SPECIFICATIONS,

United States

Department of

Commerce

Technology

Administration

National

Institute of

Standards and

Technology

TOLERANCES, AND

REQUIREMENTS FOR

OTHER TECHNICAL

WEIGHI GAD

MEASURrNG DEVICES

as adopted by the 84th

National Conference on

Weights and Measures 1999

H

NISTandbook 44

2000

") t ,:

.. .~.~

.,. . .. , .

'''.- -- - - ----
Specifications,

Tolerances, and 

Other Technical 

Requirements for

Weighing and 

Measuring Devices

as adopted by the 84th National Conference

on Weights and Measures 1999

44 NIST

Handbook 

2000 Edition (issued November 1999)

Supersedes Handbook 44 1999 Edition

Editors:

Tina G. Butcher

Terry L. Grimes

Richard Suiter

Juana Williams

NIST Office of Weights & Measuresres sG

Gilbert M. Ugiansky, Ph.D., Chie f ie f

Gaithersburg, MD 20899-2350

 

 U.S. Department of Commerce

 William M. Daley, Secretary

 Technology Administration

Dr.Cheryl L. Shavers,Under

 Secretary of Commerce

 for Technology

National Institute of Standards 

and Technology

Raymond G. Kammer,Director
National Institute of Standards and Technology Handbook 44, 2000 Edition

Natl. Inst. Stand. Technol. Handb. 44, 2000 Ed., pages (Nov. 1999)

CODEN: NIHAE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1999

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325
iii

Foreword

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

several forms, beginning in 1918.

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

and Measures. This 2000 edition was developed by the Committee on Specifications and Tolerances of the National

Conference on Weights and Measures, with the assistance of the Office of Weights and Measures of the National

Institute of Standards and Technology (NIST). The handbook includes amendments endorsed by the 84th National

Conference on Weights and Measures during its Annual Meeting in 1999.

The National Institute of Standards and Technology 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, the Institute is pleased to publish these recommendations of the National Conference.

Raymond G. Kammer

Director

National Institute of Standards

and Technology

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 inch-pound units where both units appear together and

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

in inch-pound units. In some cases, however, trade practice is currently restricted to the use of inch-pound units;

therefore, some requirements in this Handbook will continue to specify only inch-pound units until the Conference

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 National Conference on Weights and Measures.

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.
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Outline of Contents

Page

Foreword iii

1999 Amendments (2000 Edition) vii

Introduction 1

Section 1.

1.10. General Code 1-1

Section 2.

2.20. Scales 2-3

2.21. Belt-Conveyor Scale Systems 2-37

2.22. Automatic Bulk Weighing Systems 2-45

2.23. Weights 2-51

2.24. Automatic Weighing Systems - Tentative Code 2-55

Section 3.

3.30. Liquid-Measuring Devices 3-3

3.31. Vehicle-Tank Meters 3-19

3.32. Liquefied Petroleum Gas and Anhydrous

 Ammonia Liquid-Measuring Devices 3-27

3.33. Hydrocarbon Gas Vapor-Measuring Devices 3-35

3.34. Cryogenic Liquid-Measuring Devices 3-43

3.35. Milk Meters 3-49

3.36. Water Meters 3-55

3.37. Mass Flow Meters 3-59

3.38. Carbon Dioxide Liquid-Measuring Devices - Tentative Code 3-69

Section 4.

4.40. Vehicle Tanks Used as Measures 4-3

4.41. Liquid Measures 4-7

4.42. Farm Milk Tanks 4-9

4.43. Measure-Containers 4-13

4.44. Graduates 4-15

4.45. Dry Measures 4-19

4.46. Berry Baskets and Boxes 4-21

v
Outline of Contents (Continued)

Section 5.

5.50. Fabric-Measuring Devices 5-3

5.51. Wire- and Cordage-Measuring Devices 5-7

5.52. Linear Measures 5-9

5.53. Odometers 5-11

5.54. Taximeters 5-13

5.55. Timing Devices 5-17

5.56.(a) Grain Moisture Meters 5-21

5.56.(b) Grain Moisture Meters 5-29

5.57. Near-Infrared Grain Analyzers - Tentative Code 5-35

5.58. Multiple Dimension Measuring Devices - Tentative Code 5-41

Appendices

A. Fundamental Considerations A-1

B. Units and Systems of Measurement B-1

C. General Tables of Units of Measurement C-1

D. Definitions D-1

vi
vii

1999 Amendments

The following table lists the codes, paragraphs, and pages in which amendments were made by the 84th National Conference on

Weights and Measures. 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 1999" or "Amended 1999."

Section Code S&T Paragraph Action Page

Item

No.

1.10 General 310-2A G-S.1. Amended 1-2

2.20. Scales 320-1 S.1.2.2.1. Added 2-3

S.1.2.2.2. Added 2-4

Table 3 Amended Footnote #1 2-12

320-3 S.1.8.3.1. Added 2-6 &7

320-4 S.2.1.3.1. Added 2-9

320-5 S.2.1.4. Amended 2-9

S.2.3.1. Amended 2-9

N.1.3.6.1. Amended 2-14

T.N.3.8. Amended 2-23

UR.2.9. Amended 2-30

320-6 Table S.6.3.a. Amended 2-15

320-7 Table S.6.3.b. Amended Note 7 2-16 

320-8 Tables S.3.6.a. Added Note 20 & 21 2-17

and b.

S.6.1. Amended 2-11

320-9 N.1.3.6.1. Amended 2-14

320-11 T.N.3.8. Amended 2-23

320-12 UR.1.3. Amended 2-28

S.1.2.2.1., Added 2-3

S.1.2.2.2., 2-4

UR.1.3.1., and 2-28

UR.3.10 2-32

320-13 Table UR.3.2.1. Amended 2-33

2.24. Automatic Weighing 324-1 Table S.7.a. Amended 2-59

Systems

3.30. Liquid-Measuring Devices 330-2 Table S.2.2. Amended 3-8

330-4 T.2.1.4. Added 3-13

330-6 T.2.3.2. Added 3-13
Section Code S&T Paragraph Action Page

Item

No.

viii

3.31. Vehicle-Tank Meters 331-1 UR.2.2.1. Added 3-24

3.37. Mass Flow Meters 337-1 S.3.3. Amended 3-62

Table T.2. Amended 3-65

N.6.1. and Added 3-64

N.6.2.

337-2 Table S.3.5. Amended 3-61

337-4 T.1. (b) Amended 3-64

Table T.2. Amended 3-65

5.54. Taximeters 354-1 S.1.9. Amended 5-14

354-3 S.1.9.1. Added 5-14

354-6 UR.3. Amended 5-16

5.57. Near-Infrared Grain 357-1 All Removed all retroactive 5-35 -

Analyzers - Tentative Code dates. Changed all 5-39

nonretroactive and effective

as of dates to January 1,

2002

5.58. Multiple Dimension 358-1 T.7. Added 5-44

Measuring Devices -

Tentative Code

Appendix D Definitions 320-5 Dynamic Added D-5

Monorail

Weighing

System

Static Monorail Added D-14

Weighing Scale

320-7 Single Cell Added D-14

Application

Load Cell

Multiple Cell Added D-9

Application

Load Cell

320-14 vmin Amended D-16

324-1 Maximum Added D-9

capacity

Minimum Added D-9

capacity
ix

1999 Editorial Changes

Section Code Paragraph Action Page

3.30 Liquid- UR.3.3. Consolidated paragraphs (a) and (b) to clarify the 3-15

Measuring effective date of January 1, 1999, and renumbered

Devices paragraphs (c) and (d) 

Table S.2.2. Clarify the note reference under Category 2, 3-8

“devices manufactured after 2005.”

3.37. Mass Flow Table S.3.5. Clarify the note reference under Category 2, 3-61

Meters “devices manufactured after 2005.”

Table T.2. Add “except asphalt” to accuracy class 0.3 for 3-65

clarification

5.50. Fabric N.1. Correct 11 mm to 11 m, the appropriate equivalent 5-4

Measuring U.S. unit is 12 yard.

Devices

Appendix General Tables C-16 Add decimal point (1.196) C-16

C of Units and

Measures 
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Introduction

1

Communications to this committee may be addressed as 2

follows: Executive Secretary, National Conference on

Weights and Measures, National Institute of Standards and

Technology, Gaithersburg, MD 20899.

When sitting as a voting body, the National Conference on 1

Weights and Measures (NCWM) is made up of State and

local weights and measures officials from all parts of the

United States. The NCWM normally meets annually.

Introduction

A. Source. - The specifications, tolerances, and other

technical requirements published herein comprise, in their

latest form, all of the current codes as adopted by the

National Conference on Weights and Measures, Inc. The 1

National Conference is sponsored by the National Institute

of Standards and Technology (NIST), which provides the

NCWM secretariat and publishes NCWM documents.

NIST also develops technical publications for use by

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

The Conference Committee on Specifications and

Tolerances, acting at the request of the Conference or upon 2

its own initiative, with the technical assistance of the

National Institute of Standards and Technology, annually

prepares proposed revisions, amendments, or additions to

the material previously adopted by the Conference (See

paragraph C.) Such revisions, amendments, or additions are

then presented to the Conference as a whole, where they are

discussed by weights and measures officials and

representatives of interested manufacturers and industries.

Eventually the proposals of the Committee are voted upon

only by the weights and measures officials.

All of the specifications, tolerances, and other technical

requirements given herein are recommended by the

National Conference on Weights and Measures 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 by a State agency.

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. - The Committee on Specifications and

Tolerances of the NCWM provides a mechanism for

consideration of amendments or additions to the

specifications, tolerances, and other technical requirements.

The following procedures are based on NCWM Publication

3, “Policy, Interpretations, and Guidelines” (see Section 1-

NCWM Management, Subsection 1 - Organization and

Committees) that were amended at the 83 NCWM Annual rd

Meeting in 1998.

D. Submission of Agenda Items - Preamble. - The

Constitution of the NCWM requires that its officers and

Committees observe the principles of due process for the

protection of the rights and interests of affected parties.

Specifically, it requires that Committees and Officers: (a)

give reasonable advance notice of contemplated studies,

issues to be considered for action, and tentative or definite

recommendations for conference vote, and (b) provide that

all interested parties have an opportunity to be heard.

E. Submission Process. - Anyone introducing an issue to

the Committee shall use the regional weights and measures

associations to initially consider its merits. Using the

regional associations ensures discussion and evaluation of

issues at the grass-roots level by involving the regional

members in the development, evaluation, and justification

of proposals. The regions include the Central,

Northeastern, Southern, and Western Weights and

Measures Associations. For information on the regional

associations contact NCWM, Inc. at the address listed

below or, by telephone at 301-975-4004, or on the Internet

at http://www.nist.gov/owm.

F. Procedures

The Committee will consider issues according to the

following procedures:

a. All issues to be considered by the Committee for action

at the upcoming Interim Meeting must be submitted in

writing to the Committee by November 1. Although use of

NCWM Form 15 (see page 7) is not required, it is

recommended for use in submitting proposals to the

NCWM. Proposals shall be sent to the Committee at:
Introduction

2

NIST Office of Weights and Measures

100 Bureau Drive, Stop 2350

Gaithersburg, Maryland 20899-2350

Attention: Specifications and Tolerances

Committee

b. A copy of the proposal must be sent to the NCWM’s 1.10. General Code, paragraph G-A.1. Commercial and

Executive Secretary at the same address. Law-Enforcement Equipment.).

G. Criteria for Inclusion in the Committee’s Agenda.

a. Any issue approved by at least one regional association

and received by the November 1 deadline will be

automatically placed on the Committee’s Interim Meeting

Agenda.

b. Issues that have not been approved by a regional

association, but which are received by November 1, will be

evaluated by the Committee using the criteria in Section H,

Exceptions to Policy and Section I, Committee Agenda.

c. Any proposal received after the November 1 deadline, Committee Agenda; Submission of “Priority” Issues.

but prior to the Interim Meeting, will be evaluated by the

Committee according to Section H, Exceptions to Policy

and Section I, Committee Agenda. Only those issues

determined to be a national “Priority” will be included on

its agenda.

d. Proposals must be in writing and must include:

(1) a concise statement of the issue or problem outlining Criteria for Inclusion in the Committee’s Agenda when

the purpose and national need for its consideration. When no Regional Association has Approved the Issues.

possible, an electronic copy of the background material and

proposed amendment(s) should be submitted in a PC

compatible word processing document format (e.g.,

Wordperfect, or Microsoft Word) on a high density 8.9 cm

(3.5 inch) disk or by electronic mail using the same format;

(2) background material including test data, analysis of test

data, or other appropriately researched and documented

material from which the Committee will be able to make a

judgment for either a firm recommendation or consideration

of the need for further study;

(3) proposed solutions to problems stated in specific

language in amendment form to Conference documents; and

(4) practical, realistic, and specific recommendations for

both regulations and test methods to provide for proper

enforcement, if a proposal involves a new area of weights

and measures activity.

When proposals are to modify or add requirements to

existing publications, such as Handbook 44, the proposal

should:

(i) Identify the pertinent portion, section, and paragraph of

the existing publication that would be changed (e.g., Sec.

(ii) Provide evidence of consistency with other NCWM

publications such as with other specific device code

sections.

(iii) Provide evidence of consistency with Federal laws and

regulations (e.g., USDA)

(iv) Relay the positions of businesses, industries, or trade

associations affected by the proposal including supporting

and opposing points of view.

H. Exceptions to Policy for Submission of Issues to a

The Committee will use the following criteria to evaluate

issues that have not been approved by a regional

association, but has been received by the November 1

deadline. If an issue is received after the November 1

deadline, it will be included on an agenda, if the Committee

determines that it is a national “Priority.”

(1) Issues must have significant legal impact on weights and

measures laws and/or regulations involving:

(a) court cases/attorney general opinions; or

(b) pre-emption by Federal statute or regulation; or

(c) conflict with international standards; or

(d) relationship to laws or regulations of an urgent nature

which could affect health and safety.

(2) The Committee may contact parties that are potentially

affected by a issue (e.g., trade associations, industry, and

consumer groups) for comments. The Committee may

consider these comments and any other information in

determining if the issue should be included on its agenda.

(3) When the Committee determines that it should consider

an issue as a “Priority” (using the criteria in (1), the issue

will be handled in the following manner:
Introduction

3

a. A “Priority” issue received prior to the Interim Meeting b. The Annual Meeting, Program and Committee Reports

may be added to the Interim Meeting agenda by majority will be prepared and distributed to Conference members

vote of the Committee. approximately three months prior to the NCWM Annual

b. A “Priority” issue received after the Interim Meeting

may be added to the Committee’s Annual Meeting agenda

as: (i) a discussion issue by majority vote of the

Committee, or (ii) as a voting item by majority vote of the At the Interim Meeting, the Committee can classify items

Committee and the NCWM Board of Directors. for voting by the NCWM membership (indicated with a

I. Committee Agenda

a. The Committee will review issues that have been comment, and development (indicated with an “I” after the

submitted and selected by majority vote to be included on item number). Items marked “W” in the agenda have been

its agenda. The Committee will only include those issues withdrawn from consideration.

that have been (1) approved by at least one of the regional

associations; or (2) forwarded by other committees,

subcommittees, NTETC Sectors, task forces, or work

groups, or those issues that meet the criteria in Section H, At the 1998 Annual Meeting, the NCWM established a

Exceptions to Policy. process for disseminating information on issues which may

b. The Committee will publish an agenda which identifies action. Past practice for handling these issues had been to

the issues to be discussed during the Interim Meetings. This either “carry” them forward as informational issues or

agenda shall be distributed to members approximately 30 withdraw them. Conference members felt that carrying

days prior to the meetings. The agenda will be provided undeveloped information items drained NCWM resources

upon request to all other interested parties. [See NCWM but also believed that withdrawn items were often

Publication 15, Policy 1.4.6.] prematurely discarded despite the valuable work that had

(Amended 1998) gone into developing the issue. The NCWM was also

J. Interim Meeting

a. The Committee shall hold public hearings at the Interim

Meeting for the purpose of discussing and taking comments The NCWM established a new “Developing” designation to

on all issues on its agenda. allow the Committees to notify the submitter of the issue,

b. Upon request, the Committee will provide the developed for action at the national level. The NCWM

opportunity for presentations by government officials, agreed that “Developing” issues should be submitted by the

industry representatives, consumer groups, or other regional associations with a recommendation that they be

interested parties during the Interim Meeting. Requests to presented as “D” issues on the national agenda. The

make presentations must be received by the Committee Committees will present “D” issues in list format at the end

Chairman or technical advisor at least two weeks prior to of their reports and include a point of contact (including the

the start of the meetings. name and telephone number of the submitter) so that

K. Interim Meeting Report

a. Issues under consideration by the Committee, and upon advance of the hearing. In these cases, the Chairman will

which it offers comments or recommendations for announce in advance that an issue will be discussed in the

Conference action during the Annual Meetings, will be session. The use of this “D” designator is seen as an issue

included in the Committee’s Interim Reports published in management tool, as well as a way to keep the membership

the Annual Meeting, Program and Committee Reports, also informed of emerging issues.

called the Announcement Book. [See NCWM Publication

15, Policy 1.4.6.]

Meeting.

L. Classifications for Agenda Items

“V” after the item number in the agenda or prior to the

voting session). The Committee may also decide to carry

issues over as “Informational” items for further study,

M. Developing Issues

have merit, but are insufficiently developed for Committee

interested in providing a mechanism to inform parties about

issues that are developing in different localities or in the

regional associations.

that, while it may have merit, it may not be adequately

interested parties can obtain additional information. No

comments will be taken on a “Developing” issue, unless the

Committee agrees to receive the new information in
Introduction

4

N. Comments on Interim Reports G. The letter G is a prefix and indicates that the

a. Weights and measures officials, industry representatives,

and all other parties are encouraged to submit written

comments on issues in the Committees' Interim Reports.

b. All comments on the Interim Meeting Reports must be

submitted to the Committee along with a copy to the

Executive Secretary no later than one month preceding the

opening of the Annual Meeting.

O. Annual Meeting

a. The Committee will hold a public hearing at the Annual

Meeting to discuss issues on its agenda.

b. Those who want to speak on an issue during the public

hearings should request time from the Committee

Chairman. Time limitations on presentations, the discussion of a question, or amendments may be imposed by the

Committee Chairman. (See NCWM Publication 15, Policy

1.2.3. General Conduct of the Meeting.)

P. Final Committee Reports and Conference Action

a. Following the public hearings, the Committee will

prepare its final report for action by the voting membership

of the Conference. Prior to the session during which it will

be acted on, copies of each final report will be provided for

study.

b. The Chairman of the Committee will present the final

report of the Committee to the Conference body. A vote

will be taken on issues, proposals, or sections in the report

as circumstances require. The Conference will vote on the

entire final report as presented in accordance with

established Conference voting procedures. Parliamentary

procedure according to Roberts Rules of Order as amended

by NCWM Publication No. 1, Bylaws, will be adhered to in

the presentation of and action on Standing Committee

reports.

(Amended 1998)

Q. 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.

The letter that appears first in a paragraph designation has

a specific meaning, as follows:

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. Weight Units.

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
Introduction

5

design of indicating and recording elements and of recorded requirements. If sufficient data are at hand to make such

representations. Paragraphs S.1.1.1., and S.1.1.2. are action feasible, publish in combination with the codes

directly related to each other, but are limited to the design themselves the date or dates at which nonretroactive

of zero indication. Likewise, paragraphs S.1.3.1., S.1.3.2., requirements are to become retroactive. In other cases, give

and S.1.3.3. are directly related to each other, but are equally effective notice at the earliest practicable date.

limited to the design of graduations.

This handbook conforms to the concept of primary use of the year from which it should be enforced and, in some

SI (metric) measurements recommended in the Omnibus cases, the date the requirement shall be changed to retroTrade and Competitiveness Act of 1988 by citing SI metric active status. For example, [Nonretroactive as of 1978 and

units before inch-pound units where both units appear to become retroactive on January 1, 1985]. As a general

together and placing separate sections containing rule, each nonretroactive requirement is reviewed after it

requirements for metric units before corresponding sections has been in effect for 10 years to determine the

containing requirements for customary units. Occasionally, appropriateness of its nonretroactive status.

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 inch-pound units. In these

few instances, separate requirements were judged to be

more easily understood than attempting to combine SI and

inch-pound 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.

R. Classification of Requirements. - The classification of It is not deemed advisable for a user to attempt to commit to

requirements into "retroactive" and "nonretroactive" status memory tolerances or tolerance tables, even though these

is made in order that the requirements may be put into force are used frequently. For the Handbook to serve its purpose,

and effect without unnecessary hardship and without it should be at hand when any of its requirements are to be

wholesale condemnation of apparatus. Retroactive applied. Direct reference is the only sure way to apply a

requirements are enforceable with respect to all equipment requirement properly and to check whether other

and are printed in upright roman type. Nonretroactive requirements may be applicable.

requirements are those that, while clearly desirable, are not

so vital that they should at once be enforced with respect to It is the intention of this Handbook to supply criteria which

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

A nonretroactive requirement, in italic type, will indicate

S. Using the Handbook. - Handbook 44 is designed to be

a working tool for the weights and measures official, the

equipment manufacturer, installer, and repairman. 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.

enable the inspector 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)
Introduction

6

NCWM Form 15

Proposal to a Standing Committee

Committee: ______________________

Date: Regional Association :

Name/Address of Contact Person Regional Actions: (votes for and against)

Phone:

Fax:

email:

Please Attach Additional Pages and Information as Needed

Proposal: (Proposed solutions to problems stated in specific language in amendment form to handbooks, if a proposal involves a

new area of weights and measures activity, the recommendations for both regulations and test methods for proper enforcement must

be provided.)

Problem/Justification: (Include a concise statement of the issue or problem outlining the purpose and national need for its consideration.)

Other Contacts: (Provide position statements, comments, etc. from names and addresses of individuals, firms, manufacturers, and/or

trade associations included in developing the proposal.)

Other Reasons For: (If none, please indicate none have emerged.)

Other Reasons Against:

Additional Considerations: (provide cost estimates and state the anticipated benefits for all parties or indicate how the proposal may

affect other requirements, programs, etc.)

Attachments: (list the accompanying documents, data, studies Suggested Action: (Be specific on what action the committee

etc.) should take on the issue.)

Recommend NCWM  Adoption  Withdrawn

 Developing Issue

 Informational Issue

 Other (Please describe)
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5VCVGNCYUQTYKVJGZKUVKPITGIWNCVKQPUQTNQECN

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UWEJUWURGPUKQPUJCNNPQVCHHGEVVJGXCNKFKV[QT

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D GSWKROGPVVJCVJCUDGGPRNCEGFKPEQOOGTEKCN VJGXCNWGQHKVUUOCNNGUVWPKVCPFWPKVRTKEGU

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)747UGT4GSWKTGOGPVU

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GNGOGPVQVJGTYKUGVJGTGUJCNNDGEQPXGPKGPVCPFRGT

OCPGPVN[KPUVCNNGFOGCPUHQTFKTGEVEQOOWPKECVKQP

QTCNQTXKUWCNDGVYGGPCPKPFKXKFWCNNQECVGFCVC

RTKOCT[KPFKECVKPIQTTGEQTFKPIGNGOGPVCPFCP
)GPGTCN%QFG



KPFKXKFWCNNQECVGFCVVJGYGKIJKPIQTOGCUWTKPIGNG EWUVQOGTCPFQRGTCVQTRQUKVKQPUJCNNDGFGVGTOKPGFKP

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C KPURGEVKPICPFVGUVKPIVJGFGXKEG OGVGTUUJCNNJCXGENGCTN[CPFEQPURKEWQWUN[FKURNC[GF


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E TGCFKN[DTKPIKPIVJGVGUVKPIGSWKROGPVQHVJG CFFTGUUCPFRJQPGPWODGTQHVJGNQECNTGURQPUKDNG

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KPENWFKPIUWEJNCDQTCUOC[DGPGGFGFVQKPURGEVVGUV

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GSWKROGPVVQCPFHTQOVJGFGXKEGCUTGSWKTGFD[VJG GSWKROGPVKPUGTXKEGCPFCNNOGEJCPKUOUCPFFGXKEGU

YGKIJVUCPFOGCUWTGUQHHKEKCN CVVCEJGFVJGTGVQQTWUGFKPEQPPGEVKQPVJGTGYKVJUJCNN


#OGPFGF DGEQPVKPWQWUN[OCKPVCKPGFKPRTQRGTQRGTCVKPI

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)74/GVJQFQH1RGTCVKQP'SWKROGPVUJCNN HCXQTCDNGVQVJGFGXKEGWUGTUJCNNPQVDGEQPUKFGTGF

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CEEWTCVGN[TGCFCPFVJGYGKIJKPIQTOGCUWTKPI KPUVCNNCVKQPQTCEEGUUQTKGUQTHQTDCFN[YQTPQT

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EWUVQOGTCPFQRGTCVQT RQUKVKQP6JGRGTOKUUKDNG KPUVCNNCVKQPEQPFKVKQPUUJCNNDGEQTTGEVGFCPFCP[

FKUVCPEGDGVYGGPVJGGSWKROGPVCPFCTGCUQPCDNGFGHGEVKXGRCTVUUJCNNDGTGPGYGFQTUWKVCDN[TGRCKTGF

RCTVKEWNCTN[VJGUK\GCPFEJCTCEVGTQHVJGKPFKECVKPI

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GSWKROGPVQTCEEGUUQTKGUQTCPCDPQTOCNCOQWPVQH

NCDQTUWEJGSWKROGPVCEEGUUQTKGUCPFNCDQTUJCNNDG

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TGSWKTGFD[VJGYGKIJVUCPFOGCUWTGUQHHKEKCN

)745GEWTKV[5GCN#UGEWTKV[UGCNUJCNNDG

CRRTQRTKCVGN[CHHKZGFVQCP[CFLWUVOGPVOGEJCPKUO

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C 9JGPFGXKEGUKPEQOOGTEKCNUGTXKEGTGSWKTG

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QTYCVGTOGVGTUVJGQYPGTQTQRGTCVQTUJCNNPQV

KPVGTTWRVVJGWVKNKV[UGTXKEGVQVJGEWUVQOGTQT

VGPCPVGZEGRVHQTVJGTGOQXCNCPFTGRNCEGOGPVQH

VJGFGXKEG2TQXKUKQPUUJCNNDGOCFGD[VJG

QYPGTQTQRGTCVQTVQOKPKOK\GKPEQPXGPKGPEGVQ

VJGEWUVQOGTQTVGPCPV#NNTGRNCEGOGPVQT

VGORQTCT[OGVGTUUJCNNDGVGUVGFCPFUGCNGFD[C

YGKIJVUCPFOGCUWTGQHHKEKCNQTDGCTCEWTTGPV

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Table 6.

Maintenance Tolerances

(All values in this table are in scale divisions)

Tolerance in scale divisions

1 2 35

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 1d for each additional 500d or fraction thereof)

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

*See Table T.1.1. for scales designed and/or used to weigh loads less than 2 lb.
2.20. Scales

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 T.N.6. Sensitivity. - This section is applicable to all

parts such as unit weights, weighbeam and nonautomatic-indicating scales marked I, II, III, III L,

weights, or multiple weighbeams that can be or IIII. 

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 (a) The test load for sensitivity for

for that load, and shall be within tolerance nonautomatic-indicating vehicle, axle-load,

limits. livestock, and animal scales shall be 1d for

(Amended 1986) scales equipped with balance indicators, and

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

tolerance limits. The addition or removal of the test load for

(Amended 1986) sensitivity shall cause a minimum permanent

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. - At constant test

conditions, the indication 20 seconds after the

application of a load and the indication after 1

hour shall not differ by more than:

(a) one-half of the absolute value of the

applicable tolerance for the applied load for

class III L devices; and

(b) the absolute value of the applicable tolerance

for the applied load for all other devices.

(Amended 1989)

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.6.1. Test Load.

2d or 0.2 percent 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 1d at zero

and 2d at maximum test load.

change as follows:

(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
2.20. Scales

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 1.4d shall cause a change

in the indication of at least 1.0d. (See N.1.5.)

T.N.7.2. Digital Automatic Indicating. - A test

load equivalent to 1.4d shall cause a change in the

indicated or recorded value of at least 2.0d. This

requires the zone of uncertainty to be not greater

than three-tenths of the value of the scale division. 

(See N.1.5.1.)

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, 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.

(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 EC to 40 EC (14 EF to 104 EF)

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.

Table T.N.8.1.2.

Class Temperature Range

I 5 EC (9 EF)

II 15 EC (27 EF)

III, III L, & IIII 30 EC (54 EF)

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 EC (9 EF) change in

temperature for Class III L devices; or

(b) one division per 5 EC (9 EF) 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. through T.N.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.
2.20. Scales

2WTEJCUGTUCPFWUGTUQHUECNGUUWEJCUTCKNYC[ 4

VTCEMJQRRGTCPFXGJKENGUECNGUUJQWNFDG

CYCTGQHRQUUKDNGCFFKVKQPCNTGSWKTGOGPVUHQTVJG

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(b) Battery operated instruments shall not

indicate nor record values outside the 

applicable tolerance limits when battery (a) For devices marked with a class designation,

power output is excessive or deficient. the typical class or type of device for

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.

604CFKQ(TGSWGPE[+PVGTHGTGPEG4(+

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5WUEGRVKDKNKV[6JGFKHHGTGPEGDGVYGGPVJG

YGKIJVKPFKECVKQPFWGVQVJGFKUVWTDCPEGCPFVJG

YGKIJVKPFKECVKQPYKVJQWVVJGFKUVWTDCPEGUJCNN

PQVGZEGGFQPGUECNGFKXKUKQPFQTVJG

GSWKROGPVUJCNN


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D RTQXKFGCPGTTQTOGUUCIGQT


EVJGKPFKECVKQPUJCNNDGUQEQORNGVGN[

WPUVCDNGVJCVKVECPPQVDGKPVGTRTGVGFQT

VTCPUOKVVGFKPVQOGOQT[QTVQCTGEQTFKPI

GNGOGPVCUCEQTTGEVOGCUWTGOGPVXCNWG

6JGVQNGTCPEGKP60KUVQDGCRRNKGF

KPFGRGPFGPVN[QHQVJGTVQNGTCPEGU(QTGZCORNG

KHKPFKECVKQPUCTGCVCNNQYCDNGDCUKEVQNGTCPEG

GTTQTNKOKVUYJGPVJGFKUVWTDCPEGQEEWTUVJGPKV

KUCEEGRVCDNGHQTVJGKPFKECVKQPVQGZEGGFVJG

CRRNKECDNGDCUKEVQNGTCPEGUFWTKPIVJG

FKUVWTDCPEG='FKVQTU	0QVG(QNNQYKPIVJG

0%9/#PPWCN/GGVKPIVJGVGZVKPVJKU

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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.

particular weighing applications is shown in

Table 7a.

(b) For devices not marked with a class

designation, Table 7b applies.

UR.1.2. Grain Hopper Scales. - The minimum

number of scale divisions for a Class III Hopper

Scale used for weighing grain shall be 2000.

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.

(Added 1995) (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.

[Nonretroactive as of January 1, 1986.]

(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
2.20. Scales

must be equipped with a recording element. 

[Nonretroactive as of January 1, 1996.]

(Added 1995)

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. 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.]

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 theweighing

elements.

(Amended 1985)

UR.2.6. Approaches.

UR.2.6.1. Vehicle Scales. - On the entrance

and exit ends of a vehicle scale installed in any

one location for a period of 6 months or more,

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

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. 

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.

[Nonretroactive as of 1976.]

(Amended 1977, 1983, 1993)

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.

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
2.20. Scales

the scale operator when the load receiving element determined by uncoupling the various

is in its designed weighing position. elements (tractor, semitrailer, trailer),

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.1.3.6.1. (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) Note: This paragraph does not apply to highwayUR.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.

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.

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74

(Added 1996)

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:

(a) the weight of a coupled combination may be

weighing each unit separately as a single

draft, and adding together the results, or

(b) the weight of 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.

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
2.20. Scales 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 10d is recommended for a weight classifier marked in accordance

with a statement identifying its use for special applications.

(Amended 1990)

weighers, shall be in a reasonably level position (including cardboard), textiles, plastic, and glass.

at the time of such determination. (Amended 1988 and 1992)

UR.3.5. Special Designs. - A scale designed and UR.3.8. Minimum Load for Weighing

marked for a special application (such as a Livestock.- A scale with scale divisions greater

prepackaging scale) shall not be used for other than 2 kg (5 lb) shall not be used for weighing net

than its intended purpose. loads smaller than 500d.

UR.3.6. Wet Commodities. - Wet commodities

not in watertight containers shall be weighed only UR.3.9. Use of Manual Gross Weight Entries. -

on a scale having a pan or platform that will drain Manual gross weight entries are permitted for use

properly. in the following applications only: (1) in point-of-

(Amended 1988) sale systems interfaced with scales when credit is

UR.3.7. Minimum Load on a Vehicle Scale. - A

vehicle scale shall not be used to weigh net loads

smaller than:

(a) 10d when weighing scrap material for

recycling;

(b) 50d for all other weighing.

As used in this paragraph, scrap materials for

recycling shall be limited to ferrous metals, paper

(Amended 1989)

being given for a weighed item; (2) when a device

or system is generating labels for standard weight

packages; (3) when postal scales or weight

classifiers are generating manifests for packages to

be picked up at a later time; and (4) on livestock

scale systems that generate weight tickets to

correct erroneous tickets.

(Added 1992)
2.20. Scales

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) 

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.

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GPIKPGGTKPICWVJQTKV[RTGHGTCDN[VJCVQHVJG

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VJGUECNGCPFD[VJGYGKIJVUCPFOGCUWTGU

CWVJQTKV[JCXKPILWTKUFKEVKQPQXGTVJGUECNG


#OGPFGF

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. and N.4.3.(a), 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 unit-train-weights-only facility, and should be

considered prior to installation.

(Added 1990; Amended 1992) 
2.20. Scales
2.20. Scales
Index

Scales Code Index

Acceptance ...................... 2-9, 2-21-23

Acceptance tolerance ............ 2-9, 2-22, 2-23

Access to weighing elements ............... 2-30

Accuracy . . . . . . . . . 2-9-12, 2-15, 2-17, 2-21, 2-22

Accuracy class ............ 2-11, 2-15, 2-17, 2-21

Adjustable components ............... 2-7, 2-11

Adjustment . . . . . . . . . . . . 2-7, 2-8, 2-11, 2-20, 2-32

Approaches ............................ 2-30

Audit trail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Automatic indicating scales ...... 2-13, 2-18, 2-24

Automatic zero-setting mechanism ...... 2-8, 2-11

Axle-load scales ............. 2-3, 2-9, 2-13, 2-24

Balance condition . . 2-3, 2-8, 2-9, 2-22, 2-27, 2-32

Balance indicator . . 2-3, 2-9, 2-10, 2-21, 2-22, 2-26

Balance indicators .................. 2-21, 2-26

Balance position . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Barometric pressure . . . . . . . . . . . . . . . . . 2-22, 2-27

Capacity 2-5, 2-6, 2-8-11, 2-13-15, 2-17-19, 2-21-24, 2-26, 2-

28, 2-30, 2-32

Capacity indication . . . . . . . . . . . . . . . . . . . . . . . 2-6

Center-of-zero . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Class 2-3, 2-4, 2-7-11, 2-13, 2-15, 2-17, 2-18, 2-21-28, 2-

31

Clearance ...................... 2-4, 2-9, 2-28

Computing scale ..................... 2-6, 2-9

Consecutive-car test .............. 2-19, 2-19-21

Coupled-in-motion ............. 2-19, 2-23, 2-32

Coupled-in-motion railroad weighing systems2-23, 2-32

Crane and hopper (other than grain hopper) . . . 2-23

Crane scales ............................ 2-18

Customer’s indications . . . . . . . . . . . . . . . . . . . . . 2-6

Dairy-product-test .............. 2-9, 2-10, 2-24

Damping means . . . . . . . . . . . . . . . . . . . . . . . . . 2-10

Direct sales .................... 2-5, 2-6, 2-8-10

Discrimination test . . . . . . . . . . . . . . . . . . . . . . . 2-18

Distributed-car test . . . . . . . . . . . . . . . . . . . . . . . 2-20

Electric power supply .................... 2-27

Environmental factors ............... 2-18, 2-28

Foundation ............................. 2-28

Graduations . . . . . . . . . . . . . . . . . . . . . . . 2-4-6, 2-9

Grain test scales .................... 2-21, 2-24

Grain-test . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9, 2-28

Hanging scale ........................... 2-28

Hanging scales .......................... 2-18

Hoists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-30

Hopper scales ................. 2-18, 2-23, 2-28

I 2-3, 2-4, 2-7-11, 2-13, 2-17, 2-18, 2-21-23, 2-25-28,

2-31

II . 2-3, 2-8-11, 2-13, 2-17, 2-21, 2-22, 2-24-27, 2-31

III . . . . . . . 2-4, 2-9, 2-11, 2-13, 2-17, 2-21-28, 2-31

III L ............. 2-9, 2-11, 2-17, 2-21-28, 2-31

IIII 2-4, 2-11, 2-13, 2-17, 2-21, 2-22, 2-25-27, 2-31

Index of an indicator . . . . . . . . . . . . . . . . . . . . . . 2-4

Indicating element .... 2-13, 2-15, 2-17, 2-23, 2-26

Indicator . 2-3-5, 2-7, 2-9, 2-10, 2-21-23, 2-26, 2-32

Influence factors ................... 2-22, 2-27

Initial verification .................. 2-19, 2-20

Initial zero-setting mechanism ........... 2-6, 2-9

Installation requirements .................. 2-28

Jewelers’ scales .................... 2-21, 2-24

Level . . . . . . . . . . . . . . . . . . . 2-8-10, 2-18, 2-30-32

Level condition .................... 2-31, 2-32

Level-indicating means ............... 2-9, 2-10

Livestock scale .......................... 2-32

Livestock scales . . 2-8, 2-11, 2-13, 2-14, 2-17, 2-28

Load cell .................... 2-11, 2-15, 2-17

Load cell verification interval ......... 2-11, 2-17

Main elements ..................... 2-13, 2-23

Maintenance . . . . . . . . . . . . . . . . . . 2-21, 2-30, 2-32

Maintenance requirements . . . . . . . . . . . . . . . . . 2-32

Maintenance tolerance . . . . . . . . . . . . . . . . . 2-22-24

Manual gross weight entries . . . . . . . . . . . 2-7, 2-32

Marking requirements . . . . . . . . . . . . . . . 2-11, 2-15

Material test ....................... 2-18, 2-24

Minimum load . . . . . . . . . . . . . . . . . . . . . . . 2-30-32

Minimum test weights . . . . . . . . . . . . . . . 2-18, 2-19

Money-value computation . . . . . . . . . . . . . . . . . . 2-6

Money-value graduations . . . . . . . . . . . . . . . . . . 2-6

Monorail scale ...................... 2-9, 2-14

Multirange ............................. 2-22

Nominal capacity 2-5, 2-10, 2-11, 2-13-15, 2-17, 2-21, 2-22, 2-30

No-load reference value . . . . . . . . . . . . . . . . . . . . 2-3

Operating temperature . . . . . . . . . . . . . . . 2-22, 2-27

Parallax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Parcel post scales ................... 2-21, 2-24

Poise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Portable axle-load weighers . . . . . . . . . . . . . . . . . 2-3

Postal . . . . . . . . . . . 2-3, 2-6, 2-17, 2-21, 2-24, 2-32

Power interruption ....................... 2-27

Prepackaging scale ................... 2-7, 2-31

Prescription . . . . . . . . . . . . . . . 2-9, 2-10, 2-21, 2-24

Provision for sealing . . . . . . . . . . . . . . . . . . . . . . 2-7

Railway track scales 2-8, 2-10, 2-13, 2-14, 2-17, 2-18, 2-21, 2-24, 2-28

Ratio test .............................. 2-18

Readability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Recorded representations ............... 2-3, 2-7

Recording elements ............. 2-3, 2-10, 2-23

Repeatability ........................... 2-26

RFI . . . . . . . . . . . . . . . . . . . . . 2-18, 2-22, 2-27, 2-28

Scale modification ....................... 2-32

Sealing ............................. 2-7, 2-8

Security seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Sensitivity requirement ................... 2-21

Sensitivity test .......................... 2-18

Shift test . . . . . . . . . . . . . . . . . 2-13, 2-14, 2-18, 2-26

Stock racks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-30

Strain-load test . . . . . . . . . . . . . . . . . . . . . 2-18, 2-19

Subsequent verification .............. 2-20, 2-22
Index

Supports .......................... 2-13, 2-28

Symmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Temperature . . . . . . . . . . . . . . 2-11, 2-15, 2-22, 2-27

Temperature effect on zero-load ............ 2-27

Test loads . . . . . . . . 2-13, 2-14, 2-18, 2-19, 2-21-24

Time dependence . . . . . . . . . . . . . . . . . . . . . . . . 2-26

Tolerances . . . . . . 2-9, 2-10, 2-18, 2-19, 2-21, 2-28

Travel . . . . . . . . . . . . . . . . . . . . . 2-4, 2-5, 2-10, 2-21

Type evaluation ........... 2-11, 2-13, 2-22, 2-23

Uncoupled-in-motion . . . . . . . . . . . . . . . . 2-21, 2-23

Uncoupled-in-motion railroad weighing system 2-21

Unit weights . . . . . . . . . . . . . . . . . . . 2-6, 2-17, 2-26

Use requirements . . . . . . . . . . . . . . . . . . . . . . . . 2-30

Value of scale division ................ 2-3, 2-15

Vehicle on-board weighing system . 2-7, 2-10, 2-18

Vehicle scale ................. 2-13, 2-30, 2-31

Vehicle scales ............. 2-8, 2-13, 2-28, 2-30

Weighbeam . . . . . . . . 2-4-6, 2-18, 2-21, 2-22, 2-26

Weighing elements ............ 2-11, 2-14, 2-30

Weight ranges . . . . . . . . . . . . . . . . . . . . . . 2-6, 2-17

Weight units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Wheel-load weighers .... 2-3, 2-9, 2-10, 2-24, 2-31

Zero indication ...................... 2-3, 2-27

Zero-load adjustment . . . . . . . . . . . . . . . . . . . . . . 2-8

Zero-load balance ................. 2-7-9, 2-27
2.21. Belt-Conveyor Scale Systems



Sec. 2.21. Belt-Conveyor Scale Systems

 A. Application

A.1. This code applies to belt-conveyor scale systems used

for the weighing of bulk materials.

A.2. 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) check-weighers; or

(d) controllers or other auxiliary devices except as they

may affect the weighing performance of the belt-conveyor scale.

A.3. See also General Code requirements.

 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 submultiple 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 0.1 percent (1/1000) of the minimum totalized

load. 

[Nonretroactive as of January 1, 1986.]

S.1.3.2. For Scales Installed Before January 1,

1986. - The value of the scale division shall not be

greater than 1/1 200 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. may be readily and accurately

determined in 20 minutes of operation.

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. The belt-conveyor scale system

shall record the initial indication and the final

indication of the master weight totalizer*, the quantity

delivered*, the unit of measurement (i.e., kilograms,

tonnes, pounds, tons, etc.), the date, and time. This

information shall be recorded for each delivery*.

[Nonretroactive as of January 1, 1986.]

[*Nonretroactive as of January 1, 1994]

(Amended 1993)

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 35

percent and when the rate of flow is equal to or greater

than 98 percent 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)

S.1.6. Advancement of Primary Indicating or

Recording Elements. - The master weight totalizer 
2.21. Belt-Conveyor Scale Systems



shall advance only when the belt conveyor is in operation mechanisms reach the limit of adjustment of the zeroand under load. setting mechanism.*

(Amended 1989) [*Nonretroactive as of January 1, 1990]

S.1.7. Master Weight Totalizer. - The master weight

totalizer shall not be resettable without breaking a S.3.2. Sensitivity at Zero Load (For Type

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.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.

 

S.2.2. Adjustable Components. - An adjustable

component that can affect the performance of the device

(except as prescribed in S.3.1) 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 percent 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. - The range

of the zero-setting mechanism shall not be greater than

±2 percent of the rated capacity of the scale without

breaking the security means. 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 

(Amended 1989)

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. - A belt-conveyor scale shall

be marked with the following: (Also see G-S.1.)

(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;

(d) the load in terms of pounds per foot or kilograms per

meter (determined by materials tests);

(e) the operational temperature range if other than 

-10 EC to 40 EC (14 EF to 104 EF). 

[Nonretroactive as of January 1, 1986.]

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

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)

 N. Notes

N.1. General. - Belt-conveyor scales are capable of

weighing bulk material accurately. (See Tolerances.)

However, their performance can be detrimentally affected

by the conditions of the installation. (See User Requirements.)
2.21. Belt-Conveyor Scale Systems



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N.1.1. Official Test. - An official test of a belt-conveyor N.3.1. Zero Load Tests. - If a belt-conveyor scale

scale system shall be a materials test. system has been idle for a period of 2 hours or more, the

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. It shall be tested

at normal use capacity and may also be tested at any other

rate of flow that may be used at the installation. Each test

shall be conducted for:

(a) not less than 1000 scale divisions,

(b) at least three revolutions of the belt, and

(c) at least 10 minutes of operation, or for a normal

weighment.

(Amended 1986)

N.3. Test Procedures.

system shall be run for not less than 30 minutes when the

temperature is above 5 EC (41 EF). When the

temperature is below 5 EC (41 EF), additional warmup

time, depending upon conditions, is required before

beginning the zero-load tests. The variation between the

beginning and ending indication of the master weight

totalizer shall not be more than ± 1 scale division when

the instrument is operated at no load for a period of time

equivalent to that required to deliver the minimum

totalized load of 1000 scale divisions.

 

The zero-load test shall be conducted over a whole

number of belt revolutions, but not less than three

revolutions or 10 minutes' operation, whichever is

greater.

 

During any portion of the zero-load test, the totalizer

shall not change more than three scale divisions from its

initial indication.

(Amended 1989)

 

N.3.2. Material Tests. - Use bulk material, preferably

that material for which the device is normally used.

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
2.21. Belt-Conveyor Scale Systems



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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 (a) As required by the official with statutory authority,

weighed and determined, the following precautions shall simulated load tests as recommended by the

be observed: manufacturer are to be conducted between material

 (a) The containers, whether railroad cars, trucks, or performance, but shall not be used for official

boxes, must not leak, and shall not be overloaded to certification.

the point that material will be lost. (Amended 1991)

 (b) The actual empty or tare weight of the containers (b) A simulated load test consisting of at least three

shall be determined at the time of the test. consecutive test runs shall be conducted as soon as

Stenciled tare weight of railway cars or trucks shall possible, but not more than 12 hours after the

not be used. Gross and tare weights shall be completion of the material test, to establish the

determined on the same scale. factor to relate the results of the simulated load test

(c) When a pre-weighed test load is passed over the (Added 1990)

scale, the belt loading hopper shall be examined

before and after the test to assure that the hopper is (c) The results of the simulated load test shall repeat

empty and that only the material of the test load has within 0.1 percent.

passed over the scale. (Added 1990)

(d) When a railway track scale is used to weigh the test

load, not more than 48 hours should elapse between

the test on the belt-conveyor scale and the

determination of the weight of the test load. When

other scales are used, the elapsed time should be

not more than 8 hours.

(e) The test shall not be conducted if the weight of the

test load has been affected by environmental

conditions.

(f) On initial verification, at least three individual tests

shall be conducted. On subsequent verifications, at

least two individual tests shall be conducted. The

performance of the equipment is not to be

determined by averaging the results of the

individual tests. The results of all of these tests

shall be within the tolerance limits. 

(Amended 1986, 1989, and 1998)

N.3.2.1. Accuracy of Material. - The quantity of

material comprising the material test shall be weighed

statically or on an uncoupled-in-motion railway track

scale to an accuracy of at least 0.1 percent. The scale

used to weigh material shall be tested immediately

prior to running the material test; where practicable,

the substitution method of weighing should be used.

Scales typically used for this purpose include Class II,

III, and III L scales or a scale with the tolerances as

described in Table T.1.1. of Handbook 44 Section

2.20.

(Added 1989)(Amended 1991, 1993, and 1998)

N.3.3. Simulated Load Tests. - 

tests to monitor the system’s operational

to the results of the material tests.

(Amended 1989 and 1990)

T. Tolerances

T.1. Tolerance Values . - Maintenance and acceptance 1

tolerances on materials tests, relative to the weight of the

material, shall be ± 0.25 percent of the test load.

(Amended 1993)

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 percent

(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; and 
2.21. Belt-Conveyor Scale Systems



(b) new types of devices submitted for approval after interference (EMI) that may adversely affect the

January 1, 1986, shall comply with the requirements operation or performance of the device.

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 if inclined, the angle shall be such that slippage of

tolerance requirements at temperatures from -10 EC to material along the belt does not occur. Installation shall

40 EC (14 EF to 104 EF). be in accordance with the scale manufacturer’s

T.3.1.1. Effect on Zero-Load Balance. - The zeroload indication shall not change by more than 0.07

percent of the rated capacity of the scale (without the

belt) for a change in temperature of 10 EC (18 EF) at

a rate not to exceed 5 EC (9 EF) per hour.

T.3.1.2. Temperature Limits. - If a temperature range

other than -10 EC to 40 EC (14 EF to 104 EF) is

specified for the device, the range shall be at least

30 EC (54 EF).

[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. Use Requirements. - A belt-conveyor scale system

shall be operated between 35 percent and 98 percent of its

rated capacity.

UR.1.1. Minimum Totalized Load. - Delivered

quantities of less than the minimum test load shall not be

considered a valid weighment.

UR.1.2. Security Means. - When a security means has

been broken, it shall be reported to the official with

statutory authority.

(Amended 1991)

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 belt-conveyor scale

shall be adequately protected from environmental factors

such as wind, moisture, dust, weather, and radio

frequency interference (RFI) and electromagnetic

UR.2.2. Conveyor Installation. - The design and

installation of the conveyor leading to and from the beltconveyor scale is critical with respect to scale performance. The conveyor may be horizontal or inclined, but,

instructions and the following:

 

(a) a belt-conveyor scale shall be so installed that

neither its performance nor operation will be

adversely affected by any characteristic of the

foundation, supports, or any other equipment;

 (b) all live portions of the scale shall be protected by

appropriate guard devices to prevent accidental

interference with the weighing operation;

 (c) suitable protection shall be provided for storage of

any simulated load equipment.

UR.2.2.1. For Scales not Installed by the

Manufacturer. - Unless the scale is installed in a

conveyor designed and furnished by the scale manufacturer or built to the scale manufacturer’s

specifications, the conveyor shall comply with the

following minimum requirements:

(Amended 1998)

 

(a) Take-up Device. - If the belt length is such that

a take-up device is required, this device shall be

of the counter-weighted type for either vertical

or horizontal travel.

(b) 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 5 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 center line of the

weigh span of the scale. Training idlers shall not

be restrained at any time in order to force belt

alignment.

(Amended 1998)

(c) 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
2.21. Belt-Conveyor Scale Systems



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m (20 ft) or 5 idler spaces, whichever is greater, conveyor loading mechanism shall be designed

before and after the scale. A concave curve to provide uniform belt loading. The distance 2

shall start no closer than 12 m (40 ft) from the from the loading point to the scale shall allow

scale to the tangent point of the concave curve. for adequate settling time of the material on the

(Amended 1998) belt before it is weighed. Feeding mechanisms

(d) Tripper and Movable Pulleys. - There shall be

no tripper or movable head pulleys in the

conveyor.

(e) Conveyor Length. - The conveyor shall be no

longer than 300 m (1000 ft) nor shorter than

12 m (40 ft) from head to tail pulley.

[Nonretroactive as of January 1, 1986.]

(f) 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. UR.2.4. Belt Travel (Speed or Velocity). - The belt

(g) Identification of Scale Area. - The scale area

and 5 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. UR.3. Use Requirements.

(Amended 1998)

(h) Belt Composition and Maintenance. -

Conveyor belting shall be no heavier than is

required for normal use. In a loaded or unloaded

condition, the belt shall make full contact with

the carry roll (center or horizontal portion) of the

idlers. Splices shall not cause any undue distur- UR.3.2. Maintenance. - Belt-conveyor scales and

bance in scale operation (see N.3.). idlers shall be maintained and serviced in accordance

(Amended 1998) with manufacturer’s instructions and the following:

(i) Uniformity of Belt Loading and Flow. - The

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.

(j) Belt Alignment. - The belt shall not extend

beyond the edge of the idler roller in any area of

the conveyor.

(Amended 1998)

UR.2.3. Material Test. - A belt-conveyor scale shall be

installed so that a material test can be conveniently

conducted.

[Nonretroactive as of January 1, 1981.]

 

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.

UR.3.1. Loading. - The feed of material to the scale

shall be controlled to assure that, during normal

operation, the material flow is in accordance with

manufacturer’s recommendation for rated capacity.

 

(a) 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.

 (b) Simulated load tests shall be conducted at periodic

intervals between official tests, to provide

reasonable assurance that the device is performing

correctly. The action to be taken as a result of

simulated load test is as follows:
2.21. Belt-Conveyor Scale Systems



- if the error is less than 0.25 percent, no adjustment (e) Records. - Records of calibration and maintenance,

is to be made; including conveyor alignment, shall be maintained

- if the error is at least 0.25 percent but not more than history of scale performance. Copies of any report

0.6 percent, adjustment may be made if the official as a result of a test or repair shall be mailed to the

with statutory authority is notified; official with statutory authority as required. The

(Amended 1991) current date and correction factor(s) for simulated

 - if the error is greater than 0.6 percent but does not the scale cabinet.

exceed 0.75 percent, adjustments shall be made (Amended 1991)

only by a competent service person and the official

with statutory authority shall be notified. After

such an adjustment, if the results of a subsequent

test require adjustment in the same direction, an

official test shall be conducted;

(Amended 1991)

- if the error is greater than 0.75 percent, an official

test is required.

(Amended 1987)

(c) Scale Alignment. - "Wire line" (0.5 mm or 0.02 in

diameter piano wire or equivalent nylon line)

alignment checks shall be conducted when

conveyor work is performed in the scale area or in

accordance with manufacturer’s recommendation.

A materials test is required after any realignment.

(Amended 1986)

(d) Simulated Load Equipment. - Simulated load

equipment shall be clean and properly maintained.

on site for at least three current years to develop a

load equipment shall be recorded and maintained in

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)
2.22. Automatic Bulk Weighing Systems


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Sec. 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. Also see General Code Requirements.

 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 percent 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.

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. An automatic zero

setting mechanism is prohibited.

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:
2.22. Automatic Bulk Weighing Systems



(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)

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close, activate an alarm, and inhibit weighing until

the overfill condition has been corrected.


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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. (See also G-S.1.)

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.
2.22. Automatic Bulk Weighing Systems



S.5.3. Temperature Limits. - Unless the temperature N.1.5. Discrimination Test. - A discrimination test shall

range is -10 EC to +40 EC (14 EF to 104 EF), the be conducted on all automatic indicating scales with the

temperature range shall be marked on the device. [Non- weighing device in equilibrium at zero-load and at

retroactive as of January 1, 1986.] maximum test load, and under controlled conditions in

(Added 1985) which environmental factors are reduced to the extent

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*.

(*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)

 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 percent

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 noload 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.

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)

 

T.2. Minimum Tolerance Values. - The minimum

tolerance value shall not be less than half the value of the

scale division.

 
2.22. Automatic Bulk Weighing Systems



T.2.1. For Systems used to Weigh Construction

Materials. - The minimum maintenance and acceptance

tolerance shall be 0.1 percent 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.7.1.1. If not marked on the device, the temperature

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 percent of test load.

T.3.3. For all Other Systems. - The basic maintenance

tolerance shall be 0.2 percent 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 1 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 1.4d shall cause a change

in the indicated or recorded value of at least 2.0d. 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: 

limits shall be:

 

-10 EC to 40 EC (14 EF to 104 EF)

 

T.7.1.2. If temperature limits are specified for the

device, the range shall be at least 30 EC (54 EF).

 

T.7.1.3. Temperature Effect on Zero-Load

Balance. - The zero-load indicator shall not vary by

more than 1 division per 5 EC (9 EF) change in

temperature.

 

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
2.22. Automatic Bulk Weighing Systems



display or record any values outside the applicable not normally be retained on the weighing element for a

tolerance limits. period longer than a normal weighing cycle.

[Nonretroactive as of January 1, 1986.] [Nonretroactive as of January 1, 1987.]

(Added 1985) (Added 1986)

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 and enforceable 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.

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 percent 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 percent of the weighing capacity of

the system except for a final partial draft. Loads shall

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)
2.23. Weights



Sec. 2.23. Weights

 A. Application

A.1. This code applies to commercial weights; that is,

weights used in connection with commercial weighing

devices.

A.2. This code does not apply to test weights or to other

"standards" of mass.

A.3. See also General Code requirements.

 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. T.1. In Excess and in Deficiency. - The tolerances

S.3. Adjusting Material. - Adjusting material shall be

securely positioned and shall not project beyond the surface

of the weight. T.2. On Avoirdupois Weights. - The maintenance

S.4. Marking Requirements.

S.4.1. General. - A weight shall be marked to show T.3. On Metric Weights. - The maintenance tolerances

clearly its nominal value, which shall include shall be as shown in Table 2. Acceptance tolerances shall

identification of the unit; however, the nominal value of be one-half the maintenance tolerances.

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 multiplyinglever scale for which it is intended.

 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. (See

Appendix A; Fundamental Considerations paragraphs 3.2.

and 3.3.)

 T. Tolerances

hereinafter prescribed shall be applied equally to errors in

excess and errors in deficiency.

tolerances shall be as shown in Table 1. Acceptance

tolerances shall be one-half the maintenance tolerances.

T.4. On Carat Weights. - The maintenance tolerances

shall be as shown in Table 2. Acceptance tolerances shall

be one-half the maintenance tolerances.
2.23. Weights



T.5. On Apothecaries’ and Troy Weights. - The

maintenance tolerances shall be as shown in Table 3.

Acceptance tolerances shall be one-half the maintenance

tolerances.

Table 1.

Maintenance Tolerance for Avoirdupois Weights

Maintenance Tolerance

Nominal Equal-Arm

Value Weights

Counterpoise Weights

For scales with multiples of For scales with multiples of 1000

less than 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 15 970 12.0 780 6.5 420

6 17 1190

7 19 1200

8 21 1400 15.0 970 9.0 580

9 23 1500

10 25 1600 18.0 1160 10.0 650

15 28 1800

20 30 1900

25 35 2300

30 40 2600

40 45 2900

50 50 3200
2.23. Weights



Table 2.

Maintenance Tolerances for Metric Weights

Nominal Maintenance Nominal Value Maintenance

Value Tolerance (g) Tolerance

(mg) (mg) (mg)

5 or less 0.1 1 4

10 0.3 2 6

20 0.4 3 8

30 0.6 5 10

50 0.8 10 15

100 1.0 20 20

200 1.5 30 30

300 2.0 50 40

500 3.0 100 70

200 100

300 150

500 175

Nominal Maintenance Nominal Maintenance

Value Tolerance Value Tolerance

(kg) (mg) (carats) (mg)

1 250 0.25* 0.6

2 400 0.5** 1.0

3 500 1.0 1.5

5 800 2.0 2.0

10 1000 3.0 3.0

20 1500 5.0 4.0

10.0 6.0

20.0 10.0

30.0 12.0

50.0 15.0

100.0 25.0

*25 points or less

**50 points
2.23. Weights



Table 3.

Maintenance Tolerances

For Apothecaries’ and Troy Weights

Nominal Nominal

Value Value Maintenance Tolerance Maintenance Tolerance

grains grains mg oz grains mg

1 0.01 0.6 1 0.4 25.0

2 0.02 1.3 2 0.6 40.0

3 0.03 2.0 3 1.0 65.0

5 0.03 2.0 4 1.5 100.0

10 0.04 2.5 5 1.6 105.0

20 0.06 4.0

scruples grains mg oz grains mg

1 0.06 4.0 6 1.8 115.0

2 0.10 6.5 7 1.9 125.0

8 2.0 130.0

9 2.1 135.0

10 2.2 145.0

dr grains mg oz grains mg

0.5 0.07 4.5 11 2.4 155.0

1.0 0.10 6.5 12 2.5 160.0

2.0 0.20 13.0 20 2.9 190.0

3.0 0.30 20.0 30 3.7 240.0

4.0 0.40 25.0 50 5.4 350.0

5.0 0.50 30.0

6.0 0.60 40.0

dwt grains mg oz grains mg

1 0.06 4.0 100 7.7 500.0

2 0.10 6.5 200 12.3 800.0

3 0.15 10.0 300 15.4 1000.0

4 0.20 13.0 500 23.1 1500.0

5 0.30 20.0 1000 38.6 2500.0

10 0.40 25.0
 2.24. Automatic Weighing Systems



Section 2.24. Automatic Weighing Systems - Tentative Code

This tentative code has only a trial or experimental status and is not intended to be enforced by weights and

measures officials. The requirements are designed for study prior to the development and adoption of a final

Code for Automatic Weighing Systems. The tentative code is intended to be used by the National Type

Evaluation Program for type evaluation of automatic weighing systems. If upgraded to become a permanent

code, all requirements, except those for tolerances, will be nonretroactive as of the effective date of the

permanent code; tolerance requirements will apply retroactively as of the effective date of the permanent code.

(Tentative Code Added 1995)(Amended 1998)

A. Application

A.1. - This code applies to devices used to weigh or fill

packages while the object is in motion.

 

This includes:

(a) Weigh-labelers

(b) Automatic checkweighers

(Amended 1997)

A.2. - This code does not apply to:

(a) Belt-conveyor Scale Systems

(b) Railway Track Scales

(c) Monorail Scales

(d) Devices that measure quantity on a time basis

(e) Controllers or other auxiliary devices except as they

may affect the weighing performance

A.3. - Also see General Code requirements.

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. Zero Indication. 

(a) A weigh-labeler shall be equipped with an indicating

or recording element. It shall either indicate or record a

zero-balance condition and an out-of-balance condition

on both sides of zero.

(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 dynamic

operation is not required on automatic checkweighers.

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; 

S.1.2.1. Weight Units. - A device shall indicate

weight values using only a single unit of measure.
2.24. Automatic Weighing Systems



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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 field applications where it would prohibit

an authorized user from having access to the calibration

functions of a device. 

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.

S.2. Design of Zero and Tare Mechanisms.

S.2.1. Zero Load Adjustment.

S.2.1.1. Automatic Zero-Setting 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.

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 percent 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 the

value of the tare division shall be equal to the value of

the division. The tare mechanism shall operate only in a

backward direction (i.e., in a direction of
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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.

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 a complete weighing

operation, including tare, net, and gross weight

determination.

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, v , to the scale division "d" for a specific min

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 10 times

the value of "d."

S.4. Weight Indicators, Weight Displays, Reports, and

Labels.

S.4.1. Weight Units. - An indicating or recording

element shall indicate weight values using only a single

unit of measure.
2.24. Automatic Weighing Systems



S.4.2. Additional Digits in Displays. - Auxiliary digital S.7. Marking Requirements. [See also G-S.1., G-S.4.,

displays that provide additional digits for use during G-S.6., G-S.7., G-U.2.1.1., and UR.3.3.]

performance evaluation may be included on automatic

checkweighers. However, in cases where these S.7.1. Location Of Marking Information. - Automatic

indications are not valid for determining the actual weighing systems which are not permanently attached to

weight of a package (e.g., only appropriate for use in an indicating element, and for which the load-receiving

statistical process control programs by users) they shall element is the only part of the weighing/load-receiving

be clearly and distinctly differentiated from valid weight element visible after installation, may have the marking

displays by indicating them to the user. information required in G-S.1. of the General Code and

For example, the additional digits may be differentiated Systems Code located in an area that is accessible only

by color, partially covered by placing crosshatch overlays through the use of a tool; provided that the information

on the display, or made visible only after the operator is easily accessible (e.g., the information may appear on

presses a button or turns a key to set the device in a mode the junction box under an access plate). The

which enables the additional digits. identification information for these automatic weighing

S.4.3. 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 S.7.2. Marking Required on Components of

shall be within applicable tolerances. Automatic Weighing Systems. - The following

S.4.4. 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.4.5. 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.4.5.1. 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 weigh-labelers 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.

Table S.7.a. and S.7.b. of the Automatic Weighing

systems shall be located on the weighbridge (loadreceiving element) near the point where the signal leaves

the weighing element or beneath the nearest access

cover.

components of automatic weighing systems shall be

marked as specified in Tables S.7.a. and S.7.b.:

(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.
2.24. Automatic Weighing Systems

ˇ ̨ ̋ ̧

Table S.7.a. Marking Requirements

Weighing

Equipment

To Be

Marked With

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

(11)

Other

equipment or

device

(10)

Manufacturer's ID (1) x x x x

Model Designation(1) x x x x

Serial Number and

Prefix(2)

xx x x

Accuracy Class (14) x x (8) x x x

Nominal Capacity(3)(15) x x x x

Value of Division, d (3) x x x (13)

Value of "e" (4) x x

Temperature Limits (5) x x x x

Special Application (11) x x x

Maximum Number of

Scale Divisions

n (6) max

x (8) x x

Minimum Verification

Division

(e ) min

x

"S" or "M" (7) x

Direction of Loading(13) x

Minimum Dead Load x

Maximum Capacity

(Max)

x x

Minimum Capacity

(Min)

x

Safe Load Limit x

Load Cell Verification

Interval (v ) min

x

Maximum Belt Speed

(m/sec or m/min)

x x

Note: See Table S.7.b. for applicable parenthetical notes.

(Amended 1999)
2.24. Automatic Weighing Systems

ˇ ̨ ̋ ̧

Table S.7.b.

Notes for Table S.7.a.

1. Manufacturer's identification and model

designation. (See G-S.1.)

2. Serial number and prefix. (See G-S.1.)

3. The nominal capacity and value of the automatic

weighing system division shall be shown together

(e.g., 50 000 x 5 kg, or 30 x 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 range is other than -10 C to 40 C (14 F to

104 F).

6. This value may be stated on load cells in units of

1000; (e.g., n: 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,

and the maximum number of divisions, n . max

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 (See G-S.1) 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.
2.24. Automatic Weighing Systems



N.1.1. Test Pucks and Packages. - N.3.1.2. Decreasing-Load Test. - The


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N.1.2. Accuracy of Test Pucks or Packages. - The

error in any test puck or package shall not exceed onefourth (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 (Class F) or the tolerances

expressed in Fundamental Considerations, paragraph 3.2.

(i.e., one-third of the smallest tolerance applied).

N.2. Test Requirements for Automatic Weighing

Systems.

N.2.1. Tests Loads. - A performance test shall consist

of four separate test runs conducted at different test loads

according to Table N.3.2.

N.2.2. Influence Factor Testing. - Influence factor

testing shall be conducted statically.

N.3. Test Procedures - Weigh-Labelers. - If the device is

designed for use in static weighing, it shall be tested

statically using mass standards.

Note: If the device is designed for only dynamic weighing,

it shall only be tested dynamically.

N.3.1. Laboratory - Static Tests.

N.3.1.1. Increasing-Load Test. - The

increasing-load test shall be conducted with the test

loads approximately centered on the load-receiving

element of the scale.

decreasing-load test shall be conducted with the test

loads approximately centered on the load- receiving

element of the scale.

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.3.1.4. 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.3.1.5. 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.) 

N.3.1.6. Influence Factor Testing. - Influence factor

testing shall be conducted.

N.3.2. Laboratory - Dynamic Tests. - The device shall

be tested at the highest speed for each weight range using

standardized test pucks or packages. Test runs shall be

conducted using four test loads as described in Table

N.3.2. Each test load shall be run a minimum of 10

consecutive times.

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 2.24. Automatic Weighing Systems



N.3.2.1. Shift Test. - To determine the effect of N.4.3. Field Test Procedures.

eccentric loading, for devices without a means to align

packages, a test load equal to One-third (1/3) N.4.3.1. Static Tests. - If the scale is designed to

maximum capacity shall be passed over the load operate statically during normal user operation, it shall

receiver or transport belt (1) half-way between the be tested statically according to Sections N.3.1.1.

center and front edge, and (2) halfway between the through N.3.1.5.

center and back edge.

N.3.3. Field Test Procedures dynamically at the highest normal operating speed

N.3.3.1. Static Tests. - If the automatic weighing normal weighing range. The number of consecutive

system is designed to operate statically, and used in weighments shall be one-half (1⁄2) of those specified in

that manner, during normal use operation, it shall be Table N.4.2., but not less than 10.

tested statically using mass standards. The device shall

not be tested statically if it is used only dynamically.

N.3.3.2. Dynamic 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., at the

lowest and highest ranges in which the device is typically

operated.) Each test load should be run a minimum of 10

consecutive times.

N.4. Test Procedures - Automatic Checkweigher

N.4.1. Laboratory - Static Tests. - If the scale is

designed to operate statically during normal user

operation, it shall be tested statically using the applicable

weigh-labeler requirements.

N.4.2. Laboratory - Dynamic 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 four test loads. The number of

consecutive test weighments shall be as described in

Table N.4.2.

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N.4.3.2. Dynamic Tests. - The device shall be tested

using packages at two test loads distributed over its

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; the tolerance

values apply to certified test loads only.

T.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.7.

T.2.3. Multiple Range and Multi-Interval Automatic

Weighing System - For multiple range and multiinterval devices, the tolerance values are based on the

value of the scale division of the range in use.

T.3. Tolerance Values. 

T.3.1. Tolerance Values - Class III Weigh-Labeler.

(See T.3.2. for Class IIIS Weigh-Labelers)
2.24. Automatic Weighing Systems



T.3.1.1. Static Tests. - Tolerance values shall be as

specified in Table T.3., Class III - Tolerances in

Divisions.

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T.3.1.2. Dynamic Tests. - Maintenance tolerance

values shall be as specified in Table T.3., Class III -

Tolerances in Divisions.

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Table T.3.2.1. Static Tolerance for Class IIIS

Weigh-labelers

Test Load in Tolerance in Divisions

Divisions

Class IIIS Acceptance Maintenance

0 - 50 ± 0.5 ± 1

51 - 200 ± 1 ± 2

201 - 1000 ± 1.5 ± 3


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able T.3.2.2. Dynamic Tolerance

for Class IIIS Weigh-labelers

Test Load in Tolerance in Divisions

Divisions

Class IIIS Acceptance Maintenance

0 - 50 ± 1.5 ± 2

51 - 200 ± 2 ± 3

201 - 1000 ± 2.5 ± 4

(Added 1997)

T.3.3. Tolerance Values - Automatic Checkweighers.

T.3.3.1. Laboratory Tests for Automatic

Checkweighers. 

T.3.3.1.1. Static Tests. The acceptance tolerance

values specified in Table T.3., Class III-Tolerances in

Divisions, shall be applied.

T.3.3.1.2. Dynamic Tests.

(a) The systematic error for each test run must be

within the acceptance tolerances for the test load as

specified in Table N.3.2.

(b) The standard deviation of the results shall not

exceed one-ninth (1/9) of the Maximum Allowable

Variation (MAV) for specific package weights (3

standard deviations cannot exceed one-third (1/3) of

the MAV value) as required in the 4th supplement to

the 3rd Edition of Handbook 133 dated October 1994

as specified below. This value does not change

regardless of whether acceptance, or maintenance

tolerances are being applied to the device under test.

(i) 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 Table 2-9, U.S.

Department of Agriculture, Meat and Poultry,

Groups and Lower Limits for Individual Packages,

or

(ii) for all other packages with a labeled net

quantity in terms of weight use Table 2-5,

Maximum Allowable Variations for Packages

Labeled by Weight.

(iii) For all packages with a labeled net quantity in

terms of liquid or dry volume use Table 2-6,
 2.24. Automatic Weighing Systems



Maximum Allowable Variations for Packages

Labeled by Liquid or Dry Volume.

T.3.3.2. Field Tests for Automatic maintenance tolerance for that load, and shall be within

Checkweighers. applicable tolerances.

T.3.3.2.1. Static Test Tolerances. - The T.6. Discrimination. - A test load equivalent to 1.4 d shall

tolerance values shall be as specified in Table cause a change in the indicated or recorded value of at least

T.3., Class III-Tolerances in Divisions. 2.0 d. This requires the zone of uncertainty to be not greater

T.3.3.2.2. Dynamic Test Tolerances. -

(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 Maximum

Allowable Variation (MAV) for specific

package weights (3 standard deviations cannot

exceed one-third (1/3) of the MAV value) as

required in the 4th supplement to the 3rd

Edition of NIST Handbook 133 dated October

1994. This value does not change regardless of

whether acceptance or maintenance tolerances

are being applied to the device under test.

(i) 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 Table 2-9, U.S. Department of

Agriculture, Meat and Poultry, Groups and

Lower Limits for Individual Packages, or

(ii) for all other packages with a labeled net

quantity in terms of weight use Table 2-5,

Maximum Allowable Variations for Packages

Labeled by Weight.

(iii) For all packages with a labeled net

quantity in terms of liquid or dry volume use

Table 2-6. Maximum Allowable Variations

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 static test

conditions shall agree within the absolute value of the

than 0.3 d (See N.3.1.4.)

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 EC to 40 EC (14 EF to 104 EF).

T.7.1.2. - If temperature limits are specified for the

device, the range shall be at least 30 EC (54 EF).

T.7.1.3. Temperature Effect on Zero-Load

Balance. - The zero-load indication shall not vary by

more than one division per 5 EC (9 EF) 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. Barometric Pressure. - The zero indication shall

not vary by more than one 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.7.3. Electric Power Supply. -

T.7.3.1. Power Supply, Voltage and Frequency.

(a) Alternating Current. - Weighing devices that

operate using alternating current must perform within

the conditions defined in paragraphs T.3. 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.
2.24. Automatic Weighing Systems



(b) Battery. - 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.

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 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

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

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 manufacturers recommendations.

UR.3. Use Requirements.

UR.3.1. Minimum Load. - The minimum load shall be

as specified by the manufacturer, but not less than 20

divisions since the use of a device to weigh light loads is

likely to result in relatively large errors.

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UR.3.2. Maximum Load. - An automatic weighing

system shall not be used to weigh a load of more than the

maximum capacity of the automatic weighing system.

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
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 2.24. Automatic Weighing Systems



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.

D. Definitions

automatic checkweigher. - A dynamic automatic weighing

system used to subdivide items of different weights into one

or more subgroups, such as identifying packages that have

acceptable or unacceptable fill levels. These systems may

be used to fill standard packages for compliance with net

weight requirements.

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. Examples include, but

are not limited to, weigh-labelers and checkweighers.

package rate. - PPM - Packages per minute.

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:

or

where:

x = error of a load indication

n = the number of loads

systematic (average) error ( ). - 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., weightable), shall be expressed

mathematically as:

where:

x = error of a load indication

n = the number of loads

test puck. - Metal or plastic object used 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 specific

accuracy so that pucks can be used to conduct performance

tests.

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). Typically, this type of weighing system

determines the weight of packages dynamically, but may

also include a scale that is incorporated in a conveyor

system that weighs packages in a static weighing mode.

Weigh-labelers are sometimes used to weigh and label

standard and random packages (also called "Prepackaging

Scales").


Section 3

Page

3.30. Liquid-Measuring Devices 3-3

3.31. Vehicle-Tank Meters 3-19

3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices 3-27

3.33. Hydrocarbon Gas Vapor-Measuring Devices 3-35

3.34. Cryogenic Liquid-Measuring Devices 3-43

3.35. Milk Meters 3-49

3.36. Water Meters 3-55

3.37. Mass Flow Meters 3-59

3.38. Carbon Dioxide Liquid-Measuring Devices - Tentative Code 3-69

Note: In this section of Handbook 44, the reference temperature for the temperature compensation of refined petroleum

products is shown as "15 EC (60 EF)." Although these values are not exact equivalents, they reflect industry usage when the

SI and inch-pound units are used in measurements.

3.30. Liquid-Measuring Devices



Sec. 3.30. Liquid-Measuring Devices

A. Application

A.1. - 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. - This code does not apply to:

(a) meters mounted on vehicle tanks (see Sec. 3.31. Code

for Vehicle-Tank Meters),

(b) devices used for dispensing liquefied petroleum gases

(see Sec. 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 (see Sec. 3.37. Code for Mass Flow

Meters.)

(Added 1994)

A.3. - In addition to the requirements of this code, liquidmeasuring 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, or binarysubmultiples or decimal subdivisions of the liter or

gallon.

(Amended 1987, 1994)

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)

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 (1 pt) on retail devices;

(b) 5 L (1 gal) on wholesale devices.

This requirement does not apply to manually operated

devices equipped with stops or stroke-limiting means.

(Amended 1983 and 1986)

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
3.30. Liquid-Measuring Devices



(b) in the case of indicating elements only, such

elements are automatically obscured until the

elements reach the correct zero position. (a) The index of an indicator shall not be wider than

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 to the practical minimum.

percent greater than the width of subordinate

graduations.

S.1.4.3. Clear Interval Between Graduations. -The

clear interval between graduations shall be not less S.1.6.1. Indication of Delivery. - The device shall

than 1.0 mm (0.04 in). If the graduations are not automatically show on its face the initial zero

parallel, the measurement shall be made: condition and the quantity delivered (up to the

(a) along the line of movement of the tip of the

index of the indicator as it passes over the However, the first 0.03 L (or 0.009 gal) of a delivery

graduations, or and its associated total sales price need not be

(b) if the indicator extends over the entire length of (Amended 1982)

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.

S.1.5.2. Length.

(a) If the indicator and the graduations are in

different planes, the index of the indicator shall S.1.6.2.2. User Information. - The device memory

extend to each graduation with which it is to be shall retain information on the quantity of fuel

used. dispensed and the sales price totals during power

(b) If the indicator is in the same plane as the [Nonretroactive as of January 1, 1983.]

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). (a) The primary indicating elements, and primary

S.1.5.3. Width.

the width of the widest graduation. 

(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

S.1.6. Operating Requirements, Retail Devices

(Except Slow Flow Meters).

nominal capacity). 

indicated.

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.]

loss.

S.1.6.3. Return to Zero.

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 self-operated device may be equipped with
3.30. Liquid-Measuring Devices



cumulative indicating or recording elements, trucks) for which the product being measured is

provided that it is also equipped with a zero- offered for sale at any delivery possible within

return indicating element. either the measurement range of the device or

(b) It shall not be possible to return primary is less.

indicating elements, or primary recording [Effective and nonretroactive as of January 1,

elements beyond the correct zero position. 1991].

(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) 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 be

displayed or shall be capable of being

displayed on the dispenser using controls

available to 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. This subsection

shall not apply to fleet sales, other contract

sales, or truck refueling sales (e.g., sales from

dispensers used to refuel trucks).

[Effective and nonretroactive as of January 1,

1991.]

(Amended 1989 and 1997)

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

the range of the computing elements, whichever

(b) The analog sales price indicated for any

delivered quantity shall not differ from a

mathematically computed price (quantity x unit

price = total sales price) by an amount greater

than the value in Table 1.

(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.

(Amended 1991)

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 inch-pound 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.]

S.1.6.5.4. 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 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

product.

[Effective and nonretroactive as of January 1,

1991.]

(Added 1989)(Amended 1991, 1992, 1993, and

1996)
3.30. Liquid-Measuring Devices



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S.1.6.5.5. 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 customer-activated

controls.

[Effective and nonretroactive as of January 1,

1994.]

(Added 1992)(Amended 1996)

S.1.6.6. 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, 1988.]

(Added 1985)(Amended 1987 and 1988)

S.1.6.7. Recorded Representations. - 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,

(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)

S.1.6.8. 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).
3.30. Liquid-Measuring Devices



S.1.7. 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 one cent of

money value.

S.2. Measuring Elements.

S.2.1. Vapor Elimination.

(a) A liquid-measuring device shall be equipped with (Amended 1983)

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 (b) adjustable to provide for deliveries within

Metering Systems. tolerances.

(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 physically applying security seals in

such a manner that no adjustment may be made of:

(a) any measurement element, or

(b) any adjustable element for controlling delivery rate

when such rate tends to affect the accuracy of

deliveries.

When applicable, the adjusting mechanism shall be

readily accessible for purposes of affixing a security seal.

(c) Audit trails shall use the format set forth in Table

S.2.2. [Nonretroactive and enforceable as of

January 1, 1995.]

(Amended 1991, 1993, and 1995)

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.

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

(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,
3.30. Liquid-Measuring Devices



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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. 

[Category 2 applies only to devices

manufactured prior to January 1, 2005. 

Devices with remote configuration capability

manufactured after that date must meet the

sealing requirements outlined in Category 3. 

Devices without remote configuration

capability manufactured after that date will be

required to meet the minimum criteria outlined

in Category 1.]

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and recording elements if the device is equipped (c) in a system with more than one dispenser supplied

and activated to record, have been returned to their by a single pump, an effective automatic control

zero positions; valve in each dispenser prevents product from

(b) the discharge nozzle cannot be returned to its designed dispenser are in a correct zero position.

hanging position (that is, any position where the tip of (Amended 1981 and 1985)

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 Devices. - For test purposes, means shall be provided to

interlock has been engaged; and determine the temperature of the liquid either:

being delivered until the indicating elements on that

S.2.6. Temperature Determination and Wholesale
3.30. Liquid-Measuring Devices



(a) in the liquid chamber of the meter, or 

(b) immediately adjacent to the meter in the meter inlet

or discharge line.

[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 EC

(60 EF).

S.2.7.2. Provision for Deactivating. - On a device

equipped with an automatic temperature-compensating

mechanism that will indicate or record only in terms

of gallons compensated to 15 EC (60 EF), 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.

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) become inoperable automatically, or

(b) give a conspicuous and distinct warning. 

S.3. Discharge Lines and Valves.

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S.3.2. Exceptions. - The provisions of S.3.1. Diversion

Prohibited shall not apply to:

(a) 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;

(b) other devices, when all discharge outlets designed

to operate simultaneously are 3.8 cm (1.5 in) in

diameter or larger.

(Amended 1982, 1990, and 1991)

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;
3.30. Liquid-Measuring Devices



(c) an automatic vacuum breaker, or equivalent discharge rate shall not exceed 20 percent of the maximechanism, shall be incorporated to prevent mum discharge rate. 

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.

S.3.5. Discharge Hose, Reinforcement. - A discharge delivered has been adjusted to the volume at 15 EC

hose shall be reinforced so that the performance of the (60 EF).

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 S.5. Totalizers for Retail Motor-Fuel Dispensers. - Retail

(b) by mutilation of a security seal with which the nonresettable totalizer for the quantity delivered through

valve is sealed open. the metering device. [Nonretroactive as of January 1,

S.3.7. Antidrain Means. - In a wet-hose pressuretype 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; or

(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

S.4.3.2. 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

S.4.4. Retail Devices. - On a retail device with a designed maximum discharge rate of 100 L (25 gal) per

minute or greater, the maximum and minimum

discharge rates shall be marked on an exterior surface

of the device and shall be visible after installation. The

minimum discharge rate shall not exceed 20 percent of

the maximum discharge rate.

[Nonretroactive as of January 1, 1985.]

(Added 1984)

motor-fuel dispensers shall be equipped with a

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
3.30. Liquid-Measuring Devices



measured and indicated through either a visible The first test shall be performed with the automatic

indication or an audible signal. temperature-compensating system operating in the "as

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 N.4.2.1. Slow-Flow Meters. - A "special" test shall

installation. be made at a flow rate:

(Amended 1984)

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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 EC (60 EF); and 

(b) with the temperature compensating system

deactivated, comparing the uncompensated

volume indicated or recorded to the actual

delivered volume.

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.4.2. Special Tests. - "Special" tests, to develop the

operating characteristics of a liquid-measuring device

and any special elements and accessories attached to or

associated with the device, shall be made as

circumstances require. Any test except as set forth in

N.4.1. shall be considered a special test. 

(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 with a flow-rate capacity less than

100 L (25 gal) per minute 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 marked on the

device, or 

(3) the minimum discharge rate at which the

device will deliver when equipped with an

automatic discharge nozzle set at its

slowest setting.

(b) Devices marked with a flow-rate capacity 100 L

(25 gal) or more per minute, shall have a

"special" test performed at the slowest of the

following rates:

(1) the minimum discharge rate marked on the

device, or

(2) the minimum discharge rate at which the

device will deliver when equipped with an

automatic discharge nozzle set at its slowest

setting.
3.30. Liquid-Measuring Devices



(Added 1984) are necessary, appropriate petroleum measurement tables

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 percent 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 the slower of the following rates:

(a) 20 percent of the marked maximum discharge

rate; or

(b) the minimum discharge rate marked on the

device.

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., MoneyValue 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.

(Amended 1984)

N.4.3.2. Field Tests. - In the conduct of field tests to

determine compliance with paragraph S.1.6.5., the

maximum allowable variation in the indicated sales

price shall be as shown in Table 1.

(Added 1982; Amended 1984)

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

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.

T.2.1. Retail Devices Except Slow-Flow Meters.

T.2.1.1. Devices Indicating in Metric Units.

(a) The maintenance tolerance on normal and

special tests, shall be 20 mL, plus 4 mL per

indicated liter, and never less than 40 mL.

(b) The acceptance tolerance on normal and special

tests shall be 10 mL, plus 2 mL per indicated

liter and never less than 20 mL.

(c) The tolerance applied to a 19-liter draft shall be

that tolerance applicable to a 20-liter draft.

(Amended 1981 and 1986)

T.2.1.2. Devices Indicating in Inch-Pound Units.

(a) The maintenance tolerance on normal and

special tests shall be 1 in plus 1 in per indicated 3 3

gallon and never less than 2 in .3

(b) The acceptance tolerance on normal and special

tests shall be 1/2 in plus 1/2 in per indicated 3 3

gallon and never less than 1 in .3

(Amended 1981 and 1986)

T.2.1.3. Repeatability. - When multiple tests are

conducted at approximately the same flow rate, the

range of the test results for the flow rate shall not

exceed 40 percent of the absolute value of the

maintenance tolerance.

(Added 1992)

T.2.1.4. Tolerances for Devices Designed to

Primarily Deliver Less than One Gallon. -

Maintenance tolerances and acceptance tolerances

shall be as shown in Table 2. Tolerances for

Slow-Flow Meters.

(Added 1999)
3.30. Liquid-Measuring Devices



T.2.2. Slow-Flow Meters. - Maintenance tolerances and

acceptance tolerances shall be as shown in Table 2.

T.2.3. Wholesale Devices.

T.2.3.1. Measurement of Agri-Chemical Liquids. -

 Acceptance tolerances and maintenance tolerances

shall be 0.3 percent and 0.5 percent, respectively.

(Amended 1995)

T.2.3.2. Measurement of Asphalt. - Maintenance

tolerances and acceptance tolerances shall be:

Acceptance Maintenance

Asphalt below 50 °C 0.2 % 0.3 %

Asphalt above 50 °C 0.3 % 0.3 %

T.2.3.3. Measurement of Other Liquids. -

Maintenance tolerances and acceptance tolerances

shall be:

#EEGRVCPEG/CKPVGPCPEG

0QTOCNVGUV  

5RGEKCNVGUV  

T.2.3.4. Repeatability. - When multiple tests are

conducted at approximately the same flow rate, the

range of the test results for the flow rate shall not

exceed 40 percent of the applicable tolerance. This

tolerance does not apply to the test of the automatic

temperature compensating system.

(Added 1992)

T.2.3.5. 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 percent for mechanical automatic

temperature compensating systems; and

(b) 0.1 percent 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.

[Nonretroactive as of January 1, 1988.]

(Added 1987) (Amended 1992 and 1996)

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)
3.30. Liquid-Measuring Devices



Table 2.

Tolerances for Slow-Flow Meters

Indication

Normal tests Special tests

Maintenance

tolerance

Acceptance

tolerance

Maintenance and

acceptance

tolerance

percent minims percent minims percent minims

1 gill 1.0 20 0.75 15 1.25 25

0.05 gallon 1.0 30 0.75 25 1.25 40

1/2 pint 1.0 40 0.75 30 1.25 50

0.10 gallon 1.0 60 0.75 45 1.25 75

1 pint 1.0 75 0.75 60 1.25 95

0.20 gallon 1.0 120 0.75 90 1.25 155

fl drams fl drams fl drams

1 quart 1.0 2-1/2 0.75 2 1.25 3

1/2 gallon 0.75 4 0.60 3 1.0 5

1 gallon and

over

0.75 8 per

gallon

0.60 6 per

gallon

1.0 10 per

gallon

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 UR.2.3. Suction Head. - A piston-type device shall be

exceed 15 m (50 ft) unless it can be demonstrated installed so that the total effective suction head will not

that a longer hose is essential. be great enough to cause vaporization of the liquid being

UR.1.1.2.2. Protection. - Discharge hoses

exceeding 8 m (26 ft) in length shall be adequately

protected from weather and other environmental UR.2.4. Diversion of Liquid Flow. - A motor-fuel

factors when not in use. device equipped with two delivery outlets used exclu-

(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.

dispensed under the highest temperature and lowest

barometric pressure likely to occur.

sively 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)

UR.2.5. Product Storage Identification.
3.30. Liquid-Measuring Devices



(a) The fill connection for any petroleum product

storage tank or vessel supplying motor-fuel devices

shall be permanently, plainly, and visibly marked as (a) Any computing device placed into service after

to product contained. January 1, 1990, in an application where a product

(b) When the fill connection device is marked by price (excluding fleet sales and other price contract

means of a color code, the color code key shall be sales), shall be used only for sales for which the

conspicuously displayed at the place of business. device computes and displays the sales price for the

(Added 1975 and Amended 1976) selected transaction. Individual single unit-price

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-lockoperated 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 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- volume of the delivery, and the price per gallon or liter

operated type, the unit price at which the dis- shall be shown, either printed or in clear hand script, on

penser is set to compute. any printed ticket issued by a device of the computing

Provided that the dispenser complies with

S.1.6.4.1., 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, and 1993)

UR.3.3. Computing Device.

or grade is offered for sale at more than one unit

computing devices installed to replace existing

devices or to add to station capacity are exempt

from this requirement. A computing device shall

be used only for sales for which the device

computes and displays the sales price for the

transaction.

(Effective and retroactive as of January 1, 1999)

(Added 1989) (Amended 1992)

(b) A truck stop dispenser used exclusively for

refueling trucks is exempt from the requirements in

(a) and (b) if 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.

(Added 1993)

(c) Unless a truck stop dispenser used exclusively for

refueling trucks 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)

UR.3.4. Printed Ticket. - The total price, the total

type and containing any one of these values.

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.
3.30. Liquid-Measuring Devices



UR.3.6. Temperature Compensation, Wholesale. UR.3.6.1.2. Invoices.

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.3.6.2. Nonautomatic.

(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 EC (60 EF).

(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.3.6.2.1. Temