Type Meters........................................................3-97

N. Notes..............................................................................................................................................................3-97

N.1. Test Liquid..........................................................................................................................................3-97

N.2. Evaporation and Volume Change. ......................................................................................................3-97

N.3. Test Drafts...........................................................................................................................................3-97

N.4. Testing Procedures..............................................................................................................................3-97

N.4.1. Normal Tests.........................................................................................................................3-97

N.4.2. Special Tests. ........................................................................................................................3-98

N.4.3. Batching Meter Tests. ...........................................................................................................3-99

T. Tolerances.....................................................................................................................................................3-99

T.1. Tolerance Values. ...............................................................................................................................3-99

T.1.1. Repeatability. ...................................................................................................................... 3-100

UR. User Requirements .................................................................................................................................... 3-100

UR.1. Batching Meters Only. ...................................................................................................................... 3-100

UR.1.1. Strainer................................................................................................................................ 3-100

UR.1.2. Siphon Breaker. .................................................................................................................. 3-100

UR.1.3. Provision for Testing........................................................................................................... 3-100

UR.2. Accessibility of Customer Indication................................................................................................ 3-100

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Section 3.36. Water Meters

A. Application

A.1. General. – This code applies to devices used for the measurement of water; generally applicable to, but not 

limited to, utilities type meters installed in residences or business establishments and meters installed in batching 

systems.

(Amended 2002)

A.2. Exceptions. – This code does not apply to:

(a) water meters mounted on vehicle tanks (for which see Section 3.31. Vehicle-Tank Meters); or

(b) mass flow meters. (Also see Section 3.37. Mass Flow Meters.)

(Added 1994)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Water Meters shall meet the 

requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A water meter shall be equipped with a primary indicating element and may also be 

equipped with a primary recording element. Such elements shall be visible at the point of measurement or 

be stored in non-volatile and non-resettable memory. The display may be remotely located provided it is 

readily accessible to the customer.

(Amended 2002)

S.1.1.2. Units. – A water meter shall indicate and record, if the device is equipped to record, its deliveries 

in terms of liters, gallons or cubic feet or binary or decimal subdivisions thereof except batch plant meters, 

which shall indicate deliveries in terms of liters, gallons or decimal subdivisions of the liter or gallon only.

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery and recorded 

delivery, if the device is equipped to record, shall not exceed the equivalent of:

(a) 50 L (10 gal or 1 ft3

) on utility type meters, sizes 1 in and smaller; or

(b) 500 L (100 gal or 10 ft3

) on utility-type meters, sizes 11⁄2 in and 2 in; or

(c) 0.2 L (1

/10 gal or 1/100 ft3) on batching meters delivering less than 375 L/min (100 gal/min or 

13 ft 3

/min); or

(d) 5 L (1 gal or 1

/10 ft3) on batching meters delivering 375 L/min (100 gal/min or 13 ft3/min) or more.

 (Amended 2009)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only by the mechanical operation of the device.

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S.1.1.5. Return to Zero. – If the meter is so designed that the primary indicating elements are readily 

returnable to a definite zero indication, means shall be provided to prevent the return of these elements beyond 

their correct zero position.

S.1.1.6. Proving indicator. – Utility-type meters shall be equipped with a proving indicator. The 

individual graduations on a mechanical (analog) proving indicator shall indicate volumes no larger than 1

/100

of the value of the smallest unit of indicated delivery required in S.1.1.3. Value of Smallest Unit. For 

electronic (digital) proving indications, the smallest unit of volume displayed shall be no larger than 1

/1000 of 

the value of the smallest unit of indicated delivery required in S.1.1.3. 

(Added 2009)

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) in width.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall not be less than 1.0 mm 

(0.04 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, the 

width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) in width.

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall not be greater than:

(a) the width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) the width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

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S.2. Design of Measuring Elements.

S.2.1. Provision for Sealing. – Adequate provision shall be made for applying security seals in such a manner 

that no adjustment or interchange may be made of:

(a) any measurement elements; and

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries.

The adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

S.2.2. Batching Meters Only.

S.2.2.1. Air Elimination. – Batching meters shall be equipped with an effective air eliminator.

S.2.2.2. Directional Flow Valves. – Valves intended to prevent reversal of flow shall be automatic in 

operation.

S.2.3. Multi-Jet Meter Identification. – Multi-Jet water meters shall be clearly and permanently marked as 

such on the device or identified on the Certificate of Conformance.

(Added 2003)

S.3. Markings 

S.3.1. Location of Marking Information; Utility Type Meters. – All required markings, including those 

required by G-S.1. Identification, shall be either on the meter body or primary indicator.

[Nonretroactive as of January 1, 2013]

(Added 2012)

N. Notes

N.1. Test Liquid. – A meter shall be tested with water.

N.2. Evaporation and Volume Change. – Care shall be exercised to reduce to a minimum, evaporation losses and 

volume changes resulting from changes to temperature of the test liquid.

N.3. Test Drafts. – Test drafts should be equal to at least the amount delivered by the device in two minutes and in 

no case less than the amount delivered by the device in one minute at the actual maximum flow rate developed by the 

installation. The test draft sizes shown in Table N.4.1. Flow Rate and Draft Size for Water Meters Normal Tests, shall 

be followed as closely as possible.

(Amended 2003)

N.4. Testing Procedures.

N.4.1. Normal Tests. – The normal test of a meter shall be made at the maximum discharge rate developed by 

the installation. Meters with maximum gallon per minute ratings higher than the values specified in Table N.4.1. 

Flow Rate and Draft Size for Water Meters Normal Tests may be tested up to the meter rating, with meter 

indications no less than those shown.

(Amended 1990, 2002, and 2003)

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Table N.4.1. 

Flow Rate and Draft Size for Water Meters Normal Tests

Meter Size

(inches)

Rate of Flow

(gal/min)

Maximum Rate

Meter Indication/Test Draft

gal ft3

Less than 5/8 8 50 5

 5/8 15 50 5

 3⁄4 25 50 5

1 40 100 10

 11⁄2 80 300 40

2 120 500 40

3 250 500 50

4 350 1000 100

6 700 1000 100

(Table Added 2003)

N.4.1.1. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2002)

N.4.2. Special Tests. – Special tests to develop the operating characteristics of meters may be made according 

to the rates and quantities shown in Table N.4.2.a. Flow Rate and Draft Size for Water Meters Special Tests and 

Table N.4.2.b. Flow Rate and Draft Size for Utility Type Water Meters Special Tests. 

(Amended 2003 and 2010) 

Table N.4.2.a.

Flow Rate and Draft Size for Batching Water Meters Special Tests

Meter Size

(inches)

Intermediate Rate Minimum Rate

Rate of Flow

(gal/min)

Meter Indication/Test Draft Rate of Flow

(gal/min)

Meter Indication/Test Draft

gal ft3 gal ft3

Less than or 

equal to 5/8 2 10 1 1⁄4 5 1

 3⁄4 3 10 1 1⁄2 5 1

1 4 10 1 3⁄4 5 1

 11⁄2 8 50 5 11⁄2 10 1

2 15 50 5 2 10 1

3 20 50 5 4 10 1

4 40 100 10 7 50 5

6 60 100 10 12 50 5

(Table Added 2003) (Table Amended 2010)

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Table N.4.2.b. 

Flow Rate and Draft Size for Utility Type Water Meters Special Tests

Meter Size

(inches)

Intermediate Rate Minimum Rate

Rate of Flow

(gal/min)

Meter Indication/Test Draft Rate of Flow

(gal/min)

Meter Indication/Test Draft

gal ft3 gal ft3

Less than 5/8 2 10 1 1⁄4 5 1

5

/8 2 10 1 1⁄4 5 1

5

/8 x 3⁄4 2 10 1 1⁄4 5 1

3⁄4 3 10 1 1⁄2 5 1

1 4 10 1 3⁄4 5 1

11⁄2 8 100 10 11⁄2 100 10

2 15 100 10 2 100 10

(Table Added 2010)

N.4.3. Batching Meter Tests. – Tests on batching meters should be conducted at the maximum and 

intermediate rates only.

T. Tolerances

T.1. Tolerance Values. – Maintenance and acceptance tolerances shall be as shown in Table T.1. Accuracy Classes 

and Tolerances for Water Meters.

(Amended 2003)

Table T.1. 

Accuracy Classes and Tolerances for Water Meters

Accuracy 

Class Application Acceptance Tolerance

Maintenance 

Tolerance

Tolerance for Special 

Tests Conducted at 

the Minimum Flow 

Rate

1.5

Water, Other 

Than MultiJet Water 

Meters

Overregistration 1.5 % 1.5 % 1.5 %

Underregistration 1.5 % 1.5 % 5.0 %

1.5

Water, MultiJet Water 

Meters

Overregistration 1.5 % 1.5 % 3.0 %

Underregistration 1.5 % 1.5 % 3.0 %

(Table Added 2003)

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T.1.1. Repeatability. – When multiple tests are conducted at approximately the same flow rate, each test shall 

be within the applicable tolerances and the range of test results shall not exceed the values shown in Table T.1.1. 

Repeatability. 

 (Added 2002) (Amended 2010)

Table T.1.1.

Repeatability

Batching Meters Utility-Type Meters

Normal Flow Rates 0.6 % 0.6 %

Intermediate Flow Rates 0.6 % 2.0 %

Minimum Flow Rate 1.3 % 4.0 %

 (Table Added 2010)

UR. User Requirements

UR.1. Batching Meters Only.

UR.1.1. Strainer. – A filter or strainer shall be provided if it is determined that the water contains excessive 

amounts of foreign material.

UR.1.2. Siphon Breaker. – An automatic siphon breaker or other effective means shall be installed in the 

discharge piping at the highest point of outlet, in no case below the top of the meter, to prevent siphoning of the 

meter and permit rapid drainage of the pipe or hose.

UR.1.3. Provision for Testing. – Acceptable provisions for testing shall be incorporated into all meter 

systems. Such provisions shall include a two-way valve, or manifold valving, and a pipe or hose installed in the 

discharge line accessible to the proper positioning of the test measure.

UR.2. Accessibility of Customer Indication. – An unobstructed standing space of at least 76 cm (30 in) wide, 

91 cm (36 in) deep, and 198 cm (78 in) high shall be maintained in front of an indication intended for use by the 

customer to allow for reading the indicator. The customer indication shall be readily observable to a person located 

within the standing space without necessity of a separate tool or device.

(Added 2008)

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Table of Contents

Section 3.37. Mass Flow Meters ....................................................................................... 3-103

A. Application ................................................................................................................................................. 3-103

A.1. Liquids. ............................................................................................................................................. 3-103

A.2. Vapor (Gases). .................................................................................................................................. 3-103

A.3. Additional Code Requirements......................................................................................................... 3-103

S. Specifications.............................................................................................................................................. 3-103

S.1. Indicating and Recording Elements. ................................................................................................. 3-103

S.1.1. Indicating Elements. ........................................................................................................... 3-103

S.1.2. Compressed Natural Gas Dispensers. ................................................................................. 3-103

S.1.3. Units.................................................................................................................................... 3-103

S.2. Operating Requirements. .................................................................................................................. 3-104

S.2.1. Return to Zero..................................................................................................................... 3-104

S.2.2. Indicator Reset Mechanism................................................................................................. 3-104

S.2.3. Non-resettable Indicator...................................................................................................... 3-104

S.2.4. Provisions for Power Loss. ................................................................................................. 3-104

S.2.5. Display of Unit Price and Product Identity. ........................................................................ 3-104

S.2.6. Money-Value Computations............................................................................................... 3-105

S.2.7. Recorded Representations, Point-of-Sale Systems.............................................................. 3-105

S.2.8. Indication of Delivery. ........................................................................................................ 3-105

S.3. Measuring Elements and Measuring Systems................................................................................... 3-106

S.3.1. Maximum and Minimum Flow-Rates................................................................................. 3-106

S.3.2. Adjustment Means. ............................................................................................................. 3-106

S.3.3. Vapor Elimination............................................................................................................... 3-106

S.3.4. Maintenance of Liquid State............................................................................................... 3-106

S.3.5. Provision for Sealing........................................................................................................... 3-106

S.3.6. Automatic Density Correction. ........................................................................................... 3-107

S.3.7. Pressurizing the Discharge Hose......................................................................................... 3-107

S.3.8. Zero-Set-Back Interlock, Retail Motor-Fuel Devices. ........................................................ 3-108

S.4. Discharge Lines and Valves.............................................................................................................. 3-108

S.4.1. Diversion of Measured Product. ......................................................................................... 3-108

S.4.2. Pump-Discharge Unit.......................................................................................................... 3-108

S.4.3. Directional Flow Valves. .................................................................................................... 3-108

S.4.4. Discharge Valves. ............................................................................................................... 3-108

S.4.5. Antidrain Means. ................................................................................................................ 3-108

S.4.6. Other Valves. ...................................................................................................................... 3-108

S.5. Markings. .......................................................................................................................................... 3-109

S.5.1. Location of Marking Information; Retail Motor-Fuel Dispensers...................................... 3-109

S.5.2. Marking of Gasoline Volume Equivalent Conversion Factor............................................. 3-109

S.6. Printer. .............................................................................................................................................. 3-109

S.6.1. Printed Receipt.................................................................................................................... 3-110

S.7. Totalizers for Retail Motor-Fuel Devices. ........................................................................................ 3-110

N. Notes............................................................................................................................................................ 3-110

N.1. Minimum Measured Quantity........................................................................................................... 3-110

N.2. Test Medium..................................................................................................................................... 3-110

N.2.1. Liquid-Measuring Devices.................................................................................................. 3-110

N.2.2. Vapor-Measuring Devices. ................................................................................................. 3-110

N.3. Test Drafts......................................................................................................................................... 3-110

N.4. Minimum Measured Quantity........................................................................................................... 3-110

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N.5. Motor-Fuel Dispenser. ...................................................................................................................... 3-110

N.6. Testing Procedures............................................................................................................................ 3-110

N.6.1. Normal Tests....................................................................................................................... 3-110

N.6.2. Special Tests. ...................................................................................................................... 3-110

T. Tolerances................................................................................................................................................... 3-111

T.1. Tolerances, General. ......................................................................................................................... 3-111

T.2. Tolerances......................................................................................................................................... 3-111

T.3. Repeatability. .................................................................................................................................... 3-111

T.4. Type Evaluation Examinations for Liquid-Measuring Devices........................................................ 3-112

UR. User Requirements .................................................................................................................................... 3-112

UR.1. Selection Requirements. ................................................................................................................... 3-112

UR.1.1. Discharge Hose-Length. ..................................................................................................... 3-112

UR.1.2. Minimum Measured Quantity............................................................................................. 3-112

UR.2. Installation Requirements. ................................................................................................................ 3-112

UR.2.1. Manufacturer’s Instructions. ............................................................................................... 3-112

UR.2.2. Discharge Rate.................................................................................................................... 3-112

UR.2.3. Low-Flow Cut-Off Valve. .................................................................................................. 3-112

UR.3. Use of Device.................................................................................................................................... 3-113

UR.3.1. Unit Price and Product Identity for Retail Dispensers. ....................................................... 3-113

UR.3.2. Vapor-Return Line.............................................................................................................. 3-113

UR.3.3. Ticket Printer; Customer Ticket.......................................................................................... 3-113

UR.3.4. Printed Ticket...................................................................................................................... 3-113

UR.3.5. Ticket in Printing Device. ................................................................................................... 3-113

UR.3.6. Steps After Dispensing. ...................................................................................................... 3-113

UR.3.7. Return of Indicating and Recording Elements to Zero. ...................................................... 3-113

UR.3.8. Return of Product to Storage, Retail Compressed Natural Gas Dispensers. ....................... 3-114

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Section 3.37. Mass Flow Meters

A. Application

A.1. Liquids. – This code applies to devices that are designed to dynamically measure the mass, or the mass and 

density of liquids. It also specifies the relevant examinations and tests that are to be conducted.

(Amended 1997)

A.2. Vapor (Gases). – This code applies to devices that are designed to dynamically measure the mass of 

hydrocarbon gas in the vapor state. Examples of these products are propane, propylene, butanes, butylenes, ethane, 

methane, natural gas and any other hydrocarbon gas/air mix.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Mass Flow Meters shall meet 

the requirements of Section 1.10. General Code.

S. Specifications

S.1. Indicating and Recording Elements.

S.1.1. Indicating Elements. – A measuring assembly shall include an indicating element. Indications shall be 

clear, definite, accurate, and easily read under normal conditions of operation of the instrument.

S.1.2. Compressed Natural Gas Dispensers. – Except for fleet sales and other price contract sales, a 

compressed natural gas dispenser used to refuel vehicles shall be of the computing type and shall indicate the 

quantity, the unit price, and the total price of each delivery. The dispenser shall display the mass measured for 

each transaction either continuously on an external or internal display accessible during the inspection and test of 

the dispenser, or display the quantity in mass units by using controls on the device.

(Added 1994)

S.1.3. Units.

S.1.3.1. Units of Measurement. – Deliveries shall be indicated and recorded in grams, kilograms, metric 

tons, pounds, tons, and/or liters, gallons, quarts, pints and decimal subdivisions thereof. The indication of a 

delivery shall be on the basis of apparent mass versus a density of 8.0 g/cm3

. The volume indication shall be 

based on the mass measurement and an automatic means to determine and correct for changes in product 

density.

(Amended 1993 and 1997)

S.1.3.1.1. Compressed Natural Gas Used as an Engine Fuel. – When compressed natural gas is 

dispensed as an engine fuel, the delivered quantity shall be indicated in “gasoline liter equivalent (GLE) 

units” or “gasoline gallon equivalent (GGE) units.” (Also see definitions.) 

(Added 1994)

S.1.3.2. Numerical Value of Quantity-Value Divisions. – The value of a scale interval shall be equal to:

(a) 1, 2, or 5; or

(b) a decimal multiple or submultiple of 1, 2, or 5.

S.1.3.3. Maximum Value of Quantity-Value Divisions.

(a) The maximum value of the quantity-value division for liquids shall not be greater than 0.2 % of the 

minimum measured quantity.

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(b) For dispensers of compressed natural gas used to refuel vehicles, the value of the division for the 

gasoline liter equivalent shall not exceed 0.01 GLE; the division for gasoline gallon equivalent 

(GGE) shall not exceed 0.001 GGE. The maximum value of the mass division shall not exceed 

0.001 kg or 0.001 lb.

(Amended 1994)

S.1.3.4. Values Defined. – Indicated values shall be adequately defined by a sufficient number of figures, 

words, symbols, or combinations thereof. A display of “zero” shall be a zero digit for all displayed digits to 

the right of the decimal mark and at least one to the left.

S.2. Operating Requirements.

S.2.1. Return to Zero. – Except for measuring assemblies in a pipeline:

(a) One indicator and the primary recording elements, if the device is equipped to record, shall be provided 

with a means for readily returning the indication to zero either automatically or manually.

(b) It shall not be possible to return primary indicating elements, or primary recording elements, beyond the 

correct zero position.

(Amended 1993)

S.2.2. Indicator Reset Mechanism. – The reset mechanism for the indicating element shall not be operable 

during a delivery. Once the zeroing operation has begun, it shall not be possible to indicate a value other than the 

latest measurement, or “zeros” when the zeroing operation has been completed.

S.2.3. Non-resettable Indicator. – An instrument may also be equipped with a non-resettable indicator if the 

indicated values cannot be construed to be the indicated values of the resettable indicator for a delivered quantity.

S.2.4. Provisions for Power Loss.

S.2.4.1. Transaction Information. – In the event of a power loss, the information needed to complete 

any transaction in progress at the time of the power loss (such as the quantity and unit price, or sales price) 

shall be determinable for at least 15 minutes at the dispenser or at the console if the console is accessible to 

the customer.

(Added 1993)

S.2.4.2. User Information. – The device memory shall retain information on the quantity of fuel 

dispensed and the sales price totals during power loss.

(Added 1993)

S.2.5. Display of Unit Price and Product Identity.

S.2.5.1. Unit Price. – A computing or money-operated device shall be able to display on each face the 

unit price at which the device is set to compute or to dispense.

(Added 1993)

S.2.5.2. Product Identity. – A device shall be able to conspicuously display on each side the identity of 

the product being dispensed.

(Added 1993)

S.2.5.3. Selection of Unit Price. – Except for dispensers used exclusively for fleet sales, other price 

contract sales, and truck refueling (e.g., truck stop dispensers used only to refuel trucks), when a product or 

grade is offered for sale at more than one unit price through a computing device, the selection of the unit 

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price shall be made prior to delivery using controls on the device or other customer-activated controls. A 

system shall not permit a change to the unit price during delivery of a product.

[Nonretroactive as of January 1, 1998]

(Added 1997)

S.2.5.4. Agreement Between Indications. – When a quantity value indicated or recorded by an auxiliary 

element is a derived or computed value based on data received from a retail motor-fuel dispenser, the value 

may differ from the quantity value displayed on the dispenser, provided the following conditions are met:

(a) all total money-values for an individual sale that are indicated or recorded by the system agree; 

and

(b) within each element the values indicated or recorded meet the formula (quantity x unit price = total 

sales price) to the closest cent.

[Nonretroactive as of January 1, 1998]

(Added 1997)

S.2.6. Money-Value Computations. – A computing device shall compute the total sales price at any 

single-purchase unit price (i.e., excluding fleet sales, other price contract sales, and truck stop dispensers used 

only to refuel trucks) for which the product being measured is offered for sale at any delivery possible within 

either the measurement range of the device or the range of the computing elements, whichever is less.

(Added 1993)

S.2.6.1. Auxiliary Elements. – If a system is equipped with auxiliary indications, all indicated moneyvalue and quantity divisions of the auxiliary element shall be identical with those of the primary element.

(Added 1993)

S.2.6.2. Display of Quantity and Total Price. – When a delivery is completed, the total price and quantity 

for that transaction shall be displayed on the face of the dispenser for at least 5 minutes or until the next 

transaction is initiated by using controls on the device or other user-activated controls.

(Added 1993)

S.2.7. Recorded Representations, Point-of-Sale Systems. – The sales information recorded by cash registers 

when interfaced with a retail motor-fuel dispenser shall contain the following information for products delivered 

by the dispenser:

(a) the total volume of the delivery; 

(b) the unit price; 

(c) the total computed price; and

(d) the product identity by name, symbol, abbreviation, or code number.

[Nonretroactive as of January 1, 1986]

(Added 1993)

S.2.8. Indication of Delivery. – The device shall automatically show on its face the initial zero condition and 

the quantity delivered (up to the nominal capacity). However, the first 0.03 L (0.009 gal) of a delivery and its 

associated total sales price need not be indicated.

[Nonretroactive as of January 1, 1998]

(Added 1997)

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S.3. Measuring Elements and Measuring Systems.

S.3.1. Maximum and Minimum Flow-Rates.

(a) The ratio of the maximum to minimum flow-rates specified by the manufacturer for devices measuring 

liquefied gases shall be 5:1 or greater.

(b) The ratio of the maximum to minimum flow-rates specified by the manufacturer for devices measuring 

other than liquefied gases shall be 10:1 or greater.

S.3.2. Adjustment Means. – An assembly shall be provided with the means to change the ratio between the

indicated quantity and the quantity of liquid measured by the assembly. A bypass on the measuring assembly 

shall not be used for these means.

S.3.2.1. Discontinuous Adjusting Means. – When the adjusting means changes the ratio between the 

indicated quantity and the quantity of measured liquid in a discontinuous manner, the consecutive values of 

the ratio shall not differ by more than 0.1 %.

S.3.3. Vapor Elimination. – A liquid-measuring instrument or measuring system shall be equipped with an 

effective vapor or air eliminator or other effective means, automatic in operation, to prevent the measurement of 

vapor and air. Vent lines from the air or vapor eliminator shall be made of metal tubing or some other suitable 

rigid material.

(Amended 1999)

S.3.3.1. Vapor Elimination on Loading Rack Liquid Metering Systems.

(a) A loading rack liquid metering system shall be equipped with a vapor or air eliminator or other 

automatic means to prevent the passage of vapor and air through the meter unless the system is 

designed or operationally controlled by a method, approved by the weights and measures 

jurisdiction having statutory authority over the device, such that neither air nor vapor can enter the 

system.

(b) Vent lines from the air or vapor eliminator (if present) shall be made of metal tubing or other rigid 

material.

(Added 1995)

S.3.4. Maintenance of Liquid State. – A liquid-measuring device shall be installed so that the measured 

product remains in a liquid state during passage through the instrument.

S.3.5. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or physically applying security seals in such a manner that no adjustment or interchange may 

be made of:

(a) any measuring or indicating element; 

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries; 

(c) the zero adjustment mechanism; and

(d) any metrological parameter that will affect the metrological integrity of the device or system.

When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

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[Audit trails shall use the format set forth in Table S.3.5. Categories of Device and Methods of Sealing]* 

[*Nonretroactive as of January 1, 1995]

(Amended 1992, 1995, and 2006)

Table S.3.5.

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but 

access is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if 

capable of printing in this mode or shall not operate 

while in this mode.

[The hardware enabling access for remote communication 

must be on-site. The hardware must be sealed using a 

physical seal or an event counter for calibration 

parameters and an event counter for configuration 

parameters. The event counters may be located either at 

the individual measuring device or at the system 

controller; however, an adequate number of counters must 

be provided to monitor the calibration and configuration 

parameters of the individual devices at a location. If the 

counters are located in the system controller rather than 

at the individual device, means must be provided to 

generate a hard copy of the information through an onsite device.]* 

[*Nonretroactive as of January 1, 1996]

Category 3: Remote configuration capability access 

may be unlimited or controlled through a software 

switch (e.g., password).

[Nonretroactive as of January 1, 1995]

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if 

capable of printing in this mode or shall not operate 

while in this mode.

[Nonretroactive as of January 1, 2001]

An event logger is required in the device; it must include 

an event counter (000 to 999), the parameter ID, the date 

and time of the change, and the new value of the 

parameter. A printed copy of the information must be 

available through the device or through another on-site 

device. The event logger shall have a capacity to retain 

records equal to 10 times the number of sealable

parameters in the device, but not more than 1000 records 

are required. (Note: Does not require 1000 changes to 

be stored for each parameter.)

[Nonretroactive as of January 1, 1995]

(Table Added 1995) (Amended 1995, 1998, 1999, and 2006)

S.3.6. Automatic Density Correction.

(a) An automatic means to determine and correct for changes in product density shall be incorporated in any 

mass flow metering system that is affected by changes in the density of the product being measured.

(b) Volume-measuring devices with automatic temperature compensation used to measure natural gas as a 

motor vehicle engine fuel shall be equipped with an automatic means to determine and correct for 

changes in product density due to changes in the temperature, pressure, and composition of the product.

(Amended 1994 and 1997)

S.3.7. Pressurizing the Discharge Hose. – The discharge hose for compressed natural gas shall automatically 

pressurize prior to the device beginning to register the delivery.

(Added 1993)

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S.3.8. Zero-Set-Back Interlock, Retail Motor-Fuel Devices. – A device shall be constructed so that:

(a) after a delivery cycle has been completed by moving the starting lever to any position that shuts off the 

device, an automatic interlock prevents a subsequent delivery until the indicating elements, and 

recording elements if the device is equipped and activated to record, have been returned to their zero 

positions;

(b) the discharge nozzle cannot be returned to its designed hanging position (that is, any position where the 

tip of the nozzle is placed in its designed receptacle and the lock can be inserted) until the starting lever 

is in its designed shut-off position and the zero-set-back interlock has been engaged; and

(c) in a system with more than one dispenser supplied by a single pump, an effective automatic control valve 

in each dispenser prevents product from being delivered until the indicating elements on that dispenser 

are in a correct zero position.

(Added 1993)

S.4. Discharge Lines and Valves.

S.4.1. Diversion of Measured Product. – No means shall be provided by which any measured product can be 

diverted from the measuring instrument. However, two or more delivery outlets may be permanently installed 

and operated simultaneously, provided that any diversion of flow to other than the intended receiving receptacle 

cannot be readily accomplished or is readily apparent. Such means include physical barriers, visible valves, or 

indications that make it clear which outlets are in operation, and explanatory signs if deemed necessary.

An outlet that may be opened for purging or draining the measuring system, or for recirculating product if 

recirculation is required in order to maintain the product in a deliverable state shall be permitted. Effective 

automatic means shall be provided to prevent the passage of liquid through any such outlet during normal 

operation of the measuring system and to inhibit meter indications (or advancement of indications) and recorded 

representations while the outlet is in operation.

(Amended 2002 and 2006)

S.4.2. Pump-Discharge Unit. – A pump-discharge unit for liquids equipped with a flexible discharge hose 

shall be of the wet-hose type.

(Added 1993)

S.4.3. Directional Flow Valves. – If a reversal of flow could result in errors that exceed the tolerance for the 

minimum measured quantity, a valve or valves or other effective means, automatic in operation (and equipped 

with a pressure limiting device, if necessary) to prevent the reversal of flow shall be properly installed in the 

system. (Also see N.1. Minimum Measured Quantity.) 

S.4.4. Discharge Valves. – A discharge valve may be installed on a discharge line only if the system is a 

wet-hose type. Any other shutoff valve on the discharge side of the instrument shall be of the automatic or 

semiautomatic predetermined-stop type or shall be operable only:

(a) by means of a tool (but not a pin) entirely separate from the device; or

(b) by means of a security seal with which the valve is sealed open.

S.4.5. Antidrain Means. – In a wet-hose type device, effective means shall be provided to prevent the drainage 

of the hose between transactions.

S.4.6. Other Valves. – Check valves and closing mechanisms that are not used to define the measured quantity 

shall have relief valves (if necessary) to dissipate any abnormally high pressure that may arise in the measuring 

assembly.

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S.5. Markings. – A measuring system shall be legibly and indelibly marked with the following information:

(a) pattern approval mark (i.e., type approval number);

(b) name and address of the manufacturer or his trademark and, if required by the weights and measures 

authority, the manufacturer’s identification mark in addition to the trademark;

(c) model identifier or product name selected by the manufacturer;

(d) nonrepetitive serial number;

(e) the accuracy class of the meter as specified by the manufacturer consistent with Table T.2. Accuracy Classes 

for Mass Flow Meter Applications Covered in NIST Handbook 44, Section 3.37 Mass Flow Meters;*

[*Nonretroactive as of January 1, 1995]

(Added 1994)

(f) maximum and minimum flow rates in pounds per unit of time;

(g) maximum working pressure;

(h) applicable range of temperature if other than − 10 °C to + 50 °C;

(i) minimum measured quantity; and

(j) product limitations, if applicable.

S.5.1. Location of Marking Information; Retail Motor-Fuel Dispensers. – The marking information required 

in General Code, paragraph G-S.1. Identification shall appear as follows:

(a) within 60 cm (24 in) to 150 cm (60 in) from the base of the dispenser;

(b) either internally and/or externally provided the information is permanent and easily read; and

(c) on a portion of the device that cannot be readily removed or interchanged (i.e., not on a service access 

panel).

Note: The use of a dispenser key or tool to access internal marking information is permitted for retail liquid-measuring devices.

[Nonretroactive as of January 1, 2003]

(Added 2006)

S.5.2. Marking of Gasoline Volume Equivalent Conversion Factor. – A device dispensing compressed 

natural gas shall have either the statement “1 Gasoline Liter Equivalent (GLE) is Equal to 0.678 kg of Natural 

Gas” or “1 Gasoline Gallon Equivalent (GGE) is Equal to 5.660 lb of Natural Gas” permanently and 

conspicuously marked on the face of the dispenser according to the method of sale used.

(Added 1994)

S.6. Printer. – When an assembly is equipped with means for printing the measured quantity, the following 

conditions apply:

(a) the scale interval shall be the same as that of the indicator;

(b) the value of the printed quantity shall be the same value as the indicated quantity;

(c) a quantity for a delivery (other than an initial reference value) cannot be recorded until the measurement and 

delivery has been completed;

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(d) the printer is returned to zero when the resettable indicator is returned to zero; and

(e) the printed values shall meet the requirements applicable to the indicated values.

S.6.1. Printed Receipt. – Any delivered, printed quantity shall include an identification number, the time and 

date, and the name of the seller. This information may be printed by the device or pre-printed on the ticket.

S.7. Totalizers for Retail Motor-Fuel Devices. – Retail motor-fuel dispensers shall be equipped with a 

nonresettable totalizer for the quantity delivered through the metering device.

[Nonretroactive as of January 1, 1998]

(Added 1997)

N. Notes

N.1. Minimum Measured Quantity. – The minimum measured quantity shall be specified by the manufacturer.

N.2. Test Medium.

N.2.1. Liquid-Measuring Devices. – The device shall be tested with the liquid that the device is intended to 

measure or another liquid with the same general physical characteristics.

N.2.2. Vapor-Measuring Devices. – The device shall be tested with air or the product to be measured.

N.3. Test Drafts. – The minimum test shall be one test draft at the maximum flow rate of the installation and one 

test draft at the minimum flow rate. More tests may be performed at these or other flow rates. (Also see 

T.3. Repeatability.) 

N.4. Minimum Measured Quantity. – The device shall be tested for a delivery equal to the declared minimum 

measured quantity when the device is likely to be used to make deliveries on the order of the minimum measured 

quantity.

N.5. Motor-Fuel Dispenser. – When a device is intended for use as a liquid motor-fuel dispenser, the type 

evaluation test shall include a test for accuracy using five starts and stops during a delivery to simulate the operation 

of the automatic shut-off nozzle. This test may be conducted as part of the normal inspection and test of the meter.

N.6. Testing Procedures.

N.6.1. Normal Tests. – The normal test of a meter shall be made at the maximum discharge rate developed by 

the installation. Any additional tests conducted at flow rates down to and including the rated minimum discharge 

flow rate shall be considered normal tests.

(Added 1999)

N.6.1.1. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2001)

N.6.2. Special Tests. – “Special” tests shall be made to develop the operating characteristics of a device and 

any special elements and accessories attached to or associated with the device. Any test except as set forth in 

N.6.1. Normal Tests shall be considered a special test. Special tests of a measuring system shall be made to 

develop operating characteristics of the measuring systems during a split compartment delivery. (Also see 

Table T.2. Accuracy Classes and Tolerances for Mass Flow Meters.) 

(Added 1999)

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T. Tolerances 

T.1. Tolerances, General.

(a) The tolerances apply equally to errors of underregistration and errors of overregistration. 

(b) The tolerances apply to all products at all temperatures measured at any flow rate within the rated measuring 

range of the meter.

(Amended 1999)

T.2. Tolerances. – The tolerances for mass flow meters for specific liquids, gases, and applications are listed in 

Table T.2. Accuracy Classes and Tolerances for Mass Flow Meters.

(Amended 1994 and 1999)

Table T.2. 

Accuracy Classes and Tolerances for Mass Flow Meters

Accuracy 

Class

Application or Commodity

Being Measured

Acceptance 

Tolerance

Maintenance 

Tolerance

Special 

Tolerance

0.3 - Large capacity motor-fuel dispensers (maximum 

discharge flow rates greater than 100 L/min or 

25 gal/min)

- Heated products (other than asphalt) at temperatures 

greater than 50 °C (122 °F)

- Asphalt at temperatures equal to or below 50 °C 

(122 °F)

- Loading rack meters

- Vehicle-tank meters

- Home heating oil

- Milk and other food products

- All other liquid applications not shown in the table 

where the minimum delivery is at least 700 kg (1500 lb)

0.2 % 0.3 % 0.5 %

 0.3A - Asphalt at temperatures greater than 50 °C (122 °F) 0.3 % 0.3 % 0.5 %

0.5 - Small capacity (retail) motor-fuel dispensers

- Agri-chemical liquids

- All other liquid applications not shown in the table where 

the minimum delivery is less than 700 kg or 1500 lb

0.3 % 0.5 % 0.5 %

1.0 - Anhydrous ammonia

- LP Gas (including vehicle-tank meters)

0.6 % 1.0 % 1.0 %

2.0 - Compressed natural gas as a motor-fuel 1.5 % 2.0 % 2.0 %

2.5 - Cryogenic liquid meters

- Liquefied compressed gases other than LP Gas

1.5 % 2.5 % 2.5 %

(Added 1994) (Amended 1999, 2001, and 2013)

T.3. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within the applicable tolerance. (Also see N.6.1.1. Repeatability Tests.) 

(Amended 1992, 1994, and 2001)

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T.4. Type Evaluation Examinations for Liquid-Measuring Devices. – For type evaluation examinations, the 

tolerance values shall apply under the following conditions:

(a) with any one liquid within the range of liquids; 

(b) at any one liquid temperature and pressure within the operating range of the meter; and

(c) at all flow rates within the range of flow rates.

(Added 1993) (Amended 1994)

UR. User Requirements

UR.1. Selection Requirements.

UR.1.1. Discharge Hose-Length. – The length of the discharge hose on a retail motor-fuel device shall not 

exceed 4.6 m (15 ft) unless it can be demonstrated that a longer hose is essential to permit deliveries to be made 

to receiving vehicles or vessels.

[Nonretroactive as of January 1, 1998]

(Added 1997)

UR.1.2. Minimum Measured Quantity.

(a) The minimum measured quantity shall be specified by the manufacturer.

(b) The minimum measured quantity appropriate for a transaction may be specified by the weights and 

measures authority. A device may have a minimum measured quantity smaller than that specified by 

the weights and measures authority; however, the device must perform within the performance 

requirements for the declared minimum measured quantity.

UR.2. Installation Requirements.

UR.2.1. Manufacturer’s Instructions. – A device shall be installed in accordance with the manufacturer’s 

instructions, and the installation shall be sufficiently secure and rigid to maintain this condition.

(Added 1997)

UR.2.2. Discharge Rate. – A device shall be installed so that the actual maximum discharge rate will not 

exceed the rated maximum discharge rate. Automatic means of flow regulation shall be incorporated in the 

installation if necessary.

(Added 1997)

UR.2.3. Low-Flow Cut-Off Valve. – If a metering system is equipped with a programmable or adjustable 

“low-flow cut-off” feature:

(a) the low-flow cut-off value shall not be set at flow rates lower than the minimum operating flow rate 

specified by the manufacturer on the meter; and

(b) the system shall be equipped with flow control valves which prevent the flow of product and stop the 

indicator from registering product flow whenever the product flow rate is less than the low-flow cut-off 

value.

(Added 1992)

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UR.3. Use of Device.

UR.3.1. Unit Price and Product Identity for Retail Dispensers. – The following information shall be 

conspicuously displayed or posted on the face of a retail dispenser used in direct sale:

(a) except for dispensers used exclusively for fleet sales, other price contract sales, and truck refueling 

(e.g., truck stop dispensers used only to refuel trucks), all of the unit prices at which the product is offered 

for sale; and

(b) in the case of a computing type or money-operated type, the unit price at which the dispenser is set to 

compute.

(Added 1993)

UR.3.2. Vapor-Return Line. – During any metered delivery of liquefied petroleum gas and other liquids from 

a supplier’s tank to a receiving container, there shall be no vapor-return line from the receiving container to the 

supplier’s tank:

(a) in the case of any receiving container to which normal deliveries can be made without the use of such 

vapor-return line; or

(b) in the case of any new receiving container when the ambient temperature is below 90 °F.

(Added 1993)

UR.3.3. Ticket Printer; Customer Ticket. – Vehicle-mounted metering systems shall be equipped with a 

ticket printer which shall be used for all sales where product is delivered through the meter. A copy of the ticket 

issued by the device shall be left with the customer at the time of delivery or as otherwise specified by the 

customer.

(Added 1994)

UR.3.4. Printed Ticket. – The total price, the total quantity of the delivery, and the price per unit shall be 

printed on any ticket issued by a device of the computing type and containing any one of these values.

(Added 1993)

UR.3.5. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket printer 

until immediately before a delivery is begun, and in no case shall a ticket be in the device when the vehicle is in 

motion while on a public street, highway, or thoroughfare.

(Added 1993)

UR.3.6. Steps After Dispensing. – After delivery to a customer from a retail motor-fuel device:

(a) the starting lever shall be returned to its shutoff position and the zero-set-back interlock engaged; and

(b) the discharge nozzle shall be returned to its designed hanging position unless the primary indicating 

elements, and recording elements, if the device is equipped and activated to record, have been returned 

to a definite zero indication.

(Added 1993)

UR.3.7. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual), 

and the primary recording elements when these are returnable to zero, shall be returned to zero immediately before 

each delivery. Exceptions to this requirement are totalizers on key-lock-operated or other self-operated dispensers 

and the primary recording element if the device is equipped to record.

(Added 1995) (Amended 1997)

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UR.3.8. Return of Product to Storage, Retail Compressed Natural Gas Dispensers. – Provisions at the site 

shall be made for returning product to storage or disposing of the product in a safe and timely manner during or 

following testing operations. Such provisions may include return lines, or cylinders adequate in size and number 

to permit this procedure.

(Added 1998)

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Table of Contents

Section 3.38. Carbon Dioxide Liquid-Measuring Devices ............................................. 3-117

A. Application ................................................................................................................................................ 3-117

A.1. General.............................................................................................................................................. 3-117

A.2. Exceptions......................................................................................................................................... 3-117

A.3. Additional Code Requirements......................................................................................................... 3-117

A.4. Type Evaluation................................................................................................................................ 3-117

S. Specifications............................................................................................................................................. 3-117

S.1. Design of Indicating and Recording Elements and of Recorded Representations. ........................... 3-117

S.1.1. Primary Elements................................................................................................................ 3-117

S.1.2. Graduations......................................................................................................................... 3-118

S.1.3. Indicators. ........................................................................................................................... 3-118

S.1.4. Computing-Type Devices. .................................................................................................. 3-119

S.2. Design of Measuring Elements......................................................................................................... 3-119

S.2.1. Vapor Elimination............................................................................................................... 3-119

S.2.2. Reverse Flow Measurement................................................................................................ 3-119

S.2.3. Maintenance of Liquid State............................................................................................... 3-119

S.2.4. Automatic Temperature or Density Compensation............................................................. 3-119

S.2.5. Provision for Sealing........................................................................................................... 3-119

S.3. Design of Discharge Lines and Discharge Line Valves.................................................................... 3-120

S.3.1. Diversion of Measured Liquid. ........................................................................................... 3-120

S.3.2. Discharge Hose. .................................................................................................................. 3-120

S.4. Marking Requirements...................................................................................................................... 3-120

S.4.1. Limitation of Use. ............................................................................................................... 3-120

S.4.2. Discharge Rates. ................................................................................................................. 3-121

N. Notes........................................................................................................................................................... 3-121

N.1. Test Liquid........................................................................................................................................ 3-121

N.2. Vaporization and Volume Change.................................................................................................... 3-121

N.3. Test Drafts......................................................................................................................................... 3-121

N.3.1. Gravimetric Test. ................................................................................................................ 3-121

N.3.2. Transfer Standard Test........................................................................................................ 3-121

N.3.3. Volumetric Prover Test Drafts............................................................................................ 3-121

N.4. Testing Procedures............................................................................................................................ 3-121

N.4.1. Normal Tests....................................................................................................................... 3-121

N.4.2. Special Tests. ...................................................................................................................... 3-121

N.4.3. Density................................................................................................................................ 3-121

N.4.4. Automatic Temperature or Density Compensation............................................................. 3-122

T. Tolerances.................................................................................................................................................. 3-128

T.1. Application........................................................................................................................................ 3-128

T.1.1. To Underregistration and to Overregistration. .................................................................... 3-128

T.2. Tolerance Values. ............................................................................................................................. 3-128

T.2.1. Repeatability. ...................................................................................................................... 3-128

T.3. On Tests Using Transfer Standards. ................................................................................................. 3-128

UR. User Requirements ................................................................................................................................... 3-128

UR.1. Installation Requirements. ................................................................................................................ 3-128

UR.1.1. Discharge Rate.................................................................................................................... 3-128

UR.1.2. Length of Discharge Hose. ................................................................................................. 3-128

UR.1.3. Maintenance of Liquid State............................................................................................... 3-128

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UR.2. Use Requirements. ............................................................................................................................ 3-128

UR.2.1. Return of Indicating and Recording Elements to Zero. ...................................................... 3-128

UR.2.2. Condition of Discharge System. ......................................................................................... 3-128

UR.2.3. Vapor Equalization Line. .................................................................................................... 3-129

UR.2.4. Temperature or Density Compensation. ............................................................................. 3-129

UR.2.5. Ticket in Printing Device. ................................................................................................... 3-129

UR.2.6. Sale by Weight.................................................................................................................... 3-129

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Section 3.38. Carbon Dioxide Liquid-Measuring Devices 

A. Application

A.1. General. – This code applies to liquid-measuring devices used for the measurement of liquid carbon dioxide.

A.2. Exceptions. – This code does not apply to devices used solely for dispensing a product in connection with 

operations in which the amount dispensed does not affect customer charges.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Carbon Dioxide LiquidMeasuring Devices shall meet the requirements of Section 1.10. General Code.

A.4. Type Evaluation. – The National Type Evaluation Program will accept for type evaluation only those devices 

that comply with all requirements of this code.

(Added 1998)

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A device shall be equipped with a primary indicating element and may also be 

equipped with a primary recording element.

S.1.1.2. Units. – A device shall indicate and record, if equipped to record, its deliveries in terms of pounds 

or kilograms or decimal subdivisions or multiples thereof.

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded 

delivery, if the device is equipped to record, shall not exceed the equivalent of:

(a) for small delivery devices:

(1) 1 kilogram; or

(2) 1 pound

(b) for large delivery devices:

(1) 10 kilograms; or

(2) 10 pounds

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only by the normal operation of the device. However, a device 

may be cleared by advancing its elements to zero, but only if:

(a) the advancing movement, once started, cannot be stopped until zero is reached; or

(b) in the case of indicating elements only, such elements are automatically obscured until the elements 

reach the correct zero position.

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S.1.1.5. Return to Zero. – Primary indicating and recording elements shall be readily returnable to a 

definite zero indication. Means shall be provided to prevent the return of primary indicating elements and of 

primary recording elements beyond their correct zero position.

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations. The width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) in width.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall be not less than 1.0 mm 

(0.04 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

(Also see S.1.3.6. Travel of Indicator.) 

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be of the same shape as the graduations at least 

throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.1.3.3. Width. – The width of the index of the indicator in relation to the series of graduations with which 

it is used shall be not greater than:

(a) the width of the narrowest graduation;* and

[*Nonretroactive as of January 1, 2002]

(Amended 2001)

(b) the width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width throughout 

the length of the index that coincides with the graduation.

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.1.3.6. Travel of Indicator. – If the most sensitive element of the primary indicating element utilizes an 

indicator and graduations, the relative movement of these parts corresponding to the smallest indicated value 

shall be no less than 5 mm (0.20 in).

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S.1.4. Computing-Type Devices.

S.1.4.1. Printed Ticket. – Any printed ticket issued by a device of the computing type on which there is 

printed the total computed price shall have printed clearly thereon also the total quantity of the delivery and 

the price per unit.

S.1.4.2. Money-Value Computations. – Money-value computations shall be of the full-computing type 

in which the money-value at a single unit price, or at each of a series of unit prices, shall be computed for 

every delivery within either the range of measurement of the device or the range of the computing elements, 

whichever is less.

The total price shall be computed on the basis of the quantity indicated when the value of the smallest division 

indicated is equal to or less than the value specified in S.1.1.3. Value of Smallest Unit.

S.1.4.3. Money-Values, Mathematical Agreement. – Any digital money-value indication and any 

recorded money-value on a computing-type device shall be in mathematical agreement with its associated 

quantity indication or representation to within 1 cent of money-value. 

S.2. Design of Measuring Elements.

S.2.1. Vapor Elimination. – A measuring system shall be equipped with an effective vapor eliminator or other 

effective means to prevent the measurement of vapor that will cause errors in excess of the applicable tolerances.

S.2.2. Reverse Flow Measurement. – Effective means, automatic in operation, shall be installed to prevent 

reverse flow measurement.

S.2.3. Maintenance of Liquid State. – A device shall be so designed that the product being measured will 

remain in a liquid state during passage through the device.

S.2.4. Automatic Temperature or Density Compensation. – A volumetric device shall be equipped with 

automatic means for adjusting the indication and recorded representation of the measured quantity of the product 

to indicate or record the quantity of the product measured in terms of pounds.

S.2.5. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or for physically applying a security seal in such a manner that requires the security seal to be 

broken before an adjustment or interchange may be made of:

(a) any measuring or indicating element; 

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries; 

(c) any automatic temperature or density compensating system; and

(d) any metrological parameter that will affect the metrological integrity of the device or system.

When applicable any adjusting mechanism shall be readily accessible for purposes of affixing a security seal.

[Audit trails shall use the format set forth in Table S.2.5. Provision for Sealing]*

[*Nonretroactive as of January 1, 1995]

(Amended 2006)

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Table S.2.5. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for 

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but 

access is controlled by physical hardware.

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable 

of printing in this mode or shall not operate while in this 

mode.

The hardware enabling access for remote 

communication must be on-site. The hardware must be 

sealed using a physical seal or an event counter for 

calibration parameters and an event counter for 

configuration parameters. The event counters may be 

located either at the individual measuring device or at 

the system controller; however, an adequate number of 

counters must be provided to monitor the calibration and 

configuration parameters of the individual devices at a 

location. If the counters are located in the system 

controller rather than at the individual device, means 

must be provided to generate a hard copy of the 

information through an on-site device.

Category 3: Remote configuration capability access 

may be unlimited or controlled through a software 

switch (e.g., password). 

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if capable 

of printing in this mode or shall not operate while in this 

mode.

An event logger is required in the device; it must include 

an event counter (000 to 999), the parameter ID, the date 

and time of the change, and the new value of the 

parameter. A printed copy of the information must be 

available through the device or through another on-site 

device. The event logger shall have a capacity to retain 

records equal to 10 times the number of sealable 

parameters in the device, but not more than 1000 records 

are required. (Note: Does not require 1000 changes to 

be stored for each parameter.)

[Nonretroactive as of January 1, 1995] 

(Table Added 2006)

S.3. Design of Discharge Lines and Discharge Line Valves.

S.3.1. Diversion of Measured Liquid. – No means shall be provided by which any measured liquid can be 

diverted from the measuring chamber of the device or the discharge line therefrom, except that a manually 

controlled outlet that may be opened for purging or draining the measuring system shall be permitted. Effective 

means shall be provided to prevent the passage of liquid through any such outlet during normal operation of the 

device and to indicate clearly and unmistakably when the valve controls are so set as to permit passage of liquid 

through such outlet.

S.3.2. Discharge Hose. – The discharge hose of a measuring system shall be of a wet hose type with a shutoff 

valve at its outlet end.

S.4. Marking Requirements.

S.4.1. Limitation of Use. – If a measuring system is intended to measure accurately only liquids having 

particular properties, or to measure accurately only under specific installation or operating conditions, or to 

measure accurately only when used in conjunction with specific accessory equipment, these limitations shall be 

clearly and permanently marked on the device.

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S.4.2. Discharge Rates. – A meter shall be marked to show its designed maximum and minimum discharge 

rates. The marked minimum discharge rate shall not exceed 20 % of the marked maximum discharge rate.

Note: Also see example in Section 3.30. Liquid-Measuring Devices Code, paragraph S.4.4.1. Discharge Rates.

(Note Added 2003)

N. Notes

N.1. Test Liquid. – The test liquid shall be carbon dioxide in a compressed liquid state.

N.2. Vaporization and Volume Change. – Care shall be exercised to reduce vaporization and volume changes to 

a minimum. When testing by weight, the weigh tank and transfer systems shall be pre-cooled to liquid temperature 

prior to the start of the test to avoid the venting of vapor from the vessel being weighed.

N.3. Test Drafts.

N.3.1. Gravimetric Test. – Weight test drafts shall be equal to at least the amount delivered by the device in 

2 minutes at its maximum discharge rate.

N.3.2. Transfer Standard Test. – When comparing a meter with a calibrated transfer standard, the test draft 

shall be equal to at least the amount delivered by the device in two minutes at its maximum discharge rate.

N.3.3. Volumetric Prover Test Drafts. – Test drafts shall be equal to at least the amount delivered in 1 minute 

at its normal discharge rate.

N.4. Testing Procedures.

N.4.1. Normal Tests. – The “normal” test of a device shall be made at the maximum discharge flow rate 

developed under the conditions of installation. Any additional tests conducted at flow rates down to and including 

one-half of the sum of the maximum discharge flow rate and the rated minimum discharge flow rate shall be 

considered normal tests.

N.4.1.1. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors such as temperature, pressure, and flow rate are reduced to the extent that they will not affect the 

results obtained.

(Added 2002)

N.4.2. Special Tests. – Any test except as set forth in N.4.1. Normal Tests shall be considered a special test. 

Tests shall be conducted, if possible, to evaluate any special elements or accessories attached to or associated 

with the device. A device shall be tested at a minimum discharge rate of:

(a) not less than the marked minimum discharge rate or 20 % of the maximum rated discharge rate of the 

device, whichever is less; or

(b) the lowest discharge rate practicable under the conditions of installation.

“Special” tests may be conducted to develop any characteristics of the device anticipated under the conditions of 

installation.

N.4.3. Density. – Temperature and pressure of the metered test liquid shall be measured during the test for the 

determination of density or volume correction when applicable. The appropriate correction values shall apply as 

specified in Table N.4.4.

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3.38. Carbon Dioxide Liquid-Measuring Devices Handbook 44 – 2016 

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N.4.4. Automatic Temperature or Density Compensation. – If a device is equipped with an automatic 

temperature or density compensator, the compensator shall be tested by comparing the quantity indicated or 

recorded by the device (with the compensator connected and operating) with the actual delivered quantity. The 

appropriate correction values shall apply as specified in Table N.4.4.

Table N.4.4.

Automatic Temperature or Density Compensation

Temp °F

Pressure Liquid Density Vapor Density Vapor 

PSIA PSIG Displacement % lb/gal (lb-oz)/gal lb/cu ft lb/gal

− 30.00 177.89 163.19 9.127 9 - 2.0 1.989 0.266 2.9

− 29.75 178.75 164.05 9.122 9 - 2.0 1.999 0.267 2.9

− 29.50 179.62 164.92 9.117 9 - 1.9 2.008 0.268 2.9

− 29.25 180.49 165.79 9.113 9 - 1.8 2.018 0.270 3.0

− 29.00 181.36 166.67 9.108 9 - 1.7 2.028 0.271 3.0

− 28.75 182.24 167.54 9.103 9 - 1.7 2.038 0.272 3.0

− 28.50 183.12 168.42 9.098 9 - 1.6 2.048 0.274 3.0

− 28.25 184.00 169.31 9.094 9 - 1.5 2.058 0.275 3.0

− 28.00 184.89 170.19 9.089 9 - 1.4 2.067 0.276 3.0

− 27.75 185.78 171.08 9.084 9 - 1.3 2.077 0.278 3.1

− 27.50 186.67 171.98 9.080 9 - 1.3 2.087 0.279 3.1

− 27.25 187.57 172.87 9.075 9 - 1.2 2.098 0.280 3.1

− 27.00 188.47 173.77 9.070 9 - 1.1 2.108 0.282 3.1

− 26.75 189.37 174.67 9.065 9 - 1.0 2.118 0.283 3.1

− 26.50 190.28 175.58 9.061 9 - 1.0 2.128 0.284 3.1

− 26.25 191.18 176.49 9.056 9 - 0.9 2.138 0.286 3.2

− 26.00 192.10 177.40 9.051 9 - 0.8 2.148 0.287 3.2

− 25.75 193.01 178.32 9.046 9 - 0.7 2.159 0.289 3.2

− 25.50 193.93 179.23 9.041 9 - 0.7 2.169 0.290 3.2

− 25.25 194.85 180.16 9.037 9 - 0.6 2.179 0.291 3.2

− 25.00 195.78 181.08 9.032 9 - 0.5 2.190 0.293 3.2

− 24.75 196.70 182.01 9.027 9 - 0.4 2.200 0.294 3.3

− 24.50 197.64 182.94 9.022 9 - 0.4 2.211 0.296 3.3

− 24.25 198.57 183.87 9.017 9 - 0.3 2.221 0.297 3.3

− 24.00 199.51 184.81 9.013 9 - 0.2 2.232 0.298 3.3

− 23.75 200.45 185.75 9.008 9 - 0.1 2.243 0.300 3.3

− 23.50 201.39 186.70 9.003 9 - 0.0 2.253 0.301 3.3

− 23.25 202.34 187.64 8.998 9 - 0.0 2.264 0.303 3.4

− 23.00 203.29 188.60 8.993 8 - 15.9 2.275 0.304 3.4

− 22.75 204.25 189.55 8.989 8 - 15.8 2.286 0.306 3.4

− 22.50 205.20 190.51 8.984 8 - 15.7 2.296 0.307 3.4

− 22.25 206.16 191.47 8.979 8 - 15.7 2.307 0.308 3.4

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Table N.4.4.

Automatic Temperature or Density Compensation

Temp °F

Pressure Liquid Density Vapor Density Vapor 

PSIA PSIG Displacement % lb/gal (lb-oz)/gal lb/cu ft lb/gal

− 22.00 207.13 192.43 8.974 8 - 15.6 2.318 0.310 3.5

− 21.75 208.09 193.40 8.969 8 - 15.5 2.329 0.311 3.5

− 21.50 209.06 194.37 8.964 8 - 15.4 2.340 0.313 3.5

− 21.25 210.04 195.34 8.959 8 - 15.4 2.351 0.314 3.5

− 21.00 211.02 196.32 8.955 8 - 15.3 2.362 0.316 3.5

− 20.75 212.00 197.30 8.950 8 - 15.2 2.374 0.317 3.5

− 20.50 212.98 198.28 8.945 8 - 15.1 2.385 0.319 3.6

− 20.25 213.97 199.27 8.940 8 - 15.0 2.396 0.320 3.6

− 20.00 214.96 200.26 8.935 8 - 15.0 2.407 0.322 3.6

− 19.75 215.95 201.26 8.930 8 - 14.9 2.419 0.323 3.6

− 19.50 216.95 202.25 8.925 8 - 14.8 2.430 0.325 3.6

− 19.25 217.95 203.25 8.920 8 - 14.7 2.441 0.326 3.7

− 19.00 218.95 204.26 8.915 8 - 14.6 2.453 0.328 3.7

− 18.75 219.96 205.27 8.911 8 - 14.6 2.464 0.329 3.7

− 18.50 220.97 206.28 8.906 8 - 14.5 2.476 0.331 3.7

− 18.25 221.99 207.29 8.901 8 - 14.4 2.488 0.333 3.7

− 18.00 223.01 208.31 8.896 8 - 14.3 2.499 0.334 3.8

− 17.75 224.03 209.33 8.891 8 - 14.3 2.511 0.336 3.8

− 17.50 225.05 210.36 8.886 8 - 14.2 2.523 0.337 3.8

− 17.25 226.08 211.38 8.881 8 - 14.1 2.534 0.339 3.8

− 17.00 227.11 212.42 8.876 8 - 14.0 2.546 0.340 3.8

− 16.75 228.15 213.45 8.871 8 - 13.9 2.558 0.342 3.9

− 16.50 229.18 214.49 8.866 8 - 13.9 2.570 0.344 3.9

− 16.25 230.23 215.53 8.861 8 - 13.8 2.582 0.345 3.9

− 16.00 231.27 216.58 8.856 8 - 13.7 2.594 0.347 3.9

− 15.75 232.32 217.62 8.851 8 - 13.6 2.606 0.348 3.9

− 15.50 233.37 218.68 8.846 8 - 13.5 2.618 0.350 4.0

− 15.25 234.43 219.73 8.841 8 - 13.5 2.630 0.352 4.0

− 15.00 235.49 220.79 8.836 8 - 13.4 2.643 0.353 4.0

− 14.75 236.55 221.86 8.831 8 - 13.3 2.655 0.355 4.0

− 14.50 237.62 222.92 8.826 8 - 13.2 2.667 0.357 4.0

− 14.25 238.69 223.99 8.821 8 - 13.1 2.680 0.358 4.1

− 14.00 239.76 225.07 8.816 8 - 13.1 2.692 0.360 4.1

− 13.75 240.84 226.14 8.811 8 - 13.0 2.704 0.362 4.1

− 13.50 241.92 227.22 8.806 8 - 12.9 2.717 0.363 4.1

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Table N.4.4.

Automatic Temperature or Density Compensation

Temp °F

Pressure Liquid Density Vapor Density Vapor 

PSIA PSIG Displacement % lb/gal (lb-oz)/gal lb/cu ft lb/gal

− 13.25 243.00 228.31 8.801 8 - 12.8 2.729 0.365 4.1

− 13.00 244.09 229.39 8.796 8 - 12.7 2.742 0.367 4.2

− 12.75 245.18 230.49 8.791 8 - 12.7 2.755 0.368 4.2

− 12.50 246.28 231.58 8.786 8 - 12.6 2.767 0.370 4.2

− 12.25 247.37 232.68 8.781 8 - 12.5 2.780 0.372 4.2

− 12.00 248.48 233.78 8.776 8 - 12.4 2.793 0.373 4.3

− 11.75 249.58 234.89 8.771 8 - 12.3 2.806 0.375 4.3

− 11.50 250.69 236.00 8.765 8 - 12.2 2.819 0.377 4.3

− 11.25 251.80 237.11 8.760 8 - 12.2 2.832 0.379 4.3

− 11.00 252.92 238.22 8.755 8 - 12.1 2.845 0.380 4.3

− 10.75 254.04 239.34 8.750 8 - 12.0 2.858 0.382 4.4

− 10.50 255.16 240.47 8.745 8 - 11.9 2.871 0.384 4.4

− 10.25 256.29 241.60 8.740 8 - 11.8 2.884 0.386 4.4

− 10.00 257.42 242.73 8.735 8 - 11.8 2.897 0.387 4.4

− 9.75 258.56 243.86 8.730 8 - 11.7 2.911 0.389 4.5

− 9.50 259.70 245.00 8.725 8 - 11.6 2.924 0.391 4.5

− 9.25 260.84 246.14 8.719 8 - 11.5 2.937 0.393 4.5

− 9.00 261.98 247.29 8.714 8 - 11.4 2.951 0.394 4.5

− 8.75 263.13 248.44 8.709 8 - 11.3 2.964 0.396 4.5

− 8.50 264.29 249.59 8.704 8 - 11.3 2.978 0.398 4.6

− 8.25 265.44 250.75 8.699 8 - 11.2 2.991 0.400 4.6

− 8.00 266.60 251.91 8.694 8 - 11.1 3.005 0.402 4.6

− 7.75 267.77 253.07 8.688 8 - 11.0 3.019 0.404 4.6

− 7.50 268.93 254.24 8.683 8 - 10.9 3.032 0.405 4.7

− 7.25 270.11 255.41 8.678 8 - 10.8 3.046 0.407 4.7

− 7.00 271.28 256.59 8.673 8 - 10.8 3.060 0.409 4.7

− 6.75 272.46 257.76 8.668 8 - 10.7 3.074 0.411 4.7

− 6.50 273.64 258.95 8.662 8 - 10.6 3.088 0.413 4.8

− 6.25 274.83 260.13 8.657 8 - 10.5 3.102 0.415 4.8

− 6.00 276.02 261.32 8.652 8 - 10.4 3.116 0.417 4.8

− 5.75 277.21 262.52 8.647 8 - 10.3 3.130 0.418 4.8

− 5.50 278.41 263.72 8.641 8 - 10.3 3.144 0.420 4.9

− 5.25 279.61 264.92 8.636 8 - 10.2 3.159 0.422 4.9

− 5.00 280.82 266.12 8.631 8 - 10.1 3.173 0.424 4.9

− 4.75 282.03 267.33 8.626 8 - 10.0 3.187 0.426 4.9

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Table N.4.4.

Automatic Temperature or Density Compensation

Temp °F

Pressure Liquid Density Vapor Density Vapor 

PSIA PSIG Displacement % lb/gal (lb-oz)/gal lb/cu ft lb/gal

− 4.50 283.24 268.55 8.620 8 - 9.9 3.202 0.428 5.0

− 4.25 284.46 269.76 8.615 8 - 9.8 3.216 0.430 5.0

− 4.00 285.68 270.98 8.610 8 - 9.8 3.231 0.432 5.0

− 3.75 286.90 272.21 8.604 8 - 9.7 3.245 0.434 5.0

− 3.50 288.13 273.44 8.599 8 - 9.6 3.260 0.436 5.1

− 3.25 289.37 274.67 8.594 8 - 9.5 3.275 0.438 5.1

− 3.00 290.60 275.91 8.589 8 - 9.4 3.289 0.440 5.1

− 2.75 291.84 277.15 8.583 8 - 9.3 3.304 0.442 5.1

− 2.50 293.09 278.39 8.578 8 - 9.2 3.319 0.444 5.2

− 2.25 294.33 279.64 8.573 8 - 9.2 3.334 0.446 5.2

− 2.00 295.58 280.89 8.567 8 - 9.1 3.349 0.448 5.2

− 1.75 296.84 282.14 8.562 8 - 9.0 3.364 0.450 5.3

− 1.50 298.10 283.40 8.556 8 - 8.9 3.379 0.452 5.3

− 1.25 299.36 284.67 8.551 8 - 8.8 3.395 0.454 5.3

− 1.00 300.63 285.93 8.546 8 - 8.7 3.410 0.456 5.3

− 0.75 301.90 287.21 8.540 8 - 8.6 3.425 0.458 5.4

− 0.50 303.18 288.48 8.535 8 - 8.6 3.440 0.460 5.4

− 0.25 304.46 289.76 8.530 8 - 8.5 3.456 0.462 5.4

0.00 305.74 291.74 8.524 8 - 8.4 3.471 0.464 5.4

0.25 307.03 292.33 8.519 8 - 8.3 3.487 0.466 5.5

0.50 308.32 293.62 8.513 8 - 8.2 3.503 0.468 5.5

0.75 309.61 294.92 8.508 8 - 8.1 3.518 0.470 5.5

1.00 310.91 296.21 8.502 8 - 8.0 3.534 0.472 5.6

1.25 312.21 297.52 8.497 8 - 8.0 3.550 0.475 5.6

1.50 313.52 298.82 8.491 8 - 7.9 3.566 0.477 5.6

1.75 314.83 300.13 8.486 8 - 7.8 3.582 0.479 5.6

2.00 316.15 301.45 8.480 8 - 7.7 3.598 0.481 5.7

2.25 317.46 302.77 8.475 8 - 7.6 3.614 0.483 5.7

2.50 318.79 304.09 8.469 8 - 7.5 3.630 0.485 5.7

2.75 320.11 305.42 8.464 8 - 7.4 3.646 0.487 5.8

3.00 321.45 306.75 8.458 8 - 7.3 3.662 0.490 5.8

3.25 322.78 308.08 8.453 8 - 7.2 3.679 0.492 5.8

3.50 324.12 309.42 8.447 8 - 7.2 3.695 0.494 5.8

3.75 325.46 310.77 8.442 8 - 7.1 3.712 0.496 5.9

4.00 326.81 312.11 8.436 8 - 7.0 3.728 0.498 5.9

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Table N.4.4.

Automatic Temperature or Density Compensation

Temp °F

Pressure Liquid Density Vapor Density Vapor 

PSIA PSIG Displacement % lb/gal (lb-oz)/gal lb/cu ft lb/gal

4.25 328.16 313.46 8.431 8 - 6.9 3.745 0.501 5.9

4.50 329.52 314.82 8.425 8 - 6.8 3.761 0.503 6.0

4.75 330.88 316.18 8.420 8 - 6.7 3.778 0.505 6.0

5.00 332.24 317.54 8.414 8 - 6.6 3.795 0.507 6.0

5.25 333.61 318.91 8.408 8 - 6.5 3.812 0.510 6.1

5.50 334.98 320.28 8.403 8 - 6.4 3.829 0.512 6.1

5.75 336.35 321.66 8.397 8 - 6.4 3.846 0.514 6.1

6.00 337.73 323.04 8.392 8 - 6.3 3.863 0.516 6.2

6.25 339.12 324.42 8.386 8 - 6.2 3.880 0.519 6.2

6.50 340.51 325.81 8.380 8 - 6.1 3.897 0.521 6.2

6.75 341.90 327.20 8.375 8 - 6.0 3.915 0.523 6.3

7.00 343.30 328.60 8.369 8 - 5.9 3.932 0.526 6.3

7.25 344.70 330.00 8.363 8 - 5.8 3.949 0.528 6.3

7.50 346.10 331.41 8.358 8 - 5.7 3.967 0.530 6.3

7.75 347.51 332.82 8.352 8 - 5.6 3.984 0.533 6.4

8.00 348.92 334.23 8.346 8 - 5.5 4.002 0.535 6.4

8.25 350.34 335.65 8.341 8 - 5.4 4.020 0.537 6.4

8.50 351.76 337.07 8.335 8 - 5.4 4.038 0.540 6.5

8.75 353.19 338.49 8.335 8 - 5.4 4.038 0.540 6.5

9.00 354.62 339.92 8.323 8 - 5.2 4.073 0.545 6.5

9.25 356.06 341.36 8.318 8 - 5.1 4.091 0.547 6.6

9.50 357.49 342.80 8.312 8 - 5.0 4.110 0.549 6.6

9.75 358.94 344.24 8.306 8 - 4.9 4.128 0.552 6.6

10.00 360.38 345.69 8.300 8 - 4.8 4.146 0.554 6.7

10.25 361.84 347.14 8.295 8 - 4.7 4.164 0.557 6.7

10.50 363.29 348.60 8.289 8 - 4.6 4.183 0.559 6.7

10.75 364.75 350.06 8.283 8 - 4.5 4.201 0.562 6.8

11.00 366.22 351.52 8.277 8 - 4.4 4.220 0.564 6.8

11.25 367.68 352.99 8.271 8 - 4.3 4.238 0.567 6.8

11.50 369.16 354.46 8.266 8 - 4.2 4.257 0.569 6.9

11.75 370.64 355.94 8.260 8 - 4.2 4.276 0.572 6.9

12.00 372.12 357.42 8.254 8 - 4.1 4.295 0.574 7.0

12.25 373.60 358.91 8.248 8 - 4.0 4.314 0.577 7.0

12.50 375.09 360.40 8.242 8 - 3.9 4.333 0.579 7.0

12.75 376.59 361.89 8.236 8 - 3.8 4.352 0.582 7.1

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Table N.4.4.

Automatic Temperature or Density Compensation

Temp °F

Pressure Liquid Density Vapor Density Vapor 

PSIA PSIG Displacement % lb/gal (lb-oz)/gal lb/cu ft lb/gal

13.00 378.09 363.39 8.230 8 - 3.7 4.371 0.584 7.1

13.25 379.59 364.89 8.224 8 - 3.6 4.390 0.587 7.1

13.50 381.10 366.40 8.219 8 - 3.5 4.410 0.589 7.2

13.75 382.61 367.91 8.213 8 - 3.4 4.429 0.592 7.2

14.00 384.13 369.43 8.207 8 - 3.3 4.449 0.595 7.2

14.25 385.65 370.95 8.201 8 - 3.2 4.468 0.597 7.3

14.50 387.17 372.48 8.195 8 - 3.1 4.488 0.600 7.3

14.75 388.70 374.01 8.189 8 - 3.0 4.508 0.603 7.4

15.00 390.24 375.54 8.183 8 - 2.9 4.527 0.605 7.4

15.25 391.78 377.08 8.177 8 - 2.8 4.547 0.608 7.4

15.50 393.32 378.62 8.171 8 - 2.7 4.567 0.611 7.5

15.75 394.87 380.17 8.165 8 - 2.6 4.587 0.613 7.5

16.00 396.42 381.72 8.159 8 - 2.5 4.608 0.616 7.5

16.25 397.98 383.28 8.153 8 - 2.4 4.628 0.619 7.6

16.50 399.54 384.84 8.147 8 - 2.3 4.648 0.621 7.6

16.75 401.10 386.41 8.141 8 - 2.2 4.669 0.624 7.7

17.00 402.67 387.98 8.134 8 - 2.2 4.689 0.627 7.7

17.25 404.25 389.55 8.128 8 - 2.1 4.710 0.630 7.7

17.50 405.82 391.13 8.122 8 - 2.0 4.731 0.632 7.8

17.75 407.41 392.71 8.116 8 - 1.9 4.751 0.635 7.8

18.00 409.00 394.30 8.110 8 - 1.8 4.772 0.638 7.9

18.25 410.59 395.89 8.104 8 - 1.7 4.793 0.641 7.9

18.50 412.19 397.49 8.098 8 - 1.6 4.814 0.644 7.9

18.75 413.79 399.09 8.092 8 - 1.5 4.835 0.646 8.0

19.00 415.39 400.70 8.085 8 - 1.4 4.857 0.649 8.0

19.25 417.00 402.31 8.079 8 - 1.3 4.878 0.652 8.1

19.50 418.62 403.92 8.073 8 - 1.2 4.900 0.655 8.1

19.75 420.24 405.54 8.067 8 - 1.1 4.921 0.658 8.2

20.00 421.86 407.17 8.061 8 - 1.0 4.943 0.661 8.2

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T. Tolerances

T.1. Application.

T.1.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied 

to errors of underregistration and errors of overregistration.

T.2. Tolerance Values. – The maintenance and acceptance tolerances for normal and special tests shall be as shown 

in Table T.2. Accuracy Classes and Tolerances for Carbon Dioxide Liquid-Measuring Devices.

Table T.2.

Accuracy Classes and Tolerances for Carbon Dioxide Liquid-Measuring Devices

Accuracy 

Class Application

Acceptance 

Tolerance

Maintenance 

Tolerance

Special Test 

Tolerance

2.5 Liquid carbon dioxide 1.5 % 2.5 % 2.5 % 

(Table Added 2003) (Amended 2003)

T.2.1. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, 

the range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance 

tolerance and the results of each test shall be within the applicable tolerance. (Also see N.4.1.1. Repeatability 

Tests.)

(Added 2002)

T.3. On Tests Using Transfer Standards. – To the basic tolerance values that would otherwise be applied, there 

shall be added an amount equal to two times the standard deviation of the applicable transfer standard when compared 

to a basic reference standard.

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Discharge Rate. – A device shall be so installed that the actual maximum discharge rate will not 

exceed the rated maximum discharge rate. If necessary, means for flow regulation shall be incorporated in the 

installation.

UR.1.2. Length of Discharge Hose. – The discharge hose shall be of such a length and design as to keep 

vaporization of the liquid to a minimum.

UR.1.3. Maintenance of Liquid State. – A device shall be so installed and operated that the product being 

measured shall remain in the liquid state during passage through the meter.

UR.2. Use Requirements.

UR.2.1. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual) 

and the primary recording elements shall be returned to zero immediately before each delivery.

UR.2.2. Condition of Discharge System. – The discharge hose, up to the valve at the end of the discharge 

hose, shall be completely filled and pre-cooled to liquid temperatures before a “zero” condition is established and 

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prior to the start of a commercial delivery. Means shall be provided to fill the discharge hose with liquid prior to 

the start of a delivery.

UR.2.3. Vapor Equalization Line. – A vapor equalization line shall not be used during a metered delivery 

unless the quantity of vapor displaced from the buyer’s tank to the seller’s tank is deducted from the metered 

quantity. The appropriate correction values shall apply as specified in Table N.4.4.

UR.2.4. Temperature or Density Compensation.

UR.2.4.1. Use of Automatic Temperature or Density Compensators. – Devices equipped with an 

automatic temperature or density compensator shall have the compensator connected, operable, and in use at 

all times. Such automatic temperature or density compensator may not be removed.

UR.2.4.2. Tickets or Invoices. – Any written invoice or printed ticket based on a reading of a device that 

is equipped with an automatic temperature or density compensator shall have shown thereon that the quantity 

delivered has been temperature or density compensated.

UR.2.5. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket printer 

until immediately before a delivery is begun, and in no case shall a ticket be in the device when the vehicle is in 

motion while on a public street, highway, or thoroughfare.

UR.2.6. Sale by Weight. – All quantity determinations shall be made by means of an approved and sealed 

weighing or measuring device. All sales shall be stated in kilograms or pounds.

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Table of Contents

Section 3.39. Hydrogen Gas-Measuring Devices – Tentative Code .............................. 3-133

A. Application ................................................................................................................................................ 3-133

A.1. General.............................................................................................................................................. 3-133

A.2. Exceptions......................................................................................................................................... 3-133

A.3. Additional Code Requirements......................................................................................................... 3-133

A.4. Type Evaluation................................................................................................................................ 3-133

S. Specifications............................................................................................................................................. 3-133

S.1. Indicating and Recording Elements. ................................................................................................. 3-133

S.1.1. Indicating Elements ............................................................................................................ 3-133

S.1.2. Vehicle Fuel Dispensers ..................................................................................................... 3-133

S.1.3. Units.................................................................................................................................... 3-133

S.1.4. Value of Smallest Unit........................................................................................................ 3-134

S.2. Operating Requirements. .................................................................................................................. 3-134

S.2.1. Return to Zero..................................................................................................................... 3-134

S.2.2. Indicator Reset Mechanism................................................................................................. 3-134

S.2.3. Provision for Power Loss.................................................................................................... 3-134

S.2.4. Display of Unit Price and Product Identity. ........................................................................ 3-134

S.2.5. Money-Value Computations............................................................................................... 3-135

S.2.6. Recorded Representations, Point of Sale Systems. ............................................................. 3-135

S.2.7. Indication of Delivery. ........................................................................................................ 3-135

S.3. Design of Measuring Elements and Measuring Systems. ................................................................. 3-135

S.3.1. Maximum and Minimum Flow-Rates................................................................................. 3-135

S.3.2. Adjustment Means. ............................................................................................................. 3-135

S.3.3. Provision for Sealing........................................................................................................... 3-135

S.3.4. Automatic Density Correction. ........................................................................................... 3-136

S.3.5. Pressurizing the Discharge Hose......................................................................................... 3-136

S.3.6. Zero-Set-Back Interlock, Retail Vehicle Fuel Devices....................................................... 3-137

S.4. Discharge Lines and Valves.............................................................................................................. 3-137

S.4.1. Diversion of Measured Product. ......................................................................................... 3-137

S.4.2. Directional Flow Valves. .................................................................................................... 3-137

S.4.3. Other Valves. ...................................................................................................................... 3-137

S.5. Markings. .......................................................................................................................................... 3-137

S.5.1. Location of Marking Information; Hydrogen-Fuel Dispensers. ......................................... 3-138

S.6. Printer. .............................................................................................................................................. 3-138

S.6.1. Printed Receipt.................................................................................................................... 3-138

S.7. Totalizers for Vehicle Fuel Dispensers. ............................................................................................ 3-138

S.8. Minimum Measured Quantity........................................................................................................... 3-138

N. Notes........................................................................................................................................................... 3-138

N.1. Minimum Measured Quantity........................................................................................................... 3-138

N.2. Test Medium..................................................................................................................................... 3-138

N.3. Test Drafts......................................................................................................................................... 3-138

N.4. Tests.................................................................................................................................................. 3-139

N.4.1. Master Meter (Transfer) Standard Test............................................................................... 3-139

N.4.2. Gravimetric Tests................................................................................................................ 3-139

N.4.3. PVT Pressure Volume Temperature Test. .......................................................................... 3-139

N.5. Minimum Measured Quantity........................................................................................................... 3-139

N.6. Testing Procedures............................................................................................................................ 3-139

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N.6.1. General................................................................................................................................ 3-139

N.7. Density.............................................................................................................................................. 3-139

T. Tolerances.................................................................................................................................................. 3-140

T.1. Tolerances, General. ......................................................................................................................... 3-140

T.2. Tolerances......................................................................................................................................... 3-140

T.3. Repeatability. .................................................................................................................................... 3-140

T.4. Tolerance Application on Test Using Transfer Standard Test Method............................................. 3-140

T.5. Tolerance Application in Type Evaluation Examinations for Devices. ............................................ 3-140

UR. User Requirements ................................................................................................................................... 3-140

UR.1. Selection Requirements. ................................................................................................................... 3-140

UR.1.1. Computing-Type Device; Retail Dispenser. ....................................................................... 3-140

UR.1.2. Discharge Hose-Length. ..................................................................................................... 3-140

UR.1.3. Minimum Measured Quantity............................................................................................. 3-141

UR.2. Installation Requirements. ................................................................................................................ 3-141

UR.2.1. Manufacturer’s Instructions. ............................................................................................... 3-141

UR.2.2. Discharge Rate.................................................................................................................... 3-141

UR.2.3. Low-Flow Cut-Off Valve. .................................................................................................. 3-141

UR.3. Use of Device.................................................................................................................................... 3-141

UR.3.1. Unit Price and Product Identity for Retail Dispensers. ....................................................... 3-141

UR.3.2. Vehicle-mounted Measuring Systems Ticket Printer.......................................................... 3-141

UR.3.3. Printed Ticket...................................................................................................................... 3-142

UR.3.4. Steps After Dispensing. ...................................................................................................... 3-142

UR.3.5. Return of Indicating and Recording Elements to Zero. ...................................................... 3-142

UR.3.6. Return of Product to Storage, Retail Hydrogen Gas Dispensers......................................... 3-142

UR.3.7. Conversion Factors. ............................................................................................................ 3-142

Appendix D. Definitions..................................................................................................................................... 3-142

audit trail...................................................................................................................................................... 3-142

automatic temperature or density compensation.......................................................................................... 3-142

calibration parameter ................................................................................................................................... 3-143

discharge hose.............................................................................................................................................. 3-143

discharge line............................................................................................................................................... 3-143

event counter................................................................................................................................................ 3-143

event logger. ................................................................................................................................................ 3-143

indicating element........................................................................................................................................ 3-143

minimum measured quantity (MMQ).......................................................................................................... 3-143

Non-resettable totalizer. ............................................................................................................................... 3-143

point-of-sale system..................................................................................................................................... 3-143

remote configuration capability. .................................................................................................................. 3-143

retail device.................................................................................................................................................. 3-144

wet hose. ...................................................................................................................................................... 3-144

wet-hose type ............................................................................................................................................... 3-144

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Section 3.39. Hydrogen Gas-Measuring Devices – Tentative Code

This tentative code has a trial or experimental status and is not intended to be enforced. The requirements are designed 

for study prior to the development and adoption of a final code. Requirements that apply to wholesale applications 

are under study and development by the U.S. National Work Group for the Development of Commercial Hydrogen 

Measurement Standards. Officials wanting to conduct an official examination of a device or system are advised to 

see paragraph G-A.3. Special and Unclassified Equipment.

(Tentative Code Added 2010)

A. Application

A.1. General. – This code applies to devices that are used for the measurement of hydrogen gas in the vapor state 

used as a vehicle fuel. 

A.2. Exceptions. – This code does not apply to: 

(a) Devices used solely for dispensing a product in connection with operations in which the amount dispensed 

does not affect customer charges.

(b) The wholesale delivery of hydrogen gas.

(c) Devices used for dispensing a hydrogen gas with a hydrogen fuel index lower than 99.97 % and 

concentrations of specified impurities that exceed level limits.

(d) Systems that measure pressure, volume, and temperature with a calculating device to determine the mass of 

gas accumulated in or discharged from a tank of known volume.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Hydrogen Gas-Measuring 

Devices shall meet the requirements of Section 1.10. General Code.

A.4. Type Evaluation. – The National Type Evaluation Program (NTEP) will accept for type evaluation only those 

devices that comply with all requirements of this code.

S. Specifications

S.1. Indicating and Recording Elements.

S.1.1. Indicating Elements. – A measuring assembly shall include an indicating element that continuously 

displays measurement results relative to quantity and total price. Indications shall be clear, definite, accurate, and 

easily read under normal conditions of operation of the device.

S.1.2. Vehicle Fuel Dispensers. – A hydrogen gas dispenser used to fuel vehicles shall be of the computing 

type and shall indicate the mass, the unit price, and the total price of each delivery.

S.1.3. Units.

S.1.3.1. Units of Measurement. – Deliveries shall be indicated and recorded in kilograms and decimal

subdivisions thereof. 

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S.1.3.2. Numerical Value of Quantity-Value Divisions. – The value of an interval (i.e., increment or 

scale division) shall be equal to:

(a) 1, 2, or 5; or

(b) a decimal multiple or submultiple of 1, 2, or 5.

Examples: quantity-value divisions may be 10, 20, 50, 100; or 0.01, 0.02, 0.05; or 0.1, 0.2, or 0.5 

etc.

S.1.3.3. Maximum Value of Quantity-Value Divisions. – The maximum value of the quantity-value 

division shall not be greater than 0.5% of the minimum measured quantity. 

S.1.3.4. Values Defined. – Indicated values shall be adequately defined by a sufficient number of figures, 

words, symbols, or combinations thereof. A display of “zero” shall be a zero digit for all displayed digits to 

the right of the decimal mark and at least one to the left.

S.1.4. Value of Smallest Unit. – The value of the smallest unit of indicated delivery, and recorded delivery if 

the device is equipped to record, shall not exceed the equivalent of: 

(a) 0.001 kg on devices with a marked maximum flow rated of 30 kg/min or less; or

(b) 0.01 kg on devices with a marked maximum flow rate of more than 30 kg/min.

S.2. Operating Requirements. 

S.2.1. Return to Zero. 

(a) The primary indicating and the primary recording elements, if the device is equipped to record, shall be 

provided with a means for readily returning the indication to zero either automatically or manually.

(b) It shall not be possible to return primary indicating elements, or primary recording elements, beyond the 

correct zero position. 

S.2.2. Indicator Reset Mechanism. – The reset mechanism for the indicating element shall not be operable 

during a delivery. Once the zeroing operation has begun, it shall not be possible to indicate a value other than the 

latest measurement, or “zeros” when the zeroing operation has been completed.

S.2.3. Provision for Power Loss. 

S.2.3.1. Transaction Information. – In the event of a power loss, the information needed to complete 

any transaction in progress at the time of the power loss (such as the quantity and unit price, or sales price) 

shall be determinable for at least 15 minutes at the dispenser or at the console if the console is accessible to 

the customer. 

S.2.3.2. User Information. – The device memory shall retain information on the quantity of fuel 

dispensed and the sales price totals during power loss. 

S.2.4. Display of Unit Price and Product Identity. 

S.2.4.1. Unit Price. – A computing or money-operated device shall be able to display on each face the 

unit price at which the device is set to compute or to dispense.

S.2.4.2. Product Identity. – A device shall be able to conspicuously display on each side the identity of 

the product being dispensed.

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S.2.4.3. Selection of Unit Price. – When a product is offered for sale at more than on unit price through 

a computing device, the selection of the unit price shall be made prior to delivery using controls on the device 

or other customer-activated controls. A system shall not permit a change to the unit price during delivery of 

a product.

S.2.4.4. Agreement Between Indications. – All quantity, unit price, and total price indications within a 

measuring system shall agree for each transaction.

S.2.5. Money-Value Computations. – A computing device shall compute the total sales price at any singlepurchase unit price for which the product being measured is offered for sale at any delivery possible within either 

the measurement range of the device or the range of the computing elements, whichever is less.

S.2.5.1. Auxiliary Elements. – If a system is equipped with auxiliary indications, all indicated money 

value and quantity divisions of the auxiliary element shall be identical with those of the primary element. 

S.2.5.2. Display of Quantity and Total Price. – When a delivery is completed, the total price and quantity 

for that transaction shall be displayed on the face of the dispenser for at least 5 minutes or until the next 

transaction is initiated by using controls on the device or other user-activated controls. 

S.2.6. Recorded Representations, Point of Sale Systems. – A printed receipt shall be available through a 

built-in or separate recording element for transactions conducted with point-of-sale systems or devices activated 

by debit cards, credit cards, and/or cash. The printed receipt shall contain the following information for products 

delivered by the dispenser:

(a) the total mass of the delivery;

(b) the unit price;

(c) the total computed price; and

(d) the product identity by name, symbol, abbreviation, or code number.

S.2.7. Indication of Delivery. – The device shall automatically show on its face the initial zero condition and 

the quantity delivered (up to the nominal capacity).

S.3. Design of Measuring Elements and Measuring Systems. 

S.3.1. Maximum and Minimum Flow-Rates. – The ratio of the maximum to minimum flow-rates specified 

by the manufacturer for devices measuring gases shall be 10:1 or greater. 

S.3.2. Adjustment Means. – An assembly shall be provided with means to change the ratio between the 

indicated quantity and the quantity of gas measured by the assembly. A bypass on the measuring assembly shall 

not be used for these means.

S.3.2.1. Discontinuous Adjusting Means. – When the adjusting means changes ratio between the indicated 

quantity and the quantity of measured gas in a discontinuous manner, the consecutive values of the ratio shall 

not differ by more than 0.1 %.

S.3.3. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or physically applying security seals in such a manner that no adjustment may be made of: 

(a) each individual measurement element;

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of 

deliveries;

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(c) the zero adjustment mechanism; and

(d) any metrological parameter that detrimentally affects the metrological integrity of the device or system.

When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal. Audit 

trails shall use the format set forth in Table S.3.3. Categories of Device and Methods of Sealing.

Table S.3.3.

Categories of Device and Methods of Sealing

Categories of Device Method of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but 

access is controlled by physical hardware. 

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if 

capable of printing in this mode or shall not operate 

while in this mode.

The hardware enabling access for remote 

communication must be on-site. The hardware must 

be sealed using a physical seal or an event counter for 

calibration parameters and an event counter for 

configuration parameters. The event counters may be 

located either at the individual measuring device or at

the system controller; however, an adequate number of 

counters must be provided to monitor the calibration 

and configuration parameters of the individual devices 

at a location. If the counters are located in the system 

controller rather than at the individual device, means 

must be provided to generate a hard copy of the 

information through an on-site device.

Category 3: Remote configuration capability access 

may be unlimited or controlled through a software 

switch (e.g., password).

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if 

capable of printing in this mode or shall not operate 

while in this mode.

An event logger is required in the device; it must 

include an event counter (000 to 999), the parameter 

ID, the date and time of the change, and the new value 

of the parameter. A printed copy of the information 

must be available through the device or through 

another on-site device. The event logger shall have a 

capacity to retain records equal to 10 times the number 

of sealable parameters in the device, but not more than 

1000 records are required. (Note: Does not require 

1000 changes to be stored for each parameter.)

S.3.4. Automatic Density Correction.

(a) An automatic means to determine and correct for changes in product density shall be incorporated in any 

hydrogen gas-measuring system where measurements are affected by changes in the density of the 

product being measured.

(b) Volume-measuring devices with automatic temperature compensation used to measure hydrogen gas as 

a vehicle fuel shall be equipped with an automatic means to determine and correct for changes in product 

density due to changes in the temperature, pressure, and composition of the product. 

S.3.5. Pressurizing the Discharge Hose. – The discharge hose for hydrogen gas shall automatically pressurize 

to a pressure equal to or greater than the receiving vessel prior to the device beginning to register the delivery. 

The indications shall not advance as a result of the initial pressurization or the purging/bleeding of the discharge 

hose.

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S.3.6. Zero-Set-Back Interlock, Retail Vehicle Fuel Devices. 

(a) A device shall be constructed so that:

(1) when the device is shut-off at the end of a delivery an automatic interlock prevents a subsequent 

delivery until the indicating element and recording elements, if the device is equipped and ac-tivated

to record, have been returned to their zero positions; and

(2) it shall not be possible to return the discharge nozzle to its start position unless the zero set back 

interlock is engaged or becomes engaged.

(b) For systems with more than one:

(1) dispenser supplied by a single measuring element, an effective automatic control valve in each 

dispenser prevents product from being delivered until the indicating elements on that dispenser are 

in a correct zero position; or 

(2) hose supplied by a single measuring element, effective automatic means must be provided to prevent 

product from being delivered until the indicating element(s) corresponding to each hose are in a 

correct zero position.

S.4. Discharge Lines and Valves. 

S.4.1. Diversion of Measured Product. – No means shall be provided by which any measured product can be 

diverted from the measuring device. 

S.4.2. Directional Flow Valves. – If a reversal of flow could result in errors that exceed the tolerance for the 

minimum measured quantity, a valve or valves or other effective means, automatic in operation (and equipped 

with a pressure limiting device, if necessary) to prevent the reversal of flow shall be properly installed in the 

system. (Also see N.1. Minimum Measured Quantity.) 

S.4.3. Other Valves. – Check valves and closing mechanisms that are not used to define the measured quantity 

shall have relief valves (if necessary) to dissipate any abnormally high pressure that may arise in the measuring 

assembly.

S.5. Markings. – A measuring system shall be conspicuously, legibly, and indelibly marked with the following 

information:

(a) pattern approval mark (i.e., type approval number);

(b) name and address of the manufacturer or his trademark and, if required by the weights and measures 

authority, the manufacturer's identification mark in addition to the trademark;

(c) model designation or product name selected by the manufacturer;

(d) nonrepetitive serial number;

(e) the accuracy class of the device as specified by the manufacturer consistent with Table T.2. Accuracy Classes 

and Tolerances for Hydrogen-Gas Measuring Devices;

(f) maximum and minimum flow rates in kilograms per unit of time;

(g) maximum working pressure;

(h) applicable range of ambient temperature if other than – 10 °C to + 50 °C;

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(i) minimum measured quantity; and

(j) product limitations (such as fuel quality), if applicable.

S.5.1. Location of Marking Information; Hydrogen-Fuel Dispensers. – The marking information required 

in General Code, paragraph G S.1. Identification shall appear as follows:

(a) within 60 cm (24 in) to 150 cm (60 in) from the base of the dispenser;

(b) either internally and/or externally provided the information is permanent and easily read; and accessible 

for inspection; and

(c) on a portion of the device that cannot be readily removed or interchanged (i.e., not on a service access 

panel).

Note: The use of a dispenser key or tool to access internal marking information is permitted for retail hydrogen-measuring 

devices. 

S.6. Printer. – When an assembly is equipped with means for printing the measured quantity, the printed 

information must agree with the indications on the dispenser for the transaction and the printed values shall be clearly 

defined.

S.6.1. Printed Receipt. – Any delivered, printed quantity shall include an identification number, the time and 

date, and the name of the seller. This information may be printed by the device or pre-printed on the ticket.

S.7. Totalizers for Vehicle Fuel Dispensers. – Vehicle fuel dispensers shall be equipped with a nonresettable

totalizer for the quantity delivered through each separate measuring device.

S.8. Minimum Measured Quantity. – The minimum measured quantity shall satisfy the conditions of use of the 

measuring system as follows:

(a) Measuring systems having a maximum flow rate less than or equal to 4 kg/min shall have a minimum 

measured quantity not exceeding 0.5 kg.

(b) Measuring systems having a maximum flow rate greater than 4 kg/min but not greater than 12 kg/min shall 

have a minimum measured quantity not exceeding 1.0 kg.

N. Notes

N.1. Minimum Measured Quantity. – The minimum measured quantity shall be specified by the manufacturer.

N.2. Test Medium. – The device shall be tested with the product commercially measured except that, in a type 

evaluation examination, hydrogen gas as specified in NIST Handbook 130 shall be used.

Note: Corresponding requirements are under development and this paragraph will be revisited.

N.3. Test Drafts. – The minimum test shall be one test draft at the declared minimum measured quantity and one 

test draft at approximately ten times the minimum measured quantity or 1 kg, whichever is greater. More tests may 

be performed over the range of normal quantities dispensed. (Also see T.3. Repeatability.) 

The test draft shall be made at flows representative of that during normal delivery. The pressure drop between the 

dispenser and the proving system shall not be greater than that for normal deliveries. The control of the flow (e.g., 

pipework or valve(s) size, etc.) shall be such that the flow of the measuring system is maintained within the range 

specified by the manufacturer.

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N.4. Tests.

N.4.1. Master Meter (Transfer) Standard Test. – When comparing a measuring system with a calibrated 

transfer standard, the minimum test shall be one test draft at the declared minimum measured quantity and one 

test draft at approximately ten times the minimum measured quantity or 1 kg, whichever is greater. More tests 

may be performed over the range of normal quantities dispensed.

N.4.1.1. Verification of Master Metering Systems. – A master metering system used to verify a hydrogen 

gas-measuring device shall be verified before and after the verification process. A master metering system 

used to calibrate a hydrogen gas-measuring device shall be verified before starting the calibration and after 

the calibration process.

N.4.2. Gravimetric Tests. – The weight of the test drafts shall be equal to at least the amount delivered by the 

device at the declared minimum measured quantity and one test draft at approximately ten times the minimum 

measured quantity or 1 kg, whichever is greater. More tests may be performed over the range of normal quantities 

dispensed. 

N.4.3. PVT Pressure Volume Temperature Test. – The minimum test with a calibrated volumetric standard 

shall be one test draft at the declared minimum measured quantity and one test draft at approximately ten times 

the minimum measured quantity or 1 kg, whichever is greater. More tests may be performed over the range of 

normal quantities dispensed.

N.5. Minimum Measured Quantity. – The device shall be tested for a delivery equal to the declared minimum 

measured quantity when the device is likely to be used to make deliveries on the order of the declared minimum 

measured quantity.

N.6. Testing Procedures.

N.6.1. General. – The device or system shall be tested under normal operating conditions of the dispenser.

The test draft shall be made at flows representative of that during normal delivery. The pressure drop between 

the dispenser and the proving system shall not be greater than that for normal deliveries. The control of the flow 

(e.g., pipework or valve(s) size, etc.) shall be such that the flow of the measuring system is maintained within the 

range specified by the manufacturer.

N.6.1.1. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test 

drafts of approximately the same size and be conducted under controlled conditions where variations in 

factors are reduced to minimize the effect on the results obtained.

N.7. Density. – Temperature and pressure of hydrogen gas shall be measured during the test for the determination 

of density or volume correction factors when applicable. For the thermophysical properties of hydrogen the following 

publications shall apply: for density calculations at temperatures above 255 K and pressures up to 120 MPa, a simple 

relationship may be used that is given in the publication of Lemmon et al., J. Res. NIST, 2008. Calculations for a 

wider range of conditions and additional thermophysical properties of hydrogen are available free of charge online at 

the “NIST Chemistry WebBook” http://webbook.nist.gov/chemistry, or available for purchase from NIST as the 

computer program NIST Standard Reference Database 23 “NIST Reference Fluid Thermodynamic and Transport 

Properties Database (REFPROP): Version 8.0” http://www.nist.gov/srd/nist23.cfm. These calculations are based 

on the reference Leachman, J.W., Jacobsen, R.T, Lemmon, E.W., and Penoncello, S.G. “Fundamental Equations of 

State for Parahydrogen, Normal Hydrogen, and Orthohydrogen" to be published in the Journal of Physical and 

Chemical Reference Data (http://www.nist.gov/manuscript-publication-search.cfm?pub_id=832374). More 

information may be obtained from NIST online at http://www.boulder.nist.gov/div838/Hydrogen/Index.htm. 

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T. Tolerances

T.1. Tolerances, General. 

(a) The tolerances apply equally to errors of underregistration and errors of overregistration. 

(b) The tolerances apply to all products at all temperatures measured at any flow rate within the rated measuring 

range of the device.

T.2. Tolerances. – The tolerances for hydrogen gas measuring devices are listed in Table T.2. Accuracy Classes 

and Tolerances for Hydrogen Gas-Measuring Devices. (Proposed tolerance values are based on previous work with 

compressed gas products and will be confirmed based on performance data evaluated by the U.S. National Work 

Group.)

Table T.2.

Accuracy Classes and Tolerances for Hydrogen Gas-Measuring Devices

Accuracy Class

Application or Commodity Being 

Measured

Acceptance 

Tolerance

Maintenance 

Tolerance

2.0 Hydrogen gas as a vehicle fuel 1.5 % 2.0 % 

T.3. Repeatability. – When multiple tests are conducted at approximately the same flow rate and draft size, the 

range of the test results for the flow rate shall not exceed 40 % of the absolute value of the maintenance tolerance and 

the results of each test shall be within the applicable tolerance. (Also see N.6.1.1. Repeatability Tests.) 

T.4. Tolerance Application on Test Using Transfer Standard Test Method. – To the basic tolerance values that 

would otherwise be applied, there shall be added an amount equal to two times the standard deviation of the applicable 

transfer standard when compared to a basic reference standard.

T.5. Tolerance Application in Type Evaluation Examinations for Devices. – For type evaluation examinations, 

the tolerance values shall apply under the following conditions:

(a) at any temperature and pressure within the operating range of the device, and

(b) for all quantities greater than the minimum measured quantity.

UR. User Requirements

UR.1. Selection Requirements. 

UR.1.1. Computing-Type Device; Retail Dispenser. – A hydrogen gas dispenser used to refuel vehicles shall 

be of the computing type and shall indicate the mass, the unit price, and the total price of each delivery.

UR.1.2. Discharge Hose-Length. – The length of the discharge hose on a retail fuel dispenser:

(a) shall not exceed 4.6 m (15 ft) unless it can be demonstrated that a longer hose is essential to permit 

deliveries to be made to receiving vehicles or vessels; 

(b) shall be measured from its housing or outlet of the discharge line to the inlet of the discharge nozzle; and

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(c) shall be measured with the hose fully extended if it is coiled or otherwise retained or connected inside a 

housing.

An unnecessarily remote location of a device shall not be accepted as justification for an abnormally long hose.

UR.1.3. Minimum Measured Quantity. 

(a) The minimum measured quantity shall be specified by the manufacturer. 

(b) The minimum measured quantity appropriate for a transaction may be specified by the weights and 

measures authority. A device may have a declared minimum measured quantity smaller than that 

specified by the weights and measures authority; however, the device must perform within the 

performance requirements for the declared or specified minimum measured quantity up to deliveries at 

the maximum measurement range.

(c) The minimum measured quantity shall satisfy the conditions of use of the measuring system as follows:

(1) measuring systems having a maximum flow rate less than or equal to 4 kg/min shall have a minimum 

measured quantity not exceeding 0.5 kg; and

(2) measuring systems having a maximum flow rate greater than 4 kg/min but not greater than 

12 kg/min shall have a minimum measured quantity not exceeding 1.0 kg. 

UR.2. Installation Requirements.

UR.2.1. Manufacturer’s Instructions. – A device shall be installed in accordance with the manufacturer’s 

instructions, and the installation shall be sufficiently secure and rigid to maintain this condition.

UR.2.2. Discharge Rate. – A device shall be installed so that after initial equalization the actual maximum 

discharge rate will not exceed the rated maximum discharge rate. Automatic means of flow regulation shall be 

incorporated in the installation if necessary.

UR.2.3. Low-Flow Cut-Off Valve. – If a measuring system is equipped with a programmable or adjustable 

"low-flow cut-off" feature:

(a) the low-flow cut-off value shall not be set at flow rates lower than the minimum operating flow rate 

specified by the manufacturer on the measuring device; and

(b) the system shall be equipped with flow control valves which prevent the flow of product and stop the 

indicator from registering product flow whenever the product flow rate is less than the low-flow cut-off

value.

UR.3. Use of Device.

UR.3.1. Unit Price and Product Identity for Retail Dispensers. – The unit price at which the dispenser is 

set to compute shall be conspicuously displayed or posted on the face of a retail dispenser used in direct sale.

UR.3.2. Vehicle-mounted Measuring Systems Ticket Printer. 

UR.3.2.1. Customer Ticket. – Vehicle-mounted measuring systems shall be equipped with a ticket printer 

which shall be used for all sales where product is delivered through the device. A copy of the ticket issued 

by the device shall be left with the customer at the time of delivery or as otherwise specified by the customer.

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UR.3.2.2. Ticket in Printing Device. – A ticket shall not be inserted into a device equipped with a ticket 

printer until immediately before a delivery is begun, and in no case shall a ticket be in the device when the 

vehicle is in motion while on a public street, highway, or thoroughfare.

UR.3.3. Printed Ticket. – The total price, the total quantity of the delivery, and the price per unit shall be 

printed on any ticket issued by a device of the computing type and containing any one of these values.

UR.3.4. Steps After Dispensing. – After delivery to a customer from a retail dispenser:

(a) the device shall be shut-off at the end of a delivery, through an automatic interlock that prevents a 

subsequent delivery until the indicating elements and recording elements, if the device is equipped and 

activated to record, have been returned to their zero positions; and

(b) the discharge nozzle shall not be returned to its start position unless the zero set-back interlock is engaged 

or becomes engaged by the act of disconnecting the nozzle or the act of returning the discharge nozzle. 

UR.3.5. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual), 

and the primary recording elements shall be returned to zero immediately before each delivery. 

UR.3.6. Return of Product to Storage, Retail Hydrogen Gas Dispensers. – Provisions at the site shall be 

made for returning product to storage or disposing of the product in a safe and timely manner during or following 

testing operations. Such provisions may include return lines, or cylinders adequate in size and number to permit 

this procedure.

UR.3.7. Conversion Factors. – Established correction values. (Also see references in N.7. Density.) shall be 

used whenever measured hydrogen gas is billed. All sales shall be based on kilograms.

Appendix D. Definitions 

The specific code to which the definition applies is shown in [brackets] at the end of the definition. Definitions for

the General Code [1.10] apply to all codes in Handbook 44.

A 

audit trail. – An electronic count and/or information record of the changes to the values of the calibration or 

configuration parameters of a device. [1.10, 2.20, 2.21, 2.24, 3.30, 3.37, 3.39, 5.56(a)] 

automatic temperature or density compensation. – The use of integrated or ancillary equipment to obtain from the 

output of a volumetric meter an equivalent mass, or an equivalent liquid volume at the assigned reference temperature 

below and a pressure of 14.696 lb/in2 absolute. 

Cryogenic liquids 21 °C (70 °F) [3.34]

Hydrocarbon gas vapor 15 °C (60 °F) [3.33]

Hydrogen gas 21 °C (70 °F) [3.39]

Liquid carbon dioxide 21 °C (70 °F) [3.38]

Liquefied petroleum gas (LPG) and Anhydrous ammonia 15 °C (60 °F) [3.32]

Petroleum liquid fuels and lubricants 15 °C (60 °F) [3.30]

[3.39] 

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C 

calibration parameter. – Any adjustable parameter that can affect measurement or performance accuracy and, due 

to its nature, needs to be updated on an ongoing basis to maintain device accuracy (e.g., span adjustments, linearization

factors, and coarse zero adjustments). [2.20, 2.21, 2.24, 3.30, 3.37, 3.39, 5.56(a)] 

D 

discharge hose. – A flexible hose connected to the discharge outlet of a measuring device or its discharge line. [3.30, 

3.31, 3.32, 3.34, 3.37, 3.38, 3.39]

discharge line. – A rigid pipe connected to the outlet of a measuring device. [3.30, 3.31, 3.32, 3.34, 3.37, 3.39]

E 

event counter. – A non-resettable counter that increments once each time the mode that permits changes to sealable

parameters is entered and one or more changes are made to sealable calibration or configuration parameters of a 

device. [2.20, 2.21, 3.30, 3.37, 3.39, 5.54, 5.56(a), 5.56(b), 5.57] 

event logger. – A form of audit trail containing a series of records where each record contains the number from the 

event counter corresponding to the change to a sealable parameter, the identification of the parameter that was 

changed, the time and date when the parameter was changed, and the new value of the parameter. [2.20, 2.21, 3.30, 

3.37, 3.39, 5.54, 5.56(a), 5.56(b), 5.57]

I 

indicating element. – An element incorporated in a weighing or measuring device by means of which its performance 

relative to quantity or money value is "read" from the device itself as, for example, an index-and-graduated-scale 

combination, a weighbeam-and-poise combination, a digital indicator, and the like. (Also see "primary indicating or 

recording element.") [1.10]

M 

minimum measured quantity (MMQ). – The smallest quantity delivered for which the measurement is to within 

the applicable tolerances for that system. [3.37, 3.39]

N 

Non-resettable totalizer. – An element interfaced with the measuring or weighing element that indicates the 

cumulative registration of the measured quantity with no means to return to zero. [3.30, 3.37, 3.39]

P 

point-of-sale system. – An assembly of elements including a weighing or measuring element, an indicating element, 

and a recording element (and may also be equipped with a “scanner”) used to complete a direct sales transaction. 

[2.20, 3.30, 3.32, 3.37, 3.39]

R 

remote configuration capability. – The ability to adjust a weighing or measuring device or change its sealable

parameters from or through some other device that is not itself necessary to the operation of the weighing or measuring 

device or is not a permanent part of that device. [2.20, 2.21, 2.24, 3.30, 3.37, 3.39, 5.56(a)]

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retail device. – A measuring device primarily used to measure product for the purpose of sale to the end user. [3.30, 

3.32, 3.37, 3.39]

W 

wet hose. – A discharge hose intended to be full of product at all times. (Also see "wet-hose type.") [3.30, 3.31, 3.38, 

3.39]

wet-hose type. – A type of device designed to be operated with the discharge hose full of product at all times. (Also 

see "wet hose.") [3.30, 3.32, 3.34, 3.37, 3.38, 3.39]

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Table of Contents

Section 3.40. Electric Vehicle Fueling Systems – Tentative Code .............................. 3-149

A. Application ................................................................................................................................................ 3-149

A.1. General.............................................................................................................................................. 3-149

A.2. Exceptions......................................................................................................................................... 3-149

A.3. Additional Code Requirements......................................................................................................... 3-149

A.3.1. Electric Vehicle Supply Equipment (EVSE) with Integral Time-Measuring Devices........ 3-149

A.4. Type Evaluation................................................................................................................................ 3-149

S. Specifications............................................................................................................................................. 3-149

S.1. Primary Indicating and Recording Elements. ................................................................................... 3-149

S.1.1. Electric Vehicle Supply Equipment (EVSE) ...................................................................... 3-149

S.1.2. EVSE Indicating Elements ................................................................................................. 3-150

S.1.3. EVSE Units......................................................................................................................... 3-150

S.2. EVSE Operating Requirements. ....................................................................................................... 3-150

S.2.1. EVSE Return to Zero.......................................................................................................... 3-150

S.2.2. EVSE Indicator Zero Reset Mechanism. ............................................................................ 3-150

S.2.3. EVSE Provision for Power Loss......................................................................................... 3-150

S.2.4. EVSE Indication of Unit Price and Equipment Capacity and Type of Voltage.................. 3-151

S.2.5. EVSE Money-Value Computations. ................................................................................... 3-151

S.2.6. EVSE Recorded Representations........................................................................................ 3-152

S.2.7. Indication of Delivery. ........................................................................................................ 3-152

S.3. Design of Measuring Elements and Measuring Systems. ................................................................. 3-152

S.3.1. Metrological Components................................................................................................... 3-152

S.3.2. Terminals. ........................................................................................................................... 3-152

S.3.3. Provision for Sealing........................................................................................................... 3-152

S.3.4. Data Storage and Retrieval. ................................................................................................ 3-153

S.3.5. Temperature Range for System Components. .................................................................... 3-154

S.4. Connections. ..................................................................................................................................... 3-154

S.4.1. Diversion of Measured Electricity. ..................................................................................... 3-154

S.4.2. Directional Control. ............................................................................................................ 3-154

S.5. Markings. .......................................................................................................................................... 3-154

S.5.1. Location of Marking Information; EVSE. .......................................................................... 3-154

S.5.2. EVSE Identification and Marking Requirements................................................................ 3-154

S.5.3. Abbreviations and Symbols. ............................................................................................... 3-154

S.6. Printer. .............................................................................................................................................. 3-154

S.6.1. Printed Receipt.................................................................................................................... 3-155

S.7. Totalizers for EVSE Systems............................................................................................................ 3-155

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S.8. Minimum Measured Quantity (MMQ). ............................................................................................ 3-155

N. Notes........................................................................................................................................................... 3-155

N.1. No Load Test. ................................................................................................................................... 3-155

N.2. Starting Load Test............................................................................................................................. 3-155

N.3. Minimum Test Draft (Size)............................................................................................................... 3-155

N.4. EVSE System Test Loads. ................................................................................................................ 3-155

N.5. Test of an EVSE System................................................................................................................... 3-155

N.5.1. Performance Verification in the Field................................................................................. 3-155

N.5.2. Accuracy Testing. ............................................................................................................... 3-155

N.6. Repeatability Tests............................................................................................................................ 3-156

T. Tolerances.................................................................................................................................................. 3-156

T.1. Tolerances, General. ......................................................................................................................... 3-156

T.2. Load Test Tolerances........................................................................................................................ 3-156

T.2.1. EVSE Load Test Tolerances............................................................................................... 3-156

T.3. Repeatability. .................................................................................................................................... 3-156

T.4. Tolerance Application in Type Evaluation Examinations for EVSEs. ............................................. 3-156

T.5. No Load Test. ................................................................................................................................... 3-156

T.6. Starting Load..................................................................................................................................... 3-156

UR. User Requirements...................................................................................................................................... 3-157

UR.1. Selection Requirements. ................................................................................................................... 3-157

UR.1.1. Computing-Type Device; Retail EVSE. ............................................................................. 3-157

UR.1.2. Connection Cord-Length. ................................................................................................... 3-157

UR.2. Installation Requirements. ................................................................................................................ 3-157

UR.2.1. Maximum Deliverable Current. .......................................................................................... 3-157

UR.2.2. Manufacturer’s Instructions. ............................................................................................... 3-157

UR.2.3. Load Range......................................................................................................................... 3-157

UR.2.4. Regulation Conflicts and Permit Compliance..................................................................... 3-157

UR.2.5. Responsibility, Unattended EVSE. ..................................................................................... 3-157

UR.3. Use of EVSE..................................................................................................................................... 3-157

UR.3.1. Unit Price for Retail EVSE Devices. .................................................................................. 3-157

UR.3.2. Return of Indicating and Recording Elements to Zero. ...................................................... 3-157

UR.3.3. EVSE Recorded Representations........................................................................................ 3-157

UR.3.4. EVSE in Operation. ............................................................................................................ 3-158

UR.3.5. Steps After Charging........................................................................................................... 3-158

Appendix D. Definitions..................................................................................................................................... 3-158

alternating current (AC)............................................................................................................................... 3-158

ampere. ....................................................................................................................................................... 3-158

audit trail...................................................................................................................................................... 3-159

calibration parameter. .................................................................................................................................. 3-159

configuration parameter............................................................................................................................... 3-159

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creep. ....................................................................................................................................................... 3-159

current. ....................................................................................................................................................... 3-159

direct current (DC)....................................................................................................................................... 3-159

electric vehicle, plug-in................................................................................................................................ 3-159

electric vehicle supply equipment (EVSE). ................................................................................................. 3-159

electricity as vehicle fuel. ............................................................................................................................ 3-159

energy. ....................................................................................................................................................... 3-159

energy flow. ................................................................................................................................................. 3-159

equipment, commercial................................................................................................................................ 3-160

event counter................................................................................................................................................ 3-160

event logger. ................................................................................................................................................ 3-160

EVSE field reference standard..................................................................................................................... 3-160

face. ....................................................................................................................................................... 3-160

hertz (Hz)..................................................................................................................................................... 3-160

megajoule (MJ)............................................................................................................................................ 3-160

kilowatt (kW)............................................................................................................................................... 3-160

kilowatt-hour (kWh). ................................................................................................................................... 3-160

load, full....................................................................................................................................................... 3-160

load, light. .................................................................................................................................................... 3-160

master meter, electric................................................................................................................................... 3-161

meter, electricity. ......................................................................................................................................... 3-161

metrological components............................................................................................................................. 3-161

nationally recognized testing laboratory (NRTL)........................................................................................ 3-161

nonresettable totalizer.................................................................................................................................. 3-161

ohm (Ω). ...................................................................................................................................................... 3-161

percent registration. ..................................................................................................................................... 3-161

power factor................................................................................................................................................. 3-161

primary indicating or recording elements. ................................................................................................... 3-161

recorded representation................................................................................................................................ 3-161

recording element. ....................................................................................................................................... 3-162

remote configuration capability. .................................................................................................................. 3-162

retail device.................................................................................................................................................. 3-162

serving utility............................................................................................................................................... 3-162

starting load. ................................................................................................................................................ 3-162

submeter....................................................................................................................................................... 3-162

test accuracy – in-service............................................................................................................................. 3-162

test amperes (TA). ....................................................................................................................................... 3-162

thermal overload protector. .......................................................................................................................... 3-162

unit price...................................................................................................................................................... 3-162

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vehicle connector......................................................................................................................................... 3-162

vehicle coupler............................................................................................................................................. 3-162

vehicle inlet.................................................................................................................................................. 3-162

volt. ....................................................................................................................................................... 3-162

watt. ....................................................................................................................................................... 3-163

watthour (Wh).............................................................................................................................................. 3-163

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Section 3.40. Electric Vehicle Fueling Systems – Tentative Code

This tentative code has a trial or experimental status and is not intended to be enforced. The requirements are designed 

for study prior to the development and adoption of a final code. Officials wanting to conduct an official examination 

of an Electric Vehicle Supply Equipment (EVSE) or system are advised to see paragraph G-A.3. Special and 

Unclassified Equipment.

(Tentative Code Added 2015) 

A. Application

A.1. General. – This code applies to devices, accessories, and systems used for the measurement of electricity

dispensed in vehicle fuel applications wherein a quantity determination or statement of measure is used wholly or 

partially as a basis for sale or upon which a charge for service is based. 

A.2. Exceptions. – This code does not apply to: 

(a) The use of any measure or measuring device owned, maintained, and used by a public utility or municipality

only in connection with measuring electricity subject to the authority having jurisdiction such as the Public 

Utilities Commission.

(b) Electric Vehicle Supply Equipment (EVSEs) used solely for dispensing electrical energy in connection with 

operations in which the amount dispensed does not affect customer charges or compensation. 

(c) The wholesale delivery of electricity. 

A.3. Additional Code Requirements. – In addition to the requirements of this code, Electric Fueling Systems shall 

meet the requirements of Section 1.10. General Code.

A.3.1. Electric Vehicle Supply Equipment (EVSE) with Integral Time-Measuring Devices. – An EVSE

that is used for both the sale of electricity as vehicle fuel and used to measure time during which services

(e.g., vehicle parking) are received. These devices shall also meet the requirements of Section 5.55. Timing 

Devices.

A.4. Type Evaluation. – The National Type Evaluation Program (NTEP) will accept for type evaluation only those 

EVSEs that comply with all requirements of this code and have received safety certification by a nationally recognized 

testing laboratory (NRTL). 

S. Specifications

S.1. Primary Indicating and Recording Elements.

S.1.1. Electric Vehicle Supply Equipment (EVSE). – An EVSE used to charge electric vehicles shall be of 

the computing type and shall indicate the electrical energy, the unit price, and the total price of each transaction. 

(a) EVSEs capable of applying multiple unit prices over the course of a single transaction shall also be 

capable of indicating the start and stop time, the total quantity of energy delivered, the unit price, and 

the total price for the quantity of energy delivered during each discrete phase corresponding to one of 

the multiple unit prices.

(b) EVSEs capable of applying additional fees for time-based and other services shall also be capable of 

indicating the total time measured; the unit price(s) for the additional time based service(s); the total 

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computed price(s) for the time measured; and the total transaction price, including the total price for the 

energy and all additional fees.

S.1.2. EVSE Indicating Elements. – An EVSE used to charge electric vehicles shall include an indicating 

element that accumulates continuously and displays, for a minimum of 15 seconds at the activation by the user 

and at the start and end of the transaction, the correct measurement results relative to quantity and total price. 

Indications shall be clear, definite, accurate, and easily read under normal conditions of operation of the device. 

All indications and representations of electricity sold shall be clearly identified and separate from other timebased fees indicated by an EVSE that is used for both the sale of electricity as vehicle fuel and the sale of other 

separate time-based services (e.g., vehicle parking). 

S.1.2.1. Multiple EVSEs Associated with a Single Indicating Element. – A system with a single 

indicating element for two or more EVSEs shall be provided with means to display information from the 

individual EVSE(s) selected or displayed, and shall be provided with an automatic means to indicate clearly 

and definitely which EVSE is associated with the displayed information.

S.1.3. EVSE Units. 

S.1.3.1. EVSE Units of Measurement. – EVSE units used to charge electric vehicles shall be indicated 

and recorded in megajoules (MJ) or kilowatt-hours (kWh) and decimal subdivisions thereof. 

S.1.3.2. EVSE Value of Smallest Unit. – The value of the smallest unit of indicated delivery by an EVSE, 

and recorded delivery if the EVSE is equipped to record, shall be 0.005 MJ or 0.001 kWh.

S.1.3.3. Values Defined. – Indicated values shall be adequately defined by a sufficient number of figures, 

words, symbols, or combinations thereof. An indication of “zero” shall be a zero digit for all displayed digits 

to the right of the decimal mark and at least one to the left.

S.2. EVSE Operating Requirements. 

S.2.1. EVSE Return to Zero. 

(a) The primary indicating and the primary recording elements of an EVSE used to charge electric vehicles, 

if the EVSE is equipped to record, shall be provided with a means for readily returning the indication to 

zero either automatically or manually.

(b) It shall not be possible to return primary indicating elements, or primary recording elements, beyond the 

correct zero position. 

S.2.2. EVSE Indicator Zero Reset Mechanism. – The reset mechanism for the indicating element of an EVSE

used to charge electric vehicles shall not be operable during a transaction. Once the zeroing operation has begun, 

it shall not be possible to indicate a value other than: the latest measurement; “all zeros;” blank the indication; or 

provide other indications that cannot be interpreted as a measurement during the zeroing operation.

S.2.3. EVSE Provision for Power Loss. 

S.2.3.1. Transaction Information. – In the event of a power loss, the information needed to complete 

any transaction (i.e., delivery is complete and payment is settled) in progress at the time of the power loss 

(such as the quantity and unit price, or sales price) shall be determinable through one of the means listed 

below or the transaction shall be terminated without any charge for the electrical energy transfer to the 

vehicle: 

(a) at the EVSE; 

(b) at the console, if the console is accessible to the customer; 

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(c) via on site internet access; or

(d) through toll-free phone access. 

For EVSEs in parking areas where vehicles are commonly left for extended periods, the information needed 

to complete any transaction in progress at the time of the power loss shall be determinable through one of the 

above means for at least eight hours.

S.2.3.2. Transaction Termination. – In the event of a power loss, either: 

(a) the transaction shall terminate at the time of the power loss; or 

(b) the EVSE may continue charging without additional authorization if the EVSE is able to determine 

it is connected to the same vehicle before and after the supply power outage. 

In either case, there must be a clear indication on the receipt provided to the customer of the interruption, 

including the date and time of the interruption along with other information required under S.2.6. EVSE 

Recorded Representations. 

S.2.3.3. User Information. – The EVSE memory, or equipment on the network supporting the EVSE, 

shall retain information on the quantity of fuel dispensed and the sales price totals during power loss. 

S.2.4. EVSE Indication of Unit Price and Equipment Capacity and Type of Voltage. 

S.2.4.1. Unit Price. – An EVSE shall be able to indicate on each face the unit price at which the EVSE is 

set to compute or to dispense at any point in time during a transaction. 

S.2.4.2. Equipment Capacity and Type of Voltage. – An EVSE shall be able to conspicuously indicate

on each face the maximum rate of energy transfer (i.e., maximum power) and the type of current associated

with each unit price offered (e.g., 7 kW AC, 25 kW DC, etc.).

S.2.4.3. Selection of Unit Price. – When electrical energy is offered for sale at more than one unit price 

through an EVSE, the selection of the unit price shall be made prior to delivery through a deliberate action 

of the purchaser to select the unit price for the fuel delivery. Except when the conditions for variable price 

structure have been approved by the customer prior to the sale, a system shall not permit a change to the unit 

price during delivery of electrical energy. 

Note: When electrical energy is offered at more than one unit price, selection of the unit price may be through the 

deliberate action of the purchaser: 1) using controls on the EVSE; 2) through the purchaser’s use of personal or vehiclemounted electronic equipment communicating with the system; or 3) verbal instructions by the customer.

S.2.4.4. Agreement Between Indications. – All quantity, unit price, and total price indications within a 

measuring system shall agree for each transaction.

S.2.5. EVSE Money-Value Computations. – An EVSE shall compute the total sales price at any 

single-purchase unit price for which the electrical energy being measured is offered for sale at any delivery 

possible within either the measurement range of the EVSE or the range of the computing elements, whichever is 

less.

S.2.5.1. Money-Value Divisions Digital. – An EVSE with digital indications shall comply with the 

requirements of paragraph G-S.5.5. Money-Values, Mathematical Agreement, and the total price 

computation shall be based on quantities not exceeding 0.5 MJ or 0.1 kWh.

S.2.5.2. Auxiliary Elements. – If a system is equipped with auxiliary indications, all indicated money 

value and quantity divisions of the auxiliary element shall be identical to those of the primary element. 

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S.2.6. EVSE Recorded Representations. – A receipt, either printed or electronic, providing the following 

information shall be available at the completion of all transactions: 

(a) the total quantity of the energy delivered with unit of measure; 

(b) the total computed price of the energy sale;

(c) the unit price of the energy, and for systems capable of applying multiple unit prices for energy during 

a single transaction, the following additional information is required:

(1) the start and stop time of each phase during which one of the multiple unit prices was applied;

(2) the unit price applied during each phase;

(3) the total quantity of energy delivered during each phase;

(4) the total purchase price for the quantity of energy delivered during each phase;

(d) the maximum rate of energy transfer (i.e., maximum power) and type of current (e.g., 7 kW AC, 

25 kW DC, etc.); 

(e) any additional separate charges included in the transaction (e.g., charges for parking time) including:

(1) the time and date when the service begins and the time and date when the service ends; or the total 

time interval purchased, and the time and date that the service either begins or ends;

(2) the unit price applied for the time-based service; 

(3) the total purchase price for the quantity of time measured during the complete transaction; 

(f) the final total price of the complete transaction including all items; 

(g) the unique EVSE identification number;

(h) the business name; and

(i) the business location.

S.2.7. Indication of Delivery. – The EVSE shall automatically show on its face the initial zero condition and 

the quantity delivered (up to the capacity of the indicating elements).

S.3. Design of Measuring Elements and Measuring Systems.

S.3.1. Metrological Components. – An EVSE measuring system shall be designed and constructed so that 

metrological components are adequately protected from environmental conditions likely to be detrimental to 

accuracy. The system shall be designed to prevent undetected access to adjustment mechanisms and terminal 

blocks by providing for application of a physical security seal or an audit trail.

S.3.2. Terminals. – The terminals of the EVSE system shall be arranged so that the possibility of short circuits 

while removing or replacing the cover, making connections, or adjusting the system, is minimized. 

S.3.3. Provision for Sealing. – Adequate provision shall be made for an approved means of security (e.g., data 

change audit trail) or physically applying security seals in such a manner that no adjustment may be made of:

(a) each individual measurement element;

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(b) any adjustable element for controlling voltage or current when such control tends to affect the accuracy 

of deliveries;

(c) any adjustment mechanism that corrects or compensates for energy loss between the system and vehicle 

connection; and

(d) any metrological parameter that detrimentally affects the metrological integrity of the EVSE or system.

When applicable, the adjusting mechanism shall be readily accessible for purposes of affixing a security seal. 

Audit trails shall use the format set forth in Table S.3.3. Categories of Device and Methods of Sealing.

Table S.3.3.

Categories of Device and Methods of Sealing

Categories of Device Method of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for 

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but 

access is controlled by physical hardware. 

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if 

capable of printing in this mode or shall not operate 

while in this mode.

The hardware enabling access for remote 

communication must be on-site. The hardware must 

be sealed using a physical seal or an event counter for 

calibration parameters and an event counter for 

configuration parameters. The event counters may be 

located either at the individual measuring EVSE or at 

the system controller; however, an adequate number of 

counters must be provided to monitor the calibration 

and configuration parameters of the individual EVSEs 

at a location. If the counters are located in the system 

controller rather than at the individual EVSE, means 

must be provided to generate a hard copy of the 

information through an on-site device.

Category 3: Remote configuration capability access 

may be unlimited or controlled through a software 

switch (e.g., password).

The device shall clearly indicate that it is in the remote 

configuration mode and record such message if 

capable of printing in this mode or shall not operate 

while in this mode.

An event logger is required in the device; it must 

include an event counter (000 to 999), the parameter 

ID, the date and time of the change, and the new value 

of the parameter. A printed copy of the information 

must be available through the EVSE or through 

another on-site device. The event logger shall have a 

capacity to retain records equal to 10 times the number 

of sealable parameters in the EVSE, but not more than 

1000 records are required. (Note: Does not require 

1000 changes to be stored for each parameter.)

S.3.4. Data Storage and Retrieval.

(a) EVSE data accumulated and indicated shall be unalterable and accessible.

(b) Values indicated or stored in memory shall not be affected by electrical, mechanical, or temperature 

variations, radio-frequency interference, power failure, or any other environmental influences to the 

extent that accuracy is impaired.

(c) Memory and/or display shall be recallable for a minimum of three years. A replaceable battery shall not 

be used for this purpose.

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S.3.5. Temperature Range for System Components. – EVSEs shall be accurate and correct over the 

temperature range of – 40 °C to + 85 °C (− 40 °F to 185 °F). If the system or any measuring system components 

are not capable of meeting these requirements, the temperature range over which the system is capable shall be 

stated on the NTEP CC, marked on the EVSE, and installations shall be limited to the narrower temperature 

limits.

S.4. Connections. 

S.4.1. Diversion of Measured Electricity. – No means shall be provided by which any measured electricity

can be diverted from the measuring device.

S.4.1.1. Unauthorized Disconnection. – Means shall be provided to automatically terminate the 

transaction in the event that there is an unauthorized break in the connection with the vehicle.

S.4.2. Directional Control. – If a reversal of energy flow could result in errors that exceed the tolerance for 

the minimum measured quantity, effective means, automatic in operation to prevent or account for the reversal of 

flow shall be properly installed in the system. (See N.3. Minimum Test Draft [Size]) 

S.5. Markings. – The following identification and marking requirements are in addition to the requirements of 

Section 1.10. General Code, paragraph G-S.1. Identification.

S.5.1. Location of Marking Information; EVSE. – The marking information required in General Code, 

paragraph G-S.1. Identification shall appear as follows:

(a) within 60 cm (24 in) to 150 cm (60 in) from ground level; and

(b) on a portion of the EVSE that cannot be readily removed or interchanged (e.g., not on a service access 

panel).

S.5.2. EVSE Identification and Marking Requirements. – In addition to all the marking requirements of 

Section 1.10. General Code, paragraph G-S.1. Identification, each EVSE shall have the following information 

conspicuously, legibly, and indelibly marked: 

(a) voltage rating;

(b) maximum current deliverable; 

(c) type of current (AC or DC or, if capable of both, both shall be listed); 

(d) minimum measured quantity (MMQ); and

(e) temperature limits, if narrower than and within – 20 °C to + 50 °C (− 4 °F to 122 °F).

S.5.3. Abbreviations and Symbols. – The following abbreviations or symbols may appear on an EVSE 

system. 

(a) VAC = volts alternating current; 

(b) VDC = volts direct current; 

(c) MDA = maximum deliverable amperes; 

(d) J = joule. 

S.6. Printer. – When a system is equipped with means for printing the measured quantity, the printed information 

must agree with the indications on the EVSE for the transaction and the printed values shall be clearly defined.

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S.6.1. Printed Receipt. – Any delivered, printed quantity shall include an EVSE identification number that 

uniquely identifies the EVSE from all other EVSEs within the seller’s facility, the time and date, and the name of 

the seller. This information may be printed by the EVSE system or pre-printed on the ticket.

S.7. Totalizers for EVSE Systems. – EVSE systems shall be designed with a nonresettable totalizer for the quantity 

delivered through each separate measuring device. Totalizer information shall be adequately protected and 

unalterable. Totalizer information shall be provided by the system and readily available on site or via on site internet 

access. 

S.8. Minimum Measured Quantity (MMQ). – The minimum measured quantity shall satisfy the conditions of use 

of the measuring system as follows:

(a) Measuring systems shall have a minimum measured quantity not exceeding 2.5 MJ or 0.5 kWh. 

N. Notes 

N.1. No Load Test. – A no load test may be conducted on an EVSE measuring system by applying rated voltage to 

the system under test and no load applied.

N.2. Starting Load Test. – A system starting load test maybe conducted by applying rated voltage and 0.5-ampere 

load.

N.3. Minimum Test Draft (Size). – Full and light load tests shall require test of the EVSE System for a delivery of 

the minimum measured quantity as declared by the manufacturer. 

N.4. EVSE System Test Loads. – EVSE measuring system testing shall be accomplished by connecting the test 

load and test standard at the point where the fixed cord is connected to the vehicle. Losses in the cord between the 

EVSE under test and the test standard should be automatically corrected for in the EVSE quantity indication for direct 

comparison to the test standard and also while the EVSE is in normal operation. For EVSEs that require a customersupplied cord, system testing shall be accomplished by connecting the test load and test standard at the point where 

the customer’s cord is connected to the EVSE.

N.5. Test of an EVSE System.

N.5.1. Performance Verification in the Field. – Testing in the field is intended to validate the transactional

accuracy of the EVSE system. The following testing is deemed sufficient for a field validation.

N.5.2. Accuracy Testing. – The testing methodology compares the total energy delivered in a transaction and 

the total cost charged as displayed/reported by the EVSE with that measured by the measurement standard.

(a) For AC systems: 

(1) Accuracy test of the EVSE system at a load of not less than 85 % of the maximum deliverable 

amperes (expressed as MDA) as determined from the pilot signal for a total energy delivered of at 

least twice the minimum measured quantity (MMQ). If the MDA would result in maximum 

deliverable power of greater than 7.2 kW, then the test may be performed at 7.2 kW.

(2) Accuracy test of the EVSE system at a load of not greater than 10 % of the maximum deliverable 

amperes (expressed as MDA) as determined from the pilot signal for a total energy delivered of at 

least the minimum measured quantity (MMQ).

(b) For DC systems (see note): 

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(1) Accuracy test of the EVSE system at a load of not less than 85 % of the maximum deliverable 

amperes current (expressed as MDA) as determined from the digital communication message from 

the DC EVSE to the test standard for a total energy delivered of at least twice the minimum measured 

quantity (MMQ).

(2) Accuracy test of the EVSE system at a load of not more than 10 % of the maximum deliverable 

amperes (expressed as MDA) as determined from the digital communication message from the DC 

EVSE to the test standard for a total energy delivered of at least the minimum measured quantity 

(MMQ).

Note: For DC systems it is anticipated that an electric vehicle may be used as the test load. Under that 

circumstance, testing at the load presented by the vehicle shall be sufficient.

N.6. Repeatability Tests. – Tests for repeatability shall include a minimum of three consecutive tests at the same 

load, similar time period, etc., and be conducted under conditions where variations in factors are reduced to minimize 

the effect on the results obtained.

T. Tolerances

T.1. Tolerances, General. 

(a) The tolerances apply equally to errors of underregistration and errors of overregistration.

(b) The tolerances apply to all deliveries measured at any load within the rated measuring range of the EVSE. 

(c) Where instrument transformers or other components are used, the provisions of this section shall apply to 

all system components.

T.2. Load Test Tolerances.

T.2.1. EVSE Load Test Tolerances. – The tolerances for EVSE load tests are: 

 

(a) Acceotance Tolerance: 1.0 %; and 

(b) Maintenance Tolerance: 2.0 %.

T.3. Repeatability. – When multiple load tests are conducted at the same load condition, the range of the load test 

results shall not exceed 25 % of the absolute value of the maintenance tolerance and the results of each test shall be 

within the applicable tolerance. 

T.4. Tolerance Application in Type Evaluation Examinations for EVSEs. – For type evaluation examinations, 

the acceptance tolerance values shall apply under the following conditions:

(a) at any temperature, voltage, load, and power factor within the operating range of the EVSE, and

(b) regardless of the influence factors in effect at the time of the conduct of the examination, and

(c) for all quantities greater than the minimum measured quantity.

T.5. No Load Test. – An EVSE measuring system shall not register when no load is applied. 

T.6. Starting Load. – An EVSE measuring system shall register a starting load test at a 0.5 ampere (A) load. 

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UR. User Requirements

UR.1. Selection Requirements. 

UR.1.1. Computing-Type Device; Retail EVSE. – An EVSE used to charge electric vehicles shall be of the 

computing type and shall indicate the electrical energy, the unit price, and the total price of each delivery. 

UR.1.2. Connection Cord-Length. – An adequate means for cord management shall be in use when the cord 

exceeds 25 ft in length.

UR.2. Installation Requirements.

UR.2.1. Maximum Deliverable Current. – The marked maximum deliverable current shall not exceed the 

total capacity in amperes of the EVSE or the thermal overload protectors of the installation site. 

UR.2.2. Manufacturer’s Instructions. – An EVSE shall be installed in accordance with the manufacturer’s 

instructions, and the installation shall be sufficiently secure and rigid to maintain this condition.

UR.2.3. Load Range. – An EVSE shall be installed so that the current and voltage will not exceed the rated 

maximum values over which the EVSE is designed to operate continuously within the specified accuracy. Means 

to limit current and/or voltage shall be incorporated in the installation if necessary.

UR.2.4. Regulation Conflicts and Permit Compliance. – If any provision of Section UR.2. Installation 

Requirements is less stringent than that required of a similar installation by the serving utility, the installation 

shall be in accordance with those requirements of the serving utility.

The installer of any EVSE shall obtain all necessary permits.

UR.2.5. Responsibility, Unattended EVSE. – An unattended EVSE shall have clearly and conspicuously 

displayed thereon, or immediately adjacent thereto, adequate information detailing the name, address, and phone 

number of the local responsible party for the device. 

UR.3. Use of EVSE. 

UR.3.1. Unit Price for Retail EVSE Devices. – The unit price at which the EVSE is set to compute shall be 

conspicuously displayed or posted on the face of the retail EVSE used in direct sale.

UR.3.2. Return of Indicating and Recording Elements to Zero. – The primary indicating elements (visual)

and the primary recording elements shall be returned to zero immediately before each transaction. 

UR.3.3. EVSE Recorded Representations. – A receipt, either printed or electronic, providing the following 

information shall be available at the completion of all transactions:

(a) the total quantity of the energy delivered with unit of measure;

(b) the total computed price of the energy sale;

(c) the unit price of the energy; and for systems capable of applying multiple unit prices for energy during 

a single transaction, the following additional information is required:

(1) the start and stop time of each phase during which one of the multiple unit prices was applied;

(2) the unit price applied during each phase;

(3) the total quantity of energy delivered during each phase;

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(4) the total purchase price for the quantity of energy delivered during each phase;

(d) the maximum rate of energy transfer (i.e., maximum power) and type of current (e.g., 7 kW AC, 

25 kW DC, etc.);

(e) any additional separate charges included in the transaction (e.g., charges for parking time) including:

(1) the time and date when the service begins and the time and date when the service ends; or the total 

time interval purchased, and the time and date that the service either begins or ends;

(2) the unit price applied for the time-based service;

(3) the total purchase price for the quantity of time measured during the complete transaction; 

(f) the final total price of the complete transaction including all items;

(g) the unique EVSE identification number;

(h) the business name; and

(i) the business location.

UR.3.4. EVSE in Operation. – The EVSE shall be permanently, plainly, and visibly identified so that it is 

clear which EVSE and connector is in operation. 

UR.3.5. Steps After Charging. – After delivery to a customer from a retail EVSE: 

(a) the EVSE shall be shut-off at the end of a charge, through an automatic interlock that prevents subsequent 

charging until the indicating elements and recording elements, if the EVSE is equipped and activated to 

record, have been returned to their zero positions; and

(b) the vehicle connector shall not be returned to its starting position unless the zero set-back interlock is 

engaged or becomes engaged by the act of disconnecting from the vehicle or the act of returning the 

connector to the starting position. 

Appendix D. Definitions 

The following includes new definitions to address Electric Vehicle Fueling Systems. Also included are those 

definitions currently found in Appendix D that are intended to apply to these systems. The specific code(s) to which 

each definition applies is shown in [brackets] at the end of the definition. Definitions for the General Code [1.10] 

apply to all codes in Handbook 44.

A

alternating current (AC). – An electric current that reverses direction in a circuit at regular intervals. [3.40] 

ampere. – The practical unit of electric current. It is the quantity of current caused to flow by a potential difference 

of one volt through a resistance of one ohm. One ampere (A) is equal to the flow of one coulomb of charge per second. 

One coulomb (C) is the unit of electric charge equal in magnitude to the charge of 6.24 × 1018 electrons. [3.40] 

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audit trail. – An electronic count and/or information record of the changes to the values of the calibration or 

configuration parameters of a device. [1.10, 2.20, 2.21, 2.24, 3.30, 3.37, 3.39, 3.40, 5.56(a)]

(Added 1993)

C 

calibration parameter. – Any adjustable parameter that can affect measurement or performance accuracy and, due 

to its nature, needs to be updated on an ongoing basis to maintain device accuracy (e.g., span adjustments, linearization 

factors, and coarse zero adjustments). [2.20, 2.21, 2.24, 3.30, 3.37, 3.39, 3.40, 5.56(a)]

(Added 1993)

configuration parameter. – Any adjustable or selectable parameter for a device feature that can affect the accuracy 

of a transaction or can significantly increase the potential for fraudulent use of the device and, due to its nature, needs 

to be updated only during device installation or upon replacement of a component (e.g., division value [increment], 

sensor range, and units of measurement). [2.20, 2.21, 2.24, 3.30, 3.37, 3.40, 5.56(a)]

(Added 1993)

creep. – A continuous apparent measurement of energy indicated by a system with operating voltage applied and no 

power consumed (load terminals open circuited). [3.40] 

current. – The rate of the flow of electrical charge past any one point in a circuit. The unit of measurement is amperes

(A) or coulombs (C) per second. [3.40] 

D 

direct current (DC). – An electric current that flows in one direction. [3.40] 

E 

electric vehicle, plug-in. – A vehicle that employs electrical energy as a primary or secondary mode of propulsion. 

Plug-in electric vehicles may be all-electric vehicles (EV’s) or plug-in hybrid electric vehicles (PHEV’s). All-electric 

vehicles are powered by an electric motor and battery at all times. All-electric vehicles may also be called batteryelectric vehicles (BEV’s). Plug-in hybrid electric vehicles employ both an electric motor and an internal combustion 

engine that consumes either conventional or alternative fuel or a fuel cell. In a parallel type hybrid-electric vehicle, 

either the electric motor or the engine may propel the vehicle. In a series type hybrid-electric vehicle, the engine or 

fuel cell generates electricity that is then used by the electric motor to propel the vehicle. EV’s, BEV’s, and PHEV’s

are capable of receiving and storing electricity via connection to an external electrical supply. Not all hybrid-electric 

vehicles are of the plug-in type. Hybrid-electric vehicles that do not have the capability to receive electrical energy 

from an external supply (HEV’s) generate electrical energy onboard with the internal combustion engine, regenerative 

braking, or both. [3.40] 

electric vehicle supply equipment (EVSE). – A device or system designed and used specifically to transfer electrical 

energy to an electric vehicle, either as charge transferred via physical or wireless connection, by loading a fully charged 

battery, or by other means. [3.40] 

electricity as vehicle fuel. – Electrical energy transferred to and/or stored onboard an electric vehicle primarily for 

the purpose of propulsion. [3.40] 

energy. – The integral of active power with respect to time. [3.40] 

energy flow. – The flow of energy between line and load terminals (conductors) of an electricity system. Flow from 

the line to the load terminals is considered energy delivered. Energy flowing in the opposite direction (i.e., from the 

load to line terminals) is considered as energy received. [3.40] 

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equipment, commercial. – Weights, measures, and weighing and measuring devices, instruments, elements, and 

systems or portion thereof, used or employed in establishing the measurement or in computing any basic charge or 

payment for services rendered on the basis of weight or measure. As used in this definition, measurement includes 

the determination of size, quantity, value, extent, area, composition (limited to meat and poultry), constituent value 

(for grain), or measurement of quantities, things, produce, or articles for distribution or consumption, purchased, 

offered, or submitted for sale, hire, or award. [1.10, 2.20, 2.21, 2.22, 2.24, 3.30, 3.31, 3.32, 3.33, 3.34, 3.35, 3.38, 3.40, 

4.40, 5.51, 5.56.(a), 5.56.(b), 5.57, 5.58, 5.59]

(Added 2008)

event counter. – A nonresettable counter that increments once each time the mode that permits changes to sealable 

parameters is entered and one or more changes are made to sealable calibration or configuration parameters of a 

device. [2.20, 2.21, 3.30, 3.37, 3.39, 3.40, 5.54, 5.56(a), 5.56(b), 5.57]

(Added 1993)

event logger. – A form of audit trail containing a series of records where each record contains the number from the event 

counter corresponding to the change to a sealable parameter, the identification of the parameter that was changed, the time 

and date when the parameter was changed, and the new value of the parameter. [2.20, 2.21, 3.30, 3.37, 3.39, 3.40, 5.54, 

5.56(a), 5.56(b), 5.57]

(Added 1993)

EVSE field reference standard. – A portable apparatus that is traceable to NIST and is used as a standard to test 

EVSEs in commercial applications. This instrument is also known as a portable standard or working standard. [3.40] 

F 

face. – That portion of a computing-type pump or dispenser which displays the actual computation of price per unit, 

delivered quantity, and total sale price. In the case of some electronic displays, this may not be an integral part of the 

pump or dispenser. [3.30, 3.40] 

(Added 1987)

H 

hertz (Hz). – Frequency or cycles per second. One cycle of an alternating current or voltage is one complete set of 

positive and negative values of the current or voltage. [3.40] 

J 

megajoule (MJ). – An SI unit of energy equal to 1 000 000 joules (J). [3.40] 

K 

kilowatt (kW). – A unit of power equal to 1000 watts (W). [3.40] 

kilowatt-hour (kWh). – A unit of energy equal to 1000 watthours (W h). [3.40] 

L 

load, full. – A test condition with rated voltage, current at 100 % of test amps level, and power factor of 1.0. [3.40] 

load, light. – A test condition with rated voltage, current at 10 % of test amps level, and power factor of 1.0. [3.40] 

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M 

master meter, electric. – An electric watthour meter owned, maintained, and used for commercial billing purposes 

by the serving utility. All the electric energy served to a submetered service system is recorded by the master meter. 

[3.40] 

meter, electricity. – An electric watthour meter. [3.40] 

metrological components. – Elements or features of a measurement device or system that perform the measurement 

process or that may affect the final quantity determination or resulting price determinations. This includes accessories 

that can affect the validity of transactions based upon the measurement process. The measurement process includes 

determination of quantities; the transmission, processing, storage, or other corrections or adjustments of measurement 

data or values; and the indication or recording of measurement values or other derived values such as price or worth

or charges. [3.40] 

N 

nationally recognized testing laboratory (NRTL). – A laboratory that conducts testing and certification that is 

recognized by the Occupational Safety and Health Administration (OSHA). [3.40] 

nonresettable totalizer. – An element interfaced with the measuring or weighing element that indicates the 

cumulative registration of the measured quantity with no means to return to zero. [3.30, 3.37, 3.39, 3.40] 

O 

ohm (Ω). – The practical unit of electric resistance that allows one ampere of current to flow when the impressed 

potential is one volt. [3.40] 

P 

percent registration. – Percent registration is calculated as follows:

Re x 100 Wh measured by EVSE Percent gistration

Wh measured by STANDARD =

[3.40]

power factor. – The ratio of the active power to the apparent power in an AC circuit. The power factor is a number 

between 0 and 1 that is equal to 1 when the voltage and current are in phase (load is entirely resistive). [3.40] 

primary indicating or recording elements. – The term “primary” is applied to those principal indicating (visual) 

elements and recording elements that are designed to, or may, be used by the operator in the normal commercial use 

of a device. The term “primary” is applied to any element or elements that may be the determining factor in arriving 

at the sale representation when the device is used commercially. (Examples of primary elements are the visual 

indicators for meters or scales not equipped with ticket printers or other recording elements and both the visual 

indicators and the ticket printers or other recording elements for meters or scales so equipped.) The term “primary” 

is not applied to such auxiliary elements as, for example, the totalizing register, or predetermined-stop mechanism on 

a meter or the means for producing a running record of successive weighing operations, these elements being 

supplementary to those that are the determining factors in sales representations of individual deliveries or weights. 

(See “indicating element” and “recording element.”). [1.10, 3.40] 

R

recorded representation. – The printed, electronically recorded, or other representation that retains a copy of the 

quantity and any other required information generated by a weighing or measuring device. [1.10, 3.40] 

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recording element. – An element incorporated, connected to, or associated with a weighing or measuring device by 

means of which its performance relative to quantity or money value is permanently recorded in a printed or electronic 

form. [1.10, 3.40] 

remote configuration capability. – The ability to adjust a weighing or measuring device or change its sealable 

parameters from or through some other device that is not itself necessary to the operation of the weighing or measuring 

device or is not a permanent part of that device. [2.20, 2.21, 2.24, 3.30, 3.37, 3.39, 3.40, 5.56(a)]

(Added 1993)

retail device. – A measuring device primarily used to measure electrical energy for the purpose of sale to the end user.

[3.40] 

S 

serving utility. – The utility distribution company that owns the master meter and sells electric energy to the owner 

of a submeter system. [3.40] 

starting load. – The minimum load above which the device will indicate energy flow continuously. [3.40] 

submeter. – A system furnished, owned, installed, and maintained by the customer who is served through a utility 

owned master meter. [3.40] 

T 

test accuracy – in-service. – The device accuracy determined by a test made during the period that the system is in 

service. It may be made on the customer’s premises without removing the system from its mounting or by removing 

the EVSE for testing either on the premises or in a laboratory or shop. [3.40] 

test amperes (TA). – The full load current (amperage) specified by the EVSE manufacturer for testing and calibration 

adjustment. (Example: TA 30). [3.40] 

thermal overload protector. – A circuit breaker or fuse that automatically limits the maximum current in a circuit. 

[3.40] 

U 

unit price. – The price at which the electrical energy is being sold and expressed in whole units of measurement.

[1.10, 3.30, 3.40] 

(Added 1992)

V 

vehicle connector. – A device that by insertion into a vehicle inlet, establishes an electrical connection to the electric 

vehicle for the purpose of providing power and information exchange, with means for attachment of an electric vehicle 

cable. This device is a part of the vehicle coupler. [3.40] 

 

vehicle coupler. – A means enabling the connection, at will, of an electric vehicle cable to the equipment. It consists 

of a vehicle connector and a vehicle inlet. [3.40] 

vehicle inlet. – The part incorporated in, or fixed to the vehicle, which receives power from a vehicle connector. [3.40] 

volt. – The practical unit of electromotive force. One volt will cause one ampere to flow when impressed across a 

resistance of one ohm. [3.40] 

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W 

watt. – The practical unit of electric power. In an alternating-current (AC) circuit, the power in watts is volts times 

amperes multiplied by the circuit power factor. [3.40] 

watthour (Wh). – The practical unit of electric energy that is expended in one hour when the average power consumed

during the hour is one watt. [3.40] 

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Handbook 44 – 2016 Section 4 

4-1

Section 4

Table of Contents

Page 

4.40. Vehicle Tanks Used as Measures .................................................................................... 4-3 

4.41. Liquid Measures............................................................................................................... 4-9 

4.42. Farm Milk Tanks............................................................................................................ 4-13 

4.43. Measure-Containers ....................................................................................................... 4-21 

4.44. Graduates ....................................................................................................................... 4-27 

4.45. Dry Measures................................................................................................................. 4-33 

4.46. Berry Baskets and Boxes............................................................................................... 4-39 

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4-3 

Table of Contents

Section 4.40. Vehicle Tanks Used as Measures ................................................................... 4-5

A. Application .................................................................................................................................................... 4-5

A.1. General..................................................................................................................................................4-5

A.2. Exceptions.............................................................................................................................................4-5

A.3. Additional Code Requirements.............................................................................................................4-5

S. Specifications................................................................................................................................................. 4-5

S.1. Design of Compartments. .....................................................................................................................4-5

S.1.1. Compartment Distortion. ........................................................................................................4-5

S.1.2. Venting. ..................................................................................................................................4-5

S.1.3. Completeness of Delivery.......................................................................................................4-5

S.1.4. Fill or Inspection Opening. .....................................................................................................4-5

S.1.5. Dome Flange and Baffle Plates...............................................................................................4-5

S.1.6. Compartment and Piping Capacities and Emergency Valve...................................................4-5

S.1.7. Expansion Space. ....................................................................................................................4-6

S.2. Design of Compartment Indicators.......................................................................................................4-6

S.2.1. General....................................................................................................................................4-6

S.2.2. Number of Indicators. .............................................................................................................4-6

S.2.3. Identification of Multiple Indicators. ......................................................................................4-6

S.2.4. Location. .................................................................................................................................4-6

S.2.5. Permanence.............................................................................................................................4-6

S.2.6. Adjustable Indicators. .............................................................................................................4-6

S.2.7. Sensitiveness...........................................................................................................................4-6

S.3. Design of Compartment Discharge Manifold. ......................................................................................4-7

S.4. Marking of Compartments....................................................................................................................4-7

S.4.1. Compartment Identification. ...................................................................................................4-7

S.4.2. Compartment Capacity, Single Indicator................................................................................4-7

S.4.3. Compartment Capacity, Multiple Indicators...........................................................................4-7

N. Notes............................................................................................................................................................... 4-7

N.1. Test Liquid............................................................................................................................................4-7

N.2. Evaporation and Volume Change. ........................................................................................................4-7

N.3. To Deliver.............................................................................................................................................4-7

N.4. Gauging of Compartments....................................................................................................................4-7

N.5. Adjustment and Remarking. .................................................................................................................4-7

T. Tolerances...................................................................................................................................................... 4-8

T.1. Application............................................................................................................................................4-8

T.1.1. To Excess and to Deficiency...................................................................................................4-8

T.2. Tolerance Values. .................................................................................................................................4-8

UR. User Requirements ....................................................................................................................................... 4-8

UR.1. Conditions of Use. ................................................................................................................................4-8

UR.1.1. Filling......................................................................................................................................4-8

UR.1.2. Delivering. ..............................................................................................................................4-8

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4-5 

Section 4.40. Vehicle Tanks Used as Measures

A. Application

A.1. General. – This code applies to vehicle tanks when these are used as commercial measures.

A.2. Exceptions. – This code does not apply to the following devices:

(a) Devices used solely for dispensing a product in connection with operations in which the amount dispensed 

does not affect customer charges.

(b) Meters mounted on vehicle tanks (for which see Section 3.31. Code for Vehicle-Tank Meters).

A.3. Additional Code Requirements. – In addition to the requirements of this code, Vehicle Tanks Used as 

Measures shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Compartments.

S.1.1. Compartment Distortion. – The shell and bulkheads of a vehicle tank shall be so constructed that under 

any condition of liquid lading they will not become distorted sufficiently to cause a change in the capacity of any 

compartment (as determined by volumetric test) equal to more than 0.25 L per 750 L (0.5 pt per 200 gal), or 

fraction thereof, of the nominal compartment capacity, or to more than 0.5 L (1 pt), whichever is greater. (This 

specification prescribes a limit on permissible distortion only, and is not to be construed as setting up a secondary 

tolerance on compartment capacities to be added to the values given in tolerance paragraph T.2. Tolerance 

Values.)

S.1.2. Venting. – During filling operations, effective venting of a compartment shall be provided to permit air 

to escape from all spaces designed to be filled with liquid and to permit the influx of air to the compartment during 

the discharge of liquid therefrom. Venting shall prevent any formation of air pockets.

S.1.3. Completeness of Delivery. – A tank shall be so constructed that, when it is standing on a level surface, 

complete delivery can be made from any compartment through its delivery faucet or valve whether other 

compartments are full or empty, and whether or not the delivery is through a manifold.

S.1.4. Fill or Inspection Opening. – The fill or inspection opening of a compartment shall be of such size and 

location that it can readily be determined by visual inspection that the compartment has been properly filled or 

completely emptied and shall be so positioned with respect to the ends of the compartment that the indicator may 

be positioned as required. In no case shall the opening, if circular, have a diameter of less than 20 cm (75

/8 in), 

or, if other than circular, have an effective area of less than 290 cm2 (45 in2

).

S.1.5. Dome Flange and Baffle Plates. – Any dome flange extending into a compartment shall be provided 

with sufficient perforations or openings flush with the compartment shell to prevent any trapping of air. All baffle 

plates in a compartment shall be so cut away at top and bottom, and elsewhere as necessary, as to facilitate loading 

and unloading.

S.1.6. Compartment and Piping Capacities and Emergency Valve. – If a compartment is equipped with an 

emergency (or safety) valve, this shall be positioned at the lowest point of outlet from the compartment, and the 

compartment capacity or capacities shall be construed as excluding the capacity of the piping leading therefrom. 

However, the capacity of the piping leading from such a compartment shall be separately determined and reported, 

and may be separately marked as specified in S.4. Marking of Compartments.

S.1.6.1. On Vehicle Tanks Equipped for Bottom Loading. – On equipment designed for bottom 

loading, the compartment capacity shall include the piping of a compartment to the valve located on the 

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upstream side of the manifold and immediately adjacent thereto or, if not manifolded, to the outlet valve, 

provided that on or immediately adjacent to the marking as specified in S.4. Marking of Compartments the 

following words or a statement of similar meaning shall be affixed: “Warning: Emergency valves must be 

opened before checking measurement.”

S.1.7. Expansion Space. – When a compartment is filled to the level of the highest indicator in the 

compartment, there shall remain an expansion space of at least 0.75 % of the nominal compartment capacity as 

defined by that indicator.

S.2. Design of Compartment Indicators. 

S.2.1. General. – An indicator shall be so designed that it will distinctly and unmistakably define a capacity 

point of its compartment when liquid is in contact with the lowest portion of the indicator.

S.2.2. Number of Indicators. – In no case shall a compartment be provided with more than five indicators.

(Amended 1972)

S.2.3. Identification of Multiple Indicators. – If a compartment is provided with multiple indicators, each 

such indicator shall be conspicuously marked with an identifying letter or number.

S.2.4. Location. – An indicator shall be located:

(a) midway between the sides of its compartment;

(b) as nearly as practicable midway between the ends of its compartment, and in no case offset by more than 

10 % of the compartment space or 15 cm (6 in), whichever is less;

(Amended 1972)

(c) so that it does not extend into, nor more than 15 cm (6 in) from that section of the compartment defined 

by a vertical projection of the fill opening;

(Amended 1974)

(d) at a depth, measuring from the top of the dome opening, not lower than 46 cm (18 in) for fill openings 

of less than 38 cm (15 in) in diameter, or, if other than circular, an effective area of less than 1130 cm2

(175 in2

), and not lower than 61 cm (24 in) for larger fill openings; and

(e) to provide a clearance of not less than 5 cm (2 in) between indicators.

S.2.5. Permanence. – Any indicator that is not intended to remain adjustable and all brackets or supports shall 

be securely welded in position.

S.2.6. Adjustable Indicators. – Adequate provision shall be made for conveniently affixing a security seal or 

seals:

(a) to any indicator intended to remain adjustable, so that no adjustment of the indicator can be made without 

mutilating or destroying the seal; and

(b) to any removable part to which an indicator may be attached, so that the part cannot be removed without 

mutilating or destroying the seal.

S.2.7. Sensitiveness. – The position of any indicator in its compartment shall be such that at the level of the 

indicator a change of 1.0 mm (0.04 in) in the height of the liquid surface will represent a volume change of not 

more than the value of the tolerance for the nominal compartment capacity as defined by that indicator.

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4-7 

S.3. Design of Compartment Discharge Manifold. – When two or more compartments discharge through a 

common manifold or other single outlet, effective means shall be provided to ensure that: 

(a) liquid can flow through the delivery line leading from only one compartment at one time and that flow of 

liquid from one compartment to any other is automatically prevented; or

(b) all compartments will discharge simultaneously.

If the discharge valves from two or more compartments are automatically controlled so that they can only be operated 

together, thus effectively connecting these compartments to one another, such compartments shall, for purposes of 

this paragraph, be construed to be one compartment.

S.4. Marking of Compartments.

S.4.1. Compartment Identification. – Each compartment of a multiple-compartment tank shall be 

conspicuously identified by a letter or number marked on the dome or immediately below the fill opening. Such 

letters or numbers shall be in regular sequence from front to rear, and the delivery faucets or valves shall be 

marked to correspond with their respective compartments.

S.4.2. Compartment Capacity, Single Indicator. – A compartment provided with a single indicator shall be 

clearly, permanently, and conspicuously marked with a statement of its capacity as defined by its indicator.

S.4.3. Compartment Capacity, Multiple Indicators. – A compartment provided with two or more indicators 

shall be clearly, permanently, and conspicuously marked with a statement identifying:

(a) each indicator by a letter or number; and 

(b) immediately adjacent to each letter or number, the capacity of the compartment as defined by the 

particular indicator.

N. Notes

N.1. Test Liquid. – Water or light fuel oil shall be used as the test liquid for a vehicle-tank compartment.

N.2. Evaporation and Volume Change. – Care shall be exercised to reduce to a minimum, evaporation losses and 

volume changes resulting from changes in temperature of the test liquid.

N.3. To Deliver. – A vehicle-tank compartment shall be gauged “to deliver.” If the compartment is gauged by 

measuring the test liquid into the tank, the inside tank walls shall first be thoroughly wetted.

N.4. Gauging of Compartments. – When a compartment is gauged to determine the proper position for an indicator 

or to determine what a capacity marking should be, whether on a new vehicle tank or following repairs or modifications 

that might affect compartment capacities, tolerances are not applicable, and the indicator shall be set and the 

compartment capacity shall be marked as accurately as practicable.

N.5. Adjustment and Remarking. – When a compartment is found upon test to have an error in excess of the 

applicable tolerance, the capacity of the compartment shall be adjusted to agree with its marked capacity, or its marked 

capacity shall be changed to agree with its capacity as determined by the test.

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4.40. Vehicle Tanks Used as Measures Handbook 44 – 2016 

4-8 

T. Tolerances

T.1. Application.

T.1.1. To Excess and to Deficiency. – The tolerances hereinafter prescribed shall be applied to errors in excess 

and in deficiency.

T.2. Tolerance Values. – Maintenance and acceptance tolerances shall be as shown in Table 1. Maintenance and 

Acceptance Tolerances on Vehicle-Tank Compartments.

Table 1.

Maintenance and Acceptance Tolerances on Vehicle-Tank Compartments

Nominal Capacity of Compartment Maintenance and Acceptance Tolerances

Gallons Expressed in Quarts Expressed in Gallons

200 or less 2 0.5

201 to 400, inclusive 3 0.75

401 to 600, inclusive 4 1.0

601 to 800, inclusive 5 1.25

801 to 1000, inclusive 6 1.50

over 1000 Add 1 quart per 200 gallons or 

fraction thereof

Add 0.25 gallon per 200 gallons or 

fraction thereof

UR. User Requirements

UR.1. Conditions of Use.

UR.1.1. Filling. – A vehicle shall stand upon a level surface during the filling of a compartment.

UR.1.2. Delivering. – During a delivery, a vehicle shall be so positioned as to assure complete emptying of a 

compartment. Each compartment shall be used for an individual delivery only; that is, an individual delivery 

shall consist of the entire contents of a compartment or compartments.

(Amended 1976)

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Handbook 44 – 2016 4.41. Liquid Measures

4-9 

Table of Contents

Section 4.41. Liquid Measures............................................................................................ 4-11

A. Application .................................................................................................................................................. 4-11

A.1. General................................................................................................................................................4-11

A.2. Exceptions...........................................................................................................................................4-11

A.3. Additional Code Requirements...........................................................................................................4-11

S. Specifications............................................................................................................................................... 4-11

S.1. Units....................................................................................................................................................4-11

S.2. Material...............................................................................................................................................4-11

S.3. Capacity Point.....................................................................................................................................4-11

S.4. Reinforcing Rings. ..............................................................................................................................4-11

S.5. Discharge. ...........................................................................................................................................4-11

S.6. Marking Requirements........................................................................................................................4-11

T. Tolerances.................................................................................................................................................... 4-12

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Handbook 44 – 2016 4.41. Liquid Measures

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Section 4.41. Liquid Measures

A. Application

A.1. General. – This code applies to liquid measures; that is, to rigid measures of capacity designed for general and 

repeated use in the measurement of liquids.

A.2. Exceptions. – The code does not apply to test measures or other volumetric standards.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Liquid Measures shall meet 

the requirements of Section 1.10. General Code.

S. Specifications

S.1. Units.

(a) The capacity of a liquid measure shall be 0.1 L, 0.2 L, 0.5 L, 1 L, 2 L, 5 L, or a multiple of 5 L, and the 

measure shall not be subdivided.

(b) The capacity of a liquid measure shall be 1 gill, 1⁄2 liq pt, 1 liq pt, 1 liq qt, 1⁄2 gal, 11⁄4 gal, 11⁄2 gal, or a multiple 

of 1 gal, and the measure shall not be subdivided. However, 3 pt and 5 pt brick molds and 21⁄2 gal (10 qt) 

cans shall be permitted when used exclusively for ice cream.

S.2. Material. – Measures shall be made of metal, glass, earthenware, enameled ware, composition, or similar and 

suitable material. If made of metal, the thickness of the metal shall not be less than the appropriate value given in 

Table 1. Minimum Thickness of Metal for Liquid Measures.

S.3. Capacity Point. – The capacity of a measure shall be determined to a definite edge, or to the lowest portion of 

a plate, bar, or wire, at or near the top of the measure, and shall not include the capacity of any lip or rim that may be 

provided.

S.4. Reinforcing Rings. – Reinforcing rings, if used, shall be attached to the outside of the measure and shall show 

no divisions or lines on the inside surface of the measure.

S.5. Discharge. – A measure equipped with a discharge faucet or valve shall be susceptible to complete discharge 

through the faucet or valve when the measure is standing on a level surface.

S.6. Marking Requirements. – A measure shall be marked on its side with a statement of its capacity. If the 

capacity is stated in terms of the pint or quart, the word “Liquid” or the abbreviation “Liq” shall be included.

Table 1.

Minimum Thickness of Metal for Liquid Measures

Nominal Capacity

Minimum Thickness

For Iron or Steel, Plated, or Unplated

(inch)

For Copper or Aluminum

(inch)

1 pint or less 0.010 0.020

1 quart, 1⁄2 gallon, 1 gallon 0.014 0.028

Over 1 gallon 0.016 0.032

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4-12

T. Tolerances

T.1. – Maintenance tolerances in excess and in deficiency shall be as shown in Table 2. Maintenance Tolerances, in 

Excess and in Deficiency, for Liquid Measures. Acceptance tolerances shall be one-half the maintenance tolerances.

Table 2.

Maintenance Tolerances, in Excess and in Deficiency, for Liquid Measures

Nominal Capacity

Tolerance

In Excess In Deficiency

fluid drams cubic inches fluid drams cubic inches

1⁄2 pt or less 2.0 0.4 1.0 0.2

1 pt 3.0 0.7 1.5 0.3

1 qt 4.0 0.9 2.0 0.5

1⁄2 gal 6.0 1.4 3.0 0.7

fluid ounces cubic inches fluid drams cubic inches

1 and 11⁄4 gal 1.0 1.8 4.0 0.9

11⁄2 gal 1.5 2.7 6.0 1.4

fluid ounces cubic inches fluid ounces cubic inches

2 gal 2.0 3.5 1.0 1.8

3 and 4 gal 4.0 7.0 2.0 3.6

5 gal 6.0 11.0 3.0 5.4

10 gal 10.0 18.0 5.0 9.0

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Handbook 44 – 2016 4.42. Farm Milk Tanks

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Table of Contents

Section 4.42. Farm Milk Tanks ............................................................................................. 4-15

A. Application .................................................................................................................................................. 4-15

A.1. General................................................................................................................................................4-15

A.2. Exceptions...........................................................................................................................................4-15

A.3. Additional Code Requirements...........................................................................................................4-15

S. Specifications............................................................................................................................................... 4-15

S.1. Components. .......................................................................................................................................4-15

S.2. Design of Tank....................................................................................................................................4-15

S.2.1. Level. ....................................................................................................................................4-15

S.2.2. Level-Indicating Means. .......................................................................................................4-15

S.2.3. Portable Tank........................................................................................................................4-15

S.2.4. Capacity................................................................................................................................4-16

S.3. Design of Indicating Means. ...............................................................................................................4-16

S.3.1. General. ................................................................................................................................4-16

S.3.2. Gauge-Rod Bracket or Supports. ..........................................................................................4-16

S.3.3. Gauge Rod. ...........................................................................................................................4-16

S.3.4. Surface-Gauge Bracket or Supports......................................................................................4-16

S.3.5. Surface Gauge.......................................................................................................................4-16

S.3.6. External Gauge Assemblies. .................................................................................................4-16

S.3.7. Graduations...........................................................................................................................4-17

S.3.8. Design of Indicating Means on Tanks with a Capacity Greater than 8000 Liters or 

2000 Gallons.........................................................................................................................4-17

S.4. Design of Volume Chart. ....................................................................................................................4-17

S.4.1. General..................................................................................................................................4-17

S.4.2. For a Tank of 1000 Liters, or 250 Gallons, or Less. .............................................................4-18

S.4.3. For a Tank of 1001 Liters to 2000 Liters, or 251 to 500 Gallons. ........................................4-18

S.4.4. For a Tank of Greater than 2000 Liters, or 500 Gallons. ......................................................4-18

S.5. Gauging...............................................................................................................................................4-18

S.5.1. Level. ....................................................................................................................................4-18

S.5.2. To Deliver.............................................................................................................................4-18

S.5.3. Preparation of Volume Chart. ...............................................................................................4-18

S.6. Identification.......................................................................................................................................4-18

N. Notes............................................................................................................................................................. 4-18

N.1. Test Liquid..........................................................................................................................................4-18

N.2. Evaporation and Volume Change. ......................................................................................................4-18

N.3. To Deliver...........................................................................................................................................4-18

N.4. Level. ..................................................................................................................................................4-18

N.5. Test Methods.......................................................................................................................................4-18

N.5.1. Verification of Master Metering Systems. ............................................................................4-18

N.5.2. Temperature Changes in Water Supply. ...............................................................................4-18

N.6. Reading the Meniscus.........................................................................................................................4-19

T. Tolerances.................................................................................................................................................... 4-19

T.1. Application..........................................................................................................................................4-19

T.2. Minimum Tolerance Values................................................................................................................4-19

T.3. Basic Tolerance Values.......................................................................................................................4-19

T.4. Basic Tolerance Values, Master Meter Method..................................................................................4-19

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UR. User Requirements ..................................................................................................................................... 4-19

UR.1. Installation. .........................................................................................................................................4-19

UR.2. Level Condition. .................................................................................................................................4-19

UR.2.1. Stationary Tank.....................................................................................................................4-19

UR.2.2. Portable Tank........................................................................................................................4-19

UR.3. Weight Chart.......................................................................................................................................4-19

UR.4. Use. .....................................................................................................................................................4-19

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Section 4.42. Farm Milk Tanks

A. Application

A.1. General. – This code applies to farm milk tanks on the premises of producers when these are used, or are to be 

used, for the commercial measurement of milk.

A.2. Exceptions. – This code does not apply to tanks mounted on highway vehicles.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Farm Milk Tanks shall meet 

the requirements of Section 1.10. General Code.

S. Specifications

S.1. Components. – A farm milk tank, whether stationary or portable, shall be considered suitable for commercial 

use only when it comprises:

(a) a vessel, whether or not it is equipped with means for cooling its contents;

(b) a means for reading the level of liquid in the tank, such as a removable gauge rod or surface gauge; and

(c) a chart for converting level-of-liquid readings to volume.

Each compartment of a subdivided tank shall, for the purposes of this code, be construed to be a farm milk tank.

S.2. Design of Tank.

S.2.1. Level. – A farm milk tank shall be designed to be in normal operating position when it is in level. The 

tank shall be so constructed that it will maintain its condition of level under all normal conditions of lading.

S.2.2. Level-Indicating Means. – A tank shall be permanently equipped with sensitive means by which the 

level of the tank can be determined.

S.2.2.1. On a Stationary Tank. – A stationary tank shall be provided with such level-indicating means 

as a two-way or circular level, a plumb bob, two-way leveling lugs, or the like; or the top edge or edges of 

the tank shall be so constructed throughout as to provide an accurate reference for level determinations; 

provided, that when leveling lugs or the top edge or edges of the tank are used as the reference for level 

determinations, there shall be supplied with the tank a sensitive spirit level of appropriate dimensions, and 

the positions where such level is intended to be used shall be permanently marked on the reference surface 

of the tank; and provided further, that when leveling lugs are used they shall be so designed, constructed, and 

installed at the factory that any alteration of the original position or condition, such as by hammering or filing, 

would be difficult and would become obvious. A stationary tank with a nominal capacity of 2 000 L or 

500 gal, or greater shall be provided with at least two similar level-indicating means, and these shall be 

located in opposite and distant positions from each other to facilitate an accurate level determination in both 

directions of the tank’s horizontal plane.

(Amended 1980)

S.2.2.2. On a Portable Tank. – A portable tank shall be provided with either a two-way or a circular 

level.

S.2.3. Portable Tank. – A portable tank shall be of the center-reading type; that is, it shall be so designed that 

the gauge rod or surface gauge, when properly positioned for use, will be approximately in the vertical axis of the 

tank, centrally positioned with respect to the tank walls.

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S.2.4. Capacity. – A farm milk tank shall be clearly and permanently marked on a surface visible after 

installation with its capacity as determined by the manufacturer. The capacity shall not exceed an amount that 

can be agitated without overflowing and that can be measured accurately with the liquid at rest.

[Nonretroactive as of January 1, 1979]

S.3. Design of Indicating Means.

S.3.1. General. – A tank shall include indicating means and shall be calibrated over the entire range of the 

volume of the tank from 5 % of capacity or 2 m3 (500 gal) whichever is less, to its maximum capacity.

[Nonretroactive as of January 1, 1986]

(Added 1985)

S.3.2. Gauge-Rod Bracket or Supports. – If a tank is designed for use with a gauge rod, a substantial and 

rigid gauge-rod bracket or other suitable supporting elements for positioning the gauge rod shall be provided. A 

gauge rod and its brackets or other supporting elements shall be so constructed that, whenever the rod is placed 

in engagement with the bracket or supports and released, the rod will automatically seat itself at a fixed height 

and in a vertical position. When a gauge rod is properly seated on its brackets or supports, there shall be a 

clearance of at least 7.5 cm (3 in) between the graduated face of the rod and any tank wall or other surface that it 

faces.

S.3.3. Gauge Rod. – When properly seated in position, a rod shall not touch the bottom of the tank unless this 

is required by the design of the supporting elements. The rod shall be graduated throughout an interval 

corresponding to the volume range within which readings of liquid level are to be made.

S.3.4. Surface-Gauge Bracket or Supports. – If a tank is designed for use with a surface gauge, a substantial 

and rigid surface-gauge bracket or other suitable supporting elements for positioning the surface gauge shall be 

provided. A surface gauge and its brackets or other supporting elements shall be so constructed that, whenever 

the gauge assembly is placed in engagement with the bracket or supports, the indicator, if not permanently 

mounted on the tank, will automatically seat itself in correct operating position, and the graduated element will 

be vertically positioned and will be securely held at any height to which it may be manually set.

S.3.5. Surface Gauge. – When properly engaged with its bracket and set to its lowest position, a surface gauge 

shall not touch the bottom of the tank. The gauge shall be graduated throughout an interval corresponding to the 

volume range within which readings of liquid level are to be made.

S.3.6. External Gauge Assemblies.

S.3.6.1. Design and Installation. – The gauge assembly shall be designed to meet sanitary requirements 

and shall be readily accessible for cleaning purposes. The gauge assembly shall be mounted in a vertical 

position and equipped with a sliding mechanism to assist in determining the liquid level.

S.3.6.2. Gauge Tube. – The gauge tube shall be borosilicate glass or approved rigid plastic or rigidly 

supported flexible tubing with a uniform internal diameter not less than 2 cm (3⁄4 in). It shall be designed and 

constructed so that all product in the gauge can be discarded in such a manner that no product in the gauge 

tube will enter the discharge line or tank.

(Amended 1983)

S.3.6.3. Scale Plate. – The scale plate shall be mounted adjacent to and parallel with the gauge tube and 

be no more than 7 mm (1⁄4 in) from the tube.

S.3.6.4. Scale Graduations. – The graduation lines shall be clear and easily readable and shall comply 

with the requirements of paragraphs included under S.3.7. Graduations.

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S.3.6.5. Venting. – An external gauge tube shall be adequately vented at the top, open to the atmosphere. 

Any attachment to the gauge tube shall not adversely affect the operation of this vent.

(Added 1984)

(Added 1977)

S.3.7. Graduations.

S.3.7.1. Spacing and Width of Graduations. – On a gauge rod or surface gauge, the spacing of the 

graduations, center to center, shall be not more than 1.6 mm (0.0625 in or 1

/16 in) and shall not be less than 

0.8 mm (0.03125 in or 1

/32 in). The graduations shall not be less than 0.12 mm (0.005 in) in width, and the 

clear interval between adjacent edges of successive graduations shall be not less than 0.4 mm (0.015625 in 

or 1

/64 in).

S.3.7.2. Values of Graduations. – On a gauge rod or surface gauge, the graduations may be designated 

in inches or in centimeters and fractions thereof, or may be identified in a numerical series without reference 

to inches or centimeters or fractions thereof. In either case, a volume chart shall be provided for each such 

rod or gauge and each tank with which it is associated, showing values in terms of the graduation on the rod 

or gauge. If a rod or gauge is associated with but one tank, in lieu of linear or numerical series graduations 

and volume chart, values in terms of volume of liquid in the tank may be shown directly on the rod or gauge.

S.3.7.3. Value of Graduated Interval. – The value of a graduated interval on a gauge rod or surface 

gauge (exclusive on the interval from the bottom of the tank to the lowest graduation) shall not exceed:

(a) 2 L for a tank of a nominal capacity of 1000 L or less; 1⁄2 gal for a tank of a nominal capacity of 

250 gal or less;

(b) 4 L for a tank of a nominal capacity of 1001 L to 2000 L, inclusive; 1 gal for a tank of a nominal 

capacity of 251 gal to 500 gal, inclusive; 

(c) 6 L for a tank of a nominal capacity of 2001 L to 6000 L, inclusive; 11⁄2 gal for a tank of a nominal 

capacity of 501 gal to 1500 gal, inclusive; 

(d) 8 L for a tank of a nominal capacity of 6001 L to 10 000 L, inclusive; 2 gal for a tank of a nominal 

capacity of 1501 gal to 2500 gal, inclusive; or

(e) 8 L plus 4 L for each additional 10 000 L or fraction thereof, for tanks of nominal capacity above 

10 000 L or 2 gal plus 1 gal for each additional 2500 gal or fraction thereof, for tanks with nominal 

capacity above 2500 gal.

(Amended 1980)

S.3.8. Design of Indicating Means on Tanks with a Capacity Greater than 8000 Liters or 2000 Gallons. –

Any farm milk tank with a capacity greater than 8000 L, or 2000 gal, shall be equipped with an external gauge 

assembly.

[Nonretroactive and applicable only to tanks manufactured after January 1, 1981]

(Added 1980)

S.4. Design of Volume Chart.

S.4.1. General. – A volume chart shall show volume values only, over the entire range of the volume of the 

tank from 5 % of capacity or 2 m3 (500 gal) whichever is less, to its maximum capacity.* All letters and figures 

on the chart shall be distinct and easily readable. The chart shall be substantially constructed, and the face of the 

chart shall be so protected that its lettering and figures will not tend easily to become obliterated or illegible.

[*Nonretroactive as of January 1, 1986]

(Amended 1985)

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S.4.2. For a Tank of 1 000 Liters, or 250 Gallons, or Less. – The volume chart for a tank of nominal capacity 

of 1000 L, or 250 gal, or less shall show values at least to the nearest 1 L, or 1⁄4 gal.

S.4.3. For a Tank of 1 001 Liters to 2000 Liters, or 251 to 500 Gallons. – The volume chart for a tank of 

nominal capacity of 1001 L to 2000 L, or 251 gal to 500 gal, inclusive, shall show values at least to the nearest 

2 L, or 1⁄2 gal.

S.4.4. For a Tank of Greater than 2000 Liters, or 500 Gallons. – The volume chart for a tank of nominal 

capacity of greater than 2000 L, or 500 gal, shall show values at least to the nearest gallon, or 4 L.

(Amended 1980)

S.5. Gauging.

S.5.1. Level. – A farm milk tank shall be level, as shown by the level-indicating means, during the original 

gauging operation.

S.5.2. To Deliver. – A farm milk tank shall be originally gauged “to deliver.” If the tank is gauged by 

measuring the test liquid into the tank, the inside tank walls shall first be thoroughly wetted and the tank shall 

then be drained for 30 seconds after the main drainage flow has ceased.

S.5.3. Preparation of Volume Chart. – When a tank is gauged for the purposes of preparing a volume chart, 

tolerances are not applicable, and the chart shall be prepared as accurately as practicable.

S.6. Identification. – A tank and any gauge rod, surface gauge, spirit level, and volume chart intended to be used 

therewith shall be mutually identified, as by a common serial number, in a prominent and permanent manner.

N. Notes

N.1. Test Liquid. – Water shall be used as the test liquid for a farm milk tank.

N.2. Evaporation and Volume Change. – Care shall be exercised to reduce to a minimum, evaporation losses and 

volume changes resulting from changes in temperature of the test liquid.

N.3. To Deliver. – A farm milk tank shall be tested “to deliver.” If the tank is gauged by measuring the test liquid 

delivered into the tank, the inside tank walls shall first be thoroughly wetted and the tank then shall be drained for 

30 seconds after the main drainage flow has ceased.

N.4. Level. – A farm milk tank shall be level, as shown by the level-indicating means, during gauging and testing.

N.5. Test Methods. – Acceptance tests of milk tanks may be of either the prover method or the master meter method 

provided that the master metering system is capable of operating within 25 % of the applicable tolerance found in T.3. 

Basic Tolerance Values. Subsequent tests may be of either the prover method or the master meter method provided 

that the master metering system is capable of operating within 25 % of the applicable tolerance found in T.4. Basic 

Tolerance Values, Master Meter Method.

N.5.1. Verification of Master Metering Systems. – A master metering system used to gauge a milk tank shall 

be verified before and after the gauging process. A master metering system used to calibrate a milk tank shall be 

verified before starting the calibration and re-verified at least every quarter of the tank capacity, or every 2000 L 

(500 gal), whichever is greater. The above process of re-verifying the master metering system may be waived if 

the system is verified using a NIST traceable prover with a minimum of two tests immediately before and one 

test immediately after the gauging process and that each test result is within 25 % of T.3. Basic Tolerance Values.

(Added 2001) (Amended 2012) 

N.5.2. Temperature Changes in Water Supply. – When using a master metering system to gauge or calibrate 

a milk tank, the official shall monitor the temperature of the water before and after changing sources of supply. 

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If the water temperature of the new source changes by more than 2.8 °C (5 °F) from the previous supply, the 

official shall re-verify the accuracy of the master metering system as soon as possible after the system reaches 

temperature equilibrium with the new supply source.

(Added 2001)

N.6. Reading the Meniscus. – When a reading or setting is to be obtained from a meniscus formed by milk or other 

opaque liquid, the index or reading line is the position of the highest point of the center of the meniscus. When 

calibrating a device with water and the device is to be used with an opaque liquid, the reading should be obtained 

accordingly; that is, the position of the highest point of the center of the meniscus.

(Added 1984)

T. Tolerances

T.1. Application. – The tolerances hereinafter prescribed shall be applied equally to errors in excess and errors in 

deficiency.

T.2. Minimum Tolerance Values. – On a particular tank, the maintenance and acceptance tolerance applied shall 

be not smaller than the volume corresponding to the graduated interval at the point of test draft on the indicating means 

or 2 L (1⁄2 gal), whichever is greater.

(Amended 1980)

T.3. Basic Tolerance Values. – The basic maintenance and acceptance tolerance shall be 0.2 % of the volume of 

test liquid in the tank at each test draft.

(Amended 1975)

T.4. Basic Tolerance Values, Master Meter Method. – The basic maintenance and acceptance tolerance for tanks 

tested by the master meter method shall be 0.4 % of the volume of test liquid in the tank at each test draft.

(Added 1975)

UR. User Requirements

UR.1. Installation. – A stationary tank shall be rigidly installed in level without the use of removable blocks or 

shims under the legs. If such tank is not mounted permanently in position, the correct position on the floor for each 

leg shall be clearly and permanently defined.

UR.2. Level Condition.

UR.2.1. Stationary Tank. – A stationary farm milk tank shall be maintained in level.

UR.2.1.1. Leveling Lugs. – If leveling lugs are provided on a stationary tank, such lugs shall not be 

hammered or filed to establish or change a level condition of the tank.

UR.2.2. Portable Tank. – On a portable tank, measurement readings shall be made only when the tank is 

approximately level; that is, when it is not out of level by more than 5 % or approximately three degrees in any 

direction.

UR.3. Weight Chart. – An auxiliary weight chart may be provided, on which shall be prominently displayed the 

weight per unit volume value used to derive the weight values from the official volume chart.

UR.4. Use. – A farm milk tank shall not be used to measure quantities greater than an amount that can be agitated 

without overflowing.

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Table of Contents

Section 4.43. Measure-Containers ..................................................................................... 4-23

A. Application .................................................................................................................................................. 4-23

A.1. General................................................................................................................................................4-23

A.2. Exceptions...........................................................................................................................................4-23

A.3. Additional Code Requirements...........................................................................................................4-23

S. Specifications............................................................................................................................................... 4-23

S.1. Units....................................................................................................................................................4-23

S.2. Capacity Point.....................................................................................................................................4-23

S.3. Shape...................................................................................................................................................4-23

S.4. Marking...............................................................................................................................................4-23

S.4.1. Capacity Point.......................................................................................................................4-23

S.4.2. Capacity Statement. ..............................................................................................................4-23

N. Notes............................................................................................................................................................. 4-24

N.1. Test Liquid..........................................................................................................................................4-24

N.2. Preparation of Container for Test........................................................................................................4-24

N.2.1. General..................................................................................................................................4-24

N.2.2. Restraining Form for Test.....................................................................................................4-24

T. Tolerances.................................................................................................................................................... 4-24

T.1. Tolerances on an Individual Measure. ................................................................................................4-24

T.2. Tolerance on Average Capacity..........................................................................................................4-24

UR. User Requirements ..................................................................................................................................... 4-24

UR.1. Limitation of Use. ...............................................................................................................................4-24

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Section 4.43. Measure-Containers

A. Application

A.1. General. – This code applies to measure-containers, including lids or closures if such are necessary to provide 

total enclosure of the measured commodity, as follows:

(a) Retail measure-containers intended to be used only once to determine at the time of retail sale, and from bulk 

supply, the quantity of commodity on the basis of liquid measure. The retail measure-container serves as the 

container for the delivery of the commodity.

(b) Prepackaged measure-containers intended to be used only once to determine in advance of sale the quantity 

of a commodity (such as ice cream, ice milk, or sherbet) on the basis of liquid measure. The prepackaged 

measure-container serves as the container for the delivery of the commodity, in either a wholesale or a retail 

marketing unit.

A.2. Exceptions. – This code does not apply to rigid containers used for milk, cream, or other fluid dairy products, 

which are covered by packaging requirements.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Measure-Containers shall meet 

the requirements of Section 1.10. General Code.

S. Specifications

S.1. Units. – The capacity of a measure-container shall be a multiple of or a binary submultiple of a quart or a liter, 

and the measure shall not be subdivided. However, for prepackaged measure-containers, any capacity less than 1⁄4 L 

or 1⁄2 liq pt shall be permitted.

(Amended 1979)

S.2. Capacity Point. – The capacity of a measure-container shall be sharply defined by:

(a) the top edge; 

(b) a line near the top edge; or

(c) the horizontal cross-sectional plane established by the bottom surface of the removable lid or cap when seated 

in the container.

S.3. Shape. – A measure-container shall be designed as some suitable geometrical shape, and its capacity shall be 

determined without distortion from its normal assembled shape.

S.4. Marking.

S.4.1. Capacity Point. – If the capacity point of a measure-container is defined by a line, the container shall 

be marked conspicuously on its side with a suitable statement clearly identifying this line as the capacity point.

S.4.2. Capacity Statement. – A measure-container shall be clearly and conspicuously marked with a statement 

of its capacity in terms of one of the units prescribed in Section S.1. Units.

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N. Notes

N.1. Test Liquid. – Water shall be used as the test liquid for a measure-container.

N.2. Preparation of Container for Test.

N.2.1. General. – Before an actual test is begun, a measure-container shall, if necessary, be so restrained that 

it will maintain its normal assembled shape and that its sides will not bulge when it is filled with water.

N.2.2. Restraining Form for Test.

N.2.2.1. For Rectangular Containers of One Liter, One Quarter Less. – Bulging of the sides of a 

rectangular measure-container of 1 L (1 qt) capacity or less may be controlled by holding against each side 

of the container, with a cord, rubber bands, or tape, a metal plate or a piece of heavy cardboard slightly 

smaller than the side of the container.

(Amended 1979)

N.2.2.2. For Rectangular Prepackaged Measure-container of Two Quarts or Two Liters or Greater.

– A rectangular prepackaged measure-container of 2 L (2 qt) capacity or greater shall be supported during a 

test by a rigid restraining form. This form shall restrain not less than the entire area of the central two-thirds 

of each side of the container, measured from bottom to top. The inside width dimension of any side panel of 

the restraining form shall be 1.6 mm (1

/16 in) greater than the corresponding outside dimension of the 

container. (The outside width dimension of any side panel of the container shall be established by adding to 

the inner side center-of-score to center-of-score dimension two thicknesses of the board used, and the sum 

thus obtained shall be rounded off to the nearest 0.4 mm (1

/64 in).)

(Amended 1979)

T. Tolerances

T.1. Tolerances on an Individual Measure. – The acceptance tolerances in excess and in deficiency on an 

individual measure shall be as shown in Table 1. Acceptance Tolerances, in Excess and in Deficiency, for MeasureContainers.

T.2. Tolerance on Average Capacity. – The average capacity on a random sample of 10 measures selected from a 

lot of 25 or more shall be equal to or greater than the nominal capacity.

(Amended 1979)

UR. User Requirements

UR.1. Limitation of Use. – The use of a measure-container with a rectangular cross section of a capacity of 2 L 

(2 qt) or greater shall be limited to the packaging, in advance of sale, of ice cream, sherbet, or other similar frozen 

desserts.

(Amended 1979)

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Table 1.

Acceptance Tolerances, in Excess and in Deficiency, for Measure-Containers

Nominal Capacity Tolerance

In Excess In Deficiency

milliliters milliliters

1⁄4 liter or less 10 5.0

1⁄2 liter 15 7.5

1 liter 20 10.0

Over 1 liter Add per liter

10 milliliters

Add per liter

5.0 milliliters

fluid drams cubic inches fluid drams cubic inches

1⁄2 pint or less 3 0.6 1.5 0.3

1 pint 4 1.0 2.0 0.5

1 quart 6 1.4 3.0 0.7

2 quarts 9 2.0 4.5 1.0

3 quarts 10 2.4 5.0 1.2

4 quarts 12 2.8 6.0 1.2

Over 4 quarts Add per quart

3 fluid drams

Add per quart

0.7 cubic inch

Add per quart

1.5 fluid drams

Add per quart

0.35 cubic inch

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Table of Contents

Section 4.44. Graduates .......................................................................................................... 4-29

A. Application .................................................................................................................................................. 4-29

A.1. General................................................................................................................................................4-29

A.2. Additional Code Requirements...........................................................................................................4-29

S. Specifications............................................................................................................................................... 4-29

S.1. Units....................................................................................................................................................4-29

S.2. Initial Interval. ....................................................................................................................................4-29

S.3. Shape...................................................................................................................................................4-29

S.4. Material...............................................................................................................................................4-30

S.5. Dimensional Proportions. ...................................................................................................................4-30

S.5.1. On a Circular Conical Graduate............................................................................................4-30

S.5.2. On a Cylindrical Graduate. ...................................................................................................4-30

S.6. Base.....................................................................................................................................................4-30

S.7. Design of Graduations. .......................................................................................................................4-30

S.7.1. General..................................................................................................................................4-30

S.7.2. On a Single-Scale Graduate. .................................................................................................4-30

S.7.3. On a Double-Scale or a Duplex Graduate.............................................................................4-30

S.8. Basis of Graduation.............................................................................................................................4-30

S.9. Marking Requirements........................................................................................................................4-30

N. Notes............................................................................................................................................................. 4-31

N.1. Test Liquid..........................................................................................................................................4-31

N.2. Temperature Control...........................................................................................................................4-31

T. Tolerances.................................................................................................................................................... 4-31

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Section 4.44. Graduates

A. Application

A.1. General. – This code applies to subdivided glass measures of capacity, either cylindrical or conical in shape.

A.2. Additional Code Requirements. – In addition to the requirements of this code, Graduates shall meet the 

requirements of Section 1.10. General Code. 

S. Specifications

S.1. Units. – Nominal capacities, graduation ranges, values of graduated intervals, and numbered graduations 

applicable to single-scale graduates and to the appropriate portions of double scale graduates shall be as shown in 

Table 1. Design Details for Graduates.

Table 1.

Design Details for Graduates

Nominal

Capacity To be Graduated Between

Value of

Graduated Intervals

Number at Each 

Graduation 

Divisible by

milliliters milliliters milliliters milliliters

5

10

25

50

100

500

1000

1 and

2 and

5 and

10 and

20 and

100 and

200 and

5

10

25

50

100

500

1000

1⁄2

1 

5 

5 

10

25

50

1

2 

5 

10

20

50

100

minims minims minims minims

60

120

15 and

30 and

60

120

5

10

10a

20b

fluid drams fluid drams fluid drams fluid drams

4

8

1 and

2 and

4

8

1⁄2

1

1

2

fluid ounces fluid ounces fluid ounces fluid ounces

2

4 

8 

16

32

1⁄2 and

1 and

2 and

4 and

8 and

2

4 

8 

16

32

1⁄4

1⁄2 

1⁄2 

1 

2

1⁄2

1 

1 

2 

4

a And, in addition, at the first (15-minim) graduation. b And, in addition, at the first (30-minim) graduation.

S.2. Initial Interval. – A graduate shall have an initial interval that is not subdivided, equal to not less than one-fifth 

and not more than one-fourth of the capacity of the graduate.

S.3. Shape. – A graduate of a capacity of more than 15 mL (4 fl dr) may be of either the cylindrical or circular 

conical type. A graduate of a capacity of 15 mL (4 fl dr) or less shall be of the single-scale cylindrical type.

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S.4. Material. – A graduate shall be made of good-quality, thoroughly annealed, clear, transparent glass, free from 

bubbles and streaks that might affect the accuracy of measurement. The glass shall be uniform in thickness and shall 

not be excessively thick.

S.5. Dimensional Proportions.

S.5.1. On a Circular Conical Graduate. – The inside measurement from the bottom of a circular conical 

graduate to the capacity graduation shall be not less than two times the inside diameter at the capacity graduation. 

The inside measurement from the bottom of the graduate to the point representing one-fourth of the capacity shall 

be not less than the inside diameter at that point.

S.5.2. On a Cylindrical Graduate. – The inside measurement from the bottom of a cylindrical graduate to the 

capacity graduation shall be not less than five times the inside diameter at the capacity graduation.

S.6. Base. – The base of the graduate shall be perpendicular to the vertical axis of the graduate. The diameter of 

the base shall be of such size that the empty graduate will remain standing on an inclined surface of 25 %, or 

approximately 15 degrees, from the horizontal.

S.7. Design of Graduations.

S.7.1. General. – Graduations shall be perpendicular to the vertical axis of the graduate and parallel to each 

other. Graduations shall be continuous, of uniform thickness not greater than 0.4 mm (0.015 in), clearly visible, 

permanent, and indelible under normal conditions of use.

(Amended 1977)

S.7.2. On a Single-Scale Graduate. – On a single-scale graduate, the main graduations shall completely 

encircle the graduate and subordinate graduations shall extend at least one-half the distance around the graduate.

S.7.3. On a Double-Scale or a Duplex Graduate. – On a double-scale or duplex graduate, there shall be a 

clear space between the ends of the main graduations on the two scales, and this space shall be approximately 

90 degrees from the lip of the graduate and shall conform to the requirements of Table 2. Clear Space Between 

Ends of Main Graduations on Double Scale Graduates.

Table 2.

Clear Space Between Ends of Main Graduations on Double Scale Graduates

Inside Diameter of Graduate at the Graduations

(inches)

Clear Space Between Ends of Main Graduations

(inch)

Less than 1.5 1/8 to 1⁄4

1.5 to 3, inclusive 1⁄4 to 1⁄2

Over 3 3/8 to 5/8

S.8. Basis of Graduation. – A graduate shall be graduated “to deliver” when the temperature of the graduate is 

20 °C (68 °F), and shall be marked accordingly in a permanent and conspicuous manner.

S.9. Marking Requirements. – Each main graduation shall be marked to show its value. Intermediate graduations 

shall not be marked. Value figures shall be uniformly positioned either directly upon or immediately above the 

graduations to which they refer. Figures placed upon graduations shall be set in from the ends of the graduations a 

sufficient distance to allow the ends of the graduations to be used in making a setting.

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N. Notes

N.1. Test Liquid. – Water shall be used as the test liquid for graduates.

N.2. Temperature Control. – During the test of a graduate, appropriate precautions shall be exercised to reduce 

any detrimental temperature effects to the practicable minimum.

T. Tolerances

T.1. – Maintenance and acceptance tolerances in excess and in deficiency shall be as shown in Table 3. Maintenance 

and Acceptance Tolerances, in Excess and Deficiency, for Graduates for graduates that are graduated “to contain” or 

“to deliver.” (The tolerance to be applied at any graduation is determined by the inside diameter of the graduate at 

the graduation in question.)

Table 3.

Maintenance and Acceptance Tolerances, in Excess and

in Deficiency, for Graduates

Inside Diameter of 

Graduate

Tolerance

Inside Diameter of 

Graduate

Tolerance

From To But Not 

Including

From To But Not 

Including

millimeters milliliters inches minims

0

16

21

26

31

36

41

46

51

56

61

66

71

76

81

86

91

96

16

21

26

31

36

41

46

51

56

61

66

71

76

81

86

91

96

101

0.1

0.2

0.4

0.6

0.8

1.1

1.4

1.8

2.2

2.8

3.4

4.1

4.8

5.6

6.4

7.2

8.1

9.0

 0

 9/16

 13/16

 11

/16

 15

/16

 19

/16

 113/16

 21

/16

 25

/16

 29

/16

 213/16

 31

/16

 35

/16

 39

/16

 33

/16

 9/16

 13/16

 11

/16

 15

/16

 19

/16

 113/16

 21

/16

 25

/16

 29

/16

 213/16

 31

/16

 35

/16

 39

/16

 313/16

 41

/16

2

3 

6 

10

15

20

30

40

50

65

80

95

110

130

150

(Amended 1974)

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Handbook 44 – 2016 4.45. Dry Measures

4-33

Table of Contents

Section 4.45. Dry Measures ................................................................................................ 4-35

A. Application .................................................................................................................................................. 4-35

A.1. General................................................................................................................................................4-35

A.2. Exceptions...........................................................................................................................................4-35

A.3. Additional Code Requirements...........................................................................................................4-35

S. Specifications............................................................................................................................................... 4-35

S.1. Units....................................................................................................................................................4-35

S.2. Material...............................................................................................................................................4-35

S.3. Shape...................................................................................................................................................4-35

S.3.1. Conical Dry Measure. ...........................................................................................................4-35

S.4. Capacity Point.....................................................................................................................................4-36

S.5. Top Reinforcement. ............................................................................................................................4-36

S.6. Marking Requirements........................................................................................................................4-36

N. Notes............................................................................................................................................................. 4-36

N.1. Testing Medium..................................................................................................................................4-36

N.1.1. Watertight Dry Measures......................................................................................................4-36

N.1.2. Non-Watertight Dry Measures..............................................................................................4-36

T. Tolerances.................................................................................................................................................... 4-36

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Handbook 44 – 2016 4.45. Dry Measures

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Section 4.45. Dry Measures

A. Application

A.1. General. – This code applies to rigid measures of capacity designed for general and repeated use in the 

measurement of solids, including the capacities of 1⁄2 bu or more.

A.2. Exceptions. 

(a) This code does not apply to “standard containers” used for the measurement of fruits and vegetables and as 

shipping containers thereof.

(b) This code does not apply to berry baskets and boxes. (Also see Section 4.46. Code for Berry Baskets and 

Boxes.) 

 (Added 1976)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Dry Measures shall meet the 

requirements of Section 1.10. General Code.

S. Specifications

S.1. Units. – The capacity of a measure shall be 1 bu, a multiple of the bushel, or a binary submultiple of the bushel, 

and the measure shall not be subdivided or double-ended.

S.2. Material. – A dry measure shall be made of any suitable material that will retain its shape during normal usage.

S.3. Shape. – A measure, other than a basket, of a capacity of 1⁄2 bu or less, shall be cylindrical or conical in shape. 

The top diameter shall in no case be less than the appropriate minimum diameter shown in Table 1. Minimum Top 

Diameters for Dry Measure other than Baskets. The bottom of a measure, other than a basket, shall be perpendicular 

to the vertical axis of the measure and shall be flat, except that a metal bottom may be slightly corrugated. The bottom 

of a measure shall not be adjustable or movable.

Table 1.

Minimum Top Diameters for Dry Measures other than Baskets

Nominal Capacity Minimum Top Diameter Inches

1 pint 4 

 1 quart 53/8

 2 quarts 65/8

 1⁄2 peck 81⁄2

 1 peck 107/8

 1⁄2 bushel 133⁄4

S.3.1. Conical Dry Measure. – If conical, the top diameter shall exceed the bottom diameter by not more than 

10 % of the bottom diameter.

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4.45. Dry Measures Handbook 44 – 2016 

4-36

S.4. Capacity Point. – The capacity of a measure shall be determined by the top edge of the measure.

S.5. Top Reinforcement. – The top edge of a measure shall be reinforced. On a wooden measure other than a 

basket, of a capacity of 1 qt or more, this reinforcement shall be in the form of a firmly attached metal band.

S.6. Marking Requirements. – A measure shall be conspicuously marked on its side with a statement of its 

capacity. If the capacity is stated in terms of the pint or quart, the word “Dry” shall be included. The capacity 

statement shall be in letters of the following dimensions:

(a) At least 1⁄2 in high and 1⁄4 in wide on a measure of any capacity between 1⁄2 pt and 1 pk.

(b) At least 1 in high and 1⁄2 in wide on a measure of a capacity of 1⁄2 bu or more.

(c) On a measure of a capacity of 1⁄4 pt or less, the statement shall be as prominent as practicable, considering 

the size and design of such measure.

N. Notes

N.1. Testing Medium.

N.1.1. Watertight Dry Measures. – Water shall be used as the testing medium for watertight dry measures.

N.1.2. Non-Watertight Dry Measures. – A dry measure shall be tested either volumetrically using rapeseed 

as a testing medium or geometrically through inside measurement and calculation.

(Amended 1988)

T. Tolerances

T.1. – Maintenance tolerances in excess and in deficiency shall be as shown in Table 2. Maintenance Tolerances, in 

Excess and in Deficiency, for Dry Measure. Acceptance tolerances shall be one-half the maintenance tolerances.

Table 2.

Maintenance Tolerances, in Excess and in Deficiency, for Dry Measures

Nominal Capacity

Tolerance

In Excess

Cubic Inches

In Deficiency

Cubic Inches

1

/32 pint or less 0.1 0.05

1

/16 pint 0.15 0.1

1

/8 pint 0.25 0.15

1⁄4 pint 0.5 0.3

1⁄2 pint 1.0 0.5

1 pint 2.0 1.0

1 quart 3.0 1.5

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Table 2.

Maintenance Tolerances, in Excess and in Deficiency, for Dry Measures

Nominal Capacity

Tolerance

In Excess

Cubic Inches

In Deficiency

Cubic Inches

2 quarts 5.0 2.5

1⁄2 peck 10.0 5.0

1 peck 16.0 8.0

1⁄2 bushel 30.0 15.0

1 bushel 50.0 25.0

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Handbook 44 – 2016 4.46. Berry Baskets and Boxes

4-39

Table of Contents

Section 4.46. Berry Baskets and Boxes .............................................................................. 4-41

A. Application .................................................................................................................................................. 4-41

A.1. General................................................................................................................................................4-41

A.2. Additional Code Requirements...........................................................................................................4-41

S. Specifications............................................................................................................................................... 4-41

S.1. Units....................................................................................................................................................4-41

S.2. Materials. ............................................................................................................................................4-41

S.3. Capacity Point.....................................................................................................................................4-41

N. Notes............................................................................................................................................................. 4-41

N.1. Method of Test....................................................................................................................................4-41

T. Tolerances.................................................................................................................................................... 4-41

T.1. Tolerances on Individual Measures. ...................................................................................................4-41

T.2. Tolerances on Average Capacity. .......................................................................................................4-41

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4-41

Section 4.46. Berry Baskets and Boxes

A. Application

A.1. General. – This code applies to baskets and boxes for berries and small fruits in capacities of 1 dry quart and 

less.

A.2. Additional Code Requirements. – In addition to the requirements of this code, berry baskets and boxes shall 

meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Units. – The capacity of a berry basket or box shall be 1⁄2 dry pint, 1 dry pint, or 1 dry quart.

S.2. Materials. – A berry basket or box shall be made of any suitable materials that will retain its shape during 

normal filling, storage, and handling.

S.3. Capacity Point. – The capacity of a berry basket or box shall be determined by its top edges.

N. Notes

N.1. Method of Test. – A berry basket or box may be tested either volumetrically, using rape seed as the testing 

medium, or geometrically through accurate inside dimension measurement and calculation.

T. Tolerances

T.1. Tolerances on Individual Measures. – Maintenance and acceptance tolerances in excess and deficiency on an 

individual measure shall be as shown in Table 1. Maintenance and Acceptance Tolerances in Excess and in Deficiency.

T.2. Tolerances on Average Capacity. – The average capacity on a random sample of 10 measures selected from 

a lot of 25 or more shall be equal to or greater than the nominal capacity.

(Amended 1979)

Table 1.

Maintenance and Acceptance Tolerances in Excess and in Deficiency

Nominal Capacity

Tolerance

In Excess

Cubic Inches

In Deficiency

Cubic Inches

1⁄2 pint 1 0.5

1 pint 2 1.0

1 quart 3 1.5

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Handbook 44 – 2016 Section 5

5-1

Section 5

Table of Contents

Page 

5.50. Fabric-Measuring Devices............................................................................................ 5-3 

5.51. Wire- and Cordage-Measuring Devices........................................................................ 5-9 

5.52. Linear Measures.......................................................................................................... 5-15 

5.53. Odometers................................................................................................................... 5-19 

5.54. Taximeters................................................................................................................... 5-25 

5.55. Timing Devices........................................................................................................... 5-35 

5.56.(a) Grain Moisture Meters................................................................................................ 5-43 

5.56.(b) Grain Moisture Meters................................................................................................ 5-55 

5.57. Near-Infrared Grain Analyzers .................................................................................. 5-65 

5.58. Multiple Dimension Measuring Devices.................................................................... 5-75 

5.59. Electronic Livestock, Meat, and Poultry Evaluation Systems and/or Devices .......... 5-87 

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Handbook 44 – 2016 5.50. Fabric-Measuring Devices

5-3 

Table of Contents

Section 5.50. Fabric-Measuring Devices.............................................................................. 5-5

A. Application .................................................................................................................................................... 5-5

A.1. General..................................................................................................................................................5-5

A.2. Devices Used to Measure Other Similar Material in Sheet, Roll, or Bolt Form. ..................................5-5

A.3. Additional Code Requirements.............................................................................................................5-5

S. Specifications................................................................................................................................................. 5-5

S.1. Units......................................................................................................................................................5-5

S.2. Design of Indicating Elements..............................................................................................................5-5

S.2.1. Graduations.............................................................................................................................5-5

S.2.2. Indicator..................................................................................................................................5-5

S.2.3. Money-Value Computations...................................................................................................5-6

S.2.4. Return to Zero.........................................................................................................................5-6

S.3. Marking Requirements..........................................................................................................................5-6

S.4. Design Accuracy...................................................................................................................................5-6

N. Notes............................................................................................................................................................... 5-6

N.1. Testing Medium....................................................................................................................................5-6

T. Tolerances...................................................................................................................................................... 5-7

T.1. Tolerance Values. .................................................................................................................................5-7

UR. User Requirements ....................................................................................................................................... 5-7

UR.1. Installation Requirements. ....................................................................................................................5-7

UR.1.1. Installation. .............................................................................................................................5-7

UR.2. Use Requirements. ................................................................................................................................5-7

UR.2.1. Limitation of Use. ...................................................................................................................5-7

UR.2.2. Return of Indicating Elements to Zero....................................................................................5-7

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Handbook 44 – 2016 5.50. Fabric-Measuring Devices

5-5 

Section 5.50. Fabric-Measuring Devices

A. Application

A.1. General. – This code applies only to mechanisms and machines designed to indicate automatically (with or 

without value-computing capabilities) the length of fabric passed through the measuring elements.

A.2. Devices Used to Measure Other Similar Material in Sheet, Roll, or Bolt Form. – Insofar as they are clearly 

appropriate, the requirements and provisions of this code apply also to devices designed for the commercial 

measurement of other material similar to fabrics, in sheet, roll, or bolt form.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Fabric-Measuring Devices 

shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Units. – A fabric-measuring device shall indicate lengths as follows: 

(a) For devices indicating in metric units, lengths shall be indicated in terms of 5 cm; 10 cm; 25 cm; or 50 cm 

and meters. 

In addition, lengths may be indicated in terms of any or all of the following subdivisions: millimeters and 

centimeters.

(b) For devices indicating in U.S. customary units, lengths shall be indicated in terms of 1/8 yd; 1⁄4 yd; or 1⁄2 yd; 

and yards.

In addition, lengths may be indicated in terms of any or all of the following subdivisions: 1/8 yd; 1

/16 yd; 

inches and feet. 

Digital indicators may indicate values in decimal fractions.

(Amended 1977)

S.2. Design of Indicating Elements.

S.2.1. Graduations.

S.2.1.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.2.1.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) in width.

S.2.1.3. Clear Interval between Graduations. – The clear interval between graduations shall be at least 

6 mm for cm graduations (1⁄4 in for 1

/8 yd graduations), and 3 mm for 20 cm graduations (1/8 in for 1 in 

graduations).

S.2.2. Indicator.

S.2.2.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

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S.2.2.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.2.2.3. Width. – The index of an indicator shall not be wider than the narrowest graduations with which 

it is used, and shall in no case exceed 0.4 mm (0.015 in).

S.2.2.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.2.2.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.2.3. Money-Value Computations.

S.2.3.1. Full-Computing Type. – In this type, the money value at each of a series of unit prices shall be 

computed automatically for every length within the range of measurement of the fabric-measuring device. 

Value graduations shall be provided and shall be accurately positioned. The value of each graduated interval 

shall be 1 cent at all prices per yard of 30 cents and less, and shall not exceed 2 cents at higher prices per 

yard. Five-cent intervals may be represented in the two-cent range by special graduations, but these shall not 

be positioned in the clear intervals between graduations of the regular series.

S.2.3.2. Limited-Computing Type. – In this type, the money value at each of a series of unit prices shall 

be computed automatically only for lengths corresponding to a definite series of length graduations. There 

shall be no value graduations. At no position that the chart can assume shall two value figures at the same 

price per yard be completely and clearly exposed to view at one time. Money values shown shall be 

mathematically accurate, except that a fraction of less than 1⁄2 cent shall be dropped and the next higher cent 

shall be shown in the case of a fraction of 1⁄2 cent or more. One of the following requirements shall be met:

(a) There shall be a money-value computation for each length graduation within the range of 

measurement of the device.

(b) No money-value computation shall be exposed to view except at such times as the device shows a 

length indication for which a corresponding series of value indications is computed.

(c) Each column or row of money-value computations shall be marked to show the length to which the 

computations correspond, the device shall be marked to show the character and limitations of the 

computations, and there shall be computations corresponding to at least 10 cm (1

/8 yd) throughout 

the range of measurement of the device.

S.2.4. Return to Zero. – Primary indicating elements shall be readily returnable to a definite zero indication. 

Means shall be provided to prevent the return of the indicating elements beyond their correct zero positions.

S.3. Marking Requirements. – If a device will not accurately measure all fabrics, it shall be marked to indicate 

clearly its limitations.

S.4. Design Accuracy. – Indications of length and money value shall be accurate whether the values of the 

indications are being increased or decreased.

N. Notes

N.1. Testing Medium. – A fabric-measuring device shall be tested with a suitable testing tape approximately 

7.62 cm (3 in) wide and with a graduated length of at least 11 m (12 yd), made from such material and having such 

surface finish as to provide dimensional stability and reduce slippage to the practicable minimum.

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5-7 

T. Tolerances

T.1. Tolerance Values. – Maintenance and acceptance tolerances shall be as shown in Table 1. Maintenance and 

Acceptance Tolerances for Fabric-Measuring Devices.

Table 1.

Maintenance and Acceptance Tolerances for Fabric-Measuring Devices

Indication of

Device

(yards)

Maintenance Tolerance Acceptance Tolerance

On Underregistration

(inches)

On Overregistration

(inches)

On Underregistration

(inches)

On Overregistration

(inches)

2 or less 3/8 1⁄4 1⁄4 1/8

3 3/8 5/16 1⁄4 5/32

4 1⁄2 5/16 1⁄4 5/32

5 5/8 3/8 5/16 3/16

6 3⁄4 3/8 3/8 3/16

7 and 8 1 1⁄2 1⁄2 1⁄4

9 11⁄4 5/8 5/8 5/16

10 and 11 11⁄2 3⁄4 3⁄4 3/8

12 and 13 13⁄4 7/8 7/8 7/16

14 and 15 2 1 1 1⁄2

Over 15 Add 1

/8 inch

per indicated yard

Add 1/16 inch

per indicated yard

Add 1/16 inch

per indicated yard

Add 1/32 inch

per indicated yard

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Installation. – A fabric-measuring device shall be securely supported and firmly fixed in position.

UR.2. Use Requirements.

UR.2.1. Limitation of Use. – A fabric-measuring device shall be used to measure only those fabrics that it was 

designed to measure, and in no case shall it be used to measure a fabric that a marking on the device indicates 

should not be measured.

UR.2.2. Return of Indicating Elements to Zero. – The primary indicating elements shall be returned to zero 

before each measurement.

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Handbook 44 – 2016 5.51. Wire- and Cordage-Measuring Devices

5-9 

Table of Contents

Section 5.51. Wire- and Cordage-Measuring Devices ...................................................... 5-11

A. Application .................................................................................................................................................. 5-11

A.1. General................................................................................................................................................5-11

A.2. Additional Code Requirements...........................................................................................................5-11

S. Specifications............................................................................................................................................... 5-11

S.1. Units....................................................................................................................................................5-11

S.2. Design of Indicating Elements............................................................................................................5-11

S.2.1. Graduations...........................................................................................................................5-11

S.2.2. Indicator................................................................................................................................5-11

S.2.3. Zero Indication......................................................................................................................5-11

S.3. Design of Measuring Elements...........................................................................................................5-12

S.3.1. Sensitiveness.........................................................................................................................5-12

S.3.2. Slippage. ...............................................................................................................................5-12

S.3.3. Accessibility..........................................................................................................................5-12

S.4. Marking Requirements. .........................................................................................................................5-12

S.4.1. Limitation of Use. .................................................................................................................5-12

S.4.2. Operating Instructions...........................................................................................................5-12

S.4.3. Indications.............................................................................................................................5-12

S.5. Design Accuracy....................................................................................................................................5-12

N. Notes............................................................................................................................................................. 5-12

N.1. Testing Medium....................................................................................................................................5-12

N.2. Minimum Test.......................................................................................................................................5-12

T. Tolerances......................................................................................................................................................... 5-12

T.1. Tolerance Values...................................................................................................................................5-12

UR. User Requirements........................................................................................................................................ 5-13

UR.1. Installation Requirements. ..................................................................................................................5-13

UR.1.1. Installation. ...........................................................................................................................5-13

UR.2. Use Requirements. ..............................................................................................................................5-13

UR.2.1. Limitation of Use. .................................................................................................................5-13

UR.2.2. Return to Zero.......................................................................................................................5-13

UR.2.3. Operation of Device..............................................................................................................5-13

UR.2.4. Cleanliness............................................................................................................................5-13

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Handbook 44 – 2016 5.51. Wire- and Cordage-Measuring Devices

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Section 5.51. Wire- and Cordage-Measuring Devices

A. Application

A.1. General. – This code applies to mechanisms and machines designed to indicate automatically the length of 

cordage, rope, wire, cable, or similar flexible material passed through the measuring elements.

A.2. Additional Code Requirements. – In addition to the requirements of this code, Wire- and Cordage-Measuring 

Devices shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Units. – A wire- or cordage-measuring device shall indicate lengths in terms of feet, yards, or meters, or 

combinations of units of the same measurement system, and shall have minimum increments with values that do not 

exceed the equivalent of 0.1 meter or 0.1 yard.

(Amended 1989)

S.2. Design of Indicating Elements.

S.2.1. Graduations.

S.2.1.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.2.1.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in), nor more than 1.0 mm (0.04 in), in width.

S.2.1.3. Clear Interval between Graduations. – The clear interval between graduations shall be at least 

as wide as the widest graduation, and in no case less than 0.8 mm (0.03 in).

S.2.2. Indicator.

S.2.2.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.2.2.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.2.2.3. Width. – The index of an indicator shall not be wider than the narrowest graduations with which 

it is used, and shall in no case exceed 0.4 mm (0.015 in).

S.2.2.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.2.2.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.2.3. Zero Indication. – Primary indicating elements shall be readily returnable to a definite zero indication.

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S.3. Design of Measuring Elements.

S.3.1. Sensitiveness. – If the most sensitive element of the indicating system utilizes an indicator and 

graduations, the relative movement of these parts corresponding to a measurement of 30 cm (1 ft) shall be not 

less than 6 mm (1⁄4 in).

S.3.2. Slippage. – The measuring elements of a wire- or cordage-measuring device shall be so designed and 

constructed as to reduce to the practicable minimum any slippage of material being measured and any lost motion 

in the measuring mechanism.

S.3.3. Accessibility. – A wire- or cordage-measuring device shall be so constructed that the measuring 

elements are readily visible and accessible, without disassembly of any supporting frame or section of the main 

body, for purposes of cleaning or removing any foreign matter carried into the mechanism by the material being 

measured.

S.4. Marking Requirements.

S.4.1. Limitation of Use. – If a device will measure accurately only certain configurations, diameters, types, 

or varieties of materials, or with certain accessory equipment, all limitations shall be clearly and permanently 

stated on the device.

S.4.2. Operating Instructions. – Any necessary operating instructions shall be clearly stated on the device.

S.4.3. Indications. – Indicating elements shall be identified by suitable words or legends so that the values of 

the indications will be unmistakable.

S.5. Design Accuracy. – Indications of length shall be accurate whether the values of the indications are being 

increased or decreased.

N. Notes

N.1. Testing Medium. – Wherever feasible, a wire- or cordage-measuring device shall be tested with a steel tape not 

less than 10 mm (3

/8 in) in width and at least 15 m (50 ft) in length. When a device cannot be tested in this manner 

because of the design of the device, it shall be tested with a dimensionally stable material appropriately marked and 

compared at frequent periodic intervals with a steel tape in order to assure that any marked interval is not in error by 

more than 1⁄3 of the tolerance of the device at that particular interval.

(Amended 1981)

N.2. Minimum Test. – Tests shall be conducted at a minimum initial increment of 5 m (20 ft) and appropriate 

increments up to at least 15 m (50 ft).

T. Tolerances

T.1. Tolerance Values. – Maintenance and acceptance tolerances shall be as shown in Table 1. Maintenance and

Acceptance Tolerances for Wire- and Cordage-Measuring Devices.

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UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Installation. – A wire- or cordage-measuring device shall be securely supported and firmly fixed in 

position.

UR.2. Use Requirements.

UR.2.1. Limitation of Use. – A wire- or cordage-measuring device shall be used to measure only those 

materials that it was designed to measure, and in no case shall it be used to measure a material that a marking on 

the device indicates should not be measured.

UR.2.2. Return to Zero. – The primary indicating elements of a wire- or cordage-measuring device shall be 

returned to zero before each measurement.

UR.2.3. Operation of Device. – A wire- or cordage-measuring device shall not be operated in such a manner 

as to cause slippage or inaccurate measurement.

UR.2.4. Cleanliness. – The measuring elements of a wire- or cordage-measuring device shall be kept clean to 

prevent buildup of dirt and foreign material that would adversely affect the measuring capability of the device.

Table 1.

Maintenance and Acceptance Tolerances for Wire- and Cordage-Measuring Devices

Indication of Device

(feet)

Acceptance and Maintenance Tolerances

On Underregistration

(inches)

On Overregistration

(inches)

20

Over 20 to 30

Over 30 to 40

Over 40 to 50

Over 50

 6

 8 

10

12

Add 2 inches per indicated 10 feet

3

4 

5 

6 

Add 1 inch per indicated 10 feet

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Handbook 44 – 2016 5.52. Linear Measures

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Table of Contents

Section 5.52. Linear Measures ............................................................................................ 5-17

A. Application .................................................................................................................................................. 5-17

A.1. General................................................................................................................................................5-17

A.2. Additional Code Requirements...........................................................................................................5-17

S. Specifications............................................................................................................................................... 5-17

S.1.M.Units....................................................................................................................................................5-17

S.1. Units....................................................................................................................................................5-17

S.2. Material...............................................................................................................................................5-17

S.2.1. Flexible Tape. .......................................................................................................................5-17

S.2.2. End Measure. ........................................................................................................................5-17

S.3. Finish. .................................................................................................................................................5-17

S.4. Design. ................................................................................................................................................5-17

S.4.1. Rigid Measure.......................................................................................................................5-17

S.4.2. Folding Measure. ..................................................................................................................5-17

S.5. Graduations.........................................................................................................................................5-18

S.5.1. General..................................................................................................................................5-18

S.5.2. Width. ...................................................................................................................................5-18

T. Tolerances.................................................................................................................................................... 5-18

T.1. For Measures Except Metal Tapes......................................................................................................5-18

T.2. For Metal Tapes..................................................................................................................................5-18

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Handbook 44 – 2016 5.52. Linear Measures

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Section 5.52. Linear Measures

A. Application

A.1. General. – This code applies to any linear measure or measure of length, whether flexible or inflexible, 

permanently installed or portable.

A.2. Additional Code Requirements. – In addition to the requirements of this code, Linear Measures shall meet 

the requirements of Section 1.10. General Code.

S. Specifications

S.1.M. Units. – A linear measure may be in total length, and the total length may be subdivided in any or all of the 

following:

(a) centimeters and tenths of the centimeter;

(b) meters; and

(c) multiples of meters.

An one-meter measure may be graduated, in addition, to show 0.1 m and multiples of 0.1 m subdivisions.

S.1. Units. – A linear measure may be in total length, and the total length may be subdivided in any or all of the 

following:

(a) inches and binary submultiples of the inch;

(b) feet;

(c) yards and multiples of yards.

A 1-yard measure may be graduated, in addition, to show 1⁄3 yd and 2⁄3 yd subdivisions. A flexible tape may be 

graduated in tenths or hundredths of a foot, or both tenths and hundredths of a foot. (Any other subdivisions are 

allowable only on measures of special purposes and when required for such purposes.)

S.2. Material.

S.2.1. Flexible Tape. – A flexible tape shall be made of metal.

S.2.2. End Measure. – If an end measure is made of material softer than brass, the ends of the measure shall 

be protected by brass (or other metal at least equally hard) securely attached.

S.3. Finish. – Measures shall be smoothly finished.

S.4. Design.

S.4.1. Rigid Measure. – A rigid measure shall be straight.

S.4.2. Folding Measure. – A folding measure shall open to a definite stop, and when so opened shall be 

straight.

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S.5. Graduations.

S.5.1. General. – Graduations shall be perpendicular to the edge of the measure.

S.5.2. Width. – The width of the graduations on any measure shall not exceed one-half the width of the smallest 

graduated interval on the measure, and in no case shall be wider than 0.75 mm (0.03 in).

(Amended 1982)

T. Tolerances

T.1. For Measures Except Metal Tapes. – Maintenance tolerances in excess and in deficiency for measures except 

metal tapes shall be as shown in Table 1. Maintenance Tolerances, in Excess and in Deficiency, for Linear Measures 

Except Metal Tapes. Acceptance tolerances shall be one-half the maintenance tolerances.

Table 1.

Maintenance Tolerances, in Excess and in Deficiency, for Linear Measures Except Metal Tapes

Nominal Interval from Zero Tolerance

Feet Inch

1⁄2 or less

1 

2 

3 

4 

5 

6

1

/64

1

/32

1

/16

3

/32

1

/8

5

/32

3

/16

T.2. For Metal Tapes. – Maintenance and acceptance tolerances in excess and in deficiency for metal tapes shall 

be as shown in Table 2. Maintenance and Acceptance Tolerances, in Excess and in Deficiency, for Metal Tapes. Tapes 

of 10 m (25 ft) or over shall be tested at a tension resulting from a load of 5 kg (10 lb). Tapes less than 10 m (25 ft) 

shall be tested at a tension resulting from a load of 2.5 kg (5 lb). However, flexible metal tapes of 10 m (25 ft) or less 

that are not normally used under tension shall be tested with no tension applied. All tapes shall be supported 

throughout on a horizontal flat surface whenever tested.

(Amended 1972)

Table 2.

Maintenance and Acceptance Tolerances, in Excess and in Deficiency, for Metal Tapes

Nominal Interval from Zero Tolerance

Feet Inch

6 or less

7 to 30, inclusive

31 to 55, inclusive

56 to 80, inclusive

81 to 100, inclusive

1

/32

1

/16

1

/8

3

/16

1⁄4

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Handbook 44 – 2016 5.53. Odometers

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Table of Contents

Section 5.53. Odometers ...................................................................................................... 5-21

A. Application .................................................................................................................................................. 5-21

A.1. General................................................................................................................................................5-21

A.2. Exceptions...........................................................................................................................................5-21

A.3. Additional Code Requirements...........................................................................................................5-21

S. Specifications............................................................................................................................................... 5-21

S.1. Design of Indicating Elements............................................................................................................5-21

S.1.1. General..................................................................................................................................5-21

S.1.2. Units......................................................................................................................................5-21

S.1.3. Minimum Indicated Value. ...................................................................................................5-21

S.1.4. Advancement of Indicating Elements. ..................................................................................5-21

S.1.5. Readability............................................................................................................................5-21

S.1.6. Digital Indications and Representation. ................................................................................5-22

N. Notes............................................................................................................................................................. 5-22

N.1. Testing Procedures..............................................................................................................................5-22

N.1.1. Test Methods.........................................................................................................................5-22

N.1.2. Test Runs. .............................................................................................................................5-22

N.1.3. Test Conditions. ....................................................................................................................5-22

T. Tolerances.................................................................................................................................................... 5-23

T.1. To Underregistration and to Overregistration. ....................................................................................5-23

T.2. Tolerance Values. ...............................................................................................................................5-23

T.2.1. Tolerances for Unloaded Trucks...........................................................................................5-23

UR. User Requirements........................................................................................................................................ 5-23

UR.1. Inflation of Vehicle Tires....................................................................................................................5-23

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Section 5.53. Odometers

A. Application

A.1. General. – This code applies to odometers that are used or are to be used to determine the charges for rent or 

hire of passenger vehicles and trucks and buses. (When official examinations are undertaken on odometers that form 

the basis for the payment of fees or taxes to, or the preparation of reports for, governmental agencies, and in similar 

cases, the requirements of this code shall be applied insofar as they are applicable and appropriate to the conditions of 

such special uses.)

(Amended 1977)

A.2. Exceptions. – This code does not apply to taximeters (for which see Section 5.54. Code for Taximeters).

(Amended 1977)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Odometers shall meet the 

requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating Elements.

S.1.1. General. – The primary indicating element of an odometer may be:

(a) the distance-traveled portion of the “speedometer” assembly of a motor vehicle;

(b) a special cable-driven distance-indicating device; or

(c) a hub odometer attached to the hub of a wheel on a motor vehicle.

(Amended 1977)

S.1.2. Units. – An odometer shall indicate in terms of miles or kilometers.

(Amended 1977)

S.1.3. Minimum Indicated Value. – The value of the interval of indicated distance shall be:

(a) for odometers indicating in kilometers, 0.1 km; or

(b) for odometers indicating in miles, 0.1 mi. 

(Amended 1977)

S.1.4. Advancement of Indicating Elements. – The most sensitive indicating elements of an odometer may 

advance continuously or intermittently; all other elements shall advance intermittently. Except when the 

indications are being returned to zero, the indications of an installed odometer shall be susceptible to advancement 

only by the rotation of the vehicle wheel or wheels.

(Amended 1977)

S.1.5. Readability. – Distance figures and their background shall be of sharply contrasting colors. Figures 

indicating tenth units shall be differentiated from other figures with different colors, or with a decimal point, or 

by other equally effective means. Except during the period of advance of any decade to the next higher indication, 

only one figure in each decade shall be exposed to view. Any protective covering intended to be transparent shall 

be in such condition that it can be made transparent by ordinary cleaning of its exposed surface.

(Amended 1977)

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S.1.6. Digital Indications and Representation. – Digital indicating odometers (discontinuous registration) 

shall “round off” indications to the nearest minimum division or truncate indications to the lower minimum 

division. 

(Added 1990)

N. Notes

N.1. Testing Procedures.

N.1.1. Test Methods. – To determine compliance with distance tolerances, a distance test of an odometer shall 

be conducted using one or more of the following test methods:

(a) Road Test. – A road test consists of driving the vehicle over a precisely measured road course.

(b) Fifth-Wheel Test. – A fifth-wheel test consists of driving the vehicle over any reasonable road course 

and determining the distance actually traveled through the use of a mechanism known as a “fifth wheel” 

that is attached to the vehicle and that independently measures and indicates the distance.

(c) Simulated-Road Test. – A simulated-road test consists of determining the distance traveled by use of a 

roller device, or by computation from rolling circumference and wheel-turn data.

(Amended 1977)

N.1.2. Test Runs. – Not less than two test runs shall be conducted. Acceleration and deceleration shall be 

carefully controlled to avoid spinning or skidding the wheels.

(Amended 1977)

N.1.2.1. For Devices Indicating in Miles. – The test runs shall be 2 mi in length, shall start from, and 

finish at, a dead stop with a minimum of 80 % of the run between 30 mi/h and 45 mi/h.

(Added 1977)

N.1.2.2. For Devices Indicating in Kilometers. – The test runs shall be 3 km in length, shall start from, 

and finish at, a dead stop with a minimum of 80 % of the run between 50 km/h and 75 km/h.

(Added 1977)

N.1.3. Test Conditions.

N.1.3.1. Tire Stabilization. – Road tests or fifth-wheel tests shall be preceded by a run of at least 8 km or 

5 mi, for the purpose of stabilizing tire pressures. Simulated road tests on a roller device shall be made at 

stable tire pressures.

(Amended 1977)

N.1.3.2. Tire Pressure. – At the completion of the test run or runs, the tires of the vehicle under test shall 

be checked to determine that the tire pressure is that operating tire pressure posted in the vehicle. If not, the 

tire pressure should be adjusted to the posted tire pressure and further tests may be conducted to determine 

the operating characteristics of the odometer.

(Amended 1977)

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N.1.3.3. Vehicle Loading.

(a) Passenger Load. – During the distance test of an odometer, the vehicle may carry two persons.

(b) Truck Cargo Load. – Truck odometers shall be tested by one of the following methods:

(1) the truck is loaded with one-half of the maximum cargo load; or

(2) unloaded if unloaded test tolerances are applied.

(Amended 1977 and 1987)

T. Tolerances

T.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied to 

errors of underregistration and errors of overregistration. 

T.2. Tolerance Values. – Except for unloaded trucks, maintenance and acceptance tolerances on odometers shall 

be 4 % of the interval under test.

(Amended 1977and 1987)

T.2.1. Tolerances for Unloaded Trucks. – Maintenance and acceptance tolerances on truck odometers shall 

be 5 % for underregistration and 3 % for overregistration of the interval under test.

(Added 1987)

UR. User Requirements

UR.1. Inflation of Vehicle Tires. – The operational tire pressure of passenger vehicle and truck tires shall be posted 

in the vehicle and tires shall be maintained at the posted pressure.

(Amended 1977)

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Handbook 44 – 2016 5.54. Taximeters

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Table of Contents

Section 5.54. Taximeters ........................................................................................................ 5-27

A. Application .................................................................................................................................................. 5-27

A.1. General................................................................................................................................................5-27

A.2. Exceptions...........................................................................................................................................5-27

A.3. Additional Code Requirements...........................................................................................................5-27

S. Specifications............................................................................................................................................... 5-27

S.1. Design of Indicating and Recording Elements....................................................................................5-27

S.1.1. General..................................................................................................................................5-27

S.1.2. Advancement of Indicating Elements. ..................................................................................5-27

S.1.3. Visibility of Indications. .......................................................................................................5-27

S.1.4. Actuation of Fare-Indicating Mechanism. ............................................................................5-28

S.1.5. Operating Condition..............................................................................................................5-28

S.1.6. Fare Identification.................................................................................................................5-28

S.1.7. Extras. ...................................................................................................................................5-28

S.1.8. Protection of Indications. ......................................................................................................5-29

(Amended 2015)..................................................................................................................................5-29

S.1.9. Recorded Representation......................................................................................................5-29

S.1.10. Non-fare Information............................................................................................................5-29

S.2. Basis of Fare Calculations. .................................................................................................................5-30

S.2.1. Initial Time and Distance Intervals.......................................................................................5-30

S.3. Design of Operating Control...............................................................................................................5-30

S.3.1. Positions of Control. .............................................................................................................5-30

S.3.2. Flag. ......................................................................................................................................5-30

S.3.3. Control for Extras Mechanism..............................................................................................5-30

S.4. Interference. ........................................................................................................................................5-30

S.5. Provision for Security Seals................................................................................................................5-30

S.6. Power Interruption, Electronic Taximeters. ........................................................................................5-31

S.7. Anti-Fraud Provisions, Electronic Taximeters....................................................................................5-31

N. Notes............................................................................................................................................................. 5-31

N.1. Distance Tests.....................................................................................................................................5-31

N.1.1. Test Methods.........................................................................................................................5-31

N.1.2. Test Procedures.....................................................................................................................5-31

N.1.3. Test Conditions. ....................................................................................................................5-32

N.2. Time Test. ...........................................................................................................................................5-32

N.3. Interference Test. ................................................................................................................................5-32

T. Tolerances.................................................................................................................................................... 5-32

T.1. Tolerance Values. ...............................................................................................................................5-32

T.1.1. On Distance Tests. ................................................................................................................5-32

T.1.2. On Time Tests.......................................................................................................................5-32

T.1.3. On Interference Tests............................................................................................................5-33

UR. User Requirements ..................................................................................................................................... 5-33

UR.1. Inflation of Vehicle Tires....................................................................................................................5-33

UR.2. Position and Illumination of Taximeter. .............................................................................................5-33

UR.3. Statement of Rates. .............................................................................................................................5-33

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Section 5.54. Taximeters

A. Application

A.1. General. – This code applies to taximeters; that is, to devices that automatically calculates at a predetermined 

rate or rates and indicate the charge for hire of a vehicle.

A.2. Exceptions. – This code does not apply to odometers on vehicles that are rented on a distance basis (for which 

see Section 5.53. Code for Odometers).

(Amended 1977)

A.3. Additional Code Requirements. – In addition to the requirements of this code, Taximeters shall meet the 

requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements.

S.1.1. General. – A taximeter shall be equipped with a primary indicating element.

(Amended 1988 and 2015) 

S.1.1.1. Recording Elements. – A receipt providing information as required in S.1.9. Recorded 

Representations shall be available from a taximeter or taximeter system through an integral or separate 

recording element for all transactions conducted.

[Nonretroactive January 1, 2016]

(Added 2015)

S.1.2. Advancement of Indicating Elements. – Except when a taximeter is being cleared, the primary 

indicating and recording elements shall be susceptible of advancement only by the movement of the vehicle or 

by the time mechanism.

(Amended 1988)

S.1.3. Visibility of Indications. – The indications of fare, including extras, and the mode of operation, such as 

“time” or “hired,” shall be constantly displayed whenever the meter is in operation. All indications of passenger 

interest shall be easily read from a distance of 1.2 m (4 ft) under any condition of normal operation.

(Amended 1977, 1986, and 1988)

S.1.3.1. Minimum Height of Figures, Words, and Symbols. – The minimum height of the figures used 

to indicate the fare shall be 10 mm and for extras, 8 mm. The minimum height of the figures, words, or 

symbols used for other indications, including those used to identify or define, shall be 3.5 mm.

(Added 1986)

S.1.3.2. Lighting of Indications. – Integral lighting shall be provided to illuminate the fare, extras, the 

rate or rate code, and the taximeter status (i.e., vacant, hired, and time off).

[Nonretroactive as of January 1, 1989]

(Added 1988) (Amended 1990)

S.1.3.3. Passenger’s Indications. – A supplementary indicating element installed in a taxi to provide 

information regarding the taxi service to the passenger, shall clearly display the current total of all charges 

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5.54. Taximeters Handbook 44 – 2016 

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incurred for the transaction. The accruing total of all charges must remain clearly visible on the passenger’s 

display (unless disabled by the passenger) at all times during the transaction.

[Nonretroactive as of January 1, 2016]

(Added 2015)

S.1.3.3.1. Additional Information. – Additional information shall be displayed or made available 

through a passenger’s indicating element (as described in S.1.3.3. Passenger’s Indications) and shall 

be current and reflect any charges that have accrued. This additional information shall include:

(a) an itemized account of all charges incurred including fare, extras, and other additional 

charges; and

(b) the rate(s) in use at which any fare is calculated.

Any additional information made available must not obscure the accruing total of charges for the taxi 

service. This additional information may be made accessible through clearly identified operational 

controls (e.g., keypad, button, menu, touch-screen).

[Non retroactive as of January 1, 2016]

(Added 2015)

S.1.3.3.2. Fare and Extras Charges. – The indication of fare and extras charges on a passenger’s 

indicating element shall agree with similar indications displayed on all other indicating elements in the 

system.

[Nonretroactive as of January 1, 2016]

(Added 2015)

S.1.4. Actuation of Fare-Indicating Mechanism. – When a taximeter designed to calculate fares upon the 

basis of a combination of distance traveled and time elapsed is operative with respect to fare indication, the 

fare-indicating mechanism shall be actuated by the distance mechanism whenever the vehicle is in motion at such 

a speed that the rate of distance revenue equals or exceeds the time rate, and may be actuated by the time 

mechanism whenever the vehicle speed is less than this and when the vehicle is not in motion. Means shall be

provided for the vehicle operator to render the time mechanism either operative or inoperative with respect to the 

fare-indicating mechanism.

(Amended 1977)

S.1.5. Operating Condition.

S.1.5.1. General. – When a taximeter is cleared, the indication “Not Registering,” “Vacant,” or an 

equivalent expression shall be shown. Whenever a taximeter is set to register charges, it shall indicate 

“Registering,” “Hired,” or an equivalent expression and the rate at which it is set shall be automatically 

indicated (Rate 1 or Rate A, for example).

(Amended 1988)

S.1.5.2. Time not Recording. – When a taximeter is set for fare registration with the time mechanism 

inoperative, it shall indicate “Time Not Recording” or an equivalent expression.

(Amended 1988)

S.1.6. Fare Identification. – Fare indications shall be identified by the word “Fare” or by an equivalent 

expression. Values shall be defined by suitable words or monetary signs.

S.1.7. Extras. – Extras shall be indicated as a separate item and shall not be included in the fare indication. 

They shall be identified by the word “Extras” or by an equivalent expression. Values shall be defined by suitable 

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words or monetary signs. Means may be provided to totalize the fare and extras if the totalized amount returns 

to separate indications of fare and extras within 5 seconds or less.

(Amended 1988)

S.1.7.1. Nonuse of Extras. – If and when taximeter extras are prohibited by legal authority or are 

discontinued by a vehicle operator, the extras mechanisms shall be rendered inoperable or the extras 

indications shall be effectively obscured by permanent means.

S.1.8. Protection of Indications. – All indications of fare and extras shall be protected from unauthorized 

alteration or manipulation.

(Amended 2015)

S.1.9. Recorded Representation. – A printed receipt issued from a taximeter, whether through an integral or 

separate recording element, shall include as a minimum, the following information when processed through the 

taximeter system: 

(a) date; 

(b) unique vehicle identification number, such as the medallion number, taxi number, vehicle identification 

number (VIN), permit number, or other identifying information as specified by the statutory authority;* 

(c) start and end time of the trip;* 

(d) distance traveled, maximum increment of 0.1 km (0.1 mi);* 

(e) fare in $;

(f) each rate at which the fare was computed and the associated fare at that rate;* 

(g) additional charges (in $) where permitted such as extras, any surcharges, telecommunication charges, 

and taxes shall be identified and itemized;* 

(h) total charge for service in $ (inclusive of fare, extras, and all additional charges);* 

(i) trip number, if available;** and

(j) telephone number (or other contract information) for customer assistance.**

Note: When processed through the taximeter or taximeter system, any adjustments (in $) to the total charge for service 

including discounts, credits, and tips shall also be included on the receipt.**

[Nonretroactive as of January 1, 1989] *[Nonretroactive as of January 1, 2000] 

**[Nonretroactive as of January 1, 2016]

(Added 1988) (Amended 1999 and 2015) 

S.1.9.1. Multiple Recorded Representations.

S.1.9.1.1. Duplicate Receipts. – A recording element may produce a duplicate receipt for the previous 

transaction provided the information printed is identical to the original with the exception of time issued. 

The duplicate receipt shall include the words “duplicate” or “copy.” The feature to print a duplicate 

receipt shall be deactivated at the time the meter is hired for the next fare. 

[Nonretroactive as of January 1, 2000]

(Added 1999)

S.1.10. Non-fare Information. – The fare and extras displays may be used to display auxiliary information 

provided the meter is in the vacant condition and such information is only displayed for10 seconds, or less. If the 

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information consists of a list of information, the list may be displayed one item after another, provided that each 

item is displayed for 10 seconds, or less.

[Nonretroactive as of January 1, 2002]

(Added 2000)

S.2. Basis of Fare Calculations. – A taximeter shall calculate fares only upon the basis of:

(a) distance traveled; 

(b) time elapsed; or

(c) a combination of distance traveled and time elapsed.

(Amended 1977)

S.2.1. Initial Time and Distance Intervals. – The time and distance intervals of a taximeter shall be directly 

proportional as expressed in the following formula:

percenDista Non Initial Mileage Interval

InitialofancetDis Mileage Interval

perSeconds Non TimeInitial Interval

TimeInitialofSeconds Interval

 

 

 

 

− = −

(Added 1990)

S.3. Design of Operating Control.

S.3.1. Positions of Control. – The several positions of the operating controls shall be clearly defined and shall 

be so constructed that accidental or inadvertent changing of the operating condition of the taximeter is improbable. 

Movement of the operating controls to an operating position immediately following movement to the cleared 

position shall be delayed enough to permit the taximeter to come to a complete rest in the cleared position.

(Amended 1988)

S.3.2. Flag. – If the control for the operating condition is a lever-arm and flag, the flag shall be at its highest 

position when the taximeter is cleared, and in this position the whole of the flag shall be above the level of the 

taximeter housing. 

S.3.3. Control for Extras Mechanism. – The knob, handle, or other means provided to actuate the extras 

mechanism shall be inoperable whenever the taximeter is cleared.

S.4. Interference. – The design of a taximeter shall be such that there will be no interference between the time and 

the distance portions of the mechanism device at any speed of operation.

(Amended 1977 and 1988)

S.5. Provision for Security Seals. – Adequate provision shall be made to provide security for a taximeter. Security 

may be provided either by:

(a) Affixing security seals to the taximeter and to all other components required for service operation of a 

complete installation on a vehicle, so that no adjustments, alterations, or replacements affecting accuracy or 

indications of the device or the assembly can be made without mutilating the seal or seals; or

(b) Using a combination of security seals described in paragraph (a) and, in the case of a component that may be 

removed from a vehicle (e.g., slide mounting the taximeter), providing a physical or electronic link between 

components affecting accuracy or indications of the device to ensure that its performance is not affected and 

operation is permitted only with those components having the same unique properties.

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The sealing means shall be such that it is not necessary to disassemble or remove any part of the device or of the 

vehicle to apply or inspect the seals.

(Amended 1988 and 2000)

S.6. Power Interruption, Electronic Taximeters.

(a) After a power interruption of 3 seconds or less, the fare and extras indications shall return to the previously 

displayed indications and may be susceptible to advancement without the taximeter being cleared.

(b) After a power interruption exceeding 3 seconds, the fare and extras indications shall return to the previously 

displayed indications and shall not be susceptible to advancement until the taximeter is cleared.

After restoration of power following an interruption exceeding 3 seconds, the previously displayed fare shall be 

displayed for a maximum of 1 minute at which time the fare shall automatically clear and the taximeter shall return 

to the vacant condition.* 

[*Nonretroactive as of January 1, 2002]

(Added 1988) (Amended 1989, 1990, and 2000)

S.7. Anti-Fraud Provisions, Electronic Taximeters. – An electronic taximeter may have provisions to detect and 

eliminate distance input that is inconsistent with output of the vehicle’s distance sensor. When a taximeter equipped 

with this feature detects input inconsistent with the distance sensor:

(a) The meter shall either filter out the inconsistent distance input signals or cease to increment fare based on 

distance until the distance input signal returns to normal. If the meter ceases to increment fare based on 

distance, the taximeter may continue to increment fare based on elapsed time;

(b) The taximeter shall provide a visible or audible signal that inconsistent input signals are being detected; and

(c) The taximeter shall record the occurrence in an event logger. The event logger shall include an event counter 

(000 to 999), the date, and the time of at least the last 1000 occurrences.

(Added 2001)

N. Notes

N.1. Distance Tests.

N.1.1. Test Methods. – To determine compliance with distance tolerances, a distance test of a taximeter shall 

be conducted utilizing one or more of the following test methods:

(a) Road Test. – A road test consists of driving the vehicle over a precisely measured road course.

(b) Fifth-Wheel Test. – A fifth-wheel test consists of driving the vehicle over any reasonable road course 

and determining the distance actually traveled through the use of a mechanism known as a “fifth wheel” 

that is attached to the vehicle and that independently measures and indicates the distance.

(c) Simulated-Road Test. – A simulated road test consists of determining the distance traveled by use of a 

roller device, or by computation from rolling circumference and wheel-turn data.

(Amended 1977)

N.1.2. Test Procedures. – The distance test of a taximeter, whether a road test, a simulated-road test, or a 

fifth-wheel test, shall include at least duplicate runs of sufficient length to cover at least the third money drop or 

1 mi, whichever is greater, and shall be at a speed approximating the average speed traveled by the vehicle in 

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normal service. In the case of metric-calibrated taximeters, the test should cover at least the third money drop or 

2 km, whichever is greater.

(Amended 1977)

N.1.3. Test Conditions.

N.1.3.1. Vehicle Lading. – During the distance test of a taximeter, the vehicle shall carry two persons, or 

in the case of a simulated-road test, 70 kg or 150 lb of test weights may be substituted in lieu of the second 

person.

N.1.3.2. Tire Pressure. – At the completion of test run or runs, the tires of the vehicle under test shall be 

checked to determine that the tire pressure is that operating tire pressure posted in the vehicle. If not, the tire 

pressure should be adjusted to the posted tire pressure and further tests may be conducted to determine the 

operating characteristics of the taximeter. 

(Amended 1977)

N.2. Time Test. – If a taximeter is equipped with a timing device through which charges are made for time intervals, 

the timer shall be tested at the initial interval, four separate subsequent intervals, and an average time test of at least 

four consecutive subsequent time intervals.

(Amended 1988)

N.3. Interference Test. – If a taximeter is equipped with a timing device through which charges are made for time 

intervals, a test shall be conducted to determine whether there is interference between the time and distance elements. 

During the interference test, the vehicle’s operating speed shall be 3 km/h or 4 km/h, or 2 mi/h or 3 mi/h faster than 

the speed at which the basic distance rate equals the basic time rate. The basic rate per hour divided by the basic rate 

per mile is the speed (km/h or mi/h) at which the basic time rate and basic distance rate are equal.

(Amended 1988)

T. Tolerances

T.1. Tolerance Values.

T.1.1. On Distance Tests. – Maintenance and acceptance tolerances for taximeters shall be as follows:

(a) On Overregistration: 1 % of the interval under test.

(b) On Underregistration: 4 % of the interval under test, with an added tolerance of 30 m or 100 ft whenever 

the initial interval is included in the interval under test.

T.1.2. On Time Tests.

T.1.2.1. On Individual Time Intervals. – Maintenance and acceptance tolerances on individual time 

intervals shall be as follows:

(a) On Overregistration: 3 seconds per minute (5 %).

(b) On Underregistration: 9 seconds per minute (15 %) on the initial interval, and 6 seconds per minute 

(10 %) on subsequent intervals.

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T.1.2.2. On Average Time Interval Computed After the Initial Interval. – Except for the initial 

interval, maintenance and acceptance tolerances on the average time interval shall be as follows:

(a) On Overregistration: 0.2 second per minute (0.33 %).

(b) On Underregistration: 3 seconds per minute (5 %).

(Amended 1991)

T.1.3. On Interference Tests.

T.1.3.1. The registration of a taximeter in the “time on” position shall agree within 1 % of its performance 

in the “time off” position.

(Added 1988)

UR. User Requirements

UR.1. Inflation of Vehicle Tires. – The operational tire pressure of passenger vehicles and truck tires shall be 

posted in the vehicle and shall be maintained at the posted pressure.

(Amended 1977)

UR.2. Position and Illumination of Taximeter. – A taximeter shall be so positioned and illuminated that its 

indications, operational markings, and controls of passenger interest can be conveniently read by a passenger seated 

in the back seat of the vehicle.

(Amended 1985 and 1986)

UR.3. Statement of Rates. – The distance and time rates for which a taximeter is set, including the initial distance 

interval and the initial time interval, the local tax rate, and the schedule of extras when an extras indication is provided

shall be conspicuously displayed inside the front and rear passenger compartments. The words “Rate,” “Rates,” or 

“Rates of Fare” shall precede the rate statement. The rate statement shall be fully informative, self-explanatory, and 

readily understandable by the ordinary passenger, and shall either be of a permanent character or be protected by glass 

or other suitable transparent material.

(Amended 1977, 1988, 1990, and 1999)

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Table of Contents

Section 5.55. Timing Devices ................................................................................................. 5-37

A. Application .................................................................................................................................................. 5-37

A.1. General................................................................................................................................................5-37

A.2. Additional Code Requirements...........................................................................................................5-37

S. Specifications............................................................................................................................................... 5-37

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................5-37

S.1.1. Primary Elements..................................................................................................................5-37

S.1.2. Graduations...........................................................................................................................5-38

S.1.3. Indicators. .............................................................................................................................5-38

S.1.4. Recorded Representations.....................................................................................................5-38

S.2. Marking Requirements, Operating Instructions..................................................................................5-39

S.3. Interference. ........................................................................................................................................5-39

S.4. Provisions for Sealing.........................................................................................................................5-39

S.5. Power Interruption. .............................................................................................................................5-39

S.5.1. Transaction Termination.......................................................................................................5-39

S.5.2. User Information...................................................................................................................5-39

N. Notes............................................................................................................................................................. 5-40

N.1. Test Method. .......................................................................................................................................5-40

N.2. Broadcast Times and Frequencies.......................................................................................................5-40

N.3. Interference Tests, EVSE....................................................................................................................5-40

T. Tolerances.................................................................................................................................................... 5-40

T.1. Tolerance Values. ...............................................................................................................................5-40

T.1.1. For Timing Devices Other Than Those Specified in T.1.2. For Time Clocks and Time 

Recorders and T.1.3. On Parking Meters..............................................................................5-40

T.1.2. For Time Clocks and Time Recorders. .................................................................................5-41

T.1.3. On Parking Meters and Other Timing Devices Used to Assess Charges for Parking...........5-41

T.2. Tests Involving Digital Indications or Representations. .....................................................................5-41

UR. User Requirements ..................................................................................................................................... 5-41

UR.1. Statement of Rates. .............................................................................................................................5-41

UR.2. Time Representations..........................................................................................................................5-41

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Section 5.55. Timing Devices

A. Application

A.1. General. – This code applies to devices used to measure time during which services are being dispensed (such 

as vehicle parking, laundry drying, and car washing). This code also applies to Electric Vehicle Supply Equipment 

(EVSE) when used to assess charges for time-based services in addition to those charged for electrical energy.

(Amended 2015)

A.2. Additional Code Requirements. – In addition to the requirements of this code, Timing Devices shall meet the 

requirements of Section 1.10. General Code.

S. Specifications 

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A timing device shall be equipped with a primary indicating element, and may also 

be equipped with a primary recording element. A timing device incorporated into an Electric Vehicle Supply 

Equipment system for use in assessing charges for timing separate from charges for electrical energy shall 

be equipped with the capability to provide a recorded representation of the transaction through a built-in or 

separate recording element. A readily observable in-service light or other equally effective means that 

automatically indicates when laundry driers, vacuum cleaners, and car washes are in operation shall be 

deemed an appropriate primary indicating element.

(Amended 1979 and 2015) 

S.1.1.2. Units. – A timing device shall indicate and record, if the device is equipped to record, the time in 

terms of minutes for time intervals of 60 minutes or less and in hours and minutes for time intervals greater 

than 60 minutes.

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated time and recorded time, if 

the device is equipped to record, shall not exceed the equivalent of:

(a) one-half hour on parking meters indicating time in excess of two hours;

(b) six minutes on parking meters indicating time in excess of one but not greater than two hours; or

(c) five minutes on all other devices, except those equipped with an in-service light.

(Amended 1975)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only during the mechanical operation of the device, except that 

clocks may be equipped to manually reset the time.

S.1.1.5. Operation of In-Service Indicator Light. – For devices equipped with an in-service indicator 

light, the indicator shall be operative only during the time the device is in operation.

(Amended 2015)

S.1.1.6. Discontinuous Indicating Parking Meters. – An indication of the time purchased shall be 

provided at the time the meter is activated in units of no more than one minute for times less than one hour 

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and not more than two minutes for times of one hour or more. Convenient means shall be provided to indicate 

to the purchaser the unexpired time.

(Added 1975) (Amended 1976)

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations and the width of main graduations shall be not 

more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 

0.2 mm (0.008 in) in width.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall be not less than 0.75 mm 

(0.03 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than:

(a) the width of the widest graduation; and

(b) the width of the minimum clear interval between the graduations.

S.1.3.4. Parallax. – Parallax effect shall be reduced to a practicable minimum.

S.1.4. Recorded Representations. 

S.1.4.1. Recorded Representations, Electric Vehicle Supply Equipment (EVSE) Timing Devices. – A 

timing device incorporated into an EVSE for use in assessing charges for timing separate from charges for 

electrical energy shall issue a recorded representation itemizing the charges for these services as defined in 

Section 3.40. Electric Vehicle Fueling Systems.

(Added 2015)

S.1.4.1.1. Duplicate Receipts. – Duplicate receipts are permissible, provided the word “duplicate” 

or “copy” is included on the receipt.

(Added 2015)

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S.1.4.2. Recorded Representations, All Other Timing Devices. – A printed ticket issued or stamped by a 

timing device shall have printed clearly thereon:

(a) the time and day when the service ends and the time and day when the service begins, except that a

self-service money-operated device that clearly displays the time of day need not record the time 

and day when the service begins; or

(b) the time interval purchased, and the time and day that the service either begins or ends.

(Added 2015)

(Amended 1983 and 2015) 

S.2. Marking Requirements, Operating Instructions. – Operating instructions shall be clearly stated on the 

device.

S.3. Interference. – The design of the EVSE shall be such that there will be no interference between the time and 

electrical energy measurement elements of the system.

(Added 2015)

S.4. Provisions for Sealing. – Adequate provisions shall be made to provide security for the timing element.

(Added 2015)

S.5. Power Interruption. – In the event of a power loss, the information needed to complete any transaction 

(i.e., delivery is complete and payment is settled) in progress at the time of the power loss (such as the quantity and 

unit price, or sales price) shall be determinable through one of the means listed below or the transaction shall be 

terminated without any charge for the electrical energy transfer to the vehicle: 

(a) at the EVSE;

(b) at the console, if the console is accessible to the customer;

(c) via on site Internet access; or

(d) through toll-free phone access.

For EVSEs in parking areas where vehicles are commonly left for extended periods, the information needed to 

complete any transaction in progress at the time of the power loss shall be determinable through one of the above 

means for at least eight hours. 

(Added 2015)

S.5.1. Transaction Termination. – In the event of a power loss, either:

(a) the transaction shall terminate at the time of the power loss; or 

(b) the EVSE may continue charging without additional authorization if the EVSE is able to determine it is 

connected to the same vehicle before and after the supply power outage. 

In either case, there must be a clear indication on the receipt provided to the customer of the interruption, including 

the date and time of the interruption along with other information required under S.1.4.2. Recorded 

Representations, All Other Timing Devices.

(Added 2015)

S.5.2. User Information. – The EVSE memory, or equipment on the network supporting the EVSE, shall 

retain information on the quantity of time and the sales price totals during a power loss.

(Added 2015)

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N. Notes

N.1. Test Method. – A timing device shall be tested with a timepiece with an error of not greater than plus or minus 

15 seconds per 24-hour period. In the test of timing devices with a nominal capacity of 1 hour or less, stopwatches 

with a minimum division of not greater than one-fifth second shall be used. In the test of timing devices with a 

nominal capacity of more than one hour, the value of the minimum division on the timepiece shall be not greater than 

one second. Time pieces and stopwatches shall be calibrated with standard time signals as described in National 

Institute of Standards and Technology Special Publication 432, NIST Time and Frequency Dissemination Services, 

or any superseding publication.

(Amended 1978)

N.2. Broadcast Times and Frequencies. – Time and frequency standards are broadcast by the stations listed in 

Table N.2. Broadcast Times and Frequencies.

Table N.2.*

Broadcast Times and Frequencies

Station Location,

Latitude,

Longitude

Frequency

(MHz)

Times of

Transmission

(UTC)

WWV

Fort Collins, Colorado

4041' N

10502' W

2.5

5.0

10.0

15.0

20.0

Continuous

WWVH

Kauai, Hawaii

2159' N

15946' W

2.5

5.0

10.0

15.0

Continuous

CHU

Ottawa, Canada

4518' N

7545' W

3.330

7.335

14.670

14.670

Continuous

*From NIST Special Publication 559, “Time and Frequency Users’ Manual,” 1990.

(Added 1988)

N.3.Interference Tests, EVSE. – On an EVSE equipped with a timing device used to calculate time-based charges 

in addition to any charges assessed for electrical energy, a test shall be conducted to ensure that there is no interference 

between time and electrical energy measuring elements.

(Added 2015)

T. Tolerances

T.1. Tolerance Values. – Maintenance and acceptance tolerances for timing devices shall be as follows:

T.1.1. For Timing Devices Other Than Those Specified in T.1.2. For Time Clocks and Time Recorders 

and T.1.3. On Parking Meters. – The maintenance and acceptance tolerances shall be:

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(a) On Overregistration: five seconds for any time interval of one minute or more; and

(Amended 1986)

(b) On Underregistration: six seconds per indicated minute.

(Amended 1975)

T.1.2. For Time Clocks and Time Recorders. – The maintenance and acceptance tolerances on overregistration and underregistration shall be three seconds per hour, but not to exceed one minute per day.

(Amended 1975)

T.1.3. On Parking Meters and Other Timing Devices Used to Assess Charges for Parking. – The 

maintenance and acceptance tolerances are shown in Table T.1.3. Maintenance and Acceptance Tolerances for 

Parking Meters and Other Timing Devices Used to Assess Charges For Parking. 

(Amended 2015)

(Amended 2015)

T.2. Tests Involving Digital Indications or Representations. – To the tolerances that would otherwise be applied, 

there shall be added an amount equal to one-half the minimum value that can be indicated or recorded.

UR. User Requirements

UR.1. Statement of Rates. – The following information shall be clearly, prominently, and conspicuously displayed: 

(a) the price in terms of money per unit or units of time for the service dispensed; and

(b) for a timing device other than an EVSE, the number of coins the device will accept and be activated by at 

one time. 

(Amended 1976 and 2015) 

UR.2. Time Representations. – Any time representation shall be within plus or minus two minutes of the correct 

time in effect in the area, except on an individual clock used only for “time out”; in addition, the time indication of 

the “time-out” clock shall be the same as or less than that of the “time-in” clock.

(Amended 1975)

Table T.1.3.

Maintenance and Acceptance Tolerances for Parking Meters and

Other Timing Devices Used to Assess Charges for Parking

Maintenance and Acceptance Tolerances

Nominal Time Capacity On Overregistration On Underregistration

30 minutes or less No tolerance 10 seconds per minute,

but not less than 2 minutes

Over 30 minutes to and 

including 1 hour No tolerance 5 minutes plus 4 secondsper minute over 30 minutes

Over 1 hour No tolerance 7 minutes plus 2 minutes

per hour over 1 hour

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Table of Contents

Section 5.56.(a) Grain Moisture Meters ............................................................................ 5-45

A. Application .................................................................................................................................................. 5-45

A.1. General Code. .....................................................................................................................................5-45

A.2. Exceptions...........................................................................................................................................5-45

A.3. Type Evaluation..................................................................................................................................5-45

A.4. Additional Code Requirements. ..........................................................................................5-45

S. Specifications............................................................................................................................................... 5-45

S.1. Design of Indicating, Recording, and Measuring Elements................................................................5-45

S.1.1. Digital Indications and Recording Elements.......................................................................5-45

S.1.2. Selecting or Recording Grain or Seed Type and Class. ......................................................5-46

S.1.3. Operating Range..................................................................................................................5-47

S.1.4. Value of Smallest Unit. .......................................................................................................5-47

S.1.5. Operating Temperature. ......................................................................................................5-47

S.2. Design of Grain Moisture Meters. ......................................................................................................5-47

S.2.1. Minimum Sample Size........................................................................................................5-47

S.2.2. Electric Power Supply.........................................................................................................5-48

S.2.3. Level Indicating Means.......................................................................................................5-48

S.2.4. Calibration Integrity. ...........................................................................................................5-48

S.2.5. Provision for Sealing...........................................................................................................5-48

S.2.6. Determination of Quantity and Temperature. .....................................................................5-50

S.3. Accessory Equipment. ........................................................................................................................5-50

S.4. Operating Instructions and Use Limitations. ......................................................................................5-50

N. Notes............................................................................................................................................................. 5-50

N.1. Testing Procedures..............................................................................................................................5-50

N.1.1. Air Oven Reference Method Transfer Standards. ...............................................................5-50

N.1.2. Minimum Test.....................................................................................................................5-51

N.1.3. Meter to Like-Type Meter Method Transfer Standards. .....................................................5-51

T. Tolerances.................................................................................................................................................... 5-51

T.1. To Underregistration and to Overregistration. ....................................................................................5-51

T.2. Tolerances...........................................................................................................................................5-51

T.2.1. Air Oven Reference Method. ..............................................................................................5-51

T.2.2. Meter to Like-Type Meter Method. ....................................................................................5-51

T.3. For Test Weight Per Bushel Indications or Recorded Representations. .............................................5-52

UR. User Requirements ..................................................................................................................................... 5-52

UR.1. Selection Requirements. .....................................................................................................................5-52

UR.1.1. Value of the Smallest Unit on Primary Indicating and Recording Elements. .....................5-52

UR.1.2. See G-UR.1.2. Environment. .............................................................................................5-52

UR.2. Installation Requirements. ..................................................................................................................5-52

UR.3. Use Requirements. ..............................................................................................................................5-52

UR.3.1. Operating Instructions.........................................................................................................5-52

UR.3.2. Other Devices Not Used for Commercial Measurement.....................................................5-52

UR.3.3. Maintaining Integrity of Grain Samples..............................................................................5-52

UR.3.4. Printed Tickets. ...................................................................................................................5-53

UR.3.5. Accessory Devices. .............................................................................................................5-53

UR.3.6. Sampling. ............................................................................................................................5-53

UR.3.7. Location. .............................................................................................................................5-53

UR.3.8. Level Condition...................................................................................................................5-53

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UR.3.9. Current Calibration Data. ....................................................................................................5-53

UR.3.10. Posting of Meter Operating Range......................................................................................5-53

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Section 5.56.(a) Grain Moisture Meters

Section 5.56. was reorganized into two sections beginning with the 1997 Edition of NIST Handbook 44. This 

Section, 5.56.(a), applies to all NTEP grain moisture meters. It also applies to any grain moisture meter 

manufactured or placed into service after January 1, 1998. 

(Code reorganized and renumbered 1996) 

A. Application

A.1. General Code. – This code applies to grain moisture meters, that is, devices used to indicate directly the 

moisture content of cereal grain and oil seeds. The code consists of general requirements applicable to all moisture 

meters and specific requirements applicable only to certain types of moisture meters. Requirements cited for “test 

weight per bushel” indications or recorded representations are applicable only to devices incorporating an automatic 

test weight per bushel measuring feature.

(Amended 2003)

A.2. Exceptions. – This code does not apply to devices used for in-motion measurement of grain moisture content 

or seed moisture content.

A.3. Type Evaluation. – The National Type Evaluation Program (NTEP) will accept for type evaluation only those 

devices that comply with this code. State enforcement will be based upon the effective dates identified with each 

requirement when specific dates are shown.

(Added 1993)

A.4. Additional Code Requirements. – In addition to the requirements of this code, 5.56.(a) Grain Moisture Meters

shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating, Recording, and Measuring Elements.

S.1.1. Digital Indications and Recording Elements.

(a) Meters shall be equipped with a digital indicating element.

(b) The minimum height for the digits used to display moisture content shall be 10 mm.

(c) Meters shall be equipped with a communication interface that permits interfacing with a recording 

element and transmitting the date, grain type, grain moisture results, test weight per volume results, and 

calibration version identification.

(d) A digital indicating element shall not display, and a recording element shall not record, any moisture 

content values or test weight per volume values before the end of the measurement cycle.

(e) Moisture content results shall be displayed and recorded as percent moisture content, wet basis. Test 

weight per bushel results shall be displayed and recorded as pounds per bushel. Subdivisions of these 

units shall be in terms of decimal subdivisions (not fractions).

(f) A meter shall not display or record any moisture content or test weight per volume values when the 

moisture content of the grain sample is beyond the operating range of the device, unless the moisture 

and test weight representations include a clear error indication (and recorded error message with the 

recorded representation).

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(g) On multi-constituent meters (e.g., meters which also measure grain protein), provision shall be made for 

displaying and recording the constituent label (such as moisture, protein, etc.) to make it clear which 

constituent is associated with each of the displayed and recorded values.

(Added 1995)

(Amended 1993, 1994, 1995, 1996, and 2003)

S.1.2. Selecting or Recording Grain or Seed Type and Class. – Provision shall be made for selecting and 

recording the type and class or multi-class group (as appropriate) of grain or seed to be measured. The means to 

select the type and class or multi-class group of grain or seed shall be readily visible and the type and class or 

multi-class group of grain or seed selected shall be clearly and definitely identified. Abbreviations for grain types 

and multi-class groups indicated on the meter must meet the minimum acceptable abbreviations listed in 

Table S.1.2. Grain Types and Multi-Class Groups Considered for Type Evaluation and Calibration and Their 

Minimum Acceptable Abbreviations.

(Amended 1993, 1995, and 2007)

Table S.1.2.

Grain Types and Multi-Class Groups Considered for Type Evaluation and Calibration and Their 

Minimum Acceptable Abbreviations

Grain Type Grain Class Minimum Acceptable Abbreviation

Barley

All-Class Barley* BARLEY

Six-Rowed Barley SRB

Two-Rowed Barley TRB

Corn --- CORN

Grain Sorghum --- SORG or MILO

Oats --- OATS

Rice

All-Class Rough Rice* RGHRICE

Long Grain Rough Rice LGRR

Medium Grain Rough Rice MGRR

Small Oil Seeds

(under consideration) --- ---

Soybeans --- SOYB

Sunflower seed (Oil) --- SUNF

Wheat

All-Class Wheat* WHEAT

Durum Wheat DURW

Hard Red Spring Wheat HRSW

Hard Red Winter Wheat HRWW

Hard White Wheat HDWW

Soft Red Winter Wheat SRWW

Soft White Wheat SWW

Wheat Excluding Durum* WHTEXDUR

Note: Grain Types marked with an asterisk (*) are “Multi-Class Calibrations.”

[Nonretroactive as of January 1, 1998]

(Table Added 1993) (Amended 1995, 1998, and 2007)

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S.1.3. Operating Range. – A meter shall automatically and clearly indicate when the operating range of the 

meter has been exceeded. The operating range shall specify the following:

(a) Temperature Range of the Meter. – The temperature range over which the meter may be used and still

comply with the applicable requirements shall be specified. The minimum temperature range shall be 

10 °C to 30 °C. No moisture value may be displayed when the temperature range is exceeded. An 

appropriate message shall be displayed when the temperature of the meter is outside its specified 

operating range.

(b) Temperature Range of each Grain or Seed. – The temperature range for each grain or seed for which 

the meter is to be used shall be specified. The minimum temperature range for each grain shall be 0 °C 

to 40 °C. No moisture value may be displayed when the temperature range is exceeded. An appropriate 

error message shall be displayed when the temperature of the grain sample exceeds the specified 

temperature range for the grain.

(c) Moisture Range of the Grain or Seed. – The moisture range for each grain or seed for which the meter 

is to be used shall be specified. Moisture and test weight per bushel values may be displayed when the 

moisture range is exceeded if accompanied by a clear indication that the moisture range has been 

exceeded.

(Amended 2003)

(d) Maximum Allowable Meter/Grain Temperature Difference. – The maximum allowable difference 

in temperature between the meter and the sample for which an accurate moisture determination can be 

made shall be specified. The minimum temperature difference shall be 10 °C. No moisture value may 

be displayed when the maximum allowable temperature difference is exceeded. An appropriate error 

message shall be displayed when the difference in temperature between the meter and the sample exceeds 

the specified difference.

(Added 1993) (Amended 1995)

S.1.4. Value of Smallest Unit. – The display shall permit moisture value determination to both 0.01 % and 

0.1 % resolution. The 0.1 % resolution is for commercial transactions; the 0.01 % resolution is for type evaluation 

and calibration purposes only, not for commercial purposes. Test weight per bushel values shall be determined 

to the nearest 0.1 pound per bushel.

(Amended 2003)

S.1.5. Operating Temperature.

(a) Warm-up period: When a meter is turned on it shall not display or record any usable values until the 

operating temperature necessary for accurate determination has been attained, or the meter shall bear a 

conspicuous statement adjacent to the indication stating that the meter shall be turned on for a time period 

specified by the manufacturer prior to use.

(b) A meter shall meet the requirements of T.2. Tolerances when operated in the temperature range of 10 °C 

to 30 °C (50 °F to 86 °F) or within the range specified by the meter manufacturer.

(c) If the manufacturer specifies a temperature range, the range shall be at least 20 °C (36 °F).

(Added 1993) (Amended 1995 and 1996)

S.2. Design of Grain Moisture Meters.

S.2.1. Minimum Sample Size. – Meters shall be designed to measure the moisture content of representativesize grain samples. The minimum allowable sample size used in analysis shall be 100 g or 400 kernels or seeds, 

whichever is smaller.

(Added 1993) (Amended 1995)

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S.2.2. Electric Power Supply.

S.2.2.1. Power Supply, Voltage and Frequency.

(a) A meter that operates using alternating current must perform within the tolerances defined in 

Section T.2. Tolerances over the line voltage range 100 V to 130 V, or 200 V to 250 V rms as 

designed, and over the frequency range of 59.5 Hz to 60.5 Hz.

(b) Battery-operated instruments shall not indicate or record values outside the applicable tolerance 

limits when battery power output is excessive or deficient.

S.2.2.2. Power Interruption. – A power interruption shall not cause an indicating or recording element 

to display or record any values outside the applicable tolerance limits.

(Added 1988)

S.2.3. Level Indicating Means. – A meter shall be equipped with a level indicator and leveling adjustments if 

its performance is changed by an amount greater than the applicable tolerance when the meter is moved from a 

level position to a position that is out of level in any upright direction by up to 5 % (approximately three degrees). 

The level-indicating means shall be readable without removing any meter parts requiring a tool.

(Added 1988) (Amended 1994)

S.2.4. Calibration Integrity.

S.2.4.1. Calibration Version. – A meter must be capable of displaying either calibration constants, a 

unique calibration name, or a unique calibration version number for use in verifying that the latest version of 

the calibration is being used to make moisture content and test weight per bushel determinations.

(Added 1993) (Amended 1995 and 2003)

S.2.4.2. Calibration Corruption. – If calibration constants are digitally stored in an electronically 

alterable form, the meter shall be designed to make automatic checks to detect corruption of calibration 

constants. An error message must be displayed if calibration constants have been electronically altered.

(Added 1993) (Amended 1995)

S.2.4.3. Calibration Transfer. – The instrument hardware/software design and calibration procedures 

shall permit calibration development and the transfer of calibrations between instruments of like models 

without requiring user slope or bias adjustments.

[Note: Only the manufacturer or the manufacturer’s designated service agency may make standardization 

adjustments on moisture meters. This does not preclude the possibility of the operator installing 

manufacturer-specified calibration constants under the instructions of the manufacturer or its designated 

service agency.] Standardization adjustments (not to be confused with grain calibrations) are those physical 

adjustments or software parameters which make meters of like type respond identically to the grain(s) being 

measured.

[Nonretroactive as of January 1, 1999]

(Added 1994) (Amended 1998)

S.2.5. Provision for Sealing. – Provision shall be made for applying a security seal in a manner that requires 

the security seal to be broken, or for using other approved means of providing security (e.g., audit trail available 

at the time of inspection as defined in Table S.2.5. Categories of Device and Methods of Sealing) before any

change that affects the metrological integrity of the device can be made to any mechanism.

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Table S.2.5. 

Categories of Device and Methods of Sealing

Categories of Device Methods of Sealing

Category 1: No remote configuration capability. Seal by physical seal or two event counters: one for

calibration parameters (000 to 999) and one for

configuration parameters (000 to 999). If equipped 

with event counters, the device must be capable of 

displaying, or printing through the device or through 

another on-site device, the contents of the counters.

Category 2: Remote configuration capability, but 

access is controlled by physical hardware.

A device shall clearly indicate that it is in the remote 

configuration mode and shall not be capable of 

operating in the measure mode while enabled for 

remote configuration.

The hardware enabling access for remote 

communication must be at the device and sealed using 

a physical seal or two event counters: one for

calibration parameters (000 to 999) and one for

configuration parameters (000 to 999). If equipped 

with event counters, the device must be capable of 

displaying, or printing through the device or through 

another on-site device, the contents of the counters.

Category 3: Remote configuration capability access 

may be unlimited or controlled through a software 

switch (e.g., password).

When accessed for the purpose of modifying sealable

parameters, the device shall clearly indicate that it is in 

the configuration mode and shall not be capable of 

operating in the measuring mode.

An event logger is required in the device; it must 

include an event counter (000 to 999), the parameter 

ID, the date and time of the change, and the new value 

of the parameter (for calibration changes consisting of 

multiple constants, the calibration version number may 

be used rather than the calibration constants). A 

printed copy of the information must be available 

through the device or through another on-site device. 

The event logger shall have a capacity to retain records 

equal to 25 times the number of sealable parameters in 

the device, but not more than 1000 records are 

required. (Note: Does not require 1000 changes to be 

stored for each parameter.)

Category 3a: No remote capability, but operator is 

able to make changes that affect the metrological

integrity of the device (e.g., slope, bias, etc.) in normal 

operation.

*When accessed for the purpose of modifying sealable 

parameters, the device shall clearly indicate that it is in 

the configuration mode and shall not be capable of 

operating in the measuring mode.

Same as Category 3

Category 3b: No remote capability, but access to 

metrological parameters is controlled through a 

software switch (e.g., password).

*When accessed for the purpose of modifying sealable 

parameters, the device shall clearly indicate that it is in 

the configuration mode and shall not be capable of 

operating in the measuring mode.

Same as Category 3

[Nonretroactive as of January 1, 1999]

[*Nonretroactive as of January 1, 2014]

(Amended 1998 and 2013)

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Note: Zero-setting and test point adjustments are considered to affect metrological characteristics and must be sealed.

(Added 1993) (Amended 1995 and 1997)

S.2.6. Determination of Quantity and Temperature. – The moisture meter system shall not require the 

operator to judge the precise volume or weight and temperature needed to make an accurate moisture 

determination. External grinding, weighing, and temperature measurement operations are not permitted. In 

addition, if the meter is capable of measuring test weight per bushel, determination of sample volume and weight 

for this measurement shall be fully automatic and means shall be provided to ensure that measurements of test 

weight per volume are not allowed to be displayed or printed when an insufficient sample volume is available to 

provide an accurate measurement. [Nonretroactive as of January 1, 2004]

(Added 1994) (Amended 1995 and 2003)

S.3. Accessory Equipment. – When the operating instructions for a moisture meter require accessory equipment 

separate from and external to the moisture meter, such equipment shall be appropriate and complete for the 

measurement.

S.4. Operating Instructions and Use Limitations. – The manufacturer shall furnish operating instructions for the 

device and accessories that include complete information concerning the accuracy, sensitivity, and use of accessory 

equipment necessary in obtaining a moisture content. Operating instructions shall include the following information:

(a) name and address or trademark of the manufacturer;

(b) the type or design of the device with which it is intended to be used;

(c) date of issue;

(d) the kinds or classes of grain or seed for which the device is designed to measure moisture content and test 

weight per bushel; and

(Amended 2003)

(e) the limitations of use, including but not confined to the moisture measurement range, grain or seed 

temperature, maximum allowable temperature difference between grain sample and meter, kind or class of 

grain or seed, moisture meter temperature, voltage and frequency ranges, electromagnetic interferences, and 

necessary accessory equipment.

(Added 1984)

N. Notes

N.1. Testing Procedures. – Field evaluation of grain moisture meters shall be performed by one of the following 

methods:

N.1.1. Air Oven Reference Method Transfer Standards. – Official grain samples shall be used as the official 

transfer standards with moisture content and test weight per bushel values assigned by the reference methods. 

The reference methods for moisture shall be the oven drying methods as specified by the USDA GIPSA. The test 

weight per bushel value assigned to a test weight transfer standard shall be the average of 10 test weight per bushel 

determinations using the quart kettle test weight per bushel apparatus as specified by the USDA GIPSA. 

Tolerances shall be applied to the average of at least three measurements on each official grain sample. Official 

grain samples shall be clean and naturally moist, but not tempered (i.e., water not added).

(Amended 1992, 2001, and 2003)

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N.1.2. Minimum Test. – A minimum test of a grain moisture meter shall consist of tests using samples (need 

not exceed three) of each grain or seed type for which the device is used, and for each grain or seed type shall 

include the following:

(a) tests of moisture indications, using samples having at least two different moisture content values within 

the operating range of the device; and

(b) if applicable, tests of test weight per volume indications, with at least the lowest moisture samples used 

in (a) above.

(Added 2003)

(Amended 1986, 1989, and 2003)

N.1.3. Meter to Like-Type Meter Method Transfer Standards. – Properly standardized reference meters 

using National Type Evaluation Program approved calibrations shall be used as transfer standards. A reference 

meter shall be of the same type as the meter under test. Tests shall be conducted side-by-side using, as a 

comparison medium, grain samples that are clean and naturally moist, but not tempered (i.e., water not added).

(Added 2001)

T. Tolerances

T.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied to 

errors of underregistration and errors of overregistration.

T.2. Tolerances.

T.2.1. Air Oven Reference Method. – Maintenance and acceptance tolerances shall be as shown in 

Table T.2.1. Acceptance and Maintenance Tolerances Air Oven Reference Method. Tolerances are expressed as 

a fraction of the percent moisture content of the official grain sample, together with a minimum tolerance.

(Amended 2001)

Table T.2.1. 

Acceptance and Maintenance Tolerances Air Oven Reference Method

Type of Grain, Class, or Seed Tolerance Minimum Tolerance

Corn, oats, rice, sorghum, 

sunflower

0.05 of the percent

moisture content

0.8 %

in moisture content

All other cereal grains and oil 

seeds

0.04 of the percent

moisture content

0.7 %

in moisture content

(Amended 2001)

T.2.2. Meter to Like-Type Meter Method. – Maintenance and acceptance tolerances shall be as shown in 

Table T.2.2. Acceptance and Maintenance Tolerances Meter to Like-Type Meter Method. The tolerances shall 

apply to all types of grain and seed.

(Added 2001)

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Table T.2.2. 

Acceptance and Maintenance Tolerances Meter to Like-Type Meter Method

Sample Reference Moisture Tolerance

Up to 22 % 0.5 %

in moisture content

(Added 2001)

T.3. For Test Weight Per Bushel Indications or Recorded Representations. – The maintenance and acceptance 

tolerances on test weight per bushel indications or recorded representations shall be as shown in Table T.3. Acceptance 

and Maintenance Tolerances Test Weight per Bushel. Tolerances are (+) positive or (−) negative with respect to the 

value assigned to the official grain sample.

(Amended 1992 and 2003)

Table T.3.

Acceptance and Maintenance Tolerances Test Weight per Bushel

Type of Grain 

or Seed

Tolerance

(Pounds Per Bushel)

Corn, oats 0.8

All wheat classes 0.5

Soybeans, all barley classes, all rice 

classes, sunflower, sorghum 0.7

(Added 2003)

UR. User Requirements

UR.1. Selection Requirements.

UR.1.1. Value of the Smallest Unit on Primary Indicating and Recording Elements. – The resolution of 

the moisture meter display shall be 0.1 % moisture and 0.1 pounds per bushel test weight during commercial use.

(Amended 2003)

UR.1.2. See G-UR.1.2. Environment.

UR.2. Installation Requirements. – The grain moisture meter shall be installed in an environment within the range 

of temperature and/or other environmental factors specified in the operating instructions.

UR.3. Use Requirements.

UR.3.1. Operating Instructions. – The operating instructions for the use of the grain moisture meter shall be 

readily available to the user, service technician, and weights and measures official at the place of installation. It 

shall include a list of accessory equipment and the kinds of grain or seed to be measured with the moisture meter.

(Amended 1988)

UR.3.2. Other Devices Not Used for Commercial Measurement. – If there are other moisture meters on the 

premises not used for trade or determining other charges for services, these devices shall be clearly and 

conspicuously marked “Not for Use in Trade or Commerce.”

UR.3.3. Maintaining Integrity of Grain Samples. – Whenever there is a time lapse (temperature change) 

between taking the sample and testing the sample, means to prevent condensation of moisture or loss of moisture 

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from grain samples shall be used. For example, a cold grain sample may be kept in a closed container in order to 

permit the cold grain to come to the operating temperature range of the meter before the grain moisture 

measurements are made.

UR.3.4. Printed Tickets.

(a) Printed tickets shall be free from any previous indication of moisture content or type of grain or seed 

selected.

(b) The customer shall be given a printed ticket at the time of the transaction or as otherwise specified by 

the customer. The printed ticket shall include the date, grain type, grain moisture results, test weight per 

bushel, and calibration version identification. The ticket information shall be generated by the grain 

moisture meter system.

(Amended 1993, 1995, 2003, and 2013) 

UR.3.5. Accessory Devices. – Accessory devices, if necessary in the determination of a moisture content value, 

shall be in close proximity to the moisture meter and allow immediate use.

UR.3.6. Sampling. – A grain sample shall be obtained by following appropriate sampling methods and 

equipment. These include, but are not limited to grain probes of appropriate length used at random locations in 

the bulk, the use of a pelican sampler, or other techniques and equipment giving equivalent results. The grain 

sample shall be taken such that it is representative of the lot.

UR.3.7. Location. – Also see G-UR.3.3. Position of Equipment.

UR.3.8. Level Condition. – If equipped with a level indicator, a meter shall be maintained in a level condition.

(Added 1988)

UR.3.9. Current Calibration Data. – Grain moisture determinations shall be made using only the most 

recently published calibration data.

(Added 1988)

UR.3.10. Posting of Meter Operating Range. – The operating range of the grain moisture meter shall be clearly 

and conspicuously posted in the place of business such that the information is readily visible from a reasonable 

customer position. The posted information shall include the following:

(a) The temperature range over which the meter may be used and still comply with the applicable 

requirements. If the temperature range varies for different grains or seed, the range shall be specified 

for each.

(b) The moisture range for each grain or seed for which the meter is to be used.

(c) The temperature range for each grain or seed for which the meter is to be used.

(d) The maximum allowable difference in temperature that may exist between the meter and the sample for 

which an accurate moisture determination can be made.

(Added 1988)

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Table of Contents

Section 5.56.(b) Grain Moisture Meters ................................................................................. 5-57

A. Application .................................................................................................................................................. 5-57

A.1. General................................................................................................................................................5-57

A.2. Exceptions...........................................................................................................................................5-57

A.3. Additional Code Requirements...........................................................................................................5-57

S. Specifications............................................................................................................................................... 5-57

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................5-57

S.1.1. Primary Elements, General. ................................................................................................5-57

S.1.2. Digital Indications...............................................................................................................5-57

S.1.3. Graduations. ........................................................................................................................5-57

S.1.4. Indicators.............................................................................................................................5-58

S.1.5. Recording Elements. ...........................................................................................................5-58

S.1.6. Design of Direct Reading Grain Moisture Meters. .............................................................5-58

S.1.7. Electric Power Supply.........................................................................................................5-59

S.1.8. Level Indicating Means. ......................................................................................................5-59

S.1.9. Operating Temperature.......................................................................................................5-59

S.2. Design of Measuring Elements...........................................................................................................5-60

S.2.1. Design of Zero-Setting and Test Point Mechanisms. ..........................................................5-60

S.2.2. Provision for Sealing...........................................................................................................5-60

S.3. Accessory Equipment. ........................................................................................................................5-60

S.3.1. Grain-Test Scale..................................................................................................................5-60

S.3.2. Thermometers or Other Temperature Sensing Equipment..................................................5-60

S.3.3. Conversion and Correction Tables......................................................................................5-60

S.3.4. Operating Instructions and Use Limitations........................................................................5-61

N. Notes............................................................................................................................................................. 5-61

N.1. Testing Procedures..............................................................................................................................5-61

N.1.1. Transfer Standards. .............................................................................................................5-61

N.1.2. Minimum Test.....................................................................................................................5-61

N.1.3. Temperature Measuring Equipment....................................................................................5-61

T. Tolerances......................................................................................................................................................... 5-61

T.1. To Underregistration and to Overregistration. ....................................................................................5-61

T.2. Tolerance Values. ...............................................................................................................................5-61

T.3. For Test Weight Per Bushel Devices. .................................................................................................5-61

T.4. Thermometers or Other Temperature Sensing Equipment..................................................................5-62

UR. User Requirements ..................................................................................................................................... 5-62

UR.1. Selection Requirements. .....................................................................................................................5-62

UR.1.1. Value of the Smallest Unit on Primary Indicating and Recording Elements. .....................5-62

UR.1.2. Environment........................................................................................................................5-62

UR.2. Installation Requirements. ..................................................................................................................5-62

UR.3. Use Requirements. ..............................................................................................................................5-62

UR.3.1. Operating Instructions.........................................................................................................5-62

UR.3.2. Other Devices not used for Commercial Measurement.......................................................5-62

UR.3.3. Maintaining Integrity of Grain Samples..............................................................................5-62

UR.3.4. Printed Tickets. ...................................................................................................................5-62

UR.3.5. Accessory Devices. .............................................................................................................5-62

UR.3.6. Sampling. ............................................................................................................................5-62

UR.3.7. Location. .............................................................................................................................5-63

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UR.3.8. Level Condition...................................................................................................................5-63

UR.3.9. Operating Limitation...........................................................................................................5-63

UR.3.10. Current Calibration Chart or Data.......................................................................................5-63

UR.3.11. Posting of Meter Operating Range......................................................................................5-63

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Section 5.56.(b) Grain Moisture Meters

Section 5.56. was reorganized into two sections beginning with the 1997 Edition of NIST Handbook 44. This 

Section, 5.56.(b), applies to all non-NTEP grain moisture meters manufactured or placed into service before 

January 1, 1998.

(Code reorganized and renumbered 1996) 

A. Application

A.1. General. – This code applies to grain moisture meters; that is, devices used to indicate directly or through 

conversion and/or correction tables the moisture content of cereal grain and oil seeds. The code consists of general 

requirements applicable to all moisture meters and specific requirements applicable only to certain types of moisture 

meters.

A.2. Exceptions. – This code does not apply to devices used for in-motion measurement of grain moisture content 

or seed moisture content.

A.3. Additional Code Requirements. – In addition to the requirements of this code, 5.56.(b) Grain Moisture Meters 

shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements, General. – A meter shall be equipped with a primary indicating element and may 

also be equipped with a primary recording element. If the meter indicates directly and/or is equipped to record, 

the meter shall indicate and/or record its measurements in terms of percent moisture content, wet basis. 

Subdivisions of this unit shall be in terms of decimal subdivisions (not fractions). If the meter indicates in the 

conventional scale and requires conversion or correction tables, the resulting values after use of such tables shall 

be in terms of percent moisture content, wet basis. Subdivisions of this unit shall be in terms of decimal 

subdivisions (not fractions).

S.1.2. Digital Indications.

S.1.2.1. Measurement Completion. – A digital indicating element shall not display any values (either 

moisture content or conventional scale) before the end of the measurement cycle.

S.1.3. Graduations.

S.1.3.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.3.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations, and the width of the main graduations shall be 

not more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less 

than 0.2 mm (0.008 in) in width.

S.1.3.3. Clear Interval between Graduations. – The clear interval shall be not less than 0.75 mm 

(0.03 in) between graduations. If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

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S.1.4. Indicators.

S.1.4.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.4.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end of 

the indicator and the ends of the graduations, measured along the line of the graduations, shall be not more 

than 1.0 mm (0.04 in).

S.1.4.3. Width. – The width of the index of an indicator in relation to the series of graduations with which 

it is used shall be not greater than:

(a) the width of the widest graduation; nor

(b) the width of the minimum clear interval between graduations.

When the index of an indicator extends along the entire length of a graduation, that portion of the index of 

the indicator that may be brought into coincidence with the graduation shall be of the same width as the 

graduation throughout the length of the index that coincides with the graduation.

S.1.4.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case 

be more than 1.5 mm (0.06 in).

S.1.4.5. Parallax. – Parallax effects shall be reduced to the practicable minimum.

S.1.5. Recording Elements.

S.1.5.1. General. – If a meter is equipped with a recording element, it shall record in terms of percent 

moisture content, wet basis only, and not in terms of conventional scale.

S.1.5.2. Measurement Completion. – A recording element shall not record any values before the end of 

the measurement cycle.

S.1.5.3. Range of Moisture Content. – A recording element shall not record any values when the 

moisture content of the grain sample is beyond the operating range of the device.

S.1.6. Design of Direct Reading Grain Moisture Meters.

S.1.6.1. Grain or Seed Kind and Class Selection and Recording. – Provision shall be made for selecting 

and recording, if equipped to record, the kind and class (as appropriate) of grain or seed to be measured. The 

means to select the kind and class of grain or seed shall be readily visible and the kind and class of grain or 

seed selected shall be clearly and definitely identified in letters (such as Wheat or WHT, HRWW, etc.).

S.1.6.2. Operating Range. – A meter shall automatically and clearly indicate when the operating range 

of the meter has been exceeded or the manufacturer shall:

(a) clearly and conspicuously mark the operating ranges on the meter; or

(b) furnish the operating ranges of the meter and the means to clearly and conspicuously display this 

information on or immediately adjacent to the device.

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The operating range shall specify the following:

(a) the temperature range over which the meter may be used and still comply with the applicable 

requirements;

(b) the moisture range for each grain or seed for which the meter is to be used;

(c) the temperature range for each grain or seed for which the meter is to be used; and

(d) the maximum allowable difference in temperature between the meter and the sample for which an 

accurate moisture determination can be made.

Examples of clearly indicating these conditions include an error indication, flashing the displayed moisture 

value, or blanking the display.

[Nonretroactive as of January 1, 1989]

(Amended 1986 and 1988)

S.1.6.3. Value of Smallest Unit. – The value of the minimum indicated or recorded moisture indication 

shall not be greater than 0.1 %.

S.1.7. Electric Power Supply.

S.1.7.1. Power Supply, Voltage and Frequency.

(a) A meter that operates using alternating current must perform within the tolerances defined in 

Section T.2. Tolerance Values over the line voltage range 100 V to 130 V, or 200 V to 250 V rms as 

designed, and over the frequency range of 59.5 Hz to 60.5 Hz.

(b) Battery-operated instruments shall not indicate or record values outside the applicable tolerance 

limits when battery power output is excessive or deficient.

[Nonretroactive as of January 1, 1989]

S.1.7.2. Power Interruption. – A power interruption shall not cause an indicating or recording element 

to display or record any values outside the applicable tolerance limits.

[Nonretroactive as of January 1, 1989]

(Added 1988)

S.1.8. Level Indicating Means. – A meter shall be equipped with a level indicator and leveling adjustments if 

its performance is changed by an amount greater than the applicable tolerance when the meter is moved from a 

level position to a position that is out of level in any upright direction by up to 5 % (approximately 3 degrees).

The level-indicating means shall be readable without removing any meter parts requiring a tool.

[Nonretroactive as of January 1, 1989]

(Added 1988) (Amended 1994)

S.1.9. Operating Temperature.

(a) A meter shall not display or record any usable values until the operating temperature necessary for 

accurate determination has been attained, or the meter shall bear a conspicuous statement adjacent to 

the indication stating that the meter shall be turned on for a time period specified by the manufacturer 

prior to use.

(b) A meter shall meet the requirements of T.2. Tolerance Values when operated in the temperature range 

of 2 °C to 40 °C (35 °F to 104 °F) or within the range specified by the meter manufacturer.

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(c) If the manufacturer specifies a temperature range, the range shall be at least 10 °C (20 °F) and shall be 

marked on the device.

[Nonretroactive as of January 1, 1989]

(Added 1988)

S.2. Design of Measuring Elements.

S.2.1. Design of Zero-Setting and Test Point Mechanisms. – If a grain moisture meter is equipped with a 

zero setting and/or test point mechanism(s), this (these) mechanism(s) shall be adjustable only with a tool outside 

and entirely separate from this mechanism or enclosed in a cabinet. This requirement shall not apply to manual 

operations that the operator must make (following operating instructions) in order to obtain a meter reading on a 

grain sample.

S.2.2. Provision for Sealing. – Provision shall be made for applying a security seal in a manner that requires 

the security seal to be broken before an adjustment can be made to any component of the grain moisture meter 

that is set by the manufacturer or authorized service representative and not intended to be adjusted by the user.

S.3. Accessory Equipment. – When the operating instructions for a moisture meter require accessory equipment 

separate from and external to the moisture meter, such equipment shall be appropriate and complete for the 

measurement.

S.3.1. Grain-Test Scale. – If the moisture meter requires the weighing of the grain sample, the weighing device 

shall meet the requirements of the General Code and those applicable portions of the Scales Code.

S.3.2. Thermometers or Other Temperature Sensing Equipment.

(a) The temperature sensing equipment or thermometer shall be designed to be in direct contact with a grain 

sample in a closed container. It is acceptable to insert thermometer through a small hole in the lid of the 

container used to hold the grain sample.

(b) A separate thermometer or other temperature sensing equipment shall have temperature divisions not 

greater than the temperature increments used by the manufacturer in the correction table.

(Amended 1988)

S.3.3. Conversion and Correction Tables. – Conversion and correction tables, charts, graphs, slide rules, or 

other apparatus to convert the conventional scale values read from a moisture meter to moisture content values, 

if such apparatus is required, shall be appropriate and correct for the moisture meter being used and shall be 

marked with the following information:

(a) name and address or trademark of the manufacturer;

(b) the type or design of the device with which it is intended to be used;

(c) date of issue;

(d) the kinds or classes of grain or seed for which the device is designed to measure moisture content;

(e) the limitations of use, including but not confined to the moisture measurement range, grain or seed 

temperature, kind or class of grain or seed, moisture meter temperature, voltage and frequency ranges, 

electromagnetic interferences, and necessary accessory equipment; but

(f) values exceeding any measurement range shall not be included.

(Added 1984)

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S.3.4. Operating Instructions and Use Limitations. – Operating instructions shall be furnished by the 

manufacturer with each device with all of the information required by paragraph S.3.3. Conversion and Correction 

Tables. Complete information concerning the accuracy, sensitivity, and use of accessory equipment (e.g., test 

weight per bushel equipment, thermometer, etc.) necessary in obtaining moisture content shall be included.

N. Notes

N.1. Testing Procedures.

N.1.1. Transfer Standards. – Official grain samples shall be used as the official transfer standards with 

moisture content values assigned by the reference methods. The reference methods shall be the oven drying 

methods as specified by the USDA GIPSA. Tolerances shall be applied to the average of at least three 

measurements on each official grain sample. Official grain samples shall be clean and naturally moist, but not 

tempered (i.e., water not added).

(Amended 1992)

N.1.2. Minimum Test. – A minimum test of a grain moisture meter shall consist of tests with: 

(a) samples (need not exceed three) of each grain or seed for which the device is used; and

(b) samples having at least two different moisture content values within the operating range of the device.

(Amended 1986 and 1989)

N.1.3. Temperature Measuring Equipment. – The accuracy of accessory temperature measuring equipment 

shall be determined by comparison with a calibrated temperature sensor, such as a total immersion thermometer 

with 0.1 °C (0.2 °F) subdivisions, indicating over a range of from 0 °C to 40 °C (32 °F to 104 °F) with a maximum 

error of ± 0.1 °C (0.2 °F). Tests shall be conducted at two temperatures using liquid baths (e.g., ice water and 

room temperature water). The two temperatures selected shall not exceed the range of temperatures identified in 

the moisture meter operating instructions.

(Amended 1988)

T. Tolerances1

T.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied to 

errors of underregistration and errors of overregistration. 

T.2. Tolerance Values. – Maintenance and acceptance tolerances shall be as shown in Table T.2. Acceptance and 

Maintenance Tolerances for Grain Moisture Meters. Tolerances are expressed as a fraction of the percent moisture 

content of the official grain sample, together with a minimum tolerance.

Table T.2. 

Acceptance and Maintenance Tolerances for Grain Moisture Meters

Type of Grain or Seed Tolerance Minimum Tolerance

Corn, oats, rice, sorghum, 

sunflower

0.05 of the percent

moisture content

0.8 %

in moisture content

All other cereal grains

and oil seeds

0.04 of the percent

moisture content

0.7 %

in moisture content

T.3. For Test Weight Per Bushel Devices. – The maintenance and acceptance tolerances on separate test weight 

per bushel devices used to determine the test weight per bushel of grain samples for the purposes of making density 

 

1 These tolerances do not apply to tests in which grain moisture meters are the transfer standards.

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corrections in moisture determination shall be 0.193 kg/hL or 0.15 lb/bu. The test methods used shall be those 

specified by the USDA GIPSA using a dockage-free sample of dry hard red winter wheat.

(Amended 1992 and 2003)

T.4. Thermometers or Other Temperature Sensing Equipment. – The tolerance for a separate thermometer or 

temperature sensing equipment used to determine the temperature of grain samples for the purpose of making 

temperature corrections in moisture determinations shall be ± 0.5 °C (1 °F).

(Added 1988)

UR. User Requirements

UR.1. Selection Requirements.

UR.1.1. Value of the Smallest Unit on Primary Indicating and Recording Elements. – The value of the 

smallest unit on a moisture meter, whether the moisture meter reads directly in terms of moisture content, or when 

the conventional scale unit is converted or corrected to moisture content, shall be equal to or less than 0.1 %.

UR.1.2. Environment. – Equipment shall be suitable for the environment in which it is used including, but 

not limited to, the effects of wind, weather, and RFI.

UR.2. Installation Requirements. – The grain moisture meter shall be installed in an environment within the range 

of temperature and/or other environmental factors specified: 

(a) in the operating manual; and 

(b) on the conversion or correction tables if such tables are necessary for the operation of the device.

UR.3. Use Requirements.

UR.3.1. Operating Instructions. – The operating instructions for the use of the grain moisture meter shall be 

readily available to the user, service technician, and weights and measures official at the place of installation. It 

shall include a list of accessory equipment, conversion and correction charts if any are required to obtain moisture 

content values, and the kinds of grain or seed to be measured with the moisture meter.

(Amended 1988)

UR.3.2. Other Devices not used for Commercial Measurement. – If there are other moisture meters on the 

premises not used for trade or determining other charges for services, these devices shall be clearly and 

conspicuously marked “Not for Use in Trade or Commerce.”

UR.3.3. Maintaining Integrity of Grain Samples. – Whenever there is a time lapse (temperature change) 

between taking the sample and testing the sample, means to prevent condensation of moisture or loss of moisture 

from grain samples shall be used. For example, a cold grain sample may be kept in a closed container in order to 

permit the cold grain to come to the operating temperature range of the meter before the grain moisture 

measurements are made.

UR.3.4. Printed Tickets. – Printed tickets shall be free from any previous indication of moisture content or 

type of grain or seed selected.

UR.3.5. Accessory Devices. – Accessory devices, if necessary in the determination of a moisture content value, 

shall be in close proximity to the moisture meter and allow immediate use.

UR.3.6. Sampling. – A grain sample shall be obtained by following appropriate sampling methods and 

equipment. These include, but are not limited to, grain probes of appropriate length used at random locations in 

the bulk, the use of a pelican sampler, or other techniques and equipment giving equivalent results. The grain 

sample shall be taken such that it is representative of the lot.

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UR.3.7. Location. – See G-UR.3.3. Position of Equipment.

UR.3.8. Level Condition. – If equipped with a level indicator, a meter shall be maintained in a level condition.

(Added 1988)

UR.3.9. Operating Limitation. – Unless otherwise specified by the meter manufacturer, moisture 

determinations shall not be made when the difference in temperatures between the grain sample and the meter 

exceeds 10 °C (20 °F).

(Added 1988)

UR.3.10. Current Calibration Chart or Data. – Grain moisture determinations shall be made using only the 

most recently published calibration charts or calibration data.

(Added 1988)

UR.3.11. Posting of Meter Operating Range. – The operating range of the grain moisture meter shall be clearly 

and conspicuously posted in the place of business such that the information is readily visible from a reasonable 

customer position. The posted information shall include the following:

(a) The temperature range over which the meter may be used and still comply with the applicable 

requirements. If the temperature range varies for different grains or seed, the range shall be specified 

for each.

(b) The moisture range for each grain or seed for which the meter is to be used.

(c) The temperature range for each grain or seed for which the meter is to be used.

(d) The maximum allowable difference in temperature that may exist between the meter and the sample for 

which an accurate moisture determination can be made.

(Added 1988)

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Table of Contents

Section 5.57. Near-Infrared Grain Analyzers ................................................................... 5-67

A. Application .................................................................................................................................................. 5-67

A.1. General................................................................................................................................................5-67

A.2. Exceptions...........................................................................................................................................5-67

A.3. Calibrations.........................................................................................................................................5-67

A.4. Additional Code Requirements...........................................................................................................5-67

S. Specifications............................................................................................................................................... 5-67

S.1. Design of Indicating, Recording, and Measuring Elements................................................................5-67

S.1.1. Digital Indications and Recording Elements. .......................................................................5-67

S.1.2. Selecting and Recording Grain Class and Constituent.........................................................5-68

S.1.3. Operating Range...................................................................................................................5-69

S.1.4. Operating Temperature. .......................................................................................................5-70

S.1.5. Value of Smallest Unit. .........................................................................................................5-70

S.2. Design of NIR Analyzers....................................................................................................................5-70

S.2.1. Minimum Sample Size...........................................................................................................5-70

S.2.2. Electric Power Supply...........................................................................................................5-70

S.2.3. Level Indicating Means.........................................................................................................5-70

S.2.4. Environmental Conditions. ...................................................................................................5-70

S.2.5. Calibration Transfer and Verification. ..................................................................................5-70

S.2.6. Provision for Sealing. ...........................................................................................................5-71

S.3. Accessory Equipment..........................................................................................................................5-71

S.3.1. Grinders. ..................................................................................................................................5-71

S.4. Operating Instructions and Use Limitations.......................................................................................5-71

N. Notes............................................................................................................................................................. 5-72

N.1. Testing Procedures..............................................................................................................................5-72

N.1.1. Field Inspection.....................................................................................................................5-72

N.1.2. Standard Reference Samples.................................................................................................5-72

T. Tolerances.................................................................................................................................................... 5-73

T.1. To Underregistration and to Overregistration. ....................................................................................5-73

T.2. Tolerance Values. ...............................................................................................................................5-73

UR. User Requirements ..................................................................................................................................... 5-73

UR.1. Installation Requirements. ..................................................................................................................5-73

UR.2. User Requirements..............................................................................................................................5-73

UR.2.1. Operating Instructions...........................................................................................................5-73

UR.2.2. Other Devices Not Used for Commercial Measurement.......................................................5-73

UR.2.3. Printed Tickets. .....................................................................................................................5-74

UR.2.4. Grinders. ...............................................................................................................................5-74

UR.2.5. Sampling. ..............................................................................................................................5-74

UR.2.6. Level Condition. ...................................................................................................................5-74

UR.2.7. Operating Limitation.............................................................................................................5-74

UR.2.8. Slope and Bias Adjustments. ................................................................................................5-74

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Section 5.57. Near-Infrared Grain Analyzers

A. Application

A.1. General. – This code applies to near-infrared (NIR) grain analyzers; that is, devices used to indicate the 

constituent values (other than moisture content) of grain using near-infrared reflectance or transmittance technology. 

These instruments may analyze either whole grain or ground grain samples. The code consists of general requirements 

applicable to all NIR analyzers and specific requirements applicable only to certain types of NIR analyzers, grain 

types, or grain constituents. In addition to meeting the requirements of this code, a whole grain NIR analyzer that 

displays a measured moisture value must also comply with the requirements of the Grain Moisture Meters Code.

(Added 2001)

A.2. Exceptions. – This code does not apply to devices used for in-motion measurement of grain constituent values.

A.3. Calibrations. – The National Type Evaluation Program (NTEP) Certificate of Conformance (CC) shall indicate 

the native moisture basis of each calibration. The “native” moisture basis is the default moisture basis of the sealable

constituent calibration (or constituent calibration pair when a non-displayed moisture calibration is also involved). If an 

NIR analyzer uses a self-generated moisture measurement internally but does NOT display or record a moisture value, 

the moisture calibration shall be considered to be a part of the constituent calibration. For such calibrations, the CC shall 

state: “Includes non-displayed moisture calibration.” Changes to any part of such calibrations shall require changes to 

the CC.

(Added 2001)

A.4. Additional Code Requirements. – In addition to the requirements of this code, Near-Infrared Grain Analyzers 

shall meet the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating, Recording, and Measuring Elements.

S.1.1. Digital Indications and Recording Elements.

(a) Analyzers shall be equipped with a digital indicating element.

(b) The minimum height for the digits used to display constituent values shall be 10 mm.

(c) Analyzers shall be equipped with a communication interface that permits interfacing with a recording 

element and transmitting the date, grain type or class, constituent values, the moisture basis for each 

constituent value (except moisture), and calibration version identification. If the analyzer converts 

constituent results to a manually entered moisture basis, the “native” concentration and the “native” 

moisture basis must appear on the printed ticket in addition to the converted results and the manually

entered moisture basis.

(Amended 2001 and 2003)

(d) A digital indicating element shall not display, and a recording element shall not record, any constituent 

value before the end of the measurement cycle.

(e) Constituent content shall be recorded and displayed as percent of total mass at the specified moisture 

basis. The moisture basis shall also be recorded and displayed for each constituent content result 

(except moisture). If a whole grain analyzer that is calibrated to display results on an “as is” moisture 

basis does NOT display or record a moisture value, it must clearly indicate that results are expressed 

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on an “as is” moisture basis. Ground grain analyzers must ALWAYS display and record a moisture 

measurement for “as is” content results (except moisture).

(Amended 2001 and 2003)

(f) An analyzer shall not display or record any constituent value that is beyond the operating range of the 

device unless the constituent value representation includes a clear error indication (and recorded error 

message with the recorded representation).

(g) If an NIR analyzer is used to determine a moisture value, either to determine the moisture of an “as is” 

constituent content measurement or to convert from one moisture basis to another, the moisture 

measurement must be concurrent with the measurement of other constituents.

(h) If the analyzer incorporates a built-in printer, or if a printer is available as an accessory to the analyzer, 

the information appearing on the printout shall be arranged in a consistent and unambiguous manner.

(Added 2003)

[Nonretroactive as of January 1, 2003]

(Added 2001)

S.1.2. Selecting and Recording Grain Class and Constituent. – Provision shall be made for selecting and 

recording the type or class or multi-class group of grain and the constituent(s) to be measured. The means to select 

the grain type or class or multi-class group and the constituent(s) shall be readily visible and the type or class or 

multi-class group of grain and the constituent(s) selected shall be clearly and definitely identified in letters (such as 

HRWW, HRSW, WHEAT, etc., or PROT, etc.). A symbol to identify the display of the type or class or multi-class 

group of grain and constituent(s) selected is permitted provided that it is clearly defined adjacent to the display. 

Minimum acceptable abbreviations are listed in Table S.1.2. Grain Types and Multi-Class Groups Considered for 

Type Evaluation and Calibration and Their Minimum Acceptable Abbreviations.

[Nonretroactive as of January 1, 2003]

If more than one calibration is included for a given grain type, the calibrations must be clearly distinguished 

from one another.

[Nonretroactive as of January 1, 2004]

(Amended 2003 and 2007)

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Table S.1.2. 

Grain Types and Multi-Class Groups Considered for Type Evaluation and 

Calibration and Their Minimum Acceptable Abbreviations

Grain Type Grain Class Minimum Acceptable 

Abbreviation

Barley

Two-Rowed Barley TRB

Six-Rowed Barley SRB

All-Class Barley* BARLEY

Corn --- CORN

Soybeans --- SOYB

Wheat

All-Class Wheat* WHEAT

Durum Wheat DURW

Hard Red Spring Wheat HRSW

Hard Red Winter Wheat HRWW

Hard White Wheat HDWW

Soft Red Winter Wheat SRWW

Soft White Wheat SWW

Wheat Excluding Durum* WHTEXDUR

[Note: Grain Types marked with an asterisk (*) are “Multi-Class Calibrations”]

[Nonretroactive as of January 1, 2003]

(Table Amended 2001 and 2007)

S.1.3. Operating Range. – An analyzer shall automatically and clearly indicate when the operating range of 

the device has been exceeded. The statement of the operating range shall be specified in the operator’s manual 

and shall operate as follows:

(a) The ambient temperature range over which the analyzer may be used and still comply with the applicable 

requirements shall be specified. The minimum temperature range shall be 10 °C to 30 °C. No 

constituent value may be displayed when the temperature range is exceeded. An appropriate error 

message shall be displayed when the temperature of the analyzer is outside its specified operating range.

(b) The constituent range at the moisture basis specified in Table N.1.1. Constant Moisture Basis for Type 

Evaluation and Field Inspections shall be specified for each grain or seed for which the analyzer is to 

be used. A constituent value may be displayed when the constituent range is exceeded if accompanied 

by a clear indication that the constituent range has been exceeded.

(Amended 2001)

(c) For whole grain analyzers only, the temperature range shall be specified for each grain or seed for 

which an analyzer is to be used. The minimum temperature range for each grain shall be 10 °C to 30 °C. 

No constituent value may be displayed when the temperature range is exceeded. An appropriate error 

message shall be displayed when the temperature of the grain sample exceeds the temperature range for 

the grain. The requirements of this subsection (c) are not applicable to ground grain analyzers.

(d) For whole grain analyzers, the maximum allowable difference in temperature between the instrument 

environment (ambient temperature) and the sample for which an accurate constituent determination can 

be made shall be specified. The minimum temperature range shall cover at least 10 °C. No constituent 

value may be displayed when the maximum allowable temperature difference is exceeded. An 

appropriate error message shall be displayed when the difference between the ambient temperature and 

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the sample temperature exceeds the specified difference. The requirements of this subsection (d) are not 

applicable to ground grain analyzers.

[Nonretroactive and effective as of January 1, 2003]

S.1.4. Operating Temperature.

(a) An analyzer shall not display or record any usable values until the internal operating temperature 

necessary to meet tolerance requirements has been attained, or the analyzer shall bear a conspicuous 

statement adjacent to the indication stating that the analyzer shall be turned on for a time period 

specified by the manufacturer prior to use.

(b) If an instrument does not meet tolerance requirements because there is an upper internal operating 

temperature limit that could be exceeded when operating within the ambient temperature range specified 

by the manufacturer, then a means of sensing and indicating an over-temperature condition must be 

provided.

[Nonretroactive as of January 1, 2003]

S.1.5. Value of Smallest Unit. – The display shall permit constituent value determination to both 0.01 % and 

0.1 % resolution. The 0.1 % resolution is for commercial transactions; the 0.01 % resolution is for calibration 

purposes only, not for commercial purposes.

[Nonretroactive as of January 1, 2003]

S.2. Design of NIR Analyzers.

S.2.1. Minimum Sample Size. – Analyzers shall be designed to measure constituent values of representative 

size grain samples. The minimum allowable sample size used in analysis shall be 20 g.

[Nonretroactive as of January 1, 2003]

S.2.2. Electric Power Supply.

S.2.2.1. Power Supply, Voltage and Frequency. – An analyzer that operates using alternating current 

must perform within tolerance requirements over the line voltage range 100 V to 130 V and over the 

frequency range of 59.5 Hz to 60.5 Hz.

[Nonretroactive as of January 1, 2003]

S.2.2.2. Power Interruption. – A power interruption shall not cause an indicating or recording element 

to display or record any values outside the applicable tolerance limits.

[Nonretroactive as of January 1, 2003]

S.2.3. Level Indicating Means. – Analyzers shall be equipped with a level indicator and leveling adjustments 

if its performance is changed by an amount greater than the tolerance requirement when the instrument is moved 

from a level position into a position that is out of level in any upright direction by up to 5 % (approximately three 

degrees). The level-indicating means shall be readable without removing any instrument parts requiring a tool.

[Nonretroactive as of January 1, 2003]

S.2.4. Environmental Conditions. – Instrument optics and electronics must be protected from exposure to dust 

by either sealing these areas or by protecting them with a dust filtration system suitable for the removal of 

air-borne grain dust.

[Nonretroactive as of January 1, 2003]

S.2.5. Calibration Transfer and Verification.

S.2.5.1. Calibration Transfer. – The instrument hardware/software design and calibration procedures 

shall permit calibration development and the mathematical transfer of calibrations between instruments of 

like models.

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Note: Only the manufacturer or the manufacturer’s designated service agency may make calibration transfer 

or slope adjustments on near-infrared grain analyzers and, except for instrument failure and repair, only 

during a prescribed period of time during the year. This does not preclude the possibility of the operator 

installing the manufacturer-specified calibration constants or standardization parameters under the 

instructions of the manufacturer or the manufacturer’s designated service agency. Nor does it preclude 

operator bias adjustments when made under the conditions specified in UR.2.8. Slope and Bias Adjustments.

[Nonretroactive and effective as of January 1, 2003]

(Note added 1995) (Amended 1995)

S.2.5.2. Calibration Version. – An instrument must be capable of displaying either calibration constants, 

a unique calibration name, or a unique calibration version number for use in verifying that the latest version 

of the calibration is being used to make constituent determinations, and that the appropriate instrument 

settings have been made for the calibration being used.

[Nonretroactive as of January 1, 2003]

(Amended 2001)

S.2.5.3. Calibration Corruption. – If calibration constants are digitally stored in an electronically 

alterable form, the analyzer shall be designed to make automatic checks to detect corruption of calibration 

constants. An error message must be displayed if calibration constants have been electronically altered.

[Nonretroactive as of January 1, 2003].

S.2.6. Provision for Sealing. – An event logger is required in the device; it must include an event counter 

(000 to 999), the parameter ID, the date and time of the change, and the new value of the parameter (for 

calibration changes consisting of multiple constants, the calibration version number may be used rather than the 

calibration constants.)

A printed copy of the information must be available through the device or through another on-site device. The 

event logger shall have a capacity to retain records equal to 25 times the number of sealable parameters in the 

device, but not more than 1000 records are required. (Note: Does not require 1000 changes to be stored for 

each parameter.)

[Nonretroactive as of January 1, 2003]

(Amended 1997)

S.3. Accessory Equipment. – When the operating instructions for an NIR analyzer require accessory equipment 

separate from and external to the analyzer, such equipment shall be appropriate and complete for the measurement.

[Nonretroactive as of January 1, 2003]

S.3.1. Grinders. – The make and model of grinder used for ground grain NIR analyzers must be specified by the 

manufacturer and required as auxiliary equipment in the determination of constituent values for applicable grain 

types.

[Nonretroactive as of January 1, 2003]

S.4. Operating Instructions and Use Limitations. – The manufacturer shall furnish operating instructions for the 

device and accessories that include complete information concerning the accuracy, sensitivity, and use of accessory 

equipment necessary in obtaining a constituent value. Operating instructions shall include the following information:

(a) name and address or trademark of the manufacturer;

(b) the type or design of the device for which the operating instructions are intended to be used;

(c) date of issue;

(d) the kind or classes of grain or seed for which the device is designed to measure constituent values; and

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(e) the limitations of use, including but not limited to constituent range, grain or seed temperature, kind or class 

of grain or seed, instrument temperature, voltage and frequency ranges, electromagnetic interferences, and 

necessary accessory equipment.

[Nonretroactive as of January 1, 2003]

N. Notes

N.1. Testing Procedures.

N.1.1. Field Inspection. – Whole grain samples shall be used as the official field inspection standards. Five 

samples per grain type or class shall be used to check instrument performance. Each sample will be analyzed 

once. One of the samples will be analyzed an additional four times to test instrument repeatability. For ground 

grain instruments, the ground sample will be repacked four times. A new grind is not required. Test results must 

be converted to the standard moisture bases shown in Table N.1.1. Constant Moisture Basis for Type Evaluation 

and Field Inspection before applying the tolerances of Table T.2. Acceptance and Maintenance Tolerances for 

NIR Grain Analyzers. Test results on whole grain analyzers that produce results on an “as is” basis without 

displaying or recording a moisture value shall be converted to the standard moisture bases shown in Table N.1.1. 

Constant Moisture Basis for Type Evaluation and Field Inspection using sample moisture values determined with 

the facility’s moisture meter (which must be certified for commercial use).

(Amended 2001)

Table N.1.1.

Constant Moisture Basis for Type Evaluation and Field Inspection

Grain Type or Class Constituents(s) Moisture Basis

Durum Wheat, Hard Red Spring 

Wheat, Hard Red Winter Wheat, Hard 

White Wheat, Soft Red Winter Wheat, 

Soft White Wheat

Protein 12 %

Soybeans Protein

Oil 13 %

Two-rowed Barley

Six-rowed Barley Protein 0 % (dry basis)

Corn

Protein

Oil

Starch

0 % (dry basis)

[Nonretroactive as of January 1, 2003]

(Table Added 2001)

Constituent values shall be assigned to test samples by the Grain Inspection, Packers and Stockyards Administration 

(GIPSA). Tolerances shall be applied to individual sample measurements, the average of individual measurements 

on each of the five test samples, and the maximum difference (range) in results for five analyses on one of the test 

samples.

(Amended 2001)

N.1.2. Standard Reference Samples. – Reference samples used for field inspection purposes shall be clean 

and selected to reasonably represent the constituent range. These samples shall be selected such that the difference 

between constituent values obtained using the GIPSA standard reference method and an official GIPSA NIR grain 

analyzer does not exceed one-half of the acceptance tolerance shown in Table T.2. Acceptance and Maintenance 

Tolerances for NIR Grain Analyzers for individual test samples or 0.375 times the acceptance tolerance shown 

for the average of five samples.

(Amended 2001and 2003)

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T. Tolerances

T.1. To Underregistration and to Overregistration. – The tolerances hereinafter prescribed shall be applied to 

errors of underregistration and errors of overregistration and shall be based on constituent values expressed at the 

moisture bases shown in Table N.1.1. Constant Moisture Basis for Type Evaluation and Field Inspection.

(Amended 2001)

T.2. Tolerance Values. – Acceptance and maintenance tolerances shall be equal. Tolerances for individual samples 

and the average for five samples are as shown in Table T.2. Acceptance and Maintenance Tolerances for NIR Grain 

Analyzers.

Table T.2.

Acceptance and Maintenance Tolerances for NIR Grain Analyzers

Type or Class of 

Grain Constituent

Individual 

Samples (percent)

Average for Five 

Samples (percent)

Range for Five 

Retests (percent)

Durum Wheat, Hard 

Red Spring Wheat, 

Hard Red Winter 

Wheat, Hard White 

Wheat, Soft Red 

Winter Wheat, Soft 

White Wheat

protein 0.60 0.40 0.40

Soybeans protein 0.80 0.60 0.60

oil 0.70 0.50 0.50

Two-rowed Barley

Six-rowed Barley protein 0.70 0.50 0.50

Corn

protein 0.80 0.60 0.60

oil 0.70 0.50 0.50

starch 1.00 0.80 0.80

(Amended 2001)

UR. User Requirements

UR.1. Installation Requirements. – The NIR analyzer shall be installed in an environment within the range of 

temperature and/or other environmental factors specified in the operating manual.

UR.2. User Requirements.

UR.2.1. Operating Instructions. – The operating instructions for the NIR analyzer shall be readily available 

to the user, service technician, and weights and measures official at the place of installation. It shall include a list 

of accessory equipment if any are required to obtain constituent values, and the type or class of grain to be 

measured with the NIR analyzer. If an NIR analyzer has the capability, the user is permitted to select the moisture 

basis to be used on any measurement.

(Amended 2001)

UR.2.2. Other Devices Not Used for Commercial Measurement. – If there are other NIR analyzers on the 

premises not used for trade or determining other charges for services, these devices shall be clearly and 

conspicuously marked “Not for Use in Trade or Commerce.”

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UR.2.3. Printed Tickets.

(a) Printed tickets shall be free from any previous indication of constituent or grain type selected. The 

printed ticket shall indicate constituent values and the moisture basis associated with each constituent 

value (except moisture). If the analyzer is calibrated to display results on an “as is” moisture basis and 

does NOT display or record a moisture value, the ticket must clearly indicate that results are expressed 

on an “as is” moisture basis.

(Amended 2001)

(b) The customer shall be given a printed ticket showing the date, grain type or class, constituent results, 

and calibration version identification. If the analyzer converts constituent results to a manually entered 

moisture basis, the “native” concentration and the “native” moisture basis must appear on the printed 

ticket in addition to the converted results and the manually entered moisture basis. If the manually 

entered moisture basis is intended to be the moisture value for an “as is” constituent concentration 

measurement, that moisture value must have been obtained on the same sample and must have been 

measured on a moisture meter certified for commercial use. The information presented on the ticket 

shall be arranged in a consistent and unambiguous manner. The ticket shall be generated by the 

near-infrared grain analyzer system.

[Nonretroactive as of January 1, 2003]

(Amended 2001)

UR.2.4. Grinders. – Place grinders in a separate room from the NIR analyzer to avoid instrument 

contamination. If a separate room is not available, the grinder may be in the same room with the NIR analyzer 

provided the grinder is not placed within one meter of the air intake on the NIR.

UR.2.5. Sampling. – Samples shall be obtained by following appropriate sampling methods and equipment. 

These include, but are not limited to grain probes of appropriate length used at random locations in the bulk, the 

use of a pelican sampler, or other techniques and equipment giving equivalent results. The sample shall be taken 

such that it is representative of the lot. If an NIR analyzer permits user entry of the moisture value for an “as is” 

constituent measurement, that moisture value must have been obtained on the same sample and must have been 

measured on a moisture meter certified for commercial use.

(Amended 2001)

UR.2.6. Level Condition. – If equipped with a level indicator, an analyzer shall be maintained in a level 

condition.

UR.2.7. Operating Limitation. – Constituent determinations shall not be made when the difference in 

temperatures between the grain sample and the instrument environment (ambient temperature) exceeds 

manufacturer recommendations.

UR.2.8. Slope and Bias Adjustments. – Bias changes shall be made only on the basis of tests run on a current 

set of Standard Reference Samples (SRS) traceable to GIPSA Master Instruments.1

 A written explanation and 

record of all calibration changes, including those changes made by a manufacturer or the manufacturer’s 

designated service agency, shall be maintained. The log shall indicate the date and magnitude of changes in bias 

and slope constants and the instrument serial number. A Calibration Adjustment Data Sheet for each log entry 

shall be available for inspection upon request by the field inspector. Data Sheets shall be retained by the user for 

a period of no less than 18 months following any calibration adjustment. The Data Sheet must show: date of test 

and adjustment, serial number of the instrument, calibration identification, the nature of the adjustment, the unique 

identification number and source of sample sets used, and, for each sample in the set, reference values, initial 

instrument results (except in the cases of instrument failure and repair), and instrument results after calibration 

adjustment or instrument repair.

(Amended 1995)

 

1 Established error must be known.

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Table of Contents

Section 5.58. Multiple Dimension Measuring Devices ..................................................... 5-77

A. Application .................................................................................................................................................. 5-77

A.1. General................................................................................................................................................5-77

A.2. Other Devices Designed to Make Multiple Measurement Automatically to Determine a Volume. ...5-77

A.3. Additional Code Requirements...........................................................................................................5-77

A.4. Exceptions...........................................................................................................................................5-77

A.5. Type Evaluation..................................................................................................................................5-77

S. Specifications............................................................................................................................................... 5-77

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................5-77

S.1.1. Zero or Ready Indication. .....................................................................................................5-77

S.1.2. Digital Indications.................................................................................................................5-77

S.1.3. Negative Values....................................................................................................................5-78

S.1.4. Dimensions Indication. .........................................................................................................5-78

S.1.5. Value of Dimension/Volume Division Units........................................................................5-78

S.1.6. Customer Indications and Recorded Representations...........................................................5-78

S.1.7. Minimum Lengths.................................................................................................................5-79

S.1.8. Indications Below Minimum and Above Maximum.............................................................5-79

S.1.9. Operating Temperature. ........................................................................................................5-80

S.1.10. Adjustable Components. .......................................................................................................5-80

S.1.11. Provision for Sealing.............................................................................................................5-80

S.2. Design of Zero and Tare. ....................................................................................................................5-80

S.2.1. Zero or Ready Adjustment....................................................................................................5-80

S.2.2. Tare.......................................................................................................................................5-81

S.3. Systems with Two or More Measuring Elements. ..............................................................................5-81

S.4. Marking Requirements........................................................................................................................5-81

S.4.1. Multiple Dimension Measuring Devices, Main Elements, and Components of Measuring 

Devices. ................................................................................................................................5-81

S.4.2. Location of Marking Information. ........................................................................................5-82

N. Notes............................................................................................................................................................. 5-82

N.1. Test Procedures...................................................................................................................................5-82

N.1.1. General..................................................................................................................................5-82

N.1.2. Position Test. ........................................................................................................................5-82

N.1.3. Disturbance Tests, Field Evaluation. ....................................................................................5-82

N.1.4. Test Object Size....................................................................................................................5-82

N.1.5. Digital Zero Stability. ...........................................................................................................5-83

T. Tolerances.................................................................................................................................................... 5-83

T.1. Design. ................................................................................................................................................5-83

T.2. Tolerance Application.........................................................................................................................5-83

T.2.1. Type Evaluation....................................................................................................................5-83

T.2.2. Subsequent Verification........................................................................................................5-83

T.2.3. Multi-interval (Variable Division-Value) Devices. ..............................................................5-83

T.3. Tolerance Values. ...............................................................................................................................5-83

T.4. Position Tests......................................................................................................................................5-83

T.5. Influence Factors.................................................................................................................................5-83

T.5.1. Temperature..........................................................................................................................5-83

T.5.2. Power Supply Voltage. .........................................................................................................5-84

T.6. Disturbances, Field Evaluation. ..........................................................................................................5-84

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UR. User Requirements ..................................................................................................................................... 5-84

UR.1. Selection Requirements. .....................................................................................................................5-84

UR.1.1. Value of the Indicated and Recorded Division. ....................................................................5-84

UR.2. Installation Requirements. ..................................................................................................................5-84

UR.2.1. Supports. ...............................................................................................................................5-84

UR.2.2. Foundation, Supports, and Clearance....................................................................................5-84

UR.2.3. Protection from Environmental Factors................................................................................5-84

UR.3. Use Requirements. ..............................................................................................................................5-85

UR.3.1. Minimum and Maximum Measuring Ranges. ......................................................................5-85

UR.3.2. Special Designs.....................................................................................................................5-85

UR.3.3. Object Placement. .................................................................................................................5-85

UR.4. Maintenance Requirements.................................................................................................................5-85

UR.4.1. Zero or Ready Condition. .....................................................................................................5-85

UR.4.2. Level Condition. ...................................................................................................................5-85

UR.4.3. Device Modification. ............................................................................................................5-85

UR.5. Customer Information Provided..........................................................................................................5-85

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Section 5.58. Multiple Dimension Measuring Devices

A. Application

A.1. General. – This code applies to dimension and volume measuring devices used for determining the dimensions 

and/or volume of objects for the purpose of calculating freight, storage, or postal charges based on the dimensions 

and/or volume occupied by the object. A multiple dimension measuring device:

(a) is generally used to measure hexahedron-shaped objects; and

(Added 2008)

(b) may be used to measure irregularly-shaped objects.

(Added 2008)

(Amended 2008)

A.2. Other Devices Designed to Make Multiple Measurement Automatically to Determine a Volume. – Insofar 

as they are clearly applicable, the provisions of this code apply also to devices designed to make multiple 

measurements automatically to determine a volume for other applications as defined by Section 1.10. General Code 

paragraph G-A.1. Commercial and Law-Enforcement Equipment.

A.3. Additional Code Requirements. – In addition to the requirements of this code, Multiple Dimension Measuring 

Devices shall meet the requirements of Section 1.10. General Code.

A.4. Exceptions. – This code does not apply to:

(a) devices designed to indicate automatically (with or without value-computing capabilities) the length of fabric 

passed through the measuring elements (also see Section 5.50. for Fabric-Measuring Devices); 

(b) devices designed to indicate automatically the length of cordage, rope, wire, cable, or similar flexible material 

passed through the measuring elements (also see Section 5.51. for Wire- and Cordage-Measuring Devices); 

or

(c) any linear measure, measure of length, or devices used to measure individual dimensions for the purpose of 

assessing a charge per unit of measurement of the individual dimension (also see Section 5.52. for Linear 

Measures).

A.5. Type Evaluation. – The National Type Evaluation Program (NTEP) will accept for type evaluation only those 

devices that comply with all requirements of this code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Zero or Ready Indication.

(a) Provision shall be made to indicate or record either a zero or ready condition.

(b) A zero or ready condition may be indicated by other than a continuous digital zero indication, provided 

that an effective automatic means is provided to inhibit a measuring operation when the device is in an

out-of-zero or non-ready condition.

S.1.2. Digital Indications. – Indicated and recorded values shall be presented digitally.

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S.1.3. Negative Values. – Except when in the tare mode, negative values shall not be indicated or recorded.

S.1.4. Dimensions Indication. – If in normal operation the device indicates or records only volume, a testing 

mode shall be provided to indicate dimensions for all objects measured.

S.1.5. Value of Dimension/Volume Division Units. – The value of a device division “d” expressed in a unit 

of dimension shall be presented in a decimal format with the value of the division expressed as:

(a) 1, 2, or 5; 

(b) a decimal multiple or submultiple of 1, 2, or 5; or

(c) a binary submultiple of a specific U.S. customary unit of measure.

Examples: device divisions may be 0.01, 0.02, 0.05; 0.1, 0.2, or 0.5; 1, 2, or 5; 10, 20, 50, or 100; 0.5, 0.25, 

0.125, 0.0625, etc.

S.1.5.1. For Indirect Sales. – In addition to the values specified in S.1.5. Value of Dimension/Volume 

Division Units, the value of the division may be 0.3 inch and 0.4 inch.

S.1.5.2. Devices Capable of Measuring Irregularly-Shaped Objects. – For devices capable of 

measuring irregularly shaped objects, the value of the division size (d) shall be the same for the length axis (x) 

and the width axis (y) and may be different for the height axis (z), provided that electronic rotation of the 

object to determine the smallest hexahedron is calculated in only a two-dimension horizontal plane, retaining 

the stable side plane as the bottom of the hexahedron. 

(Added 2008)

S.1.6. Customer Indications and Recorded Representations. – Multiple dimension measuring devices or 

systems must provide information as specified in Table S.1.6. Required Information to be Provided by Multiple 

Dimension Measuring Systems. As a minimum, all devices or systems must be able to meet either column I or 

column II in Table S.1.6. Required Information to be Provided by Multiple Dimension Measuring Systems.

(Amended 2004)

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Table S.1.6. 

Required Information to be Provided by Multiple Dimension Measuring Systems

Information

Column I1 Column II1 Column III

Provided by 

device

Provided by invoice or 

other means

Provided by 

invoice or other 

means as 

specified in 

contractual 

agreement 

Customer

present

Customer 

not present

1. Device identification2 D or P P P P or A

2. Error message (when applicable) D or P P N/A N/A

3. Hexahedron dimensions3 D or P P P P or A

4. Hexahedron volume (if used)3 D or P P P P or A

5. Actual weight (if used)3 D or P P P P or A

6. Tare (if used)3 D or P N/A N/A N/A

7. Hexahedron measurement statement4 D or P or M P P P or G

A = AVAILABLE UPON REQUEST BY CUSTOMER5

D = DISPLAYED

G = PUBLISHED GUIDELINES OR CONTRACTS

M = MARKED

N/A = NOT APPLICABLE

P = PRINTED or RECORDED IN A MEMORY DEVICE and AVAILABLE UPON REQUEST BY CUSTOMER5

Notes:

1 As a minimum all devices or systems must be able to meet either column I or column II.

2 This is only required in systems where more than one device or measuring element is being used.

3 Some devices or systems may not utilize all of these values; however as a minimum either hexahedron dimensions 

or hexahedron volume must be displayed or printed.

4 This is an explanation that the dimensions and/or volume shown are those of the smallest hexahedron in which the 

object that was measured may be enclosed rather than those of the object itself.

5 The information “available upon request by customer” shall be retained by the party having issued the invoice for 

at least 30 calendar days after the date of invoicing.

(Amended 2004)

S.1.7. Minimum Lengths. – Except for entries of tare, the minimum length to be measured by a device is 

12 divisions. The manufacturer may specify a longer minimum length.

S.1.8. Indications Below Minimum and Above Maximum. – When objects are smaller than the minimum 

dimensions identified in paragraph S.1.7. Minimum Lengths or larger than any of the maximum dimensions plus 

9 d, and/or maximum volume marked on the device plus 9 d, or when a combination of dimensions for the object 

being measured exceeds the measurement capability of the device, the indicating or recording element shall either:

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(a) not indicate or record any usable values; or

(b) identify the indicated or recorded representation with an error indication.

(Amended 2004)

S.1.9. Operating Temperature. – An indicating or recording element shall not indicate nor record any usable 

values until the operating temperature necessary for accurate measuring and a stable zero reference or ready 

condition has been attained.

S.1.10. Adjustable Components. – Adjustable components shall be held securely in adjustment and, except for 

a zeroing mechanism (when applicable), shall be located within the housing of the element.

S.1.11. Provision for Sealing.

(a) A device shall be designed with provision(s) for applying a security seal that must be broken, or for 

using other approved means of providing security (e.g., data change audit trail available at the time of 

inspection), before any change that detrimentally affects the metrological integrity of the device can be 

made to any measuring element.

(b) Audit trails shall use the format set forth in Table S.1.11. Categories of Devices and Methods of Sealing 

for Multiple Dimension Measuring Systems.

Table S.1.11.

Categories of Devices and Methods of Sealing for Multiple Dimension Measuring Systems

Categories of Devices Methods of Sealing

Category 1: No remote configuration. Seal by physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 2: Remote configuration capability, but 

access is controlled by physical hardware.

Device shall clearly indicate that it is in the remote 

configuration mode and record such message if 

capable of printing in this mode.

The hardware enabling access for remote 

communication must be at the device and sealed using 

a physical seal or two event counters: one for

calibration parameters and one for configuration 

parameters.

Category 3: Remote configuration capability 

access may be unlimited or controlled through a 

software switch (e.g., password).

An event logger is required in the device; it must 

include an event counter (000 to 999), the parameter 

ID, the date and time of the change, and the new value 

of the parameter. A printed copy of the information 

must be available through the device or through another 

on-site device. The event logger shall have a capacity 

to retain records equal to 10 times the number of 

sealable parameters in the device, but not more than 

1000 records are required. (Note: Does not require 

1000 changes to be stored for each parameter.)

S.2. Design of Zero and Tare.

S.2.1. Zero or Ready Adjustment. – A device shall be equipped with means by which the zero reference or 

ready condition can be adjusted, or the zero reference or ready condition shall be automatically maintained. The 

zero reference or ready control circuits shall be interlocked so that their use is prohibited during measurement 

operations.

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S.2.2. Tare. – The tare function shall operate only in a backward direction (that is, in a direction of underregistration) with respect to the zero reference or ready condition of the device. The value of the tare division or 

increment shall be equal to the division of its respective axis on the device. There shall be a clear indication that 

tare has been taken.

S.3. Systems with Two or More Measuring Elements. – A multiple dimension measuring system with a single 

indicating or recording element, or a combination indicating-recording element, that is coupled to two or more 

measuring elements with independent measuring systems, shall be provided with means to prohibit the activation of 

any measuring element (or elements) not in use, and shall be provided with automatic means to indicate clearly and 

definitely which measuring element is in use.

Note: This requirement does not apply to individual devices that use multiple emitters/sensors within a device in combination to 

measure objects in the same measurement field.

(Amended 2004)

S.4. Marking Requirements. (Also see G-S.1. Identification, G-S.4. Interchange or Reversal of Parts, 

G-S.5.2.5. Permanence, G-S.6. Marking Operational Controls, Indications, and Features, G-S.7. Lettering, 

G-UR.2.1.1. Visibility of Identification, and G-UR.3.1. Method of Operation.)

S.4.1. Multiple Dimension Measuring Devices, Main Elements, and Components of Measuring 

Devices. – Multiple dimension measuring devices, main elements of multiple dimension measuring devices when 

not contained in a single enclosure for the entire dimension/volume measuring device, and other components shall 

be marked as specified in Table S.4.1.a. and explained in the accompanying notes, Table S.4.1.b. Multiple 

Dimension Measuring Systems Notes for Table S.4.1.a.

Table S.4.1.a.

Marking Requirements for Multiple Dimension Measuring Systems

To Be Marked With 

Multiple Dimension Measuring Equipment

Multiple 

Dimension 

Measuring Device 

and Indicating 

Element in Same 

Housing

Indicating 

Element not 

Permanently 

Attached to 

Multiple 

Dimension 

Measuring 

Element

Multiple 

Dimension 

Measuring 

Element not 

Permanently 

Attached to the 

Indicating 

Element

Other 

Equipment

(1)

Manufacturer’s ID x x x x

Model Designation x x x x

Serial Number and Prefix x x x x (2)

Certificate of Conformance Number (8) x x x x (8)

Minimum and Maximum Dimensions 

for Each Axis (3) x x x 

Value of Measuring Division, d

(for each axis and range) x x x 

Temperature Limits (4) x x x

Minimum & Maximum speed (5) x x x

Special Application (6) x x x

Limitation of Use (7) x x x

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Table S.4.1.b.

Multiple Dimension Measuring Systems Notes for Table S.4.1.a.

1. Necessary to the dimension and/or volume measuring system, but having no effect on the measuring value, 

e.g., auxiliary remote display, keyboard, etc.

2. Modules without “intelligence” on a modular system (e.g., printer, keyboard module, etc.) are not required to have 

serial numbers.

3. The minimum and maximum dimensions (using upper or lower case type) shall be marked. For example:

 Length: min _______ max _______

 Width: min _______ max _______

 Height: min _______ max _______

4. Required if the range is other than − 10 °C to 40 °C (14 °F to 104 °F).

5. Multiple dimension measuring devices, which require that the object or device be moved relative to one another, 

shall be marked with the minimum and maximum speeds at which the device is capable of making measurements 

that are within the applicable tolerances.

6. A device designed for a special application rather than general use shall be conspicuously marked with suitable 

words visible to the operator and the customer restricting its use to that application.

7. Materials, shapes, structures, combination of object dimensions, speed, spacing, minimum protrusion size, or object 

orientations that are inappropriate for the device or those that are appropriate.

8. Required only if a Certificate of Conformance has been issued for the equipment.

(Amended 2004 and 2008)

S.4.2. Location of Marking Information. – The required marking information shall be so located that it is 

readily observable without the necessity of the disassembly of a part requiring the use of any means separate from 

the device.

N. Notes

N.1.Test Procedures.

N.1.1. General. – The device shall be tested using test standards and objects of known and stable dimensions.

N.1.2. Position Test. – Measurements are made using different positions of the test object and consistent with 

the manufacturer’s specified use for the device.

N.1.2.1. Irregularly-Shaped Test Object Placement. – Irregularly-shaped test objects must be measured 

while placed on a stable side. The rotation of the object to determine the smallest hexahedron should be 

calculated in a two-dimensional plane, retaining the stable side plane as the bottom of the hexahedron. 

(Added 2008)

N.1.3. Disturbance Tests, Field Evaluation. – A disturbance test shall be conducted at a given installation 

when the presence of disturbances specified in T.6. has been verified and characterized if those conditions are 

considered “usual and customary.”

N.1.4. Test Object Size. – Test objects may vary in size from the smallest dimension to the largest dimension 

marked on the device, and for field verification examinations, shall be an integer multiple of “d.”

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N.1.4.1. Test Objects. – Verification of devices may be conducted using appropriate test objects of various 

sizes and of stable dimensions. Test object dimensions must be known to an expanded uncertainty (coverage 

factor k = 2) of not more than one-third of the applicable device tolerance. The dimensions shall also be 

checked to the same uncertainty when used at the extreme values of the influence factors.

The dimension of all test objects shall be verified using a reference standard that is traceable to NIST (or 

equivalent national laboratory) and meet the tolerances expressed in NIST Handbook 44 Fundamental 

Considerations, paragraph 3.2. (i.e., one-third of the smallest tolerance applied to the device).

(Added 2004)

N.1.4.2. Irregularly-Shaped Test Objects. – For irregularly-shaped test objects, at least one angle shall 

be obtuse and the smallest dimension for an axis shall be equal to or greater than the minimum dimension for 

that axis.

(Added 2008)

 (Amended 2008 and 2012)

N.1.5. Digital Zero Stability. – A zero indication change test shall be conducted on all devices which show a 

digital zero. After the removal of any test object, the zero indication shall not change. (Also see 

G-UR.4.2. Abnormal Performance.)

T. Tolerances

T.1. Design. – The tolerance for a multiple dimension measuring device is a performance requirement independent 

of the design principle used.

T.2. Tolerance Application.

T.2.1. Type Evaluation. – For type evaluations, the tolerance values apply to tests within the influence factor 

limits of temperature and power supply voltage specified in T.5.1. Temperature and T.5.2. Power Supply Voltage.

T.2.2. Subsequent Verification. – For subsequent verifications, the tolerance values apply regardless of the 

influence factors in effect at the time of the verification. (Also see G-N.2. Testing with Nonassociated 

Equipment.)

T.2.3. Multi-interval (Variable Division-Value) Devices. – For multi-interval devices, the tolerance values 

are based on the value of the device division of the range in use.

T.3. Tolerance Values. – The maintenance and acceptance tolerance values shall be ± 1 division. 

(Amended 2004)

T.4. Position Tests. – For a test standard measured several times in different positions by the device all indications 

shall be within applicable tolerances.

T.5. Influence Factors. – The following factors are applicable to tests conducted under controlled conditions only.

T.5.1. Temperature. – Devices shall satisfy the tolerance requirements under the following temperature 

conditions.

T.5.1.1. Temperature Limits. – If not marked on the device, the temperature limits shall be − 10 °C to 

40 °C (14 °F to 104 °F).

T.5.1.2. Minimum Temperature Range. – If temperature limits are specified for the device, the range 

shall be at least 30 °C or 54 °F.

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T.5.1.3. Temperature Effect on Zero Indication. – The zero indication shall not vary by more than one 

division per 5 °C (9 °F) change in temperature.

T.5.2. Power Supply Voltage.

T.5.2.1. Alternating Current Power Supply. – Devices that operate using alternating current must 

perform within the conditions defined in paragraphs T.3. through T.6., inclusive, from − 15 % to + 10 % of 

the marked nominal line voltage(s) at 60 Hz, or the voltage range marked by the manufacturer, at 60 Hz.

(Added 2004)

T.5.2.2. Direct Current Power Supply. – Devices that operate using direct current shall operate and 

perform within the applicable tolerance at any voltage level at which the device is capable of displaying 

metrological registrations. 

(Added 2004)

(Amended 2004)

T.6. Disturbances, Field Evaluation. – The following requirements apply to devices when subjected to 

disturbances which may normally exist in the surrounding environment. These disturbances include radio frequency 

interference (RFI), electromagnetic interference (EMI), acoustic changes, ambient light emissions, etc. The difference 

between the measurement indication with the disturbance and the measurement indication without the disturbance 

shall not exceed one division “d” or the equipment shall:

(a) blank the indication; 

(b) provide an error message; or

(c) the indication shall be so completely unstable that it could not be interpreted, or transmitted into memory or 

to a recording element, as a correct measurement value.

UR. User Requirements

UR.1. Selection Requirements. – Equipment shall be suitable for the service in which it is used with respect to 

elements of its design, including but not limited to, its maximum capacity, value of the division, minimum capacity, 

and computing capability.

UR.1.1. Value of the Indicated and Recorded Division. – The value of the division recorded shall be the 

same as the division value indicated.

UR.2. Installation Requirements.

UR.2.1. Supports. – A device that is portable and is being used on a counter, table, or the floor shall be so 

positioned that it is firmly and securely supported.

UR.2.2. Foundation, Supports, and Clearance. – The foundations and support of a device installed in a fixed 

location shall be such as to provide strength, rigidity, and permanence of all components, and clearance shall be 

provided around all live parts to the extent that no contacts may result when the measuring element is empty, nor 

throughout the performance range of the device such that the operation or performance of the device is adversely 

affected.

UR.2.3. Protection from Environmental Factors. – The indicating and measuring elements of a device shall 

be adequately protected from environmental factors such as wind, weather, and RFI that may adversely affect the 

operation or performance of the device.

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UR.3. Use Requirements.

UR.3.1. Minimum and Maximum Measuring Ranges. – A device shall not be used to measure objects 

smaller than the minimum or larger than the maximum dimensions marked on the device.

UR.3.2. Special Designs. – A multiple dimension measuring device designed and marked for a special 

application shall not be used for other than its intended purpose.

UR.3.3. Object Placement. – If the object being measured must be transported (e.g., shipped) on a stable side, 

that irregularly-shaped object must be measured while placed on that stable side. The electronic rotation of the 

object to determine the smallest hexahedron shall be calculated in a two-dimensional horizontal plane, retaining 

the stable side plane as the bottom of the hexahedron. 

(Added 2008)

(Amended 2008)

UR.4. Maintenance Requirements.

UR.4.1. Zero or Ready Condition. – The zero-setting adjustment of a multiple dimension measuring device 

shall be maintained so that, with no object in or on the measuring element, the device shall indicate or record a 

zero or ready condition.

UR.4.2. Level Condition. – If a multiple dimension measuring device is equipped with a level-condition 

indicator, the device shall be maintained in a level condition.

UR.4.3. Device Modification. – The measuring capabilities of a device shall not be changed from the 

manufacturer’s design unless the modification has been approved by the manufacturer and the weights and 

measures authority having jurisdiction over the device.

UR.5. Customer Information Provided. – The user of a multiple dimension measuring device or system shall 

provide transaction information to the customer as specified in Table UR.5. Customer Information Provided.

(Added 2004)

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Table UR.5. 

Customer Information Provided

Information

No Contractual Agreement

Contractual 

Customer Agreement

Present

Customer not Present

1. Object identification N/A P P or A

2. Billing method (scale or dimensional weight if 

used)

D or P P P or A

3. Billing rate or rate chart D or P or A P or G or A P or A 

4. Dimensional weight (if used) P P P or A

5. Conversion factor (if dimensional weight is used) D or P or A P P or G

6. Dimensional weight statement1 (if dimensional 

weight is used)

D or P P P or G

7. Total price P P P or A

A = Available upon Request by Customer2

D = Displayed

G = Published Guidelines or Contracts

M = Marked

N/A = Not Applicable

P = Printed

Notes:

1 This is an explanation that the dimensional weight is not a true weight but is a calculated value obtained by applying 

a conversion factor to the hexahedron dimensions or volume of the object.

2 The information “available upon request by customer” shall be retained by the party having issued the invoice for at 

least 30 calendar days after the date of invoicing.

(Added 2004)

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Table of Contents

Section 5.59. Electronic Livestock, Meat, and Poultry Evaluation Systems and/or 

Devices ............................................................................................................ 5-89

A. Application .................................................................................................................................................. 5-89

A.1. General................................................................................................................................................5-89

A.2. Additional Code Requirements...........................................................................................................5-89

A.3. Exceptions...........................................................................................................................................5-89

S. Specifications............................................................................................................................................... 5-89

S.1. Design and Manufacture. ....................................................................................................................5-89

N. Notes............................................................................................................................................................. 5-89

N.1. Method of Test....................................................................................................................................5-89

N.2. Testing Standards................................................................................................................................5-89

N.3. Verification. ........................................................................................................................................5-89

N.3.1. Official Tests.........................................................................................................................5-89

T. Tolerances.................................................................................................................................................... 5-90

T.1. Tolerances on Individual Measurements. ...........................................................................................5-90

UR. User Requirements ..................................................................................................................................... 5-90

UR.1. Installation Requirements. ..................................................................................................................5-90

UR.1.1. Installation. ...........................................................................................................................5-90

UR.2. Maintenance of Equipment. ................................................................................................................5-90

UR.2.1. Maintenance..........................................................................................................................5-90

UR.3. Use Requirements. ..............................................................................................................................5-90

UR.3.1. Limitation of Use. .................................................................................................................5-90

UR.4. Testing Standards................................................................................................................................5-90

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Section 5.59. Electronic Livestock, Meat, and Poultry Evaluation Systems 

and/or Devices

The status of Section 5.59. Electronic Livestock, Meat, and Poultry Evaluation Systems and/or Devices was changed

from “tentative” to “permanent” effective January 1, 2013. 

(Added 2005) (Amended 2012)

A. Application

A.1. General. – This code applies to electronic devices or systems for measuring the composition or quality 

constituents of live animals, livestock and poultry carcasses, and individual cuts of meat or a combination thereof for 

the purpose of determining value.

A.2. Additional Code Requirements. – In addition to the requirements of this code, Electronic Livestock, Meat, 

and Poultry Evaluation Systems shall meet the requirements of Section 1.10. General Code.

A.3. Exceptions. – This code does not apply to scales used to weigh live animals, livestock and poultry carcasses, 

and individual cuts of meat unless the scales are part of an integrated system designed to measure composition or 

quality constituents. Scales used in integrated systems must also meet NIST Handbook 44, Section 2.20. Scale 

requirements.

S. Specifications

S.1. Design and Manufacture. – All design and manufacturing specifications shall comply with American Society 

for Testing Materials (ASTM) International Standard F2342 Standard Specification for Design and Construction of 

Composition or Quality Constituent Measuring Devices or Systems.

N. Notes

N.1. Method of Test. – Performance tests shall be conducted in accordance with ASTM Standard F2343 Test 

Method for Livestock, Meat, and Poultry Evaluation Devices.

N.2. Testing Standards. – ASTM Standard F2343 requires device or system users to maintain accurate reference 

standards that meet the tolerance expressed in NIST Handbook 44 Fundamental Considerations, 

paragraph 3.2. Tolerances for Standards (i.e., one-third of the smallest tolerance applied).

N.3. Verification. – Device or system users are required to verify and document the accuracy of a device or system 

on each production day as specified by ASTM Standard F2341 Standard Practice of User Requirements for Livestock, 

Meat, and Poultry Evaluation Devices or Systems.

N.3.1. Official Tests. – Officials are encouraged to periodically witness the required “in house” verification of 

accuracy. Officials may also conduct official tests using the on-site testing standards or other appropriate 

standards belonging to the jurisdiction with statutory authority over the device or system.

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T. Tolerances

T.1. Tolerances on Individual Measurements. – Maintenance and acceptance tolerances on an individual 

measurement shall be as shown in Table T.1. Tolerances.

Table T.1. 

Tolerances

Individual linear measurement of a single constituent ± 1 mm (0.039 in)

Measurement of area ± 1.6 cm2 (0.25 in2) 

For measurements of other constituents As specified in ASTM Standard F2343

UR. User Requirements

UR.1. Installation Requirements.

UR.1.1. Installation. – All devices and systems shall be installed in accordance with manufacturer’s 

instructions.

UR.2. Maintenance of Equipment.

UR.2.1. Maintenance. – All devices and systems shall be continually maintained in an accurate condition and 

in accordance with the manufacturer’s instructions and ASTM Standard F2341.

UR.3. Use Requirements. 

UR.3.1. Limitation of Use. – All devices and systems shall be used to make measurements in a manner 

specified by the manufacturer.

UR.4. Testing Standards. – The user of a commercial device shall make available to the official with statutory 

authority over the device testing standards that meet the tolerance expressed in Fundamental Considerations, 

paragraph 3.2. Tolerances for Standards (i.e., one-third of the smallest tolerance applied). The accuracy of the testing 

standards shall be verified annually or on a frequency as required by the official with statutory authority and shall be 

traceable to the appropriate SI standard.

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Handbook 44 – 2016 Appendix A – Fundamental Considerations

A-1 

Table of Contents

Appendix A. Fundamental Considerations Associated with the Enforcement of 

Handbook 44 Codes ........................................................................................ A-3

1. Uniformity of Requirements.................................................................................................................... A-3

1.1. National Conference Codes....................................................................................................... A-3

1.2. Form of Promulgation. .............................................................................................................. A-3

2. Tolerances for Commercial Equipment ................................................................................................. A-4

2.1. Acceptance and Maintenance Tolerances.................................................................................. A-4

2.2. Theory of Tolerances................................................................................................................. A-4

2.3. Tolerances and Adjustments...................................................................................................... A-4

3. Testing Apparatus.................................................................................................................................... A-4

3.1. Adequacy................................................................................................................................... A-4

3.2. Tolerances for Standards. .......................................................................................................... A-4

3.3. Accuracy of Standards............................................................................................................... A-5

4. Inspection of Commercial Equipment.................................................................................................... A-5

4.1. Inspection Versus Testing. ........................................................................................................ A-5

4.2. Necessity for Inspection. ........................................................................................................... A-5

4.3. Specification Requirements....................................................................................................... A-5

4.4. General Considerations. ............................................................................................................ A-6

4.5. Misuse of Equipment................................................................................................................. A-6

4.6. Recommendations. .................................................................................................................... A-6

4.7. Accurate and Correct Equipment. ............................................................................................. A-6

5. Correction of Commercial Equipment................................................................................................... A-6

5.1. Adjustable Elements.................................................................................................................. A-6

5.2. When Corrections Should Be Made. ......................................................................................... A-7

5.3. Gauging. .................................................................................................................................... A-7

6. Rejection of Commercial Equipment............................................................................................................... A-7

6.1. Rejection and Condemnation .................................................................................................... A-7

7. Tagging of Equipment.............................................................................................................................. A-8

7.1. Rejected and Condemned.......................................................................................................... A-8

7.2. Nonsealed and Noncommercial................................................................................................. A-8

8. Records of Equipment.............................................................................................................................. A-8

9. Sealing of Equipment............................................................................................................................... A-8

9.1. Types of Seals and Their Locations. ......................................................................................... A-8

9.2. Exceptions. ................................................................................................................................ A-9

10. Rounding Off Numerical Values............................................................................................................. A-9

10.1. Definition. ................................................................................................................................. A-9

10.2. General Rules. ........................................................................................................................... A-9

10.3. Rules for Reading of Indications............................................................................................. A-10

10.4. Rules for Common Fractions................................................................................................... A-10

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A-3 

Appendix A. Fundamental Considerations Associated with the Enforcement 

of Handbook 44 Codes

1. Uniformity of Requirements

1.1. National Conference Codes. – Weights and measures jurisdictions are urged to promulgate and adhere to the 

National Conference codes, to the end that uniform requirements may be in force throughout the country. This action 

is recommended even though a particular jurisdiction does not wholly agree with every detail of the National 

Conference codes. Uniformity of specifications and tolerances is an important factor in the manufacture of 

commercial equipment. Deviations from standard designs to meet the special demands of individual weights and 

measures jurisdictions are expensive, and any increase in costs of manufacture is, of course, passed on to the purchaser 

of equipment. On the other hand, if designs can be standardized by the manufacturer to conform to a single set of 

technical requirements, production costs can be kept down, to the ultimate advantage of the general public. Moreover, 

it seems entirely logical that equipment that is suitable for commercial use in the “specification” states should be 

equally suitable for such use in other states.

Another consideration supporting the recommendation for uniformity of requirements among weights and measures 

jurisdictions is the cumulative and regenerative effect of the widespread enforcement of a single standard of design 

and performance. The enforcement effort in each jurisdiction can then reinforce the enforcement effort in all other 

jurisdictions. More effective regulatory control can be realized with less individual effort under a system of uniform 

requirements than under a system in which even minor deviations from standard practice are introduced by 

independent state action. 

Since the National Conference codes represent the majority opinion of a large and representative group of experienced 

regulatory officials, and since these codes are recognized by equipment manufacturers as their basic guide in the 

design and construction of commercial weighing and measuring equipment, the acceptance and promulgation of these 

codes by each state are strongly recommended.

1.2. Form of Promulgation. – A convenient and very effective form of promulgation already successfully used in 

a considerable number of states is promulgation by citation of National Institute of Standards and Technology 

Handbook 44. It is especially helpful when the citation is so made that, as amendments are adopted from time to time 

by the National Conference on Weights and Measures, these automatically go into effect in the state regulatory 

authority. For example, the following form of promulgation has been used successfully and is recommended for 

consideration:

The specifications, tolerances, and other technical requirements for weighing and measuring devices as 

recommended by the National Conference on Weights and Measures and published in the National Institute of 

Standards and Technology Handbook 44, “Specifications, Tolerances, and Other Technical Requirements for 

Weighing and Measuring Devices,” and supplements thereto or revisions thereof, shall apply to commercial 

weighing and measuring devices in the state.

In some states, it is preferred to base technical requirements upon specific action of the state legislature rather than 

upon an act of promulgation by a state officer. The advantages cited above may be obtained and may yet be surrounded 

by adequate safeguards to insure proper freedom of action by the state enforcing officer if the legislature adopts the 

National Conference requirements by language somewhat as follows:

The specifications, tolerances, and other technical requirements for weighing and measuring devices as 

recommended by the National Conference on Weights and Measures shall be the specifications, tolerances, and 

other technical requirements for weighing and measuring devices of the state except insofar as specifically 

modified, amended, or rejected by a regulation issued by the state (insert title of enforcing officer).

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2. Tolerances for Commercial Equipment

2.1. Acceptance and Maintenance Tolerances. – The official tolerances prescribed by a weights and measures 

jurisdiction for commercial equipment are the limits of inaccuracy officially permissible within that jurisdiction. It is 

recognized that errorless value or performance of mechanical equipment is unattainable. Tolerances are established, 

therefore, to fix the range of inaccuracy within which equipment will be officially approved for commercial use. In 

the case of classes of equipment on which the magnitude of the errors of value or performance may be expected to 

change as a result of use, two sets of tolerances are established: acceptance tolerances and maintenance tolerances.

Acceptance tolerances are applied to new or newly reconditioned or adjusted equipment, and are smaller than (usually 

one-half of) the maintenance tolerances. Maintenance tolerances thus provide an additional range of inaccuracy within 

which equipment will be approved on subsequent tests, permitting a limited amount of deterioration before the 

equipment will be officially rejected for inaccuracy and before reconditioning or adjustment will be required. In 

effect, there is assured a reasonable period of use for equipment after it is placed in service before reconditioning will 

be officially required. The foregoing comments do not apply, of course, when only a single set of tolerance values is 

established, as is the case with equipment such as glass milk bottles and graduates, which maintain their original 

accuracy regardless of use, and measure-containers, which are used only once.

2.2. Theory of Tolerances. – Tolerance values are so fixed that the permissible errors are sufficiently small that 

there is no serious injury to either the buyer or the seller of commodities, yet not so small as to make manufacturing 

or maintenance costs of equipment disproportionately high. Obviously, the manufacturer must know what tolerances 

his equipment is required to meet, so that he can manufacture economically. His equipment must be good enough to 

satisfy commercial needs, but should not be subject to such stringent tolerance values as to make it unreasonably 

costly, complicated, or delicate.

2.3. Tolerances and Adjustments. – Tolerances are primarily accuracy criteria for use by the regulatory official. 

However, when equipment is being adjusted for accuracy, either initially or following repair or official rejection, the 

objective should be to adjust as closely as practicable to zero error. Equipment owners should not take advantage of 

tolerances by deliberately adjusting their equipment to have a value, or to give performance, at or close to the tolerance 

limit. Nor should the repair or service personnel bring equipment merely within tolerance range when it is possible 

to adjust closer to zero error.1

3. Testing Apparatus

3.1. Adequacy.2

 – Tests can be made properly only if, among other things, adequate testing apparatus is available. 

Testing apparatus may be considered adequate only when it is properly designed for its intended use, when it is so 

constructed that it will retain its characteristics for a reasonable period under conditions of normal use, when it is 

available in denominations appropriate for a proper determination of the value or performance of the commercial 

equipment under test, and when it is accurately calibrated.

3.2. Tolerances for Standards. – Except for work of relatively high precision, it is recommended that the accuracy 

of standards used in testing commercial weighing and measuring equipment be established and maintained so that the 

use of corrections is not necessary. When the standard is used without correction, its combined error and uncertainty 

must be less than one-third of the applicable device tolerance.

Device testing is complicated to some degree when corrections to standards are applied. When using a correction for 

a standard, the uncertainty associated with the corrected value must be less than one-third of the applicable device 

 

1 See General Code, Section 1.10.; User Requirement G-UR.4.3. Use of Adjustments.

2 Recommendations regarding the specifications and tolerances for suitable field standards may be obtained from the 

Office of Weights and Measures of the National Institute of Standards and Technology. Standards will meet the 

specifications of the National Institute of Standards and Technology Handbook 105-Series standards (or other 

suitable and designated standards). This section shall not preclude the use of additional field standards and/or 

equipment, as approved by the Director, for uniform evaluation of device performance.

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tolerance. The reason for this requirement is to give the device being tested as nearly as practicable the full benefit of 

its own tolerance.

3.3. Accuracy of Standards. – Prior to the official use of testing apparatus, its accuracy should invariably be 

verified. Field standards should be calibrated as often as circumstances require. By their nature, metal volumetric 

field standards are more susceptible to damage in handling than are standards of some other types. A field standard 

should be calibrated whenever damage is known or suspected to have occurred or significant repairs have been made. 

In addition, field standards, particularly volumetric standards, should be calibrated with sufficient frequency to affirm 

their continued accuracy, so that the official may always be in an unassailable position with respect to the accuracy of 

his testing apparatus. Secondary field standards, such as special fabric testing tapes, should be verified much more 

frequently than such basic standards as steel tapes or volumetric provers to demonstrate their constancy of value or 

performance.

Accurate and dependable results cannot be obtained with faulty or inadequate field standards. If either the service 

person or official is poorly equipped, their results cannot be expected to check consistently. Disagreements can be 

avoided and the servicing of commercial equipment can be expedited and improved if service persons and officials 

give equal attention to the adequacy and maintenance of their testing apparatus.

4. Inspection of Commercial Equipment

4.1. Inspection Versus Testing. – A distinction may be made between the inspection and the testing of commercial 

equipment that should be useful in differentiating between the two principal groups of official requirements; 

i.e., specifications and performance requirements. Although the term inspection is frequently loosely used to include 

everything that the official has to do in connection with commercial equipment, it is useful to limit the scope of that 

term primarily to examinations made to determine compliance with design, maintenance, and user requirements. The 

term testing may then be limited to those operations carried out to determine the accuracy of value or performance of 

the equipment under examination by comparison with the actual physical standards of the official. These two terms 

will be used herein in the limited senses defined.

4.2. Necessity for Inspection. – It is not enough merely to determine that the errors of equipment do not exceed the 

appropriate tolerances. Specification and user requirements are as important as tolerance requirements and should be 

enforced. Inspection is particularly important, and should be carried out with unusual thoroughness whenever the 

official examines a type of equipment not previously encountered.

This is the way the official learns whether or not the design and construction of the device conform to the specification 

requirements. But even a device of a type with which the official is thoroughly familiar and that he has previously 

found to meet specification requirements should not be accepted entirely on faith. Some part may have become 

damaged, or some detail of design may have been changed by the manufacturer, or the owner or operator may have 

removed an essential element or made an objectionable addition. Such conditions may be learned only by inspection. 

Some degree of inspection is therefore an essential part of the official examination of every piece of weighing or 

measuring equipment.

4.3. Specification Requirements. – A thorough knowledge by the official of the specification requirements is a 

prerequisite to competent inspection of equipment. The inexperienced official should have his specifications before 

him when making an inspection, and should check the requirements one by one against the equipment itself. 

Otherwise some important requirement may be overlooked. As experience is gained, the official will become 

progressively less dependent on the handbook, until finally observance of faulty conditions becomes almost automatic 

and the time and effort required to do the inspecting are reduced to a minimum. The printed specifications, however, 

should always be available for reference to refresh the official’s memory or to be displayed to support his decisions, 

and they are an essential item of his kit.

Specification requirements for a particular class of equipment are not all to be found in the separate code for that class. 

The requirements of the General Code apply, in general, to all classes of equipment, and these must always be 

considered in combination with the requirements of the appropriate separate code to arrive at the total of the 

requirements applicable to a piece of commercial equipment.

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4.4. General Considerations. – The simpler the commercial device, the fewer are the specification requirements 

affecting it, and the more easily and quickly can adequate inspection be made. As mechanical complexity increases, 

however, inspection becomes increasingly important and more time consuming, because the opportunities for the 

existence of faulty conditions are multiplied. It is on the relatively complex device, too, that the official must be on 

the alert to discover any modification that may have been made by an operator that might adversely affect the proper 

functioning of the device.

It is essential for the officials to familiarize themselves with the design and operating characteristics of the devices 

that he inspects and tests. Such knowledge can be obtained from the catalogs and advertising literature of device 

manufacturers, from trained service persons and plant engineers, from observation of the operations performed by 

service persons when reconditioning equipment in the field, and from a study of the devices themselves.

Inspection should include any auxiliary equipment and general conditions external to the device that may affect its 

performance characteristics. In order to prolong the life of the equipment and forestall rejection, inspection should 

also include observation of the general maintenance of the device and of the proper functioning of all required 

elements. The official should look for worn or weakened mechanical parts, leaks in volumetric equipment, or elements 

in need of cleaning.

4.5. Misuse of Equipment. – Inspection, coupled with judicious inquiry, will sometimes disclose that equipment 

is being improperly used, either through ignorance of the proper method of operation or because some other method 

is preferred by the operator. Equipment should be operated only in the manner that is obviously indicated by its 

construction or that is indicated by instructions on the equipment, and operation in any other manner should be 

prohibited.

4.6. Recommendations. – A comprehensive knowledge of each installation will enable the official to make 

constructive recommendations to the equipment owner regarding proper maintenance of his weighing and measuring 

devices and the suitability of his equipment for the purposes for which it is being used or for which it is proposed that 

it be used. Such recommendations are always in order and may be very helpful to an owner. The official will, of 

course, carefully avoid partiality toward or against equipment of specific makes, and will confine his recommendations 

to points upon which he is qualified, by knowledge and experience, to make suggestions of practical merit.

4.7. Accurate and Correct Equipment. – Finally, the weights and measures official is reminded that commercial 

equipment may be accurate without being correct. A piece of equipment is accurate when its performance or value 

(that is, its indications, its deliveries, its recorded representations, or its capacity or actual value, etc., as determined

by tests made with suitable standards) conforms to the standard within the applicable tolerances and other performance 

requirements. Equipment that fails so to conform is inaccurate. A piece of equipment is correct when, in addition to 

being accurate, it meets all applicable specification requirements. Equipment that fails to meet any of the requirements 

for correct equipment is incorrect. Only equipment that is correct should be sealed and approved for commercial use.3

5. Correction of Commercial Equipment

5.1. Adjustable Elements. – Many types of weighing and measuring instruments are not susceptible to adjustment 

for accuracy by means of adjustable elements. Linear measures, liquid measures, graduates, measure-containers, milk 

and lubricating-oil bottles, farm milk tanks, dry measures, and some of the more simple types of scales are in this 

category. Other types (for example, taximeters and odometers and some metering devices) may be adjusted in the 

field, but only by changing certain parts such as gears in gear trains.

Some types, of which fabric-measuring devices and cordage-measuring devices are examples, are not intended to be 

adjusted in the field and require reconditioning in shop or factory if inaccurate. Liquid-measuring devices and most 

scales are equipped with adjustable elements, and some vehicle-tank compartments have adjustable indicators. Field 

adjustments may readily be made on such equipment. In the discussion that follows, the principles pointed out and 

the recommendations made apply to adjustments on any commercial equipment, by whatever means accomplished.

 

3 See Section 1.10. General Code and Appendix D. Definitions.

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5.2. When Corrections Should Be Made. – One of the primary duties of a weights and measures official is to 

determine whether equipment is suitable for commercial use. If a device conforms to all legal requirements, the 

official “marks” or “seals” it to indicate approval. If it does not conform to all official requirements, the official is 

required to take action to ensure that the device is corrected within a reasonable period of time. Devices with 

performance errors that could result in serious economic injury to either party in a transaction should be prohibited 

from use immediately and not allowed to be returned to service until necessary corrections have been made. The 

official should consider the most appropriate action, based on all available information and economic factors.

Some officials contend that it is justifiable for the official to make minor corrections and adjustments if there is no 

service agency nearby or if the owner or operator depends on this single device and would be “out of business” if the 

use of the device were prohibited until repairs could be made. Before adjustments are made at the request of the owner 

or the owner’s representative, the official should be confident that the problem is not due to faulty installation or a 

defective part, and that the adjustment will correct the problem. The official should never undertake major repairs, or 

even minor corrections, if services of commercial agencies are readily available. The official should always be 

mindful of conflicts of interest before attempting to perform any services other than normal device examination and 

testing duties.

(Amended 1995)

5.3. Gauging. – In the majority of cases, when the weights and measures official tests commercial equipment, he 

is verifying the accuracy of a value or the accuracy of the performance as previously established either by himself or 

by someone else. There are times, however, when the test of the official is the initial test on the basis of which the 

calibration of the device is first determined or its performance first established. The most common example of such 

gauging is in connection with vehicle tanks the compartments of which are used as measures. Frequently the official 

makes the first determination on the capacities of the compartments of a vehicle tank, and his test results are used to 

determine the proper settings of the compartment indicators for the exact compartment capacities desired. 

Adjustments of the position of an indicator under these circumstances are clearly not the kind of adjustments discussed 

in the preceding paragraph.

6. Rejection of Commercial Equipment 

6.1. Rejection and Condemnation. – The Uniform Weights and Measures Law contains a provision stating that 

the director shall reject and order to be corrected such physical weights and measures or devices found to be incorrect. 

Weights and measures and devices that have been rejected, may be seized if not corrected within a reasonable time or 

if used or disposed of in a manner not specifically authorized. The director shall remove from service and may seize 

weights and measures found to be incorrect that are not capable of being made correct.

These broad powers should be used by the official with discretion. The director should always keep in mind the 

property rights of an equipment owner, and cooperate in working out arrangements whereby an owner can realize at 

least something from equipment that has been rejected. In cases of doubt, the official should initially reject rather 

than condemn outright. Destruction and confiscation of equipment are harsh procedures. Power to seize and destroy 

is necessary for adequate control of extreme situations, but seizure and destruction should be resorted to only when 

clearly justified.

On the other hand, rejection is clearly inappropriate for many items of measuring equipment. This is true for most 

linear measures, many liquid and dry measures, graduates, measure-containers, milk bottles, lubricating-oil bottles, 

and some scales. When such equipment is “incorrect,” it is either impractical or impossible to adjust or repair it, and 

the official has no alternative to outright condemnation. When only a few such items are involved, immediate 

destruction or confiscation is probably the best procedure. If a considerable number of items are involved (as, for 

example, a stock of measures in the hands of a dealer or a large shipment of bottles), return of these to the manufacturer 

for credit or replacement should ordinarily be permitted provided that the official is assured that they will not get into 

commercial use. In rare instances, confiscation and destruction are justified as a method of control when less harsh 

methods have failed.

In the case of incorrect mechanisms such as fabric-measuring devices, taximeters, liquid-measuring devices, and most 

scales, repair of the equipment is usually possible, so rejection is the customary procedure. Seizure may occasionally 

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be justified, but in the large majority of instances this should be unnecessary. Even in the case of worn-out equipment, 

some salvage is usually possible, and this should be permitted under proper controls.

(Amended 1995)

7. Tagging of Equipment 

7.1. Rejected and Condemned. – It will ordinarily be practicable to tag or mark as rejected each item of equipment 

found to be incorrect and considered susceptible of proper reconditioning. However, it can be considered justifiable 

not to mark as rejected incorrect devices capable of meeting acceptable performance requirements if they are to be 

allowed to remain in service for a reasonable time until minor problems are corrected since marks of rejection may 

tend to be misleading about a device’s ability to produce accurate measurements during the correction period. The 

tagging of equipment as condemned, or with a similar label to indicate that it is permanently out of service, is not 

recommended if there is any other way in which the equipment can definitely be put out of service. Equipment that 

cannot successfully be repaired should be dismantled, removed from the premises, or confiscated by the official rather 

than merely being tagged as “condemned.”

(Amended 1995)

7.2. Nonsealed and Noncommercial. – Rejection is not appropriate if measuring equipment cannot be tested by 

the official at the time of his regular visit–for example, when there is no gasoline in the supply tank of a 

gasoline-dispensing device. Some officials affix to such equipment a nonsealed tag stating that the device has not 

been tested and sealed and that it must not be used commercially until it has been officially tested and approved. This 

is recommended whenever considerable time will elapse before the device can be tested.

Where the official finds in the same establishment, equipment that is in commercial use and also equipment suitable 

for commercial use that is not presently in service, but which may be put into service at some future time, he may treat 

the latter equipment in any of the following ways:

(a) Test and approve the same as commercial equipment in use.

(b) Refrain from testing it and remove it from the premises to preclude its use for commercial purposes.

(c) Mark the equipment nonsealed.

Where the official finds commercial equipment and noncommercial equipment installed or used in close proximity, 

he may treat the noncommercial equipment in any of the following ways:

(a) Test and approve the same as commercial equipment.

(b) Physically separate the two groups of equipment so that misuse of the noncommercial equipment will be 

prevented.

(c) Tag it to show that it has not been officially tested and is not to be used commercially.

8. Records of Equipment

8.1. The official will be well advised to keep careful records of equipment that is rejected, so that he may follow up 

to insure that the necessary repairs have been made. As soon as practicable following completion of repairs, the 

equipment should be retested. Complete records should also be kept of equipment that has been tagged as nonsealed 

or noncommercial. Such records may be invaluable should it subsequently become necessary to take disciplinary 

steps because of improper use of such equipment.

9. Sealing of Equipment

9.1. Types of Seals and Their Locations. – Most weights and measures jurisdictions require that all equipment 

officially approved for commercial use (with certain exceptions to be pointed out later) be suitably marked or sealed 

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to show approval. This is done primarily for the benefit of the public to show that such equipment has been officially 

examined and approved. The seal of approval should be as conspicuous as circumstances permit and should be of 

such a character and so applied that it will be reasonably permanent. Uniformity of position of the seal on similar 

types of equipment is also desirable as a further aid to the public.

The official will need more than one form of seal to meet the requirements of different kinds of equipment. Good 

quality, weather-resistant, water-adhesive, or pressure-sensitive seals or decalcomania seals are recommended for 

fabric-measuring devices, liquid-measuring devices, taximeters, and most scales, because of their permanence and 

good appearance. Steel stamps are most suitable for liquid and dry measures, for some types of linear measures, and 

for weights. An etched seal, applied with suitable etching ink, is excellent for steel tapes, and greatly preferable to a 

seal applied with a steel stamp. The only practicable seal for a graduate is one marked with a diamond or carbide 

pencil, or one etched with glass-marking ink. For a vehicle tank, the official may wish to devise a relatively large 

seal, perhaps of metal, with provision for stamping data relative to compartment capacities, the whole to be welded or 

otherwise permanently attached to the shell of the tank. In general, the lead-and-wire seal is not suitable as an approval 

seal.

9.2. Exceptions. – Commercial equipment such as measure-containers, milk bottles, and lubricating-oil bottles are 

not tested individually because of the time element involved. Because manufacturing processes for these items are 

closely controlled, an essentially uniform product is produced by each manufacturer. The official normally tests 

samples of these items prior to their sale within his jurisdiction and subsequently makes spot checks by testing samples 

selected at random from new stocks.

Another exception to the general rule for sealing approved equipment is found in certain very small weights whose 

size precludes satisfactory stamping with a steel die.

10. Rounding Off Numerical Values

10.1. Definition. – To round off or round a numerical value is to change the value of recorded digits to some other 

value considered more desirable for the purpose at hand by dropping or changing certain figures. For example, if a 

computed, observed, or accumulated value is 4738, this can be rounded off to the nearest thousand, hundred, or ten, 

as desired. Such rounded-off values would be, respectively, 5000, 4700, and 4740. Similarly, a value such as 47.382 

can be rounded off to two decimal places, to one decimal place, or to the units place. The rounded-off figures in this 

example would be, respectively, 47.38, 47.4, and 47.

10.2. General Rules. – The general rules for rounding off may be stated briefly as follows:

(a) When the figure next beyond the last figure or place to be retained is less than 5, the figure in the last place 

retained is to be kept unchanged. When rounding off 4738 to the nearest hundred, it is noted that the figure 3 

(next beyond the last figure to be retained) is less than 5. Thus the rounded-off value would be 4700. 

Likewise, 47.382 rounded to two decimal places becomes 47.38.

(b) When the figure next beyond the last figure or place to be retained is greater than 5, the figure in the last 

place retained is to be increased by 1. When rounding off 4738 to the nearest thousand, it is noted that the 

figure 7 (next beyond the last figure to be retained) is greater than 5. Thus the rounded-off value would 

be 5000. Likewise, 47.382 rounded to one decimal place becomes 47.4.

(c) When the figure next beyond the last figure to be retained is 5 followed by any figures other than zero(s), 

treat as in (b) above; that is, the figure in the last place retained is to be increased by 1. When rounding 

off 4501 to the nearest thousand, 1 is added to the thousands figure and the result becomes 5000.

(d) When the figure next beyond the last figure to be retained is 5 and there are no figures, or only zeros, beyond 

this 5, the figure in the last place to be retained is to be left unchanged if it is even (0, 2, 4, 6, or 8) and is to 

be increased by 1 if it is odd (1, 3, 5, 7, or 9). This is the odd and even rule, and may be stated as follows: 

“If odd, then add.” Thus, rounding off to the first decimal place, 47.25 would become 47.2 and 47.15 would 

become 47.2. Also, rounded to the nearest thousand, 4500 would become 4000 and 1500 would 

become 2000.

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It is important to remember that, when there are two or more figures to the right of the place where the last significant 

figure of the final result is to be, the entire series of such figures must be rounded off in one step and not in two or 

more successive rounding steps. [Expressed differently, when two or more such figures are involved, these are not to 

be rounded off individually, but are to be rounded off as a group.] Thus, when rounding off 47.3499 to the first 

decimal place, the result becomes 47.3. In arriving at this result, the figures “499” are treated as a group. Since the 4 

next beyond the last figure to be retained is less than 5, the “499” is dropped (see subparagraph (a) above). It would 

be incorrect to round off these figures successively to the left so that 47.3499 would become 47.350 and then 47.35 

and then 47.4.

10.3. Rules for Reading of Indications. – An important aspect of rounding off values is the application of these 

rules to the reading of indications of an indicator-and-graduated-scale combination (where the majority of the 

indications may be expected to lie somewhere between two graduations) if it is desired to read or record values only 

to the nearest graduation. Consider a vertical graduated scale and an indicator. Obviously, if the indicator is between 

two graduations but is closer to one graduation than it is to the other adjacent graduation, the value of the closer 

graduation is the one to be read or recorded.

In the case where, as nearly as can be determined, the indicator is midway between two graduations, the odd-and-even 

rule is invoked, and the value to be read or recorded is that of the graduation whose value is even. For example, if the 

indicator lies exactly midway between two graduations having values of 471 and 472, respectively, the indication 

should be read or recorded as 472, this being an even value. If midway between graduations having values of 474 

and 475, the even value 474 should be read or recorded. Similarly, if the two graduations involved had values of 470 

and 475, the even value of 470 should be read or recorded.

A special case not covered by the foregoing paragraph is that of a graduated scale in which successive graduations are 

numbered by twos, all graduations thus having even values; for example, 470, 472, 474, etc. When, in this case, an 

indication lies midway between two graduations, the recommended procedure is to depart from the practice of reading 

or recording only to the value of the nearest graduation and to read or record the intermediate odd value. For example, 

an indication midway between 470 and 472 should be read as 471.

10.4. Rules for Common Fractions. – When applying the rounding-off rules to common fractions, the principles 

are to be applied to the numerators of the fractions that have, if necessary, been reduced to a common denominator. 

The principle of “5s” is changed to the one-half principle; that is, add if more than one-half, drop if less than one-half, 

and apply the odd-and even rule if exactly one-half.

For example, a series of values might be 11

/32, 12/32, 13/32, 14/32, 15/32, 16/32, 17/32, 18/32, 19/32. Assume that these values are 

to be rounded off to the nearest eighth (4

/32). Then, 

11

/32 becomes 1. (1/32 is less than half of 4/32 and accordingly is dropped.)

12

/32 becomes 1. (2/32 is exactly one-half of 4/32; it is dropped because it is rounded (down) to the “even” eighth, 

which in this instance is 0

/8.)

13

/32 becomes 14/32 or 11/8. (3/32 is more than half of 4/32, and accordingly is rounded “up” to 4/32 or 1/8).

14

/32 remains unchanged, being an exact eighth (11/8).

15

/32 becomes 14/32 or 11/8. (5/32 is 1/32 more than an exact 1/8; 1/32 is less than half of 4/32 and accordingly is dropped.)

16

/32 becomes 12/8 or 11⁄4. (6/32 is 2/32 more than an exact 1/8; 2/32 is exactly one-half of 4/32, and the final fraction is 

rounded (up) to the “even” eighth, which in this instance is 2

/8.)

17

/32 becomes 12/8 or 11⁄4. (7/32 is 3/32 more than an exact 1/8; 3/32 is more than one-half of 4/32 and accordingly the final 

fraction is rounded (up) to 2

/8 or 1⁄4.)

18

/32 remains unchanged, being an exact eighth (12/8 or 11⁄4.)

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19

/32 becomes 12/8 or 11⁄4. (9/32 is 1/32 more than an exact 1/8; 1/32 is less than half of 4/32 and accordingly is dropped.)

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Handbook 44 – 2016 Appendix B – Units and Systems of Measurement

B-1 

Table of Contents

Appendix B. Units and Systems of Measurement Their Origin, Development, and 

Present Status ...................................................................................................B-3

1. Introduction .................................................................................................................................................. B-3

2. Units and Systems of Measurement ............................................................................................................ B-3

2.1. Origin and Early History of Units and Standards. .............................................................................. B-3

2.1.1. General Survey of Early History of Measurement Systems. ................................................ B-3

2.1.2. Origin and Development of Some Common Customary Units. ........................................... B-4

2.2. The Metric System.............................................................................................................................. B-5

2.2.1. Definition, Origin, and Development. .................................................................................. B-5

2.2.2. International System of Units............................................................................................... B-6

2.2.3. Units and Standards of the Metric System. .......................................................................... B-6

2.2.4. International Bureau of Weights and Measures.................................................................... B-7

2.2.5. Status of the Metric System in the United States.................................................................. B-7

2.3. British and United States Systems of Measurement. .......................................................................... B-8

2.4. Subdivision of Units. .......................................................................................................................... B-9

2.5. Arithmetical Systems of Numbers...................................................................................................... B-9

3. Standards of Length, Mass, and Capacity or Volume............................................................................... B-9

3.1. Standards of Length............................................................................................................................ B-9

3.1.1. Calibration of Length Standards......................................................................................... B-10

3.2. Standards of Mass............................................................................................................................. B-10

3.2.1. Mass and Weight. ............................................................................................................... B-10

3.2.2. Effect of Air Buoyancy. ..................................................................................................... B-11

3.2.3. Calibrations of Standards of Mass...................................................................................... B-11

3.3. Standards of Capacity. ...................................................................................................................... B-11

3.3.1. Calibrations of Standards of Capacity. ............................................................................... B-11

3.4. Maintenance and Preservation of Fundamental Standard of Mass. .................................................. B-11

4. Specialized Use of the Terms “Ton” and “Tonnage” .............................................................................. B-11

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Appendix B. Units and Systems of Measurement Their Origin, 

Development, and Present Status

1. Introduction

The National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards) was 

established by Act of Congress in 1901 to serve as a national scientific laboratory in the physical sciences, and to 

provide fundamental measurement standards for science and industry. In carrying out these related functions the 

Institute conducts research and development in many fields of physics, mathematics, chemistry, and engineering. At 

the time of its founding, the Institute had custody of two primary standards – the meter bar for length and the kilogram 

cylinder for mass. With the phenomenal growth of science and technology over the past century, the Institute has 

become a major research institution concerned not only with everyday weights and measures, but also with hundreds 

of other scientific and engineering standards that are necessary to the industrial progress of the nation. Nevertheless, 

the country still looks to NIST for information on the units of measurement, particularly their definitions and 

equivalents.

The subject of measurement systems and units can be treated from several different standpoints. Scientists and 

engineers are interested in the methods by which precision measurements are made. State weights and measures 

officials are concerned with laws and regulations that assure equity in the marketplace, protect public health and safety, 

and with methods for verifying commercial weighing and measuring devices. But a vastly larger group of people is 

interested in some general knowledge of the origin and development of measurement systems, of the present status of 

units and standards, and of miscellaneous facts that will be useful in everyday life. This material has been prepared 

to supply that information on measurement systems and units that experience has shown to be the common subject of 

inquiry. 

2. Units and Systems of Measurement

The expression “weights and measures” is often used to refer to measurements of length, mass, and capacity or volume, 

thus excluding such quantities as electrical and time measurements and thermometry. This section on units and 

measurement systems presents some fundamental information to clarify the concepts of this subject and to eliminate 

erroneous and misleading use of terms.

It is essential that the distinction between the terms “units” and “standards” be established and kept in mind.

A unit is a special quantity in terms of which other quantities are expressed. In general, a unit is fixed by definition 

and is independent of such physical conditions as temperature. Examples: the meter, the liter, the gram, the yard, the 

pound, the gallon.

A standard is a physical realization or representation of a unit. In general, it is not entirely independent of physical 

conditions, and it is a representation of the unit only under specified conditions. For example, a meter standard has a 

length of one meter when at some definite temperature and supported in a certain manner. If supported in a different 

manner, it might have to be at a different temperature to have a length of one meter.

2.1. Origin and Early History of Units and Standards.

2.1.1. General Survey of Early History of Measurement Systems. – Weights and measures were among 

the earliest tools invented by man. Primitive societies needed rudimentary measures for many tasks: 

constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials.

Man understandably turned first to parts of the body and the natural surroundings for measuring instruments. 

Early Babylonian and Egyptian records and the Bible indicate that length was first measured with the forearm, 

hand, or finger and that time was measured by the periods of the sun, moon, and other heavenly bodies. When 

it was necessary to compare the capacities of containers such as gourds or clay or metal vessels, they were filled 

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with plant seeds which were then counted to measure the volumes. When means for weighing were invented, 

seeds and stones served as standards. For instance, the “carat,” still used as a unit for gems, was derived from 

the carob seed.

Our present knowledge of early weights and measures comes from many sources. Archaeologists have 

recovered some rather early standards and preserved them in museums. The comparison of the dimensions of 

buildings with the descriptions of contemporary writers is another source of information. An interesting 

example of this is the comparison of the dimensions of the Greek Parthenon with the description given by 

Plutarch from which a fairly accurate idea of the size of the Attic foot is obtained. In some cases, we have only 

plausible theories and we must sometimes select the interpretation to be given to the evidence.

For example, does the fact that the length of the double-cubit of early Babylonia was equal (within two parts 

per thousand) to the length of the seconds pendulum at Babylon suggest a scientific knowledge of the pendulum 

at a very early date, or do we merely have a curious coincidence? By studying the evidence given by all 

available sources, and by correlating the relevant facts, we obtain some idea of the origin and development of 

the units. We find that they have changed more or less gradually with the passing of time in a complex manner 

because of a great variety of modifying influences. We find the units modified and grouped into measurement 

systems: the Babylonian system, the Egyptian system, the Phileterian system of the Ptolemaic age, the Olympic 

system of Greece, the Roman system, and the British system, to mention only a few.

2.1.2. Origin and Development of Some Common Customary Units. – The origin and development of 

units of measurement has been investigated in considerable detail and a number of books have been written on 

the subject. It is only possible to give here, somewhat sketchily, the story about a few units.

Units of length: The cubit was the first recorded unit used by ancient peoples to measure length. There were 

several cubits of different magnitudes that were used. The common cubit was the length of the forearm from 

the elbow to the tip of the middle finger. It was divided into the span of the hand (one-half cubit), the palm or 

width of the hand (one sixth), and the digit or width of a finger (one twenty-fourth). The Royal or Sacred Cubit, 

which was 7 palms or 28 digits long, was used in constructing buildings and monuments and in surveying. The 

inch, foot, and yard evolved from these units through a complicated transformation not yet fully understood. 

Some believe they evolved from cubic measures; others believe they were simple proportions or multiples of 

the cubit. In any case, the Greeks and Romans inherited the foot from the Egyptians. The Roman foot was 

divided into both 12 unciae (inches) and 16 digits. The Romans also introduced the mile of 1000 paces or 

double steps, the pace being equal to five Roman feet. The Roman mile of 5000 feet was introduced into 

England during the occupation. Queen Elizabeth, who reigned from 1558 to 1603, changed, by statute, the 

mile to 5280 feet or 8 furlongs, a furlong being 40 rods of 51⁄2 yards each.

The introduction of the yard as a unit of length came later, but its origin is not definitely known. Some believe 

the origin was the double cubit, others believe that it originated from cubic measure. Whatever its origin, the 

early yard was divided by the binary method into 2, 4, 8, and 16 parts called the half-yard, span, finger, and 

nail. The association of the yard with the “gird” or circumference of a person’s waist or with the distance from 

the tip of the nose to the end of the thumb of Henry I are probably standardizing actions, since several yards 

were in use in Great Britain.

The point, which is a unit for measuring print type, is recent. It originated with Pierre Simon Fournier in 1737. 

It was modified and developed by the Didot brothers, Francois Ambroise and Pierre Francois, in 1755. The 

point was first used in the United States in 1878 by a Chicago type foundry (Marder, Luse, and Company). 

Since 1886, a point has been exactly 0.351 459 8 millimeters, or about 1

/72 inch.

Units of mass: The grain was the earliest unit of mass and is the smallest unit in the apothecary, avoirdupois, 

Tower, and Troy systems. The early unit was a grain of wheat or barleycorn used to weigh the precious metals 

silver and gold. Larger units preserved in stone standards were developed that were used as both units of mass 

and of monetary currency. The pound was derived from the mina used by ancient civilizations. A smaller unit 

was the shekel, and a larger unit was the talent. The magnitude of these units varied from place to place. The 

Babylonians and Sumerians had a system in which there were 60 shekels in a mina and 60 minas in a talent. 

The Roman talent consisted of 100 libra (pound) which were smaller in magnitude than the mina. The Troy 

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pound used in England and the United States for monetary purposes, like the Roman pound, was divided into 

12 ounces, but the Roman uncia (ounce) was smaller. The carat is a unit for measuring gemstones that had its 

origin in the carob seed, which later was standardized at 1/444 ounce and then 0.2 gram.

Goods of commerce were originally traded by number or volume. When weighing of goods began, units of 

mass based on a volume of grain or water were developed. For example, the talent in some places was 

approximately equal to the mass of one cubic foot of water. Was this a coincidence or by design? The diverse 

magnitudes of units having the same name, which still appear today in our dry and liquid measures, could have 

arisen from the various commodities traded. The larger avoirdupois pound for goods of commerce might have 

been based on volume of water, which has a higher bulk density than grain. For example, the Egyptian hon 

was a volume unit about 11 % larger than a cubic palm and corresponded to one mina of water. It was almost 

identical in volume to the present U.S. pint.

The stone, quarter, hundredweight, and ton were larger units of mass used in Great Britain. Today only the 

stone continues in customary use for measuring personal body weight. The present stone is 14 pounds, but an 

earlier unit appears to have been 16 pounds. The other units were multiples of 2, 8, and 160 times the stone, or 

28, 112, and 2240 pounds, respectively. The hundredweight was approximately equal to two talents. In the 

United States the ton of 2240 pounds is called the “long ton.” The “short ton” is equal to 2000 pounds.

Units of time and angle: We can trace the division of the circle into 360 degrees and the day into hours, minutes, 

and seconds to the Babylonians who had a sexagesimal system of numbers. The 360 degrees may have been 

related to a year of 360 days.

2.2. The Metric System.

2.2.1. Definition, Origin, and Development. – Metric systems of units have evolved since the adoption of 

the first well-defined system in France in 1791. During this evolution the use of these systems spread 

throughout the world, first to the non-English-speaking countries, and more recently to the English-speaking 

countries. The first metric system was based on the centimeter, gram, and second (cgs) and these units were 

particularly convenient in science and technology. Later metric systems were based on the meter, kilogram, 

and second (mks) to improve the value of the units for practical applications. The present metric system is the 

International System of Units (SI). It is also based on the meter, kilogram and second as well as additional base 

units for temperature, electric current, luminous intensity, and amount of substance. The International System 

of Units is referred to as the modern metric system.

The adoption of the metric system in France was slow, but its desirability as an international system was 

recognized by geodesists and others. On May 20, 1875, an international treaty known as the International 

Metric Convention or the Treaty of the Meter was signed by seventeen countries including the United States. 

This treaty established the following organizations to conduct international activities relating to a uniform 

system for measurements:

(1) The General Conference on Weights and Measures (French initials: CGPM), an intergovernmental 

conference of official delegates of member nations and the supreme authority for all actions;

(2) The International Committee of Weights and Measures (French initials: CIPM), consisting of selected 

scientists and metrologists, which prepares and executes the decisions of the CGPM and is responsible 

for the supervision of the International Bureau of Weights and Measures;

(3) The International Bureau of Weights and Measures (French initials: BIPM), a permanent laboratory 

and world center of scientific metrology, the activities of which include the establishment of the basic 

standards and scales of the principal physical quantities and maintenance of the international prototype 

standards.

The National Institute of Standards and Technology provides official United States representation in these 

organizations. The CGPM, the CIPM, and the BIPM have been major factors in the continuing refinement of 

the metric system on a scientific basis and in the evolution of the International System of Units.

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Multiples and submultiples of metric units are related by powers of ten. This relationship is compatible with 

the decimal system of numbers and it contributes greatly to the convenience of metric units.

2.2.2. International System of Units. – At the end of World War II, a number of different systems of 

measurement still existed throughout the world. Some of these systems were variations of the metric system, 

and others were based on the customary U.S. customary system of the English-speaking countries. It was 

recognized that additional steps were needed to promote a worldwide measurement system. As a result the 

9th GCPM, in 1948, asked the ICPM to conduct an international study of the measurement needs of the 

scientific, technical, and educational communities. Based on the findings of this study, the 10th General 

Conference in 1954 decided that an international system should be derived from six base units to provide for 

the measurement of temperature and optical radiation in addition to mechanical and electromagnetic quantities. 

The six base units recommended were the meter, kilogram, second, ampere, Kelvin degree (later renamed the 

kelvin), and the candela.

In 1960, the 11th General Conference of Weights and Measures named the system based on the six base 

quantities the International System of Units, abbreviated SI from the French name: Le Système International 

d’Unités. The SI metric system is now either obligatory or permissible throughout the world.

2.2.3. Units and Standards of the Metric System. – In the early metric system there were two fundamental 

or base units, the meter and the kilogram, for length and mass. The other units of length and mass, and all units 

of area, volume, and compound units such as density were derived from these two fundamental units.

The meter was originally intended to be one ten-millionth part of a meridional quadrant of the earth. The Meter 

of the Archives, the platinum length standard which was the standard for most of the 19th century, at first was 

supposed to be exactly this fractional part of the quadrant. More refined measurements over the earth’s surface 

showed that this supposition was not correct. In 1889, a new international metric standard of length, the 

International Prototype Meter, a graduated line standard of platinum-iridium, was selected from a group of bars 

because precise measurements found it to have the same length as the Meter of the Archives. The meter was 

then defined as the distance, under specified conditions, between the lines on the International Prototype Meter 

without reference to any measurements of the earth or to the Meter of the Archives, which it superseded. 

Advances in science and technology have made it possible to improve the definition of the meter and reduce 

the uncertainties associated with artifacts. From 1960 to 1983, the meter was defined as the length equal to 

1 650 763.73 wavelengths in a vacuum of the radiation corresponding to the transition between the specified 

energy levels of the krypton 86 atom. Since 1983 the meter has been defined as the length of the path traveled 

by light in a vacuum during an interval of 1

/299792458 of a second.

The kilogram, originally defined as the mass of one cubic decimeter of water at the temperature of maximum 

density, was known as the Kilogram of the Archives. It was replaced after the International Metric Convention 

in 1875 by the International Prototype Kilogram which became the unit of mass without reference to the mass 

of a cubic decimeter of water or to the Kilogram of the Archives. Each country that subscribed to the 

International Metric Convention was assigned one or more copies of the international standards; these are 

known as National Prototype Meters and Kilograms.

The liter is a unit of capacity or volume. In 1964, the 12th GCPM redefined the liter as being one cubic 

decimeter. By its previous definition – the volume occupied, under standard conditions, by a quantity of pure 

water having a mass of one kilogram – the liter was larger than the cubic decimeter by 28 parts per 1 000 000. 

Except for determinations of high precision, this difference is so small as to be of no consequence.

The modern metric system (SI) includes two classes of units:

(a) base units for length, mass, time, temperature, electric current, luminous intensity, and amount 

of substance; and

(b) derived units for all other quantities (e.g., work, force, power) expressed in terms of the seven 

base units.

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For details, see NIST Special Publication 330 (2008), The International System of Units (SI) and NIST Special 

Publication 811 (2008), Guide for the Use of the International System of Units.

2.2.4. International Bureau of Weights and Measures. – The International Bureau of Weights and 

Measures (BIPM) was established at Sèvres, a suburb of Paris, France, by the International Metric Convention 

of May 20, 1875. The BIPM maintains the International Prototype Kilogram, many secondary standards, and 

equipment for comparing standards and making precision measurements. The Bureau, funded by assessment 

of the signatory governments, is truly international. In recent years the scope of the work at the Bureau has 

been considerably broadened. It now carries on researches in the fields of electricity, photometry and 

radiometry, ionizing radiations, and time and frequency besides its work in mass, length, and thermometry. 

2.2.5. Status of the Metric System in the United States. – The use of the metric system in this country 

was legalized by Act of Congress in 1866, but was not made obligatory then or since. Following the signing of 

the Convention of the Meter in 1875, the United States acquired national prototype standards for the meter and 

the kilogram. U.S. Prototype Kilogram No. 20 continues to be the primary standard for mass in the United 

States. It is recalibrated from time to time at the BIPM. The prototype meter has been replaced by modern 

stabilized lasers following the most recent definition of the meter.

From 1893 until 1959, the yard was defined as equal exactly to 3600/3937 meter. In 1959, a small change was made 

in the definition of the yard to resolve discrepancies both in this country and abroad. Since 1959, we define the 

yard as equal exactly to 0.9144 meter; the new yard is shorter than the old yard by exactly two parts in a million. 

At the same time, it was decided that any data expressed in feet derived from geodetic surveys within the United 

States would continue to bear the relationship as defined in 1893 (one foot equals 1200/3937 meter). We call this 

foot the U.S. Survey Foot, while the foot defined in 1959 is called the International Foot. Measurements 

expressed in U.S. statute miles, survey feet, rods, chains, links, or the squares thereof, and acres should be 

converted to the corresponding metric values by using pre-1959 conversion factors if more than five significant 

figure accuracy is required.

Since 1970, actions have been taken to encourage the use of metric units of measurement in the United States. 

A brief summary of actions by Congress is provided below as reported in the Federal Register Notice dated 

July 28, 1998.

Section 403 of Public Law 93-380, the Education Amendment of 1974, states that it is the policy of the United 

States to encourage educational agencies and institutions to prepare students to use the metric system of 

measurement as part of the regular education program. Under both this act and the Metric Conversion Act of 

1975, the “metric system of measurement” is defined as the International System of Units as established in 

1960 by the General Conference on Weights and Measures and interpreted or modified for the United States 

by the Secretary of Commerce (Section 4(4)- Public Law 94-168; Section 403(a)(3)- Public Law 93-380). The 

Secretary has delegated authority under these subsections to the Director of the National Institute of Standards 

and Technology.

Section 5164 of Public Law 100-418, the Omnibus Trade and Competitiveness Act of 1988, amends Public 

Law 94-168, The Metric Conversion Act of 1975. In particular, Section 3, The Metric Conversion Act is 

amended to read as follows:

“Sec. 3. It is therefore the declared policy of the United States– 

(1) to designate the metric system of measurement as the preferred system of weights and measures for 

United States trade and commerce;

(2) to require that each federal agency, by a date certain and to the extent economically feasible by the 

end of the fiscal year 1992, use the metric system of measurement in its procurements, grants, and 

other business-related activities, except to the extent that such use is impractical or is likely to cause 

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significant inefficiencies or loss of markets to U.S. firms, such as when foreign competitors are 

producing competing products in non-metric units;

(3) to seek ways to increase understanding of the metric system of measurement through educational 

information and guidance and in government publications; and

(4) to permit the continued use of traditional systems of weights and measures in nonbusiness activities.”

The Code of Federal Regulations makes the use of metric units mandatory for agencies of the federal 

government. (Federal Register, Vol. 56, No. 23, page 160, January 2, 1991.)

2.3. British and United States Systems of Measurement. – In the past, the customary system of weights and 

measures in the British Commonwealth countries and that in the United States were very similar; however, the SI 

metric system is now the official system of units in the United Kingdom, while the customary units are still 

predominantly used in the United States. Because references to the units of the old British customary system are still 

found, the following discussion describes the differences between the U.S. and British customary systems of units.

After 1959, the U.S. and the British inches were defined identically for scientific work and were identical in 

commercial usage. A similar situation existed for the U.S. and the British pounds, and many relationships, such as 

12 inches = 1 foot, 3 feet = 1 yard, and 1760 yards = 1 international mile, were the same in both countries; but there 

were some very important differences.

In the first place, the U.S. customary bushel and the U.S. gallon, and their subdivisions differed from the corresponding 

British Imperial units. Also the British ton is 2240 pounds, whereas the ton generally used in the United States is the 

short ton of 2000 pounds. The American colonists adopted the English wine gallon of 231 cubic inches. The English 

of that period used this wine gallon and they also had another gallon, the ale gallon of 282 cubic inches. In 1824, the 

British abandoned these two gallons when they adopted the British Imperial gallon, which they defined as the volume 

of 10 pounds of water, at a temperature of 62 °F, which, by calculation, is equivalent to 277.42 cubic inches. At the 

same time, they redefined the bushel as 8 gallons.

In the customary British system, the units of dry measure are the same as those of liquid measure. In the United States 

these two are not the same; the gallon and its subdivisions are used in the measurement of liquids and the bushel, with 

its subdivisions, is used in the measurement of certain dry commodities. The U.S. gallon is divided into four liquid 

quarts and the U.S. bushel into 32 dry quarts. All the units of capacity or volume mentioned thus far are larger in the 

customary British system than in the U.S. system. But the British fluid ounce is smaller than the U.S. fluid ounce, 

because the British quart is divided into 40 fluid ounces whereas the U.S. quart is divided into 32 fluid ounces.

From this we see that in the customary British system an avoirdupois ounce of water at 62 °F has a volume of one 

fluid ounce, because 10 pounds is equivalent to 160 avoirdupois ounces, and 1 gallon is equivalent to 4 quarts, or 

160 fluid ounces. This convenient relation does not exist in the U.S. system because a U.S. gallon of water at 62 °F 

weighs about 81⁄3 pounds, or 1331⁄3 avoirdupois ounces, and the U.S. gallon is equivalent to 4 x 32, or 128 fluid ounces.

1 U.S. fluid ounce = 1.041 British fluid ounces

1 British fluid ounce = 0.961 U.S. fluid ounce

1 U.S. gallon = 0.833 British Imperial gallon

1 British Imperial gallon = 1.201 U.S. gallons

Among other differences between the customary British and the United States measurement systems, we should note 

that they abolished the use of the troy pound in England January 6, 1879; they retained only the troy ounce and its 

subdivisions, whereas the troy pound is still legal in the United States, although it is not now greatly used. We can 

mention again the common use, for body weight, in England of the stone of 14 pounds, this being a unit now unused 

in the United States, although its influence was shown in the practice until World War II of selling flour by the barrel 

of 196 pounds (14 stone). In the apothecary system of liquid measure the British add a unit, the fluid scruple, equal 

to one third of a fluid drachm (spelled dram in the United States) between their minim and their fluid drachm. In the 

United States, the general practice now is to sell dry commodities, such as fruits and vegetables, by their mass.

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2.4. Subdivision of Units. – In general, units are subdivided by one of three methods: (a) decimal, into tenths; 

(b) duodecimal, into twelfths; or (c) binary, into halves (twos). Usually the subdivision is continued by using the same 

method. Each method has its advantages for certain purposes, and it cannot properly be said that any one method is 

“best” unless the use to which the unit and its subdivisions are to be put is known.

For example, if we are concerned only with measurements of length to moderate precision, it is convenient to measure 

and to express these lengths in feet, inches, and binary fractions of an inch, thus 9 feet, 43

/8 inches. However, if these 

lengths are to be subsequently used to calculate area or volume, that method of subdivision at once becomes extremely 

inconvenient. For that reason, civil engineers, who are concerned with areas of land, volumes of cuts, fills, 

excavations, etc., instead of dividing the foot into inches and binary subdivisions of the inch, divide it decimally; that 

is, into tenths, hundredths, and thousandths of a foot.

The method of subdivision of a unit is thus largely made based on convenience to the user. The fact that units have 

commonly been subdivided into certain subunits for centuries does not preclude their also having another mode of 

subdivision in some frequently used cases where convenience indicates the value of such other method. Thus, while 

we usually subdivide the gallon into quarts and pints, most gasoline-measuring pumps, of the price-computing type, 

are graduated to show tenths, hundredths, or thousandths of a gallon.

Although the mile has for centuries been divided into rods, yards, feet, and inches, the odometer part of an automobile 

speedometer shows tenths of a mile. Although we divide our dollar into 100 parts, we habitually use and speak of 

halves and quarters. An illustration of rather complex subdividing is found on the scales used by draftsmen. These 

scales are of two types: (a) architects, which are commonly graduated with scales in which 3

/32, 3/16, 1/8, 1⁄4, 3/8, 1⁄2, 3⁄4, 1, 

11⁄2, and 3 inches, respectively, represent 1 foot full scale, and also having a scale graduated in the usual manner to 1

/16 inch; and (b) engineers, which are commonly subdivided to 10, 20, 30, 40, 50, and 60 parts to the inch.

The dictum of convenience applies not only to subdivisions of a unit but also to multiples of a unit. Land elevations 

above sea level are given in feet although the height may be several miles; the height of aircraft above sea level as 

given by an altimeter is likewise given in feet, no matter how high it may be.

On the other hand, machinists, toolmakers, gauge makers, scientists, and others who are engaged in precision 

measurements of relatively small distances, even though concerned with measurements of length only, find it 

convenient to use the inch, instead of the tenth of a foot, but to divide the inch decimally to tenths, hundredths, 

thousandths, etc., even down to millionths of an inch. Verniers, micrometers, and other precision measuring 

instruments are usually graduated in this manner. Machinist scales are commonly graduated decimally along one edge 

and are also graduated along another edge to binary fractions as small as 1

/64 inch. The scales with binary fractions are 

used only for relatively rough measurements.

It is seldom convenient or advisable to use binary subdivisions of the inch that are smaller than 1

/64. In fact, 1/32-, 1/16-, 

or 1

/8-inch subdivisions are usually preferable for use on a scale to be read with the unaided eye.

2.5. Arithmetical Systems of Numbers. – The subdivision of units of measurement is closely associated with 

arithmetical systems of numbers. The systems of units used in this country for commercial and scientific work, having 

many origins as has already been shown, naturally show traces of the various number systems associated with their 

origins and developments. Thus, (a) the binary subdivision has come down to us from the Hindus, (b) the duodecimal 

system of fractions from the Romans, (c) the decimal system from the Chinese and Egyptians, some developments 

having been made by the Hindus, and (d) the sexagesimal system (division by 60) now illustrated in the subdivision 

of units of angle and of time, from the ancient Babylonians. The use of decimal numbers in measurements is becoming 

the standard practice.

3. Standards of Length, Mass, and Capacity or Volume 

3.1. Standards of Length. – The meter, which is defined in terms of the speed of light in a vacuum, is the unit on 

which all length measurements are based.

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The yard is defined1 as follows:

1 yard = 0.914 4 meter, and

1 inch = 25.4 millimeters exactly. 

3.1.1. Calibration of Length Standards. – NIST calibrates standards of length including meter bars, yard 

bars, miscellaneous precision line standards, steel tapes, invar geodetic tapes, precision gauge blocks, 

micrometers, and limit gauges. It also measures the linear dimensions of miscellaneous apparatus such as 

penetration needles, cement sieves, and hemacytometer chambers. In general, NIST accepts for calibration 

only apparatus of such material, design, and construction as to ensure accuracy and permanence sufficient to 

justify calibration by the Institute. NIST performs calibrations in accordance with fee schedules, copies of 

which may be obtained from NIST.

NIST does not calibrate carpenters’ rules, machinist scales, draftsman scales, and the like. Such apparatus, if 

they require calibration, should be submitted to state or local weights and measures officials.

3.2. Standards of Mass. – The primary standard of mass for this country is United States Prototype Kilogram 20, 

which is a platinum-iridium cylinder kept at NIST. We know the value of this mass standard in terms of the 

International Prototype Kilogram, a platinum-iridium standard which is kept at the International Bureau of Weights 

and Measures.

In Colonial Times the British standards were considered the primary standards of the United States. Later, the U.S.

avoirdupois pound was defined in terms of the Troy Pound of the Mint, which is a brass standard kept at the United 

States Mint in Philadelphia. In 1911, the Troy Pound of the Mint was superseded, for coinage purposes, by the Troy 

Pound of the Institute.

The avoirdupois pound is defined in terms of the kilogram by the relation:

1 avoirdupois pound = 0.453 592 37 kilogram.2

These changes in definition have not made any appreciable change in the value of the pound.

The grain is 1

/7000 of the avoirdupois pound and is identical in the avoirdupois, troy, and apothecary systems. The troy 

ounce and the apothecary ounce differ from the avoirdupois ounce but are equal to each other, and equal to 480 grains. 

The avoirdupois ounce is equal to 437.5 grains.

3.2.1. Mass and Weight. – The mass of a body is a measure of its inertial property or how much matter it 

contains. The weight of a body is a measure of the force exerted on it by gravity or the force needed to support 

it. Gravity on earth gives a body a downward acceleration of about 9.8 m/s2

. (In common parlance, weight is 

often used as a synonym for mass in weights and measures.) The incorrect use of weight in place of mass 

should be phased out, and the term mass used when mass is meant.

Standards of mass are ordinarily calibrated by comparison to a reference standard of mass. If two objects are 

compared on a balance and give the same balance indication, they have the same “mass” (excluding the effect 

of air buoyancy). The forces of gravity on the two objects are balanced. Even though the value of the 

acceleration of gravity, g, is different from location to location, because the two objects of equal mass in the 

same location (where both masses are acted upon by the same g) will be affected in the same manner and by 

the same amount by any change in the value of g, the two objects will balance each other under any value of g. 

However, on a spring balance the mass of a body is not balanced against the mass of another body. Instead, 

the gravitational force on the body is balanced by the restoring force of a spring. Therefore, if a very sensitive 

spring balance is used, the indicated mass of the body would be found to change if the spring balance and the 

 

1 See Federal Register for July 1, 1959. Also see next-to-last paragraph of 2.2.5. 2 See Federal Register for July 1, 1959.

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body were moved from one locality to another locality with a different acceleration of gravity. But a spring 

balance is usually used in one locality and is adjusted or calibrated to indicate mass at that locality.

3.2.2. Effect of Air Buoyancy. – Another point that must be taken into account in the calibration and use 

of standards of mass is the buoyancy or lifting effect of the air. A body immersed in any fluid is buoyed up by 

a force equal to the force of gravity on the displaced fluid. Two bodies of equal mass, if placed one on each 

pan of an equal-arm balance, will balance each other in a vacuum. A comparison in a vacuum against a known 

mass standard gives “true mass.” If compared in air, however, they will not balance each other unless they are 

of equal volume. If of unequal volume, the larger body will displace the greater volume of air and will be 

buoyed up by a greater force than will the smaller body, and the larger body will appear to be of less mass than 

the smaller body.

The greater the difference in volume, and the greater the density of the air in which we make the comparison 

weighing, the greater will be the apparent difference in mass. For that reason, in assigning a precise numerical 

value of mass to a standard, it is necessary to base this value on definite values for the air density and the density 

of the mass standard of reference.

The apparent mass of an object is equal to the mass of just enough reference material of a specified density (at 

20 °C) that will produce a balance reading equal to that produced by the object if the measurements are done 

in air with a density of 1.2 mg/cm3 at 20 °C. The original basis for reporting apparent mass is apparent mass 

versus brass. The apparent mass versus a density of 8.0 g/cm3 is the more recent definition, and is used 

extensively throughout the world. The use of apparent mass versus 8.0 g/cm3 is encouraged over apparent mass 

versus brass. The difference in these apparent mass systems is insignificant in most commercial weighing 

applications.

A full discussion of this topic is given in NIST Monograph 133, Mass and Mass Values, by Paul E. Pontius [for 

sale by the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 

(COM 7450309)].

3.2.3. Calibrations of Standards of Mass. – Standards of mass regularly used in ordinary trade should be 

tested by state or local weights and measures officials. NIST calibrates mass standards submitted, but it does 

not manufacture or sell them. Information regarding the mass calibration service of NIST and the regulations 

governing the submission of standards of mass to NIST for calibration are contained in NIST Special 

Publication 250, Calibration and Related Measurement Services of NIST, latest edition.

3.3. Standards of Capacity. – Units of capacity or volume, being derived units, are in this country defined in terms 

of linear units. Laboratory standards have been constructed and are maintained at NIST. These have validity only by 

calibration with reference either directly or indirectly to the linear standards. Similarly, NIST has made and distributed 

standards of capacity to the several states. Other standards of capacity have been verified by calibration for a variety 

of uses in science, technology, and commerce.

3.3.1. Calibrations of Standards of Capacity. – NIST makes calibrations on capacity or volume standards 

that are in the customary units of trade; that is, the gallon, its multiples, and submultiples, or in metric units. 

Further, NIST calibrates precision-grade volumetric glassware which is normally in metric units. NIST makes 

calibrations in accordance with fee schedules, copies of which may be obtained from NIST.

3.4. Maintenance and Preservation of Fundamental Standard of Mass. – It is a statutory responsibility of NIST 

to maintain and preserve the national standard of mass at NIST and to realize all the other base units. The U.S.

Prototype Kilogram maintained at NIST is fully protected by an alarm system. All measurements made with this 

standard are conducted in special air-conditioned laboratories to which the standard is taken a sufficiently long time 

before the observations to ensure that the standard will be in a state of equilibrium under standard conditions when 

the measurements or comparisons are made. Hence, it is not necessary to maintain the standard at standard conditions, 

but care is taken to prevent large changes of temperature. More important is the care to prevent any damage to the 

standard because of careless handling.

4. Specialized Use of the Terms “Ton” and “Tonnage” 

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As weighing and measuring are important factors in our everyday lives, it is quite natural that questions arise about 

the use of various units and terms and about the magnitude of quantities involved. For example, the words “ton” and 

“tonnage” are used in widely different senses, and a great deal of confusion has arisen regarding the application of 

these terms.

The ton is used as a unit of measure in two distinct senses: (1) as a unit of mass, and (2) as a unit of capacity or 

volume.

In the first sense, the term has the following meanings:

(a) The short, or net ton of 2000 pounds.

(b) The long, gross, or shipper’s ton of 2240 pounds.

(c) The metric ton of 1000 kilograms, or 2204.6 pounds.

In the second sense (capacity), it is usually restricted to uses relating to ships and has the following meaning:

(a) The register ton of 100 cubic feet.

(b) The measurement ton of 40 cubic feet.

(c) The English water ton of 224 British Imperial gallons.

In the United States and Canada the ton (mass) most commonly used is the short ton. In Great Britain, it is the long

ton, and in countries using the metric system, it is the metric ton. The register ton and the measurement ton are 

capacity or volume units used in expressing the tonnage of ships. The English water ton is used, chiefly in Great 

Britain, in statistics dealing with petroleum products.

There have been many other uses of the term ton such as the timber ton of 40 cubic feet and the wheat ton of 20 bushels, 

but their uses have been local and the meanings have not been consistent from one place to another.

Properly, the word “tonnage” is used as a noun only in respect to the capacity or volume and dimensions of ships, and 

to the amount of the ship’s cargo. There are two distinct kinds of tonnage; namely, vessel tonnage and cargo tonnage

and each of these is used in various meanings. The several kinds of vessel tonnage are as follows:

Gross tonnage, or gross register tonnage, is the total cubical capacity or volume of a ship expressed in register tons of 

100 cubic feet, or 2.83 cubic meters, less such space as hatchways, bakeries, galleys, etc., as are exempted from 

measurement by different governments. There is some lack of uniformity in the gross tonnages as given by different 

nations due to lack of agreement on the spaces that are to be exempted. Official merchant marine statistics of most 

countries are published in terms of the gross register tonnage. Press references to ship tonnage are usually to the gross 

tonnage. 

The net tonnage, or net register tonnage, is the gross tonnage less the different spaces specified by maritime nations 

in their measurement rules and laws. The spaces deducted are those totally unavailable for carrying cargo, such as the 

engine room, coal bunkers, crew quarters, chart and instrument room, etc. The net tonnage is used in computing how 

much cargo that can be loaded on a ship. It is used as the basis for wharfage and other similar charges.

The register under-deck tonnage is the cubical capacity of a ship under her tonnage deck expressed in register tons. 

In a vessel having more than one deck, the tonnage deck is the second from the keel.

There are several variations of displacement tonnage. 

The dead weight tonnage is the difference between the “loaded” and “light” displacement tonnages of a vessel. It is 

expressed in terms of the long ton of 2240 pounds, or the metric ton of 2204.6 pounds, and is the weight of fuel, 

passengers, and cargo that a vessel can carry when loaded to its maximum draft.

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The second variety of tonnage, cargo tonnage, refers to the weight of the particular items making up the cargo. In 

overseas traffic it is usually expressed in long tons of 2240 pounds or metric tons of 2204.6 pounds. The short ton is 

only occasionally used. Therefore, the cargo tonnage is very distinct from vessel tonnage. 

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Table of Contents 

Appendix C. General Tables of Units of Measurement ........................................................ C-3

1. Tables of Metric Units of Measurement..................................................................................................... C-3

Units of Length............................................................................................................................................... C-3

Units of Area .................................................................................................................................................. C-3

Units of Liquid Volume.................................................................................................................................. C-4

Units of Volume ............................................................................................................................................. C-4

Units of Mass.................................................................................................................................................. C-4

2. Tables of U.S. Customary Units of Measurement..................................................................................... C-4

Units of Length............................................................................................................................................... C-4

Units of Area .................................................................................................................................................. C-5

Units of Volume ............................................................................................................................................. C-5

Gunter’s or Surveyors Chain Units of Measurement...................................................................................... C-5

Units of Liquid Volume.................................................................................................................................. C-5

Apothecaries Units of Liquid Volume ............................................................................................................ C-5

Units of Dry Volume ...................................................................................................................................... C-6

Avoirdupois Units of Mass............................................................................................................................. C-6

Troy Units of Mass......................................................................................................................................... C-6

Apothecaries Units of Mass............................................................................................................................ C-7

3. Notes on British Units of Measurement ..................................................................................................... C-7

4. Tables of Units of Measurement................................................................................................................. C-8

Units of Length - International Measure......................................................................................................... C-8

Units of Length - Survey Measure.................................................................................................................. C-8

Units of Area - International Measure ............................................................................................................ C-8

Units of Area - Survey Measure9 .................................................................................................................... C-9

Units of Volume ........................................................................................................................................... C-10

Units of Capacity or Volume - Dry Volume Measure .................................................................................. C-10

Units of Capacity or Volume - Liquid Volume Measure.............................................................................. C-11

Units of Mass Not Less Than Avoirdupois Ounces...................................................................................... C-12

Units of Mass Not Greater Than Pounds and Kilograms.............................................................................. C-13

5. Tables of Equivalents................................................................................................................................. C-14

Units of Length............................................................................................................................................. C-14

Units of Area ................................................................................................................................................ C-16

Units of Capacity or Volume ........................................................................................................................ C-16

Units of Mass................................................................................................................................................ C-19

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Appendix C. General Tables of Units of Measurement

These tables have been prepared for the benefit of those requiring tables of units for occasional ready reference. In 

Section 4 of this Appendix, the tables are carried out to a large number of decimal places and exact values are indicated 

by underlining. In most of the other tables, only a limited number of decimal places are given, therefore making the 

tables better adapted to the average user.

1. Tables of Metric Units of Measurement

In the metric system of measurement, designations of multiples and subdivisions of any unit may be arrived at by 

combining with the name of the unit the prefixes deka, hecto, and kilo meaning, respectively, 10, 100, and 1000, and 

deci, centi, and milli, meaning, respectively, one-tenth, one-hundredth, and one-thousandth. In some of the following 

metric tables, some such multiples and subdivisions have not been included for the reason that these have little, if any 

currency in actual usage.

In certain cases, particularly in scientific usage, it becomes convenient to provide for multiples larger than 1000 and 

for subdivisions smaller than one-thousandth. Accordingly, the following prefixes have been introduced and these 

are now generally recognized:

yotta, (Y) meaning 1024 deci, (d), meaning 10-1

zetta, (Z), meaning 1021 centi, (c), meaning 10-2

exa, (E), meaning 1018 milli, (m), meaning 10-3

peta, (P), meaning 1015 micro, (μ), meaning 10-6

tera, (T), meaning 1012 nano, (n), meaning 10-9

giga, (G), meaning 109 pico, (p), meaning 10-12

mega, (M), meaning 106 femto, (f), meaning 10-15

kilo, (k), meaning 103 atto, (a), meaning 10-18

hecto, (h), meaning 102 zepto, (z), meaning 10-21

deka, (da), meaning 101 yocto, (y), meaning 10-24

Thus a kilometer is 1000 meters and a millimeter is 0.001 meter. 

Units of Length

10 millimeters (mm) = 1 centimeter (cm)

10 centimeters = 1 decimeter (dm) = 100 millimeters

10 decimeters = 1 meter (m) = 1000 millimeters

10 meters = 1 dekameter (dam)

10 dekameters = 1 hectometer (hm) = 100 meters

10 hectometers = 1 kilometer (km) = 1000 meters

Units of Area

100 square millimeters (mm2) = 1 square centimeter (cm2)

100 square centimeters = 1 square decimeter (dm2)

100 square decimeters = 1 square meter (m2)

100 square meters = 1 square dekameter (dam2) = 1 are

100 square dekameters = 1 square hectometer (hm2) = 1 hectare (ha)

100 square hectometers = 1 square kilometer (km2)

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Units of Liquid Volume

10 milliliters (mL) = 1 centiliter (cL)

10 centiliters = 1 deciliter (dL) = 100 milliliters

10 deciliters = 1 liter1 = 1000 milliliters

10 liters = 1 dekaliter (daL)

10 dekaliters = 1 hectoliter (hL) = 100 liters

10 hectoliters = 1 kiloliter (kL) = 1000 liters

Units of Volume

1000 cubic millimeters (mm3) = 1 cubic centimeter (cm3)

1000 cubic centimeters = 1 cubic decimeter (dm3)

= 1 000 000 cubic millimeters

1000 cubic decimeters = 1 cubic meter (m3)

= 1 000 000 cubic centimeters

= 1 000 000 000 cubic millimeters

Units of Mass

10 milligrams (mg) = 1 centigram (cg)

10 centigrams = 1 decigram (dg) = 100 milligrams

10 decigrams = 1 gram (g) = 1000 milligrams

10 grams = 1 dekagram (dag)

10 dekagrams = 1 hectogram (hg) = 100 grams

10 hectograms = 1 kilogram (kg) = 1000 grams

1000 kilograms = 1 megagram (Mg) or 1 metric ton (t)

2. Tables of U.S. Customary Units of Measurement2

In these tables where foot or mile is underlined, it is survey foot or U.S. statute mile rather than international foot or 

mile that is meant.

Units of Length

12 inches (in) = 1 foot (ft)

3 feet = 1 yard (yd)

161⁄2 feet = 1 rod (rd), pole, or perch

40 rods = 1 furlong (fur) = 660 feet

8 furlongs = 1 U.S. statute mile (mi) = 5280 feet

1852 meters (m) = 6076.115 49 feet (approximately)

= 1 international nautical mile

 

1 By action of the 12th General Conference on Weights and Measures (1964), the liter is a special name for the cubic 

decimeter.

2 This section lists units of measurement that have traditionally been used in the United States. In keeping with the 

Omnibus Trade and Competitiveness Act of 1988, the ultimate objective is to make the International System of 

Units the primary measurement system used in the United States.

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Units of Area3

144 square inches (in2) = 1 square foot (ft2)

9 square feet = 1 square yard (yd2)

= 1296 square inches

2721⁄4 square feet = 1 square rod (rd2)

160 square rods = 1 acre = 43 560 square feet

640 acres = 1 square mile (mi2)

1 mile square = 1 section of land

6 miles square = 1 township

= 36 sections = 36 square miles

Units of Volume3

1728 cubic inches (in3) = 1 cubic foot (ft3)

27 cubic feet = 1 cubic yard (yd3)

Gunter’s or Surveyors Chain Units of Measurement

0.66 foot (ft) = 1 link (li)

100 links = 1 chain (ch)

= 4 rods = 66 feet

80 chains = 1 U.S. statute mile (mi)

= 320 rods = 5280 feet

Units of Liquid Volume4

4 gills (gi) = 1 pint (pt) = 28.875 cubic inches (in3)

2 pints = 1 quart (qt) = 57.75 cubic inches

4 quarts = 1 gallon (gal) = 231 cubic inches

= 8 pints = 32 gills

Apothecaries Units of Liquid Volume

60 minims = 1 fluid dram (fl dr or ƒ Ӡ)

= 0.225 6 cubic inch (in3)

8 fluid drams = 1 fluid ounce (fl oz or ƒ ℥)

= 1.804 7 cubic inches

16 fluid ounces = 1 pint (pt)

= 28.875 cubic inches

= 128 fluid drams

2 pints = 1 quart (qt) = 57.75 cubic inches

= 32 fluid ounces = 256 fluid drams

4 quarts = 1 gallon (gal) = 231 cubic inches

= 128 fluid ounces = 1024 fluid drams

 

3 Squares and cubes of customary but not of metric units are sometimes expressed by the use of abbreviations rather 

than symbols. For example, sq ft means square foot, and cu ft means cubic foot.

4 When necessary to distinguish the liquid pint or quart from the dry pint or quart, the word “liquid” or the 

abbreviation “liq” should be used in combination with the name or abbreviation of the liquid unit. 

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Units of Dry Volume5

2 pints (pt) = 1 quart (qt) = 67.200 6 cubic inches (in3)

8 quarts = 1 peck (pk) = 537.605 cubic inches

= 16 pints

4 pecks = 1 bushel (bu) = 2150.42 cubic inches

= 32 quarts

Avoirdupois Units of Mass6

[The “grain” is the same in avoirdupois, troy, and apothecaries units of mass.]

In “gross” or “long” measure, the following values are recognized:

112 pounds (lb) = 1 gross or long hundredweight (cwt)7

20 gross or long hundredweights = 1 gross or long ton

= 2240 pounds7

Troy Units of Mass

[The “grain” is the same in avoirdupois, troy, and apothecaries units of mass.]

24 grains (gr) = 1 pennyweight (dwt)

20 pennyweights = 1 ounce troy (oz t) = 480 grains

12 ounces troy = 1 pound troy (lb t)

= 240 pennyweights = 5760 grains

 

5 When necessary to distinguish dry pint or quart from the liquid pint or quart, the word “dry” should be used in 

combination with the name or abbreviation of the dry unit.

 

6 When necessary to distinguish the avoirdupois dram from the apothecaries dram, or to distinguish the avoirdupois

dram or ounce from the fluid dram or ounce, or to distinguish the avoirdupois ounce or pound from the troy or 

apothecaries ounce or pound, the word “avoirdupois” or the abbreviation “avdp” should be used in combination with 

the name or abbreviation of the avoirdupois unit.

7 When the terms “hundredweight” and “ton” are used unmodified, they are commonly understood to mean the 

100-pound hundredweight and the 2000-pound ton, respectively; these units may be designated “net” or “short” when 

necessary to distinguish them from the corresponding units in gross or long measure.

8 As of January 1, 2014, “tn” is the required abbreviation for “short ton.” Devices manufactured between 

January 1, 2008, and December 31, 2013, may use an abbreviation other than “tn” to specify “short ton.”

1 μlb = 0.000 001 pound (lb)

2711/32 grains (gr) = 1 dram (dr)

16 drams = 1 ounce (oz)

= 4371⁄2 grains

16 ounces = 1 pound (lb)

= 256 drams

= 7000 grains

100 pounds = 1 hundredweight (cwt)7

20 hundredweights = 1 ton (tn)8

= 2000 pounds7

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Apothecaries Units of Mass

[The “grain” is the same in avoirdupois, troy, and apothecaries units of mass.]

20 grains (gr) = 1 scruple (s ap or ℈) 

3 scruples = 1 dram apothecaries (dr ap or Ӡ)

= 60 grains

8 drams apothecaries = 1 ounce apothecaries (oz ap or ℥)

= 24 scruples = 480 grains

12 ounces apothecaries = 1 pound apothecaries (lb ap)

= 96 drams apothecaries

= 288 scruples = 5760 grains

3. Notes on British Units of Measurement

In Great Britain, the yard, the avoirdupois pound, the troy pound, and the apothecaries pound are identical with the 

units of the same names used in the United States. The tables of British linear measure, troy mass, and apothecaries

mass are the same as the corresponding United States tables, except for the British spelling “drachm” in the table of 

apothecaries mass. The table of British avoirdupois mass is the same as the United States table up to 1 pound; above 

that point the table reads:

14 pounds = 1 stone

2 stones = 1 quarter = 28 pounds

4 quarters = 1 hundredweight = 112 pounds

20 hundredweight = 1 ton = 2240 pounds

The present British gallon and bushel – known as the “Imperial gallon” and “Imperial bushel” – are, respectively, 

about 20 % and 3 % larger than the United States gallon and bushel. The Imperial gallon is defined as the volume of 

10 avoirdupois pounds of water under specified conditions, and the Imperial bushel is defined as 8 Imperial gallons. 

Also, the subdivision of the Imperial gallon as presented in the table of British apothecaries fluid measure differs in 

two important respects from the corresponding United States subdivision, in that the Imperial gallon is divided into 

160 fluid ounces (whereas the United States gallon is divided into 128 fluid ounces), and a “fluid scruple” is included. 

The full table of British measures of capacity (which are used alike for liquid and for dry commodities) is as follows:

4 gills = 1 pint

2 pints = 1 quart

4 quarts = 1 gallon

2 gallons = 1 peck

8 gallons (4 pecks) = 1 bushel

8 bushels = 1 quarter

The full table of British apothecaries measure is as follows:

20 minims = 1 fluid scruple

3 fluid scruples = 1 fluid drachm

= 60 minims

8 fluid drachms = 1 fluid ounce

20 fluid ounces = 1 pint

8 pints = 1 gallon (160 fluid ounces)

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4. Tables of Units of Measurement

(all underlined figures are exact)

Units of Length - International Measure9

Units Inches Feet Yards Miles Centimeters Meters

1 inch = 1 0.083 333 33 0.027 777 78 0.000 015 782 83 2.54 0.025 4

1 foot = 12 1 0.333 333 3 0.000 189 393 9 30.48 0.304 8

1 yard = 36 3 1 0.000 568 181 8 91.44 0.914 4

1 mile = 63 360 5 280 1 760 1 160 934.4 1609.344

1 centimeter = 0.393 700 8 0.032 808 40 0.010 936 13 0.000 006 213 712 1 0.01

1 meter = 39.370 08 3.280 840 1.093 613 0.000 621 371 2 100 1

Units of Length - Survey Measure9

Units Links Feet Rods Chains Miles Meters

1 link = 1 0.66 0.04 0.01 0.000 125 0.201 168 4

1 foot = 1.515 152 1 0.060 606 06 0.015 151 52 0.000 189 393 9 0.304 800 6

1 rod = 25 16.5 1 0.25 0.003 125 5.029 210

1 chain = 100 66 4 1 0.0125 20.116 84

1 mile = 8 000 5 280 320 80 1 1609.347

1 meter = 4.970 960 3.280 833 0.198 838 4 0.049 709 60 0.000 621 369 9 1

Units of Area - International Measure10

(all underlined figures are exact)

Units Square Inches Square Feet Square Yards

1 square inch = 1 0.006 944 444 0.000 771 604 9

1 square foot = 144 1 0.111 111 1

1 square yard = 1 296 9 1 

1 square mile = 4 014 489 600 27 878 400 3 097 600

1 square centimeter = 0.155 000 3 0.001 076 391 0.000 119 599 0

1 square meter = 1550.003 10.763 91 1.195 990

 

9 One international foot = 0.999 998 survey foot (exactly)

One international mile = 0.999 998 survey mile (exactly)

10 One square survey foot = 1.000 004 square international feet

One square survey mile = 1.000 004 square international miles

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Note: 1 survey foot = 1200/3937 meter (exactly)

1 international foot = 12 x 0.0254 meter (exactly)

1 international foot = 0.0254 x 39.37 survey foot (exactly

Units Square Miles Square Centimeters Square Meters

1 square inch = 0.000 000 000 249 097 7 6.451 6 0.000 645 16

1 square foot = 0.000 000 035 870 06 929.030 4 0.092 903 04

1 square yard = 0.000 000 322 830 6 8361.273 6 0.836 127 36

1 square mile = 1 25 899 881 103.36 2 589 988.110 336

1 square centimeter = 0.000 000 000 038 610 22 1 0.0001

1 square meter = 0.000 000 386 102 2 10 000 1

Units of Area - Survey Measure10, 11

Units Square Feet Square Rods Square Chains Acres

1 square foot = 1 0.003 673 095 0.000 229 568 4 0.000 022 956 84

1 square rod = 272.25 1 0.062 5 0.006 25

1 square chain = 4 356 16 1 0.1

1 acre = 43 560 160 10 1

1 square mile = 27 878 400 102 400 6 400 640

1 square meter = 10.763 87 0.039 536 70 0.002 471 044 0.000 247 104 4

1 hectare = 107 638.7 395.367 0 24.710 44 2.471 044

Units Square Miles Square Meters Hectares

1 square foot = 0.000 000 035 870 06 0.092 903 41 0.000 009 290 341

1 square rod = 0.000 009 765 625 25.292 95 0.002 529 295

1 square chain = 0.000 156 25 404.687 3 0.040 468 73

1 acre = 0.001 562 5 4 046.873 0.404 687 3

1 square mile = 1 2 589 998 258.999 8

1 square meter = 0.000 000 386 100 6 1 0.000 1

1 hectare = 0.003 861 006 10 000 1

 

10 One square survey foot = 1.000 004 square international feet

 One square survey mile = 1.000 004 square international miles

11 One international foot = 0.999 998 survey foot (exactly)

 One international mile = 0.999 998 survey mile (exactly)

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C-10

Units of Volume

(all underlined figures are exact)

Units Cubic Inches Cubic Feet Cubic Yards

1 cubic inch = 1 0.000 578 703 7 0.000 021 433 47

1 cubic foot = 1 728 1 0.037 037 04

1 cubic yard = 46 656 27 1

1 cubic centimeter = 0.061 023 74 0.000 035 314 67 0.000 001 307 951

1 cubic decimeter = 61.023 74 0.035 314 67 0.001 307 951

1 cubic meter = 61 023.74 35.314 67 1.307 951

Units Milliliters

(Cubic Centimeters)

Liters

(Cubic Decimeters) Cubic Meters

1 cubic inch = 16.387 064 0.016 387 064 0.000 016 387 064

1 cubic foot = 28 316.846 592 28.316 846 592 0.028 316 846 592

1 cubic yard = 764 554.857 984 764.554 857 984 0.764 554 857 984

1 cubic centimeter = 1 0.001 0.000 001

1 cubic decimeter = 1 000 1 0.001

1 cubic meter = 1 000 000 1000 1

Units of Capacity or Volume - Dry Volume Measure

Units Dry Pints Dry Quarts Pecks Bushels

1 dry pint = 1 0.5 0.062 5 0.015 625

1 dry quart = 2 1 0.125 0.031 25

1 peck = 16 8 1 0.25

1 bushel = 64 32 4 1

1 cubic inch = 0.029 761 6 0.014 880 8 0.001 860 10 0.000 465 025

1 cubic foot = 51.428 09 25.714 05 3.214 256 0.803 563 95

1 liter = 1.816 166 0.908 083 0 0.113 510 4 0.028 377 59

1 cubic meter = 1 816.166 908.083 0 113.510 4 28.377 59

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C-11

Units Cubic Inches Cubic Feet Liters Cubic Meters

1 dry pint = 33.600 312 5 0.019 444 63 0.550 610 5 0.000 550 610 5

1 dry quart = 67.200 625 0.038 889 25 1.101 221 0.001 101 221

1 peck = 537.605 0.311 114 8.809 768 0.008 809 768

1 bushel = 2 150.42 1.244 456 35.239 070 166 88 0.035 239 070 166 88

1 cubic inch = 1 0.000 578 703 7 0.016 387 064 0.000 016 387 064

1 cubic foot = 1728 1 28.316 846 592 0.028 316 846 592

1 liter = 61.023 74 0.035 314 67 1 0.001

1 cubic meter = 61 023.74 35.314 67 1000 1

Units of Capacity or Volume - Liquid Volume Measure

(All underlined figures are exact)

Units Minims Fluid Drams Fluid Ounces Gills

1 minim = 1 0.016 666 67 0.002 083 333 0.000 520 833 3

1 fluid dram = 60 1 0.125 0.031 25

1 fluid ounce = 480 8 1 0.25

1 gill = 1 920 32 4 1

1 liquid pint = 7 680 128 16 4

1 liquid quart = 15 360 256 32 8

1 gallon = 61 440 1024 128 32

1 cubic inch = 265.974 0 4.432 900 0.554 112 6 0.138 528 1

1 cubic foot = 459 603.1 7660.052 957.506 5 239.376 6

1 milliliter = 16.230 73 0.270 512 2 0.033 814 02 0.008 453 506

1 liter = 16 230.73 270.512 2 33.814 02 8.453 506

Units Liquid Pints Liquid Quarts Gallons Cubic Inches

1 minim = 0.000 130 208 3 0.000 065 104 17 0.000 016 276 04 0.003 759 766

1 fluid dram = 0.007 812 5 0.003 906 25 0.000 976 562 5 0.225 585 94

1 fluid ounce = 0.062 5 0.031 25 0.007 812 5 1.804 687 5

1 gill = 0.25 0.125 0.031 25 7.218 75

1 liquid pint = 1 0.5 0.125 28.875

1 liquid quart = 2 1 0.25 57.75

1 gallon = 8 4 1 231

1 cubic inch = 0.034 632 03 0.017 316 02 0.004 329 004 1

1 cubic foot = 59.844 16 29.922 08 7.480 519 1 728

1 milliliter = 0.002 113 376 0.001 056 688 0.000 264 172 1 0.061 023 74

1 liter = 2.113 376 1.056 688 0.264 172 1 61.023 74

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C-12

Units Cubic Feet Milliliters Liters

1 minim = 0.000 002 175 790 0.061 611 52 0.000 061 611 52

1 fluid dram = 0.000 130 547 4 3.696 691 0.003 696 691

1 fluid ounce = 0.001 044 379 29.573 53 0.029 573 53

1 gill = 0.004 177 517 118.294 1 0.118 294 1

1 liquid pint = 0.016 710 07 473.176 5 0.473 176 5

1 liquid quart = 0.033 420 14 946.352 9 0.946 352 9

1 gallon = 0.133 680 6 3785.411 784 3.785 411 784

1 cubic inch = 0.000 578 703 7 16.387 06 0.016 387 06

1 cubic foot = 1 28 316.85 28.316 85

1 milliliter = 0.000 035 314 67 1 0.001

1 liter = 0.035 314 67 1 000 1

Units of Mass Not Less Than Avoirdupois Ounces

(all underlined figures are exact)

Units Avoirdupois

Ounces

Avoirdupois

Pounds

Short Hundredweights Short Tons

1 avoirdupois ounce = 1 0.0625 0.000 625 0.000 031 25

1 avoirdupois pound = 16 1 0.01 0.000 5

1 short 

hundredweight = 1 600 100 1 0.05

1 short ton = 32 000 2 000 20 1

1 long ton = 35 840 2 240 22.4 1.12

1 kilogram = 35.273 96 2.204 623 0.022 046 23 0.001 102 311

1 metric ton = 35 273.96 2204.623 22.046 23 1.102 311

Units Long Tons Kilograms Metric Tons

1 avoirdupois ounce = 0.000 027 901 79 0.028 349 523 125 0.000 028 349 523 125

1 avoirdupois pound = 0.000 446 428 6 0.453 592 37 0.000 453 592 37

1 short hundredweight = 0.044 642 86 45.359 237 0.045 359 237

1 short ton = 0.892 857 1 907.184 74 0.907 184 74

1 long ton = 1 1016.046 908 8 1.016 046 908 8

1 kilogram = 0.000 984 206 5 1 0.001

1 metric ton = 0.984 206 5 1 000 1

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C-13

Units of Mass Not Greater Than Pounds and Kilograms

(all underlined figures are exact)

Units Grains Apothecaries 

Scruples Pennyweights Avoirdupois Drams

1 grain = 1 0.05 0.041 666 67 0.036 571 43

1 apoth. scruple = 20 1 0.833 333 3 0.731 428 6

1 pennyweight = 24 1.2 1 0.877 714 3

1 avdp. dram = 27.343 75 1.367 187 5 1.139 323 1

1 apoth. dram = 60 3 2.5 2.194 286

1 avdp. ounce = 437.5 21.875 18.229 17 16

1 apoth. or troy oz. = 480 24 20 17.554 29

1 apoth. or troy pound = 5 760 288 240 210.651 4

1 avdp. pound = 7 000 350 291.666 7 256

1 milligram = 0.015 432 36 0.000 771 617 9 0.000 643 014 9 0.000 564 383 4

1 gram = 15.432 36 0.771 617 9 0.643 014 9 0.564 383 4

1 kilogram = 15432.36 771.617 9 643.014 9 564.383 4

Units Apothecaries 

Drams

Avoirdupois 

Ounces

Apothecaries or 

Troy Ounces

Apothecaries or 

Troy Pounds

1 grain = 0.016 666 67 0.002 285 714 0.002 083 333 0.000 173 611 1

1 apoth. scruple = 0.333 333 3 0.045 714 29 0.041 666 67 0.003 472 222

1 pennyweight = 0.4 0.054 857 14 0.05 0.004 166 667

1 avdp. dram = 0.455 729 2 0.062 5 0.56 966 15 0.004 747 179

1 apoth. dram = 1 0.137 142 9 0.125 0.010 416 67

1 avdp. ounce = 7.291 667 1 0.911 458 3 0.075 954 86

1 apoth. or troy ounce = 8 1.097 143 1 0.083 333 333

1 apoth. or troy pound = 96 13.165 71 12 1

1 avdp. pound = 116.666 7 16 14.583 33 1.215 278

1 milligram = 0.000 257 206 0 0.000 035 273 96 0.000 032 150 75 0.000 002 679 229

1 gram = 0.257 206 0 0.035 273 96 0.032 150 75 0.002 679 229

1 kilogram = 257.206 0 35.273 96 32.150 75 2.679 229

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Appendix C – General Tables of Units of Measurement Handbook 44 – 2016 

C-14

Units Avoirdupois 

Pounds Milligrams Grams Kilograms

1 grain = 0.000 142 857 1 64.798 91 0.064 798 91 0.000 064 798 91

1 apoth. scruple = 0.002 857 143 1 295.978 2 1.295 978 2 0.001 295 978 2

1 pennyweight = 0.003 428 571 1 555.173 84 1.555 173 84 0.001 555 173 84

1 avdp. dram = 0.003 906 25 1 771.845 195 312 5 1.771 845 195 312 5 0.001 771 845 195 312 5

1 apoth. dram = 0.008 571 429 3 887.934 6 3.887 934 6 0.003 887 934 6

1 avdp. ounce = 0.062 5 28 349.523 125 28.349 523 125 0.028 349 523 125

1 apoth. or troy 

ounce = 0.068 571 43 31 103.476 8 31.103 476 8 0.031 103 476 8

1 apoth. or troy 

pound = 0.822 857 1 373 241.721 6 373.241 721 6 0.373 241 721 6

1 avdp. pound = 1 453 592.37 453.592 37 0.453 592 37

1 milligram = 0.000 002 204 623 1 0.001 0.000 001

1 gram = 0.002 204 623 1 000 1 0.001

1 kilogram = 2.204 623 1 000 000 1 000 1

5. Tables of Equivalents

In these tables it is necessary to differentiate between the “international foot” and the “survey foot.” Therefore, the 

survey foot is underlined.

When the name of a unit is enclosed in brackets (thus, [1 hand] . . . ), this indicates (1) that the unit is not in general 

current use in the United States, or (2) that the unit is believed to be based on “custom and usage” rather than on 

formal authoritative definition.

Equivalents involving decimals are, in most instances, rounded off to the third decimal place except where they are 

exact, in which cases these exact equivalents are so designated. The equivalents of the imprecise units “tablespoon” 

and “teaspoon” are rounded to the nearest milliliter.

Units of Length

angstrom ()12

0.1 nanometer (exactly)

0.000 1 micrometer (exactly)

0.000 000 1 millimeter (exactly)

0.000 000 004 inch

1 cable’s length

120 fathoms (exactly)

720 feet (exactly)

219 meters

1 centimeter (cm) 0.393 7 inch

 

12 The angstrom is basically defined as 10−10 meter. 

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C-15

Units of Length

1 chain (ch)

(Gunter’s or surveyors)

66 feet (exactly)

20.116 8 meters

1 decimeter (dm) 3.937 inches

1 dekameter (dam) 32.808 feet

1 fathom 6 feet (exactly)

1.828 8 meters

1 foot (ft) 0.304 8 meter (exactly)

1 furlong (fur)

10 chains (surveyors) (exactly)

660 feet (exactly) 1

/8 U.S. statute mile (exactly)

201.168 meters

[1 hand] 4 inches

1 inch (in) 2.54 centimeters (exactly)

1 kilometer (km) 0.621 mile

1 league (land) 3 U.S. statute miles (exactly)

4.828 kilometers

1 link (li) (Gunter’s or surveyors) 0.66 foot (exactly)

0.201 168 meter

1 meter (m) 39.37 inches

1.094 yards

1 micrometer 0.001 millimeter (exactly)

0.000 039 37 inch

1 mil 0.001 inch (exactly)

0.025 4 millimeter (exactly)

1 mile (mi) (U.S. statute)13 5280 feet survey (exactly)

1.609 kilometers

1 mile (mi) (international) 5280 feet international (exactly)

1 mile (mi) (international nautical)14 1.852 kilometers (exactly)

1.151 survey miles

1 millimeter (mm) 0.039 37 inch

0.001 meter (exactly)

1 nanometer (nm) 0.000 000 039 37 inch

1 Point (typography)

0.013 837 inch (exactly)

1

/72 inch (approximately)

0.351 millimeter

1 rod (rd), pole, or perch 161⁄2 feet (exactly)

 

13 The term “statute mile” originated with Queen Elizabeth I who changed the definition of the mile from the Roman 

mile of 5000 feet to the statute mile of 5280 feet. The international mile and the U.S. statute mile differ by about 

3 millimeters although both are defined as being equal to 5280 feet. The international mile is based on the international 

foot (0.3048 meter) whereas the U.S. statute mile is based on the survey foot (1200/3937 meter).

14 The international nautical mile of 1852 meters (6076.115 49 feet) was adopted effective July 1, 1954, for use in the 

United States. The value formerly used in the United States was 6080.20 feet = 1 nautical (geographical or sea) mile.

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Appendix C – General Tables of Units of Measurement Handbook 44 – 2016 

C-16

Units of Length

5.029 2 meters

1 yard (yd) 0.914 4 meter (exactly)

Units of Area

1 acre15 43 560 square feet (exactly)

0.405 hectare

1 are 119.599 square yards

0.025 acre

1 hectare 2.471 acres

[1 square (building)] 100 square feet

1 square centimeter (cm2) 0.155 square inch

1 square decimeter (dm2) 15.500 square inches

1 square foot (ft2) 929.030 square centimeters

1 square inch (in2) 6.451 6 square centimeters (exactly)

1 square kilometer (km2) 247.104 acres

0.386 square mile

1 square meter (m2) 1.196 square yards

10.764 square feet

1 square mile (mi2) 258.999 hectares

1 square millimeter (mm2) 0.002 square inch

1 square rod (rd2), sq pole, or sq perch 25.293 square meters

1 square yard (yd2) 0.836 square meter

Units of Capacity or Volume

1 barrel (bbl), liquid 31 to 42 gallons16

1 barrel (bbl), standard for fruits,

 vegetables, and other dry

 commodities, except cranberries

7056 cubic inches

105 dry quarts

3.281 bushels, struck measure

1 barrel (bbl), standard, cranberry

5826 cubic inches

8645/64 dry quarts

2.709 bushels, struck measure

 

15 The question is often asked as to the length of a side of an acre of ground. An acre is a unit of area containing 

43 560 square feet. It is not necessarily square, or even rectangular. But, if it is square, then the length of a side is 

equal to ft 710.208ft 43560 2 = (not exact).

16 There are a variety of “barrels” established by law or usage. For example, federal taxes on fermented liquors are 

based on a barrel of 31 gallons; many state laws fix the “barrel for liquids” as 311⁄2 gallons; one state fixes a 36-gallon 

barrel for cistern measurement; federal law recognizes a 40-gallon barrel for “proof spirits;” by custom, 42 gallons 

comprise a barrel of crude oil or petroleum products for statistical purposes, and this equivalent is recognized “for 

liquids” by four states.

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Handbook 44 – 2016 Appendix C – General Tables of Units of Measurement

C-17

Units of Capacity or Volume

1 bushel (bu) (U.S.) struck measure 2150.42 cubic inches (exactly)

35.238 liters

[1 bushel, heaped (U.S.)] 2747.715 cubic inches

1.278 bushels, struck measure17

[1 bushel (bu) (British Imperial)

(struck measure)]

1.032 U.S. bushels, struck measure

2219.36 cubic inches

1 cord (cd) (firewood) 128 cubic feet (exactly)

1 cubic centimeter (cm3) 0.061 cubic inch

1 cubic decimeter (dm3) 61.024 cubic inches

1 cubic foot (ft3) 7.481 gallons

28.316 cubic decimeters

1 cubic inch (in3) 

0.554 fluid ounce

4.433 fluid drams

16.387 cubic centimeters

1 cubic meter (m3) 1.308 cubic yards

1 cubic yard (yd3) 0.765 cubic meter

1 cup, measuring

8 fluid ounces (exactly)

237 milliliters

1⁄2 liquid pint (exactly)

1 dekaliter (daL) 2.642 gallons

1.135 pecks

1 dram, fluid (or liquid) (fl dr)

 or ƒ Ӡ) (U.S.) 

1

/8 fluid ounce (exactly)

0.226 cubic inch

3.697 milliliters

1.041 British fluid drachms

[1 drachm, fluid (fl dr) (British)]

0.961 U.S. fluid dram

0.217 cubic inch

3.552 milliliters

1 gallon (gal) (U.S.) 

231 cubic inches (exactly)

3.785 liters

0.833 British gallon

128 U.S. fluid ounces (exactly)

[1 gallon (gal) (British Imperial)]

277.42 cubic inches

1.201 U.S. gallons

4.546 liters

160 British fluid ounces (exactly)

1 gill (gi)

7.219 cubic inches

4 fluid ounces (exactly)

0.118 liter

1 hectoliter (hL) 26.418 gallons

2.838 bushels

 

17 Frequently recognized as 11⁄4 bushels, struck measure.

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C-18

Units of Capacity or Volume

1 liter (1 cubic decimeter exactly)

1.057 liquid quarts

0.908 dry quart

61.025 cubic inches

1 milliliter (mL)

0.271 fluid dram

16.231 minims

0.061 cubic inch

1 ounce, fluid (or liquid) (fl oz)

 or ƒ ) (U.S.) 

1.805 cubic inches

29.573 milliliters

1.041 British fluid ounces

[1 ounce, fluid (fl oz) (British)]

0.961 U.S. fluid ounce

1.734 cubic inches

28.412 milliliters

1 peck (pk) 8.810 liters

1 pint (pt), dry 33.600 cubic inches

0.551 liter 

1 pint (pt), liquid 28.875 cubic inches exactly

0.473 liter

1 quart (qt), dry (U.S.) 

67.201 cubic inches

1.101 liters

0.969 British quart

1 quart (qt), liquid (U.S.) 

57.75 cubic inches (exactly)

0.946 liter

0.833 British quart

[1 quart (qt) (British)]

69.354 cubic inches

1.032 U.S. dry quarts

1.201 U.S. liquid quarts

1 tablespoon, measuring

3 teaspoons (exactly)

15 milliliters

4 fluid drams

1⁄2 fluid ounce (exactly)

1 teaspoon, measuring

1⁄3 tablespoon (exactly)

5 milliliters

11⁄3 fluid drams18

1 water ton (English) 270.91 U.S. gallons

224 British Imperial gallons (exactly)

 

18 The equivalent “1 teaspoon = 11⁄3 fluid drams” has been found by the Bureau to correspond more closely with the 

actual capacities of “measuring” and silver teaspoons than the equivalent “1 teaspoon = 1 fluid dram,” which is 

given by a number of dictionaries.

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Handbook 44 – 2016 Appendix C – General Tables of Units of Measurement

C-19

Units of Mass

1 assay ton (AT)19 29.167 grams

1 carat (c) 200 milligrams (exactly)

3.086 grains

1 dram apothecaries (dr ap or 3) 60 grains (exactly)

3.888 grams

1 dram avoirdupois (dr avdp) 2711/32 (= 27.344) grains

1.772 grams

1 gamma (γ) 1 microgram (exactly)

1 grain 64.798 91 milligrams (exactly)

1 gram (g) 15.432 grains

0.035 ounce, avoirdupois

1 hundredweight, gross or long20

 (gross cwt)

112 pounds (exactly)

50.802 kilograms

1 hundredweight, gross or short

 (cwt or net cwt)

100 pounds (exactly)

45.359 kilograms

1 kilogram (kg) 2.205 pounds

1 milligram (mg) 0.015 grain

1 ounce, avoirdupois (oz avdp)

437.5 grains (exactly)

0.911 troy or apothecaries ounce

28.350 grams

1 ounce, troy or apothecaries

 (oz t or oz ap or ℥) 

480 grains (exactly)

1.097 avoirdupois ounces

31.103 grams

1 pennyweight (dwt) 1.555 grams

1 point 0.01 carat

2 milligrams

1 pound, avoirdupois (lb avdp)

7000 grains (exactly)

1.215 troy or apothecaries pounds

453.592 37 grams (exactly)

1 micropound (μlb) [the Greek letter mu

 in combination with the letters lb] 0.000 001 pound (exactly)

1 pound, troy or apothecaries

 (lb t or lb ap)

5760 grains (exactly)

0.823 avoirdupois pound

373.242 grams

1 scruple (s ap or ℈) 20 grains (exactly)

1.296 grams

 

19 Used in assaying. The assay ton bears the same relation to the milligram that a ton of 2000 pounds avoirdupois 

bears to the ounce troy; hence the mass in milligrams of precious metal obtained from one assay ton of ore gives 

directly the number of troy ounces to the net ton.

20 The gross or long ton and hundredweight are used commercially in the Untied States to only a very limitied 

extent, usually in restricted industrial fields. The units are the same as the British “ton” and the “hundredweights.”

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Appendix C – General Tables of Units of Measurement Handbook 44 – 2016 

C-20

Units of Mass

1 ton, gross or long21

2240 pounds (exactly)

1.12 net tons (exactly)

1.016 metric tons

1 ton, metric (t)

2204.623 pounds

0.984 gross ton

1.102 net tons

1 ton, net or short (tn)21

2000 pounds (exactly)

0.893 gross ton

0.907 metric ton

 

21 As of January 1, 2014, “tn” is the required abbreviation for “short ton.” Devices manufactured between January 1, 

2008, and December 31, 2013, may use an abbreviation other than “tn” to specify “short ton.”

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Handbook 44 – 2016 Appendix D – Definitions

D-1 

Table of Contents

Appendix D. Definitions............. 5

A .............................................................. 5

absolute value. ................................................... 5

acceptance test. .................................................. 5

accurate.............................................................. 5

all-class.............................................................. 5

analog or digital recorder................................... 5

analog type......................................................... 5

animal scale. ...................................................... 5

apparent mass versus 8.0 g/cm3. ........................ 5

approval seal...................................................... 5

assumed atmospheric pressure........................... 5

audit trail............................................................ 5

automatic bulk weighing system. ...................... 5

automatic checkweigher .................................... 5

automatic gravimetric filling machine 

(instrument). ...................................................... 6

automatic temperature or density compensation.

........................................................................... 6

automatic weighing system (AWS). .................. 6

automatic zero-setting mechanism (AZSM)...... 6

automatic zero-setting mechanism (beltconveyor scale).................................................. 6

automatic zero-tracking (AZT) mechanism....... 6

automatic-indicating scale. ................................ 6

auxiliary indicator.............................................. 6

axle-load scale. .................................................. 6

B .............................................................. 7

badge. ................................................................ 7

balance, zero-load.............................................. 7

balance indicator................................................ 7

balancing mechanism. ....................................... 7

base pressure...................................................... 7

basic distance rate.............................................. 7

basic time rate.................................................... 7

basic tolerances.................................................. 7

batching meter ................................................... 7

beam. ................................................................. 7

beam scale. ........................................................ 7

bell prover.......................................................... 7

belt-conveyor..................................................... 7

belt-conveyor scale ............................................ 7

belt-conveyor scale systems area....................... 7

belt load. – ......................................................... 7

belt revolution.................................................... 7

billed weight. ..................................................... 8

binary submultiples............................................ 8

built-for-purpose device .................................... 8

C .............................................................. 8

calibration parameter. ........................................ 8

carbon dioxide liquid-measuring device............ 8

car-wash timer. .................................................. 8

center-reading tank. ........................................... 8

cereal grain and oil seeds................................... 8

chart recorder..................................................... 8

check rate........................................................... 8

checkweighing scale. ......................................... 8

class of grain...................................................... 8

clear interval between graduations. ................... 8

cleared................................................................ 8

cold-tire pressure. .............................................. 8

commercial equipment. ..................................... 8

computing scale. ................................................ 9

computing type or computing type device......... 9

concave curve. ................................................... 9

concentrated load capacity (CLC) ..................... 9

configuration parameter..................................... 9

consecutive-car test train. .................................. 9

construction materials hopper scale................... 9

contract sale. ...................................................... 9

conventional scale.............................................. 9

conversion table................................................. 9

convex curve...................................................... 9

conveyor stringers.............................................. 9

correct................................................................ 9

correction table. ................................................. 9

counterbalance weight(s)................................... 9

counterpoise weight(s).....................................10

coupled-in-motion railroad weighing system. . 10

crane scale. ......................................................10

cryogenic liquid-measuring device..................10

cryogenic liquids..............................................10

cubic foot, gas..................................................10

D ............................................................ 10

“d,” dimension division value..........................10

d, value scale division......................................10

Dmax (maximum load of the measuring range). 10

Dmin (minimum load of the measuring range). . 10

dairy-product-test scale....................................10

decimal submultiples. ......................................10

decreasing-load test. ........................................10

deficiency. .......................................................10

digital type. ......................................................10

dimensional weight (or dim, weight)...............10

direct sale.........................................................11

discharge hose. ................................................11

discharge line...................................................11

discrimination (of an automatic-indicating 

scale)................................................................11

dispenser..........................................................11

distributed-car test train. ..................................11

dry hose. ..........................................................11

dry-hose type. ..................................................11

dynamic monorail weighing system ................11

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Appendix D – Definitions Handbook 44 – 2016 

D-2 

E ............................................................ 11

e, value of verification scale division. .............11

Emax (maximum capacity). ...............................11

Emin (minimum dead load). ..............................11

emin (minimum verification scale division). .....11

electronic link. .................................................11

element. ...........................................................12

equal-arm scale................................................12

equipment, commercial. ..................................12

event counter. ..................................................12

event logger. ....................................................12

excess and deficiency ......................................12

extras. ..............................................................12

F ............................................................. 12

face. ................................................................. 12

fare...................................................................12

farm milk tank. ................................................12

feeding mechanism..........................................13

fifth wheel........................................................13

fifth-wheel test.................................................13

flag...................................................................13

fractional bar....................................................13

ft3/h. ................................................................. 13

G ............................................................ 13

gasoline gallon equivalent (GGE). ..................13

gasoline liter equivalent (GLE). ......................13

gauge pressure. ................................................13

gauge rod. ........................................................13

gauging. ...........................................................13

graduated interval. ...........................................13

graduation. .......................................................13

grain class. .......................................................13

grain hopper scale............................................13

grain moisture meter........................................13

grain sample.....................................................13

grain-test scale. ................................................14

grain type.........................................................14

gravity discharge..............................................14

H ............................................................ 14

head pulley.......................................................14

hexahedron. .....................................................14

hired.................................................................14

hopper scale.....................................................14

I .............................................................. 14

idler space........................................................14

idlers or idler rollers. .......................................14

in-service light indicator.................................. 14

increasing-load test. .........................................14

increment. ........................................................14

index of an indicator........................................14

indicating element............................................14

indicator, balance.............................................14

initial distance or time interval. .......................14

initial zero-setting mechanism.........................14

integrator. – ......................................................15

interval, clear, between graduations. ...............15

interval, graduated. ..........................................15

irregularly-shaped object. ................................15

J ............................................................. 15

jewelers’ scale. ................................................15

K ............................................................ 15

kind of grain. ...................................................15

L ............................................................ 15

label. ................................................................15

large-delivery device. ......................................15

laundry-drier timer...........................................15

liquefied petroleum gas. ..................................15

liquefied petroleum gas liquid-measuring 

device...............................................................15

liquefied petroleum gas vapor-measuring device.

.........................................................................15

liquid fuel.........................................................15

liquid volume correction factor. ......................15

liquid-fuel device.............................................15

liquid-measuring device. ................................. 15

livestock scale..................................................16

load cell. ..........................................................16

load cell verification interval (v). ....................16

loading point....................................................16

load-receiving element. ...................................16

low-flame test. .................................................16

lubricant device................................................16

M ........................................................... 16

m3/h. ................................................................16

main bar...........................................................16

main graduation. ..............................................16

main-weighbeam elements. .............................16

manual zero-setting mechanism ......................16

manufactured device........................................16

mass flow meter...............................................16

master meter test method.................................16

master weight totalizer.....................................16

material test. ....................................................17

maximum capacity...........................................17

maximum cargo load. ......................................17

measurement field............................................17

measuring element...........................................17

meter register. ..................................................17

metrological integrity (of a device). ................17

minimum capacity. ..........................................17

minimum clear interval....................................17

minimum delivery............................................17

minimum tolerance. .........................................17

minimum totalized load. ..................................17

moisture content (wet basis). ...........................17

money drop......................................................17

money-operated type. ......................................17

motor-fuel........................................................17

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Handbook 44 – 2016 Appendix D – Definitions

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motor-fuel device or motor-fuel dispenser or 

retail motor-fuel device. ..................................18

multi-class........................................................18

multi-interval scale. .........................................18

multi-jet water meter. ......................................18

multi-revolution scale. .....................................18

multiple............................................................18

multiple cell application load cell....................18

multiple of a scale............................................18

multiple range scale. ........................................18

multiple-tariff taximeter...................................18

N ...................................................... 18

natural gas........................................................18

NBP. ................................................................18

nmax (maximum number of scale divisions). ....18

no-load reference value....................................19

nominal............................................................19

nominal capacity..............................................19

nominal capacity, batching scale. ....................19

nominal capacity, hopper scale........................19

non-automatic checkweigher. ..........................19

non-automatic weighing instrument. ...............19

nonretroactive. .................................................20

nose-iron..........................................................20

notes.................................................................20

NTP. ................................................................20

NTP density and volume correction factor. .....20

O ............................................................ 20

odometer..........................................................20

official grain samples.......................................20

official with statutory authority. ......................20

operating tire pressure. ....................................20

over-and-under indicator. ................................20

overregistration and underregistration. ............20

P ............................................................. 21

parallax. ...........................................................21

parking meter...................................................21

passenger vehicles. ..........................................21

performance requirements. ..............................21

point-of-sale system.........................................21

poise.................................................................21

postal scale.......................................................21

prepackaging scale...........................................21

prescription scale. ............................................21

pressure type (device)......................................21

primary indicating or recording elements........21

prover method..................................................22

prover oil. ........................................................22

proving indicator..............................................22

R ............................................................ 22

“r” factor..........................................................22

radio frequency interference (RFI). .................22

random error(s)................................................22

ranges, weight..................................................22

rated capacity. ..................................................22

rated scale capacity..........................................22

ratio test. ..........................................................22

reading face. ....................................................22

reading-face capacity.......................................22

recorded representation....................................23

recording element. ...........................................23

recording scale.................................................23

reference weight car.........................................23

remanufactured device.....................................23

remanufactured element...................................23

remote configuration capability.......................23

repaired device.................................................23

repaired element ..............................................23

retail device. ....................................................23

retroactive........................................................23

road test. ..........................................................23

rolling circumference.......................................23

S ............................................................. 24

scale. ................................................................24

scale area, belt-conveyor ................................. 24

scale division, number of (n). ..........................24

scale division, value of (d)...............................24

scale section.....................................................24

seal...................................................................24

section capacity................................................24

section test. ......................................................24

security means. ................................................24

security seal. ....................................................24

selector-type. ...................................................24

semi-automatic zero-setting mechanism..........24

sensitivity (of a nonautomatic-indicating scale).

.........................................................................24

sensitivity requirement (SR)............................24

shift test. ..........................................................24

side...................................................................24

simulated-road test...........................................25

simulated test. ..................................................25

single cell application load cell........................25

single-tariff taximeter. .....................................25

skirting.............................................................25

slow-flow meter..............................................25

small-delivery device.......................................25

span (structural). ..............................................25

specification.....................................................25

static monorail weighing system. ....................25

strain-load test. ................................................25

subordinate graduation. ...................................25

subsequent distance or time intervals ..............25

substitution test................................................25

substitution test load. .......................................25

surface gauge. ..................................................25

systematic (average) error................................26

T ............................................................ 26

tail pulley. ........................................................26

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Appendix D – Definitions Handbook 44 – 2016 

D-4 

take-up. ............................................................26

tare mechanism................................................26

tare-weighbeam elements. ...............................26

taximeter..........................................................26

test chain..........................................................26

test liquid. ........................................................26

test object.........................................................26

test puck...........................................................26

test train. ..........................................................26

test weight car..................................................26

testing. .............................................................27

time recorder....................................................27

timing device. ..................................................27

tolerance. .........................................................27

training idlers...................................................27

transfer standard. .............................................27

tripper. .............................................................27

U ............................................................ 27

uncoupled-in-motion railroad weighing system.

.........................................................................27

underregistration..............................................27

unit price..........................................................27

unit train...........................................................27

unit weight. ......................................................27

user requirement. .............................................27

usual and customary. .......................................27

utility-type water meter...................................27

V ............................................................ 28

value of minimum graduated interval..............28

vapor equalization credit.................................. 28

vapor equalization line.....................................28

vehicle on-board weighing system. .................28

vehicle scale.....................................................28

verification scale division, value of (e)............28

visible type.......................................................28

vmin (minimum load cell verification interval). 28

W ........................................................... 28

weighbeam.......................................................28

weigh-belt system............................................28

weighing element.............................................28

weigh-labeler...................................................28

weigh module ..................................................29

weighment. ......................................................29

weight, unit. .....................................................29

weight classifier...............................................29

weight ranges...................................................29

wet basis. .........................................................29

wet hose...........................................................29

wet-hose type...................................................29

wheel-load weighers. .......................................29

wholesale device..............................................29

wing pulley. .....................................................29

Z ............................................................ 29

zero-load balance.............................................29

zero-load balance, automatic-indicating scale. 29

zero-load balance, nonautomatic-indicating 

scale. ................................................................29

zero-load balance for a recording scale. ..........29

zero-load reference (belt-conveyor scales). .....29

zero-setting mechanism. ..................................30

automatic zero-setting mechanism (AZSM)...30

automatic zero-tracking (AZT) mechanism....30

initial zero-setting mechanism........................30

manual zero-setting mechanism......................30

semiautomatic zero-setting mechanism. .........30

zero-setting mechanism (belt-conveyor scale).30

zero-tracking mechanism................................. 30

zone of uncertainty. .........................................30

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Handbook 44 – 2016 Appendix D – Definitions

D-5 

Appendix D. Definitions

The specific code to which the definition applies is shown in [brackets] at the end of the definition. Definitions for 

the General Code [1.10] apply to all codes in Handbook 44.

A 

absolute value. – The absolute value of a number is the magnitude of that number without considering the positive or 

negative sign. [2.20]

acceptance test. – The first official test of a farm milk tank, at a particular location, in which the tank is accepted as 

correct. This test applies to newly constructed tanks, relocated used tanks, and recalibrated tanks. [4.42]

accurate. – A piece of equipment is “accurate” when its performance or value – that is, its indications, its deliveries, 

its recorded representations, or its capacity or actual value, etc., as determined by tests made with suitable 

standards - conforms to the standard within the applicable tolerances and other performance requirements. Equipment 

that fails so to conform is “inaccurate.” (Also see “correct.”) [Appendix A]

all-class. – A description of a multi-class calibration that includes all the classes of a grain type. [5.56(a), 5.57]

(Added 2007)

analog or digital recorder. – An element used with a belt-conveyor scale that continuously records the rate-of-flow 

of bulk material over the scale (formerly referred to as a chart recorder). [2.21]

(Amended 1989)

analog type. – A system of indication or recording in which values are presented as a series of graduations in 

combination with an indicator, or in which the most sensitive element of an indicating system moves continuously 

during the operation of the device. [1.10]

animal scale. – A scale designed for weighing single heads of livestock. [2.20]

(Amended 1987)

apparent mass versus 8.0 g/cm3

. – The apparent mass of an object versus 8.0 g/cm3 is the mass of material of density 

8.0 g/cm3 that produces exactly the same balance reading as the object when the comparison is made in air with a 

density of 1.2 mg/cm3 at 20 °C. [3.37]

approval seal. – A label, tag, stamped or etched impression, or the like, indicating official approval of a device. (Also 

see “security seal.”) [1.10]

assumed atmospheric pressure. – The average atmospheric pressure agreed to exist at the meter at various ranges of 

elevation, irrespective of variations in atmospheric pressure from time to time. [3.33]

audit trail. – An electronic count and/or information record of the changes to the values of the calibration or 

configuration parameters of a device. [1.10, 2.20, 2.21, 2.24, 3.30, 3.37, 5.56(a)]

(Added 1993)

automatic bulk weighing system. – A weighing system adapted to the automatic weighing of bulk commodities in 

successive drafts of predetermined amounts, automatically recording the no-load and loaded weight values and 

accumulating the net weight of each draft. [2.22] 

automatic checkweigher. – An automatic weighing system that does not require the intervention of an operator during 

the weighing process and used to subdivide items of different weights into one or more subgroups, such as identifying 

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Appendix D – Definitions Handbook 44 – 2016 

D-6 

packages that have acceptable or unacceptable fill levels according to the value of the difference between their weight 

and a pre-determined set point. These systems may be used to fill standard packages for compliance with net weight 

requirements. [2.24]

(Amended 2004)

automatic gravimetric filling machine (instrument). – A filling machine or instrument that fills containers or 

packages with predetermined and virtually constant mass of product from bulk by automatic weighing, and which 

comprises essentially an automatic feeding device or devices associated with one or more weighing unit and the 

appropriate discharge devices. [2.24]

(Added 2004)

automatic temperature or density compensation. – The use of integrated or ancillary equipment to obtain from the 

output of a volumetric meter an equivalent mass, or an equivalent liquid volume at the assigned reference temperature 

below and a pressure of 14.696 lb/in2 absolute.

Cryogenic liquids: 21 °C (70 °F) [3.34]

Hydrocarbon gas vapor: 15 °C (60 °F) [3.33]

Liquid carbon dioxide: 21 °C (70 °F) [3.38]

Liquefied petroleum gas (LPG) and Anhydrous ammonia: 15 °C (60 °F) [3.32]

Petroleum liquid fuels and lubricants: 15 °C (60 °F) [3.30]

automatic weighing system (AWS). – An automatic weighing system is a weighing device that, in combination with 

other hardware and/or software components, automatically weighs discrete items and that does not require the 

intervention of an operator during the weighing process. Examples include, but are not limited to, weigh-labelers and 

checkweighers. [2.24]

(Amended 2004)

automatic zero-setting mechanism (AZSM). – See “automatic zero-setting mechanism” under “zero-setting 

mechanism.” [2.22]

(Amended 2010)

automatic zero-setting mechanism (belt-conveyor scale). – A zero setting device that operates automatically 

without intervention of the operator after the belt has been running empty. [2.21]

(Added 2002)

automatic zero-tracking (AZT) mechanism. – Automatic means provided to maintain the zero balance indication, 

within specified limits, without the intervention of an operator. [2.20, 2.22, 2.24]

(Amended 2010)

automatic-indicating scale. – One on which the weights of applied loads of various magnitudes are automatically 

indicated throughout all or a portion of the weighing range of the scale. (A scale that automatically weighs out 

commodity in predetermined drafts, such as an automatic hopper scale, a packaging scale, and the like, is not an 

“automatic-indicating” scale.) [2.20. 2.22]

auxiliary indicator. – Any indicator other than the master weight totalizer that indicates the weight of material 

determined by the scale. [2.21]

axle-load scale. – A scale permanently installed in a fixed location, having a load-receiving element specially adapted 

to determine the combined load of all wheels (1) on a single axle or (2) on a tandem axle of a highway vehicle. [2.20]

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Handbook 44 – 2016 Appendix D – Definitions

D-7 

B 

badge. – A metal plate affixed to the meter by the manufacturer showing the manufacturer’s name, serial number and 

model number of the meter, and its rated capacity. [3.33]

balance, zero-load. – See “zero-load balance.” [2.20]

balance indicator. – A combination of elements, one or both of which will oscillate with respect to the other, for 

indicating the balance condition of a nonautomatic indicating scale. The combination may consist of two indicating 

edges, lines, or points, or a single edge, line, or point and a graduated scale. [2.20]

balancing mechanism. – A mechanism (including a balance ball) that is designed for adjusting a scale to an accurate 

zero-load balance condition. [2.20]

base pressure. – The absolute pressure used in defining the gas measurement unit to be used, and is the gauge pressure 

at the meter plus an agreed atmospheric pressure. [3.33]

basic distance rate. – The charge for distance for all intervals except the initial interval. [5.54]

basic time rate. – The charge for time for all intervals except the initial interval. [5.54]

basic tolerances. – Basic tolerances are those tolerances on underregistration and on overregistration, or in excess 

and in deficiency, that are established by a particular code for a particular device under all normal tests, whether 

maintenance or acceptance. Basic tolerances include minimum tolerance values when these are specified. Special 

tolerances, identified as such and pertaining to special tests, are not basic tolerances. [1.10]

batching meter. – A device used for the purpose of measuring quantities of water to be used in a batching operation.

[3.36]

beam. – See “weighbeam.” [2.20]

beam scale. – One on which the weights of loads of various magnitudes are indicated solely by means of one or more 

weighbeam bars either alone or in combination with counterpoise weights. [2.20]

bell prover. – A calibrated cylindrical metal tank of the annular type with a scale thereon that, in the downward travel 

in a surrounding tank containing a sealing medium, displaces air through the meter being proved or calibrated. [3.33]

belt-conveyor. – An endless moving belt for transporting material from place to place. [2.21]

belt-conveyor scale. – A device that employs a weighing element in contact with a belt to sense the weight of the 

material being conveyed and the speed (travel) of the material, and integrates these values to produce total delivered 

weight. [2.21]

belt-conveyor scale systems area. – The scale system area refers to the scale suspension, weigh idlers attached to the 

scale suspension, 5 approach (−) idlers, and 5 retreat (+) idlers. [2.21]

(Added 2001)

belt load. – The weight of the material carried by the conveyor belt, expressed in terms of weight units per unit of 

length (e.g., pounds per foot, kilograms per meter). Also called “belt loading.” [2.21]

(Added 2013)

belt revolution. – The amount of conveyor belt movement or travel that is equivalent to the total length of the 

conveyor belt. Also referred to as "belt circuit." [2.21]

(Added 2013)

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Appendix D – Definitions Handbook 44 – 2016 

D-8 

billed weight. – The weight used in the computation of the freight, postal, or storage charge, whether actual weight 

or dimensional weight. [5.58]

binary submultiples. – Fractional parts obtained by successively dividing by the number two. Thus, one-half, 

one-fourth, one-eighth, one-sixteenth, and so on, are binary submultiples. [1.10]

built-for-purpose device. – Any main device or element which was manufactured with the intent that it be used as, 

or part of, a weighing or measuring device or system. [1.10]

(Added 2003)

C 

calibration parameter. – Any adjustable parameter that can affect measurement or performance accuracy and, due 

to its nature, needs to be updated on an ongoing basis to maintain device accuracy, e.g., span adjustments, linearization 

factors, and coarse zero adjustments. [2.20, 2.21, 2.24, 3.30, 3.37, 5.56(a)]

(Added 1993)

carbon dioxide liquid-measuring device. – A system including a mechanism or machine of (a) the meter or (b) a 

weighing type of device mounted on a vehicle designed to measure and deliver liquid carbon dioxide. Means may be 

provided to indicate automatically, for one of a series of unit prices, the total money value of the quantity measured. 

[3.38]

car-wash timer. – A timer used in conjunction with a coin-operated device to measure the time during which car-wash 

water, cleaning solutions, or waxing solutions are dispensed. [5.55]

center-reading tank. – One so designed that the gauge rod or surface gauge, when properly positioned for use, will 

be approximately in the vertical axis of the tank, centrally positioned with respect to the tank walls. [4.43]

cereal grain and oil seeds. – Agricultural commodities including, but not limited to, corn, wheat, oats, barley, flax, 

rice, sorghum, soybeans, peanuts, dry beans, safflower, sunflower, fescue seed, etc. [5.56(a), 5.56(b)]

chart recorder. – See analog or digital recorder.

(Amended 1989)

check rate. – A rate of flow usually 20 % of the capacity rate. [3.33]

checkweighing scale. – One used to verify predetermined weight within prescribed limits. [2.24]

class of grain. – Hard Red Winter Wheat as distinguished from Hard Red Spring Wheat as distinguished from Soft 

Red Winter Wheat, etc. [5.56(a), 5.56(b), 5.57]

clear interval between graduations. – The distance between adjacent edges of successive graduations in a series of 

graduations. If the graduations are “staggered,” the interval shall be measured, if necessary, between a graduation and 

an extension of the adjacent graduation. (Also see “minimum clear interval.”) [1.10]

cleared. – A taximeter is “cleared” when it is inoperative with respect to all fare indication, when no indication of 

fare or extras is shown and when all parts are in those positions in which they are designed to be when the vehicle on 

which the taximeter is installed is not engaged by a passenger. [5.54]

cold-tire pressure. – The pressure in a tire at ambient temperature. [5.53, 5.54]

commercial equipment. – See “equipment.”

(Added 2008)

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Handbook 44 – 2016 Appendix D – Definitions

D-9 

computing scale. – One that indicates the money values of amounts of commodity weighed, at predetermined unit 

prices, throughout all or part of the weighing range of the scale. [2.20]

computing type or computing type device. – A device designed to indicate, in addition to weight or measure, the 

total money value of product weighed or measured, for one of a series of unit prices. [1.10]

concave curve. – A change in the angle of inclination of a belt conveyor where the center of the curve is above the 

conveyor. [2.21]

concentrated load capacity (CLC) (also referred to as Dual Tandem Axle Capacity[DTAC]). – A capacity rating of 

a vehicle or axle-load scale, specified by the manufacturer, defining the maximum load applied by a group of two 

axles with a centerline spaced four feet apart and an axle width of eight feet for which the weighbridge is designed. 

The concentrated load capacity rating is for both test and use. [2.20]

(Added 1988) (Amended 1991, 1994, and 2003)

configuration parameter. – Any adjustable or selectable parameter for a device feature that can affect the accuracy 

of a transaction or can significantly increase the potential for fraudulent use of the device and, due to its nature, needs 

to be updated only during device installation or upon replacement of a component, e.g., division value (increment), 

sensor range, and units of measurement. [2.20, 2.21, 2.24, 3.30, 3.37, 5.56(a)]

(Added 1993) 

consecutive-car test train. – A train consisting of cars weighed on a reference scale, then coupled consecutively and 

run over the coupled-in-motion railway track scale under test. [2.20]

(Added 1990)

construction materials hopper scale. – A scale adapted to weighing construction materials such as sand, gravel, 

cement, and hot oil. [2.20]

contract sale. – A sale where a written agreement exists, prior to the point of sale, in which both buyer and seller have 

accepted pricing conditions of the sale. Examples include, but are not limited to: e-commerce, club sales, or prepurchase agreements. Any devices used in the determination of quantity must comply with NIST Handbook 44. [3.30, 

3.32, 3.37]

(Added 1993) (Amended 2002)

conventional scale. – If the use of conversion tables is necessary to obtain a moisture content value, the moisture 

meter indicating scale is called “conventional scale.” The values indicated by the scale are dimensionless. [5.56(b)]

conversion table. – Any table, graph, slide rule, or other external device used to determine the moisture content from 

the value indicated by the moisture meter. [5.56(b)]

convex curve. – A change in the angle of inclination of a belt conveyor where the center of the curve is below the 

conveyor. [2.21]

conveyor stringers. – Support members for the conveyor on which the scale and idlers are mounted. [2.21]

correct. – A piece of equipment is “correct” when, in addition to being accurate, it meets all applicable specification 

requirements. Equipment that fails to meet any of the requirements for correct equipment is “incorrect.” (Also see 

“accurate.”) [Appendix A] 

correction table. – Any table, graph, slide rule, or other external device used to determine the moisture content from 

the value indicated by the moisture meter when the indicated value is altered by a parameter not automatically 

corrected for in the moisture meter (for example, temperature or test weight). [5.56(b)]

counterbalance weight(s). – One intended for application near the butt of a weighbeam for zero-load balancing 

purposes. [2.20]

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Appendix D – Definitions Handbook 44 – 2016 

D-10

counterpoise weight(s). – A slotted or “hanger” weight intended for application near the tip of the weighbeam of a 

scale having a multiple greater than one. [2.20]

coupled-in-motion railroad weighing system. – A device and related installation characteristics consisting of (1) the 

associated approach trackage, (2) the scale (i.e., the weighing element, the load-receiving element, and the indicating 

element with its software), and (3) the exit trackage, which permit the weighing of railroad cars coupled in motion.

[2.20, 2.23]

(Added 1992)

crane scale. – One with a nominal capacity of 5000 pounds or more designed to weigh loads while they are suspended 

freely from an overhead, track-mounted crane. [2.20]

cryogenic liquid-measuring device. – A system including a liquid-measuring element designed to measure and 

deliver cryogenic liquids in the liquid state. [3.34]

(Amended 1986 and 2003)

cryogenic liquids. – Fluids whose normal boiling point is below 120 kelvin (− 243 °F). [3.34]

cubic foot, gas. – The amount of a cryogenic liquid in the gaseous state at a temperature of 70 °F and under a pressure 

of 14.696 lb/in2 absolute that occupies one cubic foot (1 ft3

). (See NTP.) [3.34]

D 

“d,” dimension division value. – The smallest increment that the device displays for any axis and length of object in that axis.

[5.58]

d, value scale division. – See “scale division, value of (d).” [2.20, 2.22]

Dmax (maximum load of the measuring range). – Largest value of a quantity (mass) which is applied to a load cell 

during test or use. This value shall not be greater than Emax. [2.20]

(Added 2005)

Dmin (minimum load of the measuring range). – Smallest value of a quantity (mass) which is applied to a load cell 

during test or use. This value shall not be less than Emin. [2.20]

(Added 2006)

dairy-product-test scale. – A scale used in determining the moisture content of butter and/or cheese or in determining 

the butterfat content of milk, cream, or butter. [2.20]

decimal submultiples. – Parts obtained by successively dividing by the number 10. Thus 0.1, 0.01, 0.001, and so on 

are decimal submultiples. [1.10]

decreasing-load test. – A test for automatic-indicating scales only, wherein the performance of the scale is tested as 

the load is reduced. [2.20, 2.22]

(Amended 1987)

deficiency. – See “excess and deficiency.” [1.10]

digital type. – A system of indication or recording of the selector type or one that advances intermittently in which 

all values are presented digitally, or in numbers. In a digital indicating or recording element, or in digital 

representation, there are no graduations. [1.10]

dimensional weight (or dim, weight). – A value computed by dividing the object’s volume by a conversion factor; 

it may be used for the calculation of charges when the value is greater than the actual weight. [5.58]

(Added 2004)

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D-11

direct sale. – A sale in which both parties in the transaction are present when the quantity is being determined. An 

unattended automated or customer-operated weighing or measuring system is considered to represent the 

device/business owner in transactions involving an unattended device. [1.10]

(Amended 1993)

discharge hose. – A flexible hose connected to the discharge outlet of a measuring device or its discharge line. [3.30, 

3.31, 3.32, 3.34, 3.37, 3.38]

(Added 1987)

discharge line. – A rigid pipe connected to the outlet of a measuring device. [3.30, 3.31, 3.32, 3.34, 3.37]

(Added 1987)

discrimination (of an automatic-indicating scale). – The value of the test load on the load-receiving element of the 

scale that will produce a specified minimum change of the indicated or recorded value on the scale. [2.20, 2.22]

dispenser. – See motor-fuel device. [3.30, 3.37]

distributed-car test train. – A train consisting of cars weighed first on a reference scale, cars coupled consecutively 

in groups at different locations within the train, then run over the coupled-in-motion railway track scale under test. 

The groups are typically placed at the front, middle, and rear of the train. [2.20]

(Added 1990)

dry hose. – A discharge hose intended to be completely drained at the end of each delivery of product. (Also see

“dry-hose type.”) [3.30, 3.31]

(Amended 2002)

dry-hose type. – A type of device in which it is intended that the discharge hose be completely drained following the 

mechanical operations involved in each delivery. (Also see “dry hose.”) [3.30, 3.31, 3.34, 3.35]

dynamic monorail weighing system. – A weighing system which employs hardware or software to compensate for 

dynamic effects from the load or the system that do not exist in static weighing, in order to provide a stable indication. 

Dynamic factors may include shock or impact loading, system vibrations, oscillations, etc., and can occur even when 

the load is not moving across the load-receiving element. [2.20]

(Added 1999)

E 

e, value of verification scale division. – See “verification scale division, value of (e).” [2.20]

Emax (maximum capacity). – Largest value of a quantity (mass) which may be applied to a load cell without exceeding 

the mpe. [2.20]

(Added 2005)

Emin (minimum dead load). – Smallest value of a quantity (mass) which may be applied to a load cell during test or 

use without exceeding the mpe. [2.20]

(Added 2006)

emin (minimum verification scale division). – The smallest scale division for which a weighing element complies 

with the applicable requirements. [2.20, 2.21, 2.24]

(Added 1997)

electronic link. – An electronic connection between the weighing/load-receiving or other sensing element and 

indicating element where one recognizes the other and neither can be replaced without calibration. [2.20]

(Added 2001)

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Appendix D – Definitions Handbook 44 – 2016 

D-12

element. – A portion of a weighing or measuring device or system which performs a specific function and can be 

separated, evaluated separately, and is subject to specified full or partial error limits.

(Added 2002)

equal-arm scale. – A scale having only a single lever with equal arms (that is, with a multiple of one), equipped with 

two similar or dissimilar load-receiving elements (pan, plate, platter, scoop, or the like), one intended to receive 

material being weighed and the other intended to receive weights. There may or may not be a weighbeam. [2.20]

equipment, commercial. – Weights, measures, and weighing and measuring devices, instruments, elements, and 

systems or portion thereof, used or employed in establishing the measurement or in computing any basic charge or 

payment for services rendered on the basis of weight or measure. As used in this definition, measurement includes 

the determination of size, quantity, value, extent, area, composition (limited to meat and poultry), constituent value 

(for grain), or measurement of quantities, things, produce, or articles for distribution or consumption, purchased, 

offered, or submitted for sale, hire, or award. [1.10, 2.20, 2.21, 2.22, 2.24, 3.30, 3.31, 3.32, 3.33, 3.34, 3.35, 3.38, 4.40, 

5.51, 5.56.(a), 5.56.(b), 5.57, 5.58, 5.59]

(Added 2008)

event counter. – A non-resettable counter that increments once each time the mode that permits changes to sealable 

parameters is entered and one or more changes are made to sealable calibration or configuration parameters of a 

device. [2.20, 2.21, 3.30, 3.37, 5.54, 5.56(a), 5.56(b), 5.57]

(Added 1993) 

event logger. – A form of audit trail containing a series of records where each record contains the number from the event 

counter corresponding to the change to a sealable parameter, the identification of the parameter that was changed, the time 

and date when the parameter was changed, and the new value of the parameter. [2.20, 2.21, 3.30, 3.37, 5.54, 5.56(a), 5.56(b), 

5.57]

(Added 1993)

excess and deficiency. – When an instrument or device is of such a character that it has a value of its own that can be 

determined, its error is said to be “in excess” or “in deficiency,” depending upon whether its actual value is, 

respectively, greater or less than its nominal value. (Also see “nominal.”) Examples of instruments having errors “in 

excess” are: a linear measure that is too long; a liquid measure that is too large; and a weight that is “heavy.” Examples 

of instruments having errors “in deficiency” are: a lubricating-oil bottle that is too small; a vehicle tank compartment 

that is too small; and a weight that is “light.” [1.10]

extras. – Charges to be paid by a passenger in addition to the fare, including any charge at a flat rate for the 

transportation of passengers in excess of a stated number and any charge for the transportation of baggage. [5.54]

F 

face. – That side of a taximeter on which passenger charges are indicated. [5.54]

face. – That portion of a computing-type pump or dispenser which displays the actual computation of price per unit, 

delivered quantity, and total sale price. In the case of some electronic displays, this may not be an integral part of the 

pump or dispenser. [3.30]

(Added 1987)

fare. – That portion of the charge for the hire of a vehicle that is automatically calculated by a taximeter through the 

operation of the distance and/or time mechanism. [5.54]

farm milk tank. – A unit for measuring milk or other fluid dairy product, comprising a combination of (1) a stationary 

or portable tank, whether or not equipped with means for cooling its contents, (2) means for reading the level of liquid 

in the tank, such as a removable gauge rod or a surface gauge, and (3) a chart for converting level-of-liquid readings 

to volume; or such a unit in which readings are made on a gauge rod or surface gauge directly in terms of volume. 

Each compartment of a subdivided tank shall, for purposes of this code, be construed to be a “farm milk tank.” [4.43]

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D-13

feeding mechanism. – The means for depositing material to be weighed on the belt conveyor. [2.21]

fifth wheel. – A commercially-available distance-measuring device which, after calibration, is recommended for use 

as a field transfer standard for testing the accuracy of taximeters and odometers on rented vehicles. [5.53, 5.54]

fifth-wheel test. – A distance test similar to a road test, except that the distance traveled by the vehicle under test is 

determined by a mechanism known as a “fifth wheel” that is attached to the vehicle and that independently measures 

and indicates the distance. [5.53, 5.54]

flag. – A plate at the end of the lever arm or similar part by which the operating condition of a taximeter is controlled 

and indicated. [5.54]

fractional bar. – A weighbeam bar of relatively small capacity for obtaining indications intermediate between notches 

or graduations on a main or tare bar. [2.20]

ft3

/h. – Cubic feet per hour. [3.33]

G 

gasoline gallon equivalent (GGE). – Gasoline gallon equivalent (GGE) means 5.660 pounds of natural gas. [3.37]

(Added 1994)

gasoline liter equivalent (GLE). – Gasoline liter equivalent (GLE) means 0.678 kilograms of natural gas. [3.37]

(Added 1994)

gauge pressure. – The difference between the pressure at the meter and the atmospheric pressure (psi). [3.33]

gauge rod. – A graduated, “dip-stick” type of measuring rod designed to be partially immersed in the liquid and to be 

read at the point where the liquid surface crosses the rod. [4.42]

gauging. – The process of determining and assigning volumetric values to specific graduations on the gauge or gauge 

rod that serve as the basis for the tank volume chart. [4.42]

graduated interval. – The distance from the center of one graduation to the center of the next graduation in a series 

of graduations. – (Also see “value of minimum graduated interval.”) [1.10]

graduation. – A defining line or one of the lines defining the subdivisions of a graduated series. The term includes 

such special forms as raised or indented or scored reference “lines” and special characters such as dots. (Also see 

“main graduation” and “subordinate graduation.”) [1.10]

grain class. – Different grains within the same grain type. For example, there are six classes for the grain type 

“wheat:” Durum Wheat, Hard Red Spring Wheat, Hard Red Winter Wheat, Soft Red Winter Wheat, Hard White 

Wheat, and Soft White Wheat. [5.56(a), 5.57]

(Added 2007)

grain hopper scale. – One adapted to the weighing of individual loads of varying amounts of grain. [2.20]

grain moisture meter. – Any device indicating either directly or through conversion tables and/or correction tables 

the moisture content of cereal grains and oil seeds. Also termed “moisture meter.” [5.56(a), 5.56(b)]

grain sample. – That portion of grain or seed taken from a bulk quantity of grain or seed to be bought or sold and 

used to determine the moisture content of the bulk. [5.56(a), 5.56(b)]

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Appendix D – Definitions Handbook 44 – 2016 

D-14

grain-test scale. – A scale adapted to weighing grain samples used in determining moisture content, dockage, weight 

per unit volume, etc. [2.20]

grain type. – See “kind of grain.” [5.56(a), 5.57]

(Added 2007)

gravity discharge. – A type of device designed for discharge by gravity. [3.30, 3.31]

H 

head pulley. – The pulley at the discharge end of the belt conveyor. The power drive to drive the belt is generally 

applied to the head pulley. [2.21]

hexahedron. – A geometric solid (i.e., box) with six rectangular or square plane surfaces. [5.58]

(Added 2008)

hired. – A taximeter is “hired” when it is operative with respect to all applicable indications of fare or extras. The 

indications of fare include time and distance where applicable unless qualified by another indication of “Time Not 

Recording” or an equivalent expression. [5.54]

hopper scale. – A scale designed for weighing bulk commodities whose load-receiving element is a tank, box, or 

hopper mounted on a weighing element. (Also see “automatic hopper scale,” “grain hopper scale,” and “construction 

materials hopper scale.”) [2.20]

I 

idler space. – The center-to-center distance between idler rollers measured parallel to the belt. [2.21]

idlers or idler rollers. – Freely turning cylinders mounted on a frame to support the conveyor belt. For a flat belt, 

the idlers consist of one or more horizontal cylinders transverse to the direction of belt travel. For a troughed belt, the 

idlers consist of one or more horizontal cylinders and one or more cylinders at an angle to the horizontal to lift the 

sides of the belt to form a trough. [2.21]

in-service light indicator. – A light used to indicate that a timing device is in operation. [5.55]

increasing-load test. – The normal basic performance test for a scale in which observations are made as increments 

of test load are successively added to the load-receiving element of the scale. [2.20, 2.22]

increment. – The value of the smallest change in value that can be indicated or recorded by a digital device in normal 

operation. [1.10]

index of an indicator. – The particular portion of an indicator that is directly utilized in making a reading. [1.10]

indicating element. – An element incorporated in a weighing or measuring device by means of which its performance 

relative to quantity or money value is “read” from the device itself as, for example, an index-and-graduated-scale 

combination, a weighbeam-and-poise combination, a digital indicator, and the like. (Also see “primary indicating or 

recording element.”) [1.10]

indicator, balance. – See “balance indicator.” [2.20]

initial distance or time interval. – The interval corresponding to the initial money drop. [5.54]

initial zero-setting mechanism. – See “initial zero-setting mechanism” under “zero-setting mechanism.” [2.20]

(Added 1990)

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D-15

integrator. – A device used with a belt-conveyor scale that combines conveyor belt load (e.g., lb/ft) and belt travel 

(e.g., feet) to produce a total weight of material passing over the belt-conveyor scale. An integrator may be a separate, 

detached mechanism or may be a component within a totalizing device. (Also see “master weight totalizer.”) [2.21]

(Added 2013) 

interval, clear, between graduations. – See “clear interval between graduations.” [1.10]

interval, graduated. – See “graduated interval.” [1.10]

irregularly-shaped object. – Any object that is not a hexahedron shape. [5.58]

(Added 2008)

J 

jewelers’ scale. – One adapted to weighing gems and precious metals. [2.20]

K 

kind of grain. – Corn as distinguished from soybeans as distinguished from wheat, etc. [5.56(a), 5.56(b)]

L 

label. – A printed ticket, to be attached to a package, produced by a printer that is a part of a prepackaging scale or 

that is an auxiliary device. [2.20]

large-delivery device. – Devices used primarily for single deliveries greater than 200 gallons, 2000 pounds, 

20 000 cubic feet, 2000 liters, or 2000 kilograms. [3.34, 3.38]

laundry-drier timer. – A timer used in conjunction with a coin-operated device to measure the period of time that a 

laundry drier is in operation. [5.55]

liquefied petroleum gas. – A petroleum product composed predominantly of any of the following hydrocarbons or 

mixtures thereof: propane, propylene, butanes (normal butane or isobutane), and butylenes. [3.31, 3.32, 3.33, 3.34, 

3.37]

liquefied petroleum gas liquid-measuring device. – A system including a mechanism or machine of the meter type 

designed to measure and deliver liquefied petroleum gas in the liquid state by a definite quantity, whether installed in 

a permanent location or mounted on a vehicle. Means may or may not be provided to indicate automatically, for one 

of a series of unit prices, the total money value of the liquid measured. [3.33]

(Amended 1987)

liquefied petroleum gas vapor-measuring device. – A system including a mechanism or device of the meter type, 

equipped with a totalizing index, designed to measure and deliver liquefied petroleum gas in the vapor state by definite 

volumes, and generally installed in a permanent location. The meters are similar in construction and operation to the 

conventional natural- and manufactured-gas meters. [3.33]

liquid fuel. – Any liquid used for fuel purposes, that is, as a fuel, including motor-fuel. [3.30, 3.31]

liquid volume correction factor. – A correction factor used to adjust the liquid volume of a cryogenic product at the 

time of measurement to the liquid volume at NBP. [3.34]

liquid-fuel device. – A device designed for the measurement and delivery of liquid fuels. [3.30]

liquid-measuring device. – A mechanism or machine designed to measure and deliver liquid by definite volume. 

Means may or may not be provided to indicate automatically, for one of a series of unit prices, the total money value 

of the liquid measured, or to make deliveries corresponding to specific money values at a definite unit price. [3.30]

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Appendix D – Definitions Handbook 44 – 2016 

D-16

livestock scale. – A scale equipped with stock racks and gates and adapted to weighing livestock standing on the scale 

platform. [2.20]

(Amended 1989)

load cell. – A device, whether electric, hydraulic, or pneumatic, that produces a signal (change in output) proportional 

to the load applied. [2.20, 2.21, 2.23]

load cell verification interval (v). – The load cell interval, expressed in units of mass, used in the test of the load cell 

for accuracy classification. [2.20, 2.21]

(Added 1996)

loading point. – A location on a conveyor where the material is received by the belt. The location of the discharge 

from a hopper, chute, or pre-feed device used to supply material to a conveyor. [2.21]

(Amended 2013)

load-receiving element. – That element of a scale that is designed to receive the load to be weighed; for example, 

platform, deck, rail, hopper, platter, plate, scoop. [2.20, 2.21, 2.23]

low-flame test. – A test simulating extremely low-flow rates such as caused by pilot lights. [3.33]

lubricant device. – A device designed for the measurement and delivery of liquid lubricants, including, but not limited 

to, heavy gear lubricants and automatic transmission fluids (automotive). [3.30]

M 

m3/h. – Cubic meters per hour.[3.33]

main bar. – A principal weighbeam bar, usually of relatively large capacity as compared with other bars of the same 

weighbeam. (On an automatic-indicating scale equipped with a weighbeam, the main weighbeam bar is frequently 

called the “capacity bar.”) [2.20]

main graduation. – A graduation defining the primary or principal subdivisions of a graduated series. (Also see 

“graduation.”) [1.10]

main-weighbeam elements. – The combination of a main bar and its fractional bar, or a main bar alone if no fractional 

bar is associated with it. [2.20]

manual zero-setting mechanism. – See “manual zero-setting mechanism” under “zero-setting mechanism.” [2.20]

manufactured device. – Any commercial weighing or measuring device shipped as new from the original equipment 

manufacturer. [1.10]

(Amended 2001)

mass flow meter. – A device that measures the mass of a product flowing through the system. The mass measurement 

may be determined directly from the effects of mass on the sensing unit or may be inferred by measuring the properties 

of the product, such as the volume, density, temperature, or pressure, and displaying the quantity in mass units. [3.37]

master meter test method. – A method of testing milk tanks that utilizes an approved master meter system for 

measuring test liquid removed from or introduced into the tank. [4.42]

master weight totalizer. – A primary indicating element used with a belt-conveyor scale that incorporates the function 

of an integrator to indicate the totalized weight of material passed over the scale. (Also see “integrator.”) [2.21]

(Amended 2013) 

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Handbook 44 – 2016 Appendix D – Definitions

D-17

material test. – The test of a belt-conveyor scale using material (preferably that for which the device is normally 

used) that has been weighed to an accuracy of 0.1 %. [2.21]

(Amended 1989)

maximum capacity. – The largest load that may be accurately weighed. [2.20, 2.24]

(Added 1999)

maximum cargo load. – The maximum cargo load for trucks is the difference between the manufacturer’s rated gross 

vehicle weight and the actual weight of the vehicle having no cargo load. [5.53]

measurement field. – A region of space or the measurement pattern produced by the measuring instrument in which 

objects are placed or passed through, either singly or in groups, when being measured by a single device. [5.58]

measuring element. – That portion of a complete multiple dimension measuring device that does not include the 

indicating element. [5.58]

meter register. – An observation index for the cumulative reading of the gas flow through the meter. In addition 

there are one or two proving circles in which one revolution of the test hand represents 1⁄2, 1, 2, 5, or 10 cubic feet, or 

0.025, 0.05, 0.1, 0.2, or 0.25 cubic meter, depending on meter size. If two proving circles are present, the circle 

representing the smallest volume per revolution is referred to as the “leak-test circle.” [3.33]

metrological integrity (of a device). – The design, features, operation, installation, or use of a device that facilitates 

(1) the accuracy and validity of a measurement or transaction, (2) compliance of the device with weights and measures 

requirements, or (3) the suitability of the device for a given application. [1.10, 2.20]

(Added 1993)

minimum capacity. – The smallest load that may be accurately weighed. The weighing results may be subject to 

excessive error if used below this value. [2.20, 2.24]

(Added 1999)

minimum clear interval. – The shortest distance between adjacent graduations when the graduations are not parallel. 

(Also see “clear interval.”) [3.30, 3.31, 3.32, 3.33, 3.34, 3.35, 3.36, 3.38, 5.50, 5.51, 5.56(b)]

minimum delivery. – The least amount of weight that is to be delivered as a single weighment by a belt-conveyor 

scale system in normal use. [2.21]

minimum tolerance. – Minimum tolerances are the smallest tolerance values that can be applied to a scale. Minimum 

tolerances are determined on the basis of the value of the minimum graduated interval or the nominal or reading face 

capacity of the scale. (Also see definition for basic tolerances.) [2.20, 2.22, 2.24]

minimum totalized load. – The least amount of weight for which the scale is considered to be performing accurately.

[2.21]

moisture content (wet basis). – The mass of water in a grain or seed sample (determined by the reference method) 

divided by the mass of the grain or seed sample expressed as a percentage (%). [5.56(a), 5.56(b)]

money drop. – An increment of fare indication. The “initial money drop” is the first increment of fare indication 

following activation of the taximeter. [5.54]

money-operated type. – A device designed to be released for service by the insertion of money, or to be actuated by 

the insertion of money to make deliveries of product. [1.10]

motor-fuel. – Liquid used as fuel for internal-combustion engines. [3.30]

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Appendix D – Definitions Handbook 44 – 2016 

D-18

motor-fuel device or motor-fuel dispenser or retail motor-fuel device. – A device designed for the measurement 

and delivery of liquids used as fuel for internal-combustion engines. The term “motor-fuel dispenser” means the same 

as “motor-fuel device”; the term “retail motor-fuel device” applies to a unique category of device. (Also see definition 

of “retail device.”) [3.30, 3.32, 3.37]

multi-class. – A description of a grouping of grain classes, from the same grain type, in one calibration. A multi-class 

grain calibration may include (1) all the classes of a grain type (all-class calibration), or (2) some of the classes of a 

grain type within the calibration. [5.56(a), 5.57.]

(Added 2007)

multi-interval scale. – A scale having one weighing range which is divided into partial weighing ranges (segments), 

each with different scale intervals, with each partial weighing range (segment) determined automatically according to 

the load applied, both on increasing and decreasing loads. [2.20]

(Added 1995)

multi-jet water meter. – A water meter in which the moving element takes the form of a multiblade rotor mounted 

on a vertical spindle within a cylindrical measuring chamber. The liquid enters the measuring chamber through several 

tangential orifices around the circumference and leaves the measuring chamber through another set of tangential 

orifices placed at a different level in the measuring chamber. These meters register by recording the revolutions of a 

rotor set in motion by the force of flowing water striking the blades. [3.36]

(Added 2003)

multi-revolution scale. – An automatic-indicating scale having a nominal capacity that is a multiple of the 

reading-face capacity and that is achieved by more than one complete revolution of the indicator. [2.20]

multiple. – An integral multiple; that is, a result obtained by multiplying by a whole number. (Also see “multiple of 

a scale.”) [1.10]

multiple cell application load cell. – A load cell intended for use in a weighing system which incorporates more than 

one load cell. A multiple cell application load cell is designated with the letter “M” or the term “Multiple.” (Also see 

“single cell application load cell.”) [2.20]

(Added 1999)

multiple of a scale. – In general, the multiplying power of the entire system of levers or other basic weighing elements. 

(On a beam scale, the multiple of the scale is the number of pounds on the load-receiving element that will be 

counterpoised by one pound applied to the tip pivot of the weighbeam.) [2.20]

multiple range scale. – A scale having two or more weighing ranges with different maximum capacities and different 

scale intervals for the same load receptor, each range extending from zero to its maximum capacity. [2.20]

(Added 1995)

multiple-tariff taximeter. – One that may be set to calculate fares at any one of two or more rates. [5.54]

N 

natural gas. – A gaseous fuel, composed primarily of methane, that is suitable for compression and dispensing into a 

fuel storage container(s) for use as an engine fuel. [3.37]

(Added 1994)

NBP. – Normal Boiling Point of a cryogenic liquid at 14.696 lb/in2 absolute. [3.34]

nmax (maximum number of scale divisions). – The maximum number of scale divisions for which a main element or 

load cell complies with the applicable requirements. The maximum number of scale divisions permitted for an 

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D-19

installation is limited to the lowest nmax marked on the scale indicating element, weighing element, or load cell. [2.20, 

2.21, 2.24]

(Added 1997)

no-load reference value. – A positive weight value indication with no load in the load-receiving element (hopper) of 

the scale. (Used with automatic bulk-weighing systems and certain single-draft, manually-operated receiving hopper 

scales installed below grade and used to receive grain.) [2.20]

nominal. – Refers to “intended” or “named” or “stated,” as opposed to “actual.” For example, the “nominal” value of 

something is the value that it is supposed or intended to have, the value that it is claimed or stated to have, or the value by 

which it is commonly known. Thus, “1-pound weight,” “1-gallon measure,” “1-yard indication,” and “500-pound scale” 

are statements of nominal values; corresponding actual values may be greater or lesser. (Also see nominal capacity of a 

scale.) [1.10]

nominal capacity. – The nominal capacity of a scale is (a) the largest weight indication that can be obtained by the 

use of all of the reading or recording elements in combination, including the amount represented by any removable 

weights furnished or ordinarily furnished with the scale, but excluding the amount represented by any extra removable 

weights not ordinarily furnished with the scale, and excluding also the capacity of any auxiliary weighing attachment 

not contemplated by the original design of the scale, and excluding any fractional bar with a capacity less than 21⁄2 % 

of the sum of the capacities of the remaining reading elements, or (b) the capacity marked on the scale by the 

manufacturer, whichever is less. (Also see “nominal capacity, batching scale”; “nominal capacity, hopper scale.”)

[2.20]

nominal capacity, batching scale. – The nominal capacity of a batching scale is the capacity as marked on the scale 

by the scale manufacturer, or the sum of the products of the volume of each of the individual hoppers, in terms of 

cubic feet, times the weight per cubic foot of the heaviest material weighed in each hopper, whichever is less. [2.20]

nominal capacity, hopper scale. – The nominal capacity of a hopper scale is the capacity as marked on the scale by 

the scale manufacturer, or the product of the volume of the hopper in bushels or cubic feet times the maximum weight 

per bushel or cubic foot, as the case may be, of the commodity normally weighed, whichever is less. [2.20]

non-automatic checkweigher. – A weighing instrument that requires the intervention of an operator during the weighing 

process, used to subdivide items of different weights into one or more subgroups, such as identifying packages that have 

acceptable or unacceptable fill levels according to the value of the difference between their weight and a pre-determined set 

point. [2.24]

Notes: Determining the weighing result includes any intelligent action of the operator that affects the result, such 

as deciding and taking an action when an indication is stable or adjusting the weight of the weighed load.

Deciding the weighing result is acceptable means making a decision regarding the acceptance of each weighing 

result on observing the indication or releasing a print-out. The weighing process allows the operator to take an 

action which influences the weighing result in the case where the weighing result is not acceptable.

(Added 2004)

non-automatic weighing instrument. – A weighing instrument or system that requires the intervention of an operator 

during the weighing process to determine the weighing result or to decide that it is acceptable. [2.20, 2.24]

Notes: Determining the weighing result includes any intelligent action of the operator that affects the result, such 

as deciding and taking an action when an indication is stable or adjusting the weight of the weighed load.

Deciding the weighing result is acceptable means making a decision regarding the acceptance of each weighing 

result on observing the indication or releasing a print-out. The weighing process allows the operator to take an 

action which influences the weighing result in the case where the weighing result is not acceptable.

(Added 2004) (Amended 2005)

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Appendix D – Definitions Handbook 44 – 2016 

D-20

nonretroactive. – “Nonretroactive” requirements are enforceable after the effective date for:

1. devices manufactured within a state after the effective date;

2. both new and used devices brought into a state after the effective date; and

3. devices used in noncommercial applications which are placed into commercial use after the effective date.

Nonretroactive requirements are not enforceable with respect to devices that are in commercial service in the state as 

of the effective date or to new equipment in the stock of a manufacturer or a dealer in the state as of the effective date. 

(Nonretroactive requirements are printed in italic type.) [1.10]

(Amended 1989)

nose-iron. – A slide-mounted, manually-adjustable pivot assembly for changing the multiple of a lever. [2.20]

notes. – A section included in each of a number of codes, containing instructions, pertinent directives, and other 

specific information pertaining to the testing of devices. Notes are primarily directed to weights and measures 

officials.

NTP. – Normal Temperature and Pressure of a cryogen at a temperature of 21 °C (70 °F) and a pressure of 

101.325 kPa (14.696 lb/in2 absolute). [3.34]

NTP density and volume correction factor. – A correction factor used to adjust the liquid volume of a cryogenic 

product at the time of measurement to the gas equivalent at NTP. [3.34]

O 

odometer. – A device that automatically indicates the total distance traveled by a vehicle. For the purpose of this 

code, this definition includes hub odometers, cable-driven odometers, and the distance-indicating or odometer portions 

of “speedometer” assemblies for automotive vehicles. [5.53]

official grain samples. – Grain or seed used by the official as the official transfer standard from the reference standard 

method to test the accuracy and precision of grain moisture meters. [5.56(a), 5.56(b)]

official with statutory authority. – The representative of the jurisdiction(s) responsible for certifying the accuracy 

of the device. [2.20, 2.21, 2.22]

(Added 1991)

operating tire pressure. – The pressure in a tire immediately after a vehicle has been driven for at least 5 miles or 

8 kilometers. [5.53, 5.54]

over-and-under indicator. – An automatic-indicating element incorporated in or attached to a scale and comprising 

an indicator and a graduated scale with a central or intermediate “zero” graduation and a limited range of weight 

graduations on either side of the zero graduation, for indicating weights greater than and less than the predetermined 

values for which other elements of the scale may be set. (A scale having an over-and-under indicator is classed as an 

automatic-indicating scale.) [2.20]

overregistration and underregistration. – When an instrument or device is of such a character that it indicates or 

records values as a result of its operation, its error is said to be in the direction of overregistration or underregistration, 

depending upon whether the indications are, respectively, greater or less than they should be. Examples of devices 

having errors of “overregistration” are: a fabric-measuring device that indicates more than the true length of material 

passed through it; and a liquid-measuring device that indicates more than the true amount of the liquid delivered by 

the device. Examples of devices having errors of “underregistration” are: a meter that indicates less than the true 

amount of product that it delivers; and a weighing scale that indicates or records less than the true weight of the applied 

load. [1.10]

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D-21

P 

parallax. – The apparent displacement, or apparent difference in height or width, of a graduation or other object with 

respect to a fixed reference, as viewed from different points. [1.10]

parking meter. – A coin-operated device for measuring parking time for vehicles. [5.55]

passenger vehicles. – Vehicles such as automobiles, recreational vehicles, limousines, ambulances, and hearses.

[5.53]

performance requirements. – Performance requirements include all tolerance requirements and, in the case of 

nonautomatic-indicating scales, sensitivity requirements (SR). (Also see definitions for “tolerance” and “sensitivity 

requirement.”) [1.10]

point-of-sale system. – An assembly of elements including a weighing or measuring element, an indicating element, 

and a recording element (and may also be equipped with a “scanner”) used to complete a direct sales transaction. The 

system components, when operated together, must be capable of the following:

1. determining the weight or measure of a product or service offered;

2. calculating a charge for the product or service based on the weight or measure and an established price/rate 

structure;

3. determining a total cost that includes all associated charges involved with the transaction; and

4. providing a sales receipt.

[2.20, 3.30, 3.32, 3.37]

(Added 1986) (Amended 1997 and 2015) 

poise. – A movable weight mounted upon or suspended from a weighbeam bar and used in combination with 

graduations, and frequently with notches, on the bar to indicate weight values. (A suspended poise is commonly called 

a “hanging poise.”) [2.20]

postal scale. – A scale (usually a computing scale) designed for use to determine shipping weight or delivery charges 

for letters or parcels delivered by the U.S. Postal Service or private shipping companies. A weight classifier may be 

used as a postal scale. [2.20]

(Added 1987)

prepackaging scale. – A computing scale specially designed for putting up packages of random weights in advance 

of sale. [2.20]

prescription scale. – A scale or balance adapted to weighing the ingredients of medicinal and other formulas 

prescribed by physicians and others and used or intended to be used in the ordinary trade of pharmacists. [2.20]

pressure type (device). – A type of device designed for operation with the liquid under artificially produced pressure.

[3.30, 3.31]

primary indicating or recording elements. – The term “primary” is applied to those principal indicating (visual) 

elements and recording elements that are designed to, or may, be used by the operator in the normal commercial use 

of a device. The term “primary” is applied to any element or elements that may be the determining factor in arriving 

at the sale representation when the device is used commercially. (Examples of primary elements are the visual 

indicators for meters or scales not equipped with ticket printers or other recording elements and both the visual 

indicators and the ticket printers or other recording elements for meters or scales so equipped.) The term “primary”

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Appendix D – Definitions Handbook 44 – 2016 

D-22

is not applied to such auxiliary elements as, for example, the totalizing register or predetermined-stop mechanism on 

a meter or the means for producing a running record of successive weighing operations, these elements being 

supplementary to those that are the determining factors in sales representations of individual deliveries or weights. 

(Also see “indicating element” and “recording element.”) [1.10]

prover method. – A method of testing milk tanks that utilizes approved volumetric prover(s) for measuring the test 

liquid removed from or introduced into the tank. [4.42]

prover oil. – A light oil of low vapor pressure used as a sealing medium in bell provers, cubic-foot bottles, and 

portable cubic-foot standards. [3.33]

proving indicator. – The test hand or pointer of the proving or leak-test circle on the meter register or index. [3.33, 

3.36.]

R 

“r” factor. – A computation for determining the suitability of a vehicle scale for weighing vehicles with varying axle 

configurations. The factor was derived by dividing the weights in FHWA Federal Highway Bridge Gross Weight 

Table B by 34 000 lbs. (The resultant factors are contained in Table UR.3.2.1.) [2.20]

radio frequency interference (RFI). – Radio frequency interference is a type of electrical disturbance that, when 

introduced into electronic and electrical circuits, may cause deviations from the normally expected performance. [1.10]

random error(s). – The sample standard deviation of the error (indicated values) for a number of consecutive 

automatic weighings of a load, or loads, passed over the load receptor, shall be expressed mathematically as:

( ) ( )2 2 2 1

1

1

1

 or i X X

n n

X X i i n s s −

− −

     

∑ = −= ∑ ∑

where: X = error of a load indication

 n = the number of loads

[2.24]

ranges, weight. – See “weight ranges.” [2.20]

rated capacity. – The rate of flow in cubic meters per hour of a hydrocarbon gas vapor-measuring device as 

recommended by the manufacturer. This rate of flow should cause a pressure drop across the meter not exceeding 

1⁄2-inch water column. [3.33]

rated scale capacity. – That value representing the weight that can be delivered by the device in one hour. [2.21]

ratio test. – A test to determine the accuracy with which the actual multiple of a scale agrees with its designed multiple. 

This test is used for scales employing counterpoise weights and is made with standard test weights substituted in all 

cases for the weights commercially used on the scale. (It is appropriate to use this test for some scales not employing 

counterpoise weights.) [2.20]

reading face. – That portion of an automatic-indicating weighing or measuring device that gives a visible indication 

of the quantity weighed or measured. A reading face may include an indicator and a series of graduations or may 

present values digitally, and may also provide money-value indications. [1.10, 2.20]

(Amended 2005)

reading-face capacity. – The largest value that may be indicated on the reading face, exclusive of the application or 

addition of any supplemental or accessory elements. [1.10]

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Handbook 44 – 2016 Appendix D – Definitions

D-23

recorded representation. – The printed, embossed, or other representation that is recorded as a quantity by a weighing 

or measuring device. [1.10]

recording element. – An element incorporated in a weighing or measuring device by means of which its performance 

relative to quantity or money value is permanently recorded on a tape, ticket, card, or the like, in the form of a printed, 

stamped, punched, or perforated representation. [1.10, 2.21]

recording scale. – One on which the weights of applied loads may be permanently recorded on a tape, ticket, card, or 

the like in the form of a printed, stamped, punched, or perforated representation. [2.20]

reference weight car. – A railcar that has been statically weighed for temporary use as a mass standard over a short 

period of time, typically the time required to test one scale.

Note: A test weight car that is representative of the types of cars typically weighed on the scale under test may be 

used wherever reference weight cars are specified. [2.20]

(Added 1991) (Amended 2012)

remanufactured device. – A device that is disassembled, checked for wear, parts replaced or fixed, reassembled and 

made to operate like a new device of the same type. [1.10]

(Added 2001)

remanufactured element. – An element that is disassembled, checked for wear, parts replaced or fixed, reassembled 

and made to operate like a new element of the same type. [1.10]

(Added 2001)

remote configuration capability. – The ability to adjust a weighing or measuring device or change its sealable 

parameters from or through some other device that is not itself necessary to the operation of the weighing or measuring 

device or is not a permanent part of that device. [2.20, 2.21, 2.24, 3.30, 3.37, 5.56(a)]

(Added 1993)

repaired device. – A device to which work is performed that brings the device back into proper operating condition.

[1.10]

(Added 2001)

repaired element. – An element to which work is performed that brings the element back into proper operating 

condition. [1.10]

(Added 2001)

retail device. – A measuring device primarily used to measure product for the purpose of sale to the end user. [3.30, 

3.32, 3.37]

(Amended 1987 and 2004)

retroactive. – “Retroactive” requirements are enforceable with respect to all equipment. Retroactive requirements 

are printed herein in upright roman type. (Also see “nonretroactive.”) [1.10]

road test. – A distance test, over a measured course, of a complete taximeter assembly when installed on a vehicle, 

the mechanism being actuated as a result of vehicle travel. [5.53, 5.54]

rolling circumference. – The rolling circumference is the straight line distance traveled per revolution of the wheel 

(or wheels) that actuates the taximeter or odometer. If more than one wheel actuates the taximeter or odometer, the 

rolling circumference is the average distance traveled per revolution of the actuating wheels. [5.53, 5.54]

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Appendix D – Definitions Handbook 44 – 2016 

D-24

S 

scale. – See specific type of scale. [2.20]

scale area, belt-conveyor. – See belt-conveyor scale systems area. [2.21]

(Added 2001)

scale division, number of (n). – Quotient of the capacity divided by the value of the verification scale division. [2.20]

 e

Capacity n = 

scale division, value of (d). – The value of the scale division, expressed in units of mass, is the smallest subdivision 

of the scale for analog indication or the difference between two consecutively indicated or printed values for digital 

indication or printing. (Also see “verification scale division.”) [2.20, 2.22]

scale section. – A part of a vehicle, axle-load, livestock, or railway track scale consisting of two main load supports, 

usually transverse to the direction in which the load is applied. [2.20]

seal. – See “approval seal,” “security seal.” [1.10]

section capacity. – The section capacity of a scale is the maximum live load that may be divided equally on the load 

pivots or load cells of a section. [2.20]

(Added 2001)

section test. – A shift test in which the test load is applied over individual sections of the scale. This test is conducted 

to disclose the weighing performance of individual sections, since scale capacity test loads are not always available 

and loads weighed are not always distributed evenly over all main load supports. [2.20]

security means. – A method used to prevent access by other than qualified personnel, or to indicate that access has 

been made to certain parts of a scale that affect the performance of the device. [2.21]

security seal. – A uniquely identifiable physical seal, such as a lead-and-wire seal or other type of locking seal, a 

pressure-sensitive seal sufficiently permanent to reveal its removal, or similar apparatus attached to a weighing or 

measuring device for protection against or indication of access to adjustment. (Also see “approval seal.”) [1.10]

(Amended 1994)

selector-type. – A system of indication or recording in which the mechanism selects, by means of a ratchet-and-pawl 

combination or by other means, one or the other of any two successive values that can be indicated or recorded. [1.10]

semi-automatic zero-setting mechanism. – See “semi-automatic zero-setting mechanism” under “zero-setting 

mechanism.” [2.20]

sensitivity (of a nonautomatic-indicating scale). – The value of the test load on the load-receiving element of the 

scale that will produce a specified minimum change in the position of rest of the indicating element or elements of the 

scale. [2.20]

sensitivity requirement (SR). – A performance requirement for a non automatic-indicating scale; specifically, the 

minimum change in the position of rest of the indicating element or elements of the scale in response to the increase 

or decrease, by a specified amount, of the test load on the load-receiving element of the scale. [2.20]

shift test. – A test intended to disclose the weighing performance of a scale under off-center loading. [2.20]

side. – That portion of a pump or dispenser which faces the consumer during the normal delivery of product. [3.30]

(Added 1987)

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Handbook 44 – 2016 Appendix D – Definitions

D-25

simulated-road test. – A distance test during which the taximeter or odometer may be actuated by some means other 

than road travel. The distance traveled is either measured by a properly calibrated roller device or computed from 

rolling circumference and wheel-turn data. [5.53, 5.54]

simulated test. – A test using artificial means of loading the scale to determine the performance of a belt-conveyor 

scale. [2.21]

single cell application load cell. – A load cell intended for use in a weighing system which incorporates one or more 

load cells. A single cell application load cell is designated with the letter “S” or the term “Single.” (Also see “multiple 

cell application load cell.”) [2.20]

(Added 1999)

single-tariff taximeter. – One that calculates fares at a single rate only. [5.54]

skirting. – Stationary side boards or sections of belt conveyor attached to the conveyor support frame or other 

stationary support to prevent the bulk material from falling off the side of the belt. [2.21]

slow-flow meter. – A retail device designed for the measurement, at very slow rates (less than 40 L (10 gal) per 

hour), of liquid fuels at individual domestic installations. [3.30]

small-delivery device. – Any device other than a large-delivery device. [3.34, 3.38]

span (structural). The distance between adjoining sections of a scale. [2.20]

(Added 1988)

specification. – A requirement usually dealing with the design, construction, or marking of a weighing or measuring 

device. Specifications are directed primarily to the manufacturers of devices. [1.10]

static monorail weighing system. – A weighing system in which the load being applied is stationary during the 

weighing operation. [2.20]

(Added 1999)

strain-load test. – The test of a scale beginning with the scale under load and applying known test weights to 

determine accuracy over a portion of the weighing range. The scale errors for a strain-load test are the errors observed 

for the known test loads only. The tolerances to be applied are based on the known test load used for each error that 

is determined. [2.20, 2.22]

subordinate graduation. – Any graduation other than a main graduation. (Also see “graduation.”) [1.10]

subsequent distance or time intervals. – The intervals corresponding to money drops following the initial money 

drop. [5.54]

substitution test. – A scale testing process used to quantify the weight of material or objects for use as a known test load.

[2.20]

(Added 2003)

substitution test load. – The sum of the combination of field standard test weights and any other applied load used 

in the conduct of a test using substitution test methods. [2.20]

(Added 2003)

surface gauge. – A combination of (1) a stationary indicator, and (2) a movable, graduated element designed to be 

brought into contact with the surface of the liquid from above. [4.42]

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Appendix D – Definitions Handbook 44 – 2016 

D-26

systematic (average) error ( ) X . – The mean value of the error (of indication) for a number of consecutive 

automatic weighings of a load, or loads, passed over the load-receiving element (e.g., weigh-table), shall be expressed 

mathematically as:

where: x = error of a load indication

n = the number of loads

[2.24]

T 

tail pulley. – The pulley at the opposite end of the conveyor from the head pulley. [2.21]

take-up. – A device to provide sufficient tension in a conveyor belt so that the belt will be positively driven by the 

drive pulley. – A counter-weighted take-up consists of a pulley free to move in either the vertical or horizontal direction 

with dead weights applied to the pulley shaft to provide the tension required. [2.21]

tare mechanism. – A mechanism (including a tare bar) designed for determining or balancing out the weight of 

packaging material, containers, vehicles, or other materials that are not intended to be included in net weight 

determinations. [2.20]

tare-weighbeam elements. – The combination of a tare bar and its fractional bar, or a tare bar alone if no fractional 

bar is associated with it. [2.20]

taximeter. – A device that automatically calculates, at a predetermined rate or rates, and indicates the charge for hire 

of a vehicle. [5.54]

test chain. – A device used for simulated tests consisting of a series of rollers or wheels linked together in such a manner 

as to assure uniformity of weight and freedom of motion to reduce wear, with consequent loss of weight, to a minimum.

[2.21]

test liquid. – The liquid used during the test of a device. [3.30, 3.31, 3.34, 3.35, 3.36, 3.37, 3.38]

test object. – An object whose dimensions are verified by appropriate reference standards and intended to verify 

compliance of the device under test with certain metrological requirements. [5.58]

test puck. – A metal, plastic, or other suitable object that remains stable for the duration of the test, used as a test load to 

simulate a package. Pucks can be made in a variety of dimensions and have different weights to represent a wide range of 

package sizes. Metal versions may be covered with rubber cushions to eliminate the possibility of damage to weighing and 

handling equipment. The puck mass is adjusted to an accuracy specified in N.1.2. Accuracy of Test Pucks or Packages.

[2.24]

(Amended 2004)

test train. – A train consisting of or including reference weight cars and used to test coupled-in-motion railway track 

scales. The reference weight cars may be placed consecutively or distributed in different places within a train. [2.20]

(Added 1990) (Amended 1991)

test weight car. – A railroad car designed to be a stable mass standard to test railway track scales. The test weight 

car may be one of the following types: a self-contained composite car, a self-propelled car, or a standard rail car.

[2.20]

(Added 1991)

X

X

n = ∑

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Handbook 44 – 2016 Appendix D – Definitions

D-27

testing. – An operation consisting of a series of volumetric determinations made to verify the accuracy of the volume 

chart that was developed by gauging. [4.42]

time recorder. – A clock-operated mechanism designed to record the time of day. Examples of time recorders are 

those used in parking garages to record the “in” and “out” time of day for parked vehicles. [5.55]

timing device. – A device used to measure the time during which a particular paid-for service is dispensed. Examples 

of timing devices are laundry driers, car-wash timers, parking meters, and parking-garage clocks and recorders. [5.55]

tolerance. – A value fixing the limit of allowable error or departure from true performance or value. (Also see “basic 

tolerances.”) [1.10]

training idlers. – Idlers of special design or mounting intended to shift the belt sideways on the conveyor to assure 

the belt is centered on the conveying idlers. [2.21]

transfer standard. – A measurement system designed for use in proving and testing cryogenic liquid-measuring 

devices. [3.38]

tripper. – A device for unloading a belt conveyor at a point between the loading point and the head pulley. [2.21]

U 

uncoupled-in-motion railroad weighing system. – A device and related installation characteristics consisting of 

(1) the associated approach trackage, (2) the scale (i.e., the weighing element, the load-receiving element, and the 

indicating element with its software), and (3) the exit trackage, which permit the weighing of railroad cars uncoupled 

in motion. [2.20]

(Added 1993)

underregistration. – See “overregistration” and “underregistration.” [1.10]

unit price. – The price at which the product is being sold and expressed in whole units of measurement. [1.10, 3.30]

(Added 1992)

unit train. – A unit train is defined as a number of contiguous cars carrying a single commodity from one consignor 

to one consignee. The number of cars is determined by agreement among the consignor, consignee, and the operating 

railroad. [2.20]

unit weight. – One contained within the housing of an automatic-indicating scale and mechanically applied to and 

removed from the mechanism. The application of a unit weight will increase the range of automatic indication, 

normally in increments equal to the reading-face capacity. [2.20]

user requirement. – A requirement dealing with the selection, installation, use, or maintenance of a weighing or 

measuring device. User requirements are directed primarily to the users of devices. (Also see Introduction, 

Section Q.) [1.10]

usual and customary. – Commonly or ordinarily found in practice or in the normal course of events and in 

accordance with established practices. [1.10]

utility-type water meter. – 1) A device used for the measurement of water, generally applicable to meters installed 

in residences or business establishments. excluding batching meters. [3.36]

(Added 2011)

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Appendix D – Definitions Handbook 44 – 2016 

D-28

V 

value of minimum graduated interval. – (1) The value represented by the interval from the center of one graduation 

to the center of the succeeding graduation. (2) The increment between successive recorded values. (Also see 

“graduated interval.”) [1.10]

vapor equalization credit. – The quantity deducted from the metered quantity of liquid carbon dioxide when a vapor 

equalizing line is used to facilitate the transfer of liquid during a metered delivery. [3.38]

vapor equalization line. – A hose or pipe connected from the vapor space of the seller’s tank to the vapor space of 

the buyer’s tank that is used to equalize the pressure during a delivery. [3.38]

vehicle on-board weighing system. – A weighing system designed as an integral part of or attached to the frame, 

chassis, lifting mechanism, or bed of a vehicle, trailer, industrial truck, industrial tractor, or forklift truck. [2.20]

(Amended 1993)

vehicle scale. – A scale adapted to weighing highway, farm, or other large industrial vehicles (except railroad freight 

cars), loaded or unloaded. [2.20]

verification scale division, value of (e). – A value, expressed in units of weight (mass) and specified by the 

manufacturer of a device, by which the tolerance values and the accuracy class applicable to the device are determined. 

The verification scale division is applied to all scales, in particular to ungraduated devices since they have no 

graduations. The verification scale division (e) may be different from the displayed scale division (d) for certain other 

devices used for weight classifying or weighing in pre-determined amounts, and certain other Class I and II scales.

[2.20]

visible type. – A type of device in which the measurement takes place in a see-through glass measuring chamber.

[3.30]

vmin (minimum load cell verification interval). – The smallest load cell verification interval, expressed in units of 

mass* into which the load cell measuring range can be divided. [2.20, 2.24]

[*Nonretroactive as of January 1, 2001]

(Added 1996) (Amended 1999)

W 

weighbeam. – An element comprising one or more bars, equipped with movable poises or means for applying 

counterpoise weights or both. [2.20]

weigh-belt system. – A type of belt-conveyor scale system designed by the manufacturer as a self-contained conveyor 

system and that is installed as a unit. A unit is comprised of integral components and, at minimum, includes a: 

conveyor belt; belt drive; conveyor frame; and weighing system. A weigh-belt system may operate at single or 

multiple flow rates and may use variable-speed belt drives. [2.21]

(Added 2015)

weighing element. – That portion of a scale that supports the load-receiving element and transmits to the indicating 

element a signal or force resulting from the load applied to the load-receiving element. [2.20, 2.21, 2.22]

(Added 1988)

weigh-labeler. – An automatic weighing system that determines the weight of a package and prints a label or other 

document bearing a weight declaration for each discrete item (usually a label also includes unit and total price 

declarations). Weigh-labelers are sometimes used to weigh and label standard and random packages (also called 

“Prepackaging Scales”). [2.24]

(Amended 2004)

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D-29

weigh module – The portion of a load-receiving element supported by two sections. The length of a module is the 

distance to which load can be applied. [2.20]

(Added 2013) 

weighment. – A single complete weighing operation. [2.20, 2.21]

(Added 1986)

weight, unit. – See “unit weight.” [2.20]

weight classifier. – A digital scale that rounds weight values up to the next scale division. These scales usually have 

a verification scale division (e) that is smaller than the displayed scale division. [2.20]

(Added 1987)

weight ranges. – Electrical or electro-mechanical elements incorporated in an automatic indicating scale through the 

application of which the range of automatic indication of the scale is increased, normally in increments equal to the 

reading-face capacity. [2.20]

wet basis. – See “moisture content (wet basis).” [5.56(a), 5.56(b)]

wet hose. – A discharge hose intended to be full of product at all times. (Also see “wet-hose type.”) [3.30, 3.31, 3.38]

(Amended 2002)

wet-hose type. – A type of device designed to be operated with the discharge hose full of product at all times. (Also 

see “wet hose.”) [3.30, 3.32, 3.34, 3.37, 3.38]

(Amended 2002)

wheel-load weighers. – Compact, self-contained, portable weighing elements specially adapted to determining the 

wheel loads or axle loads of vehicles on highways for the enforcement of highway weight laws only. [2.20]

wholesale device. – Any device other than a retail device. (Also see “retail device.”) [3.30, 3.32]

wing pulley. – A pulley made of widely spaced metal bars in order to set up a vibration to shake loose material off 

the underside (return side) of the belt. [2.21]

Z 

zero-load balance. – A correct weight indication or representation of zero when there is no load on the load-receiving 

element. (Also see “zero-load balance for an automatic-indicating scale,” “zero-load balance for a 

nonautomatic-indicating scale,” “zero-load balance for a recording scale.”) [2.20]

zero-load balance, automatic-indicating scale. – A condition in which the indicator is at rest at, or oscillates through 

approximately equal arcs on either side of, the zero graduation. [2.20]

zero-load balance, nonautomatic-indicating scale. – A condition in which (a) the weighbeam is at rest at, or 

oscillates through approximately equal arcs above and below, the center of a trig loop; (b) the weighbeam or lever 

system is at rest at, or oscillates through approximately equal arcs above and below, a horizontal position or a position 

midway between limiting stops; or (c) the indicator of a balance indicator is at rest at, or oscillates through 

approximately equal arcs on either side of, the zero graduation. [2.20]

zero-load balance for a recording scale. – A condition in which the scale will record a representation of zero load.

[2.20]

zero-load reference (belt-conveyor scales). – A zero-load reference value represents no load on a moving conveyor 

belt. This value can be either; a number representing the electronic load cell output, a percentage of full scale capacity, 

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Appendix D – Definitions Handbook 44 – 2016 

D-30

or other reference value that accurately represents the no load condition of a moving conveyor belt. The no load 

reference value can only be updated after the completion of a zero load test.[2.21]

(Added 2002)

zero-setting mechanism. – Means provided to attain a zero balance indication with no load on the load-receiving 

element. The types of zero-setting mechanisms are: [2.20, 2.22, 2.24] 

automatic zero-setting mechanism (AZSM). – Automatic means provided to set the zero-balance indication 

without the intervention of an operator. [2.22] 

(Added 2010)

automatic zero-tracking (AZT) mechanism. – See “automatic zero-tracking (AZT) mechanism.” (NOTE: 

AZT maintains zero with specified limits. “Zero-setting sets/establishes zero with limits based on scale 

capacity.) [2.20, 2.22, 2.24]

initial zero-setting mechanism. – Automatic means provided to set the indication to zero at the time the 

instrument is switched on and before it is ready for use. [2.20]

(Added 1990)

manual zero-setting mechanism. – Nonautomatic means provided to attain a zero balance indication by the 

direct operation of a control. [2.20]

semiautomatic zero-setting mechanism. – Automatic means provided to attain a direct zero balance indication 

requiring a single initiation by an operator. [2.20]

(Amended 2010)

zero-setting mechanism (belt-conveyor scale). – A mechanism enabling zero totalization to be obtained over a whole 

number of belt revolutions. [2.21, 2.23]

(Added 2002)

zero-tracking mechanism. – See “automatic zero-tracking mechanism” under “zero-setting mechanism.” [2.20, 2.22, 

2.24]

zone of uncertainty. – The zone between adjacent increments on a digital device in which the value of either of the 

adjacent increments may be displayed. [2.20]

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This publication is available free of charge from: http://dx.doi.org/10.6028/NIST.HB.44-2016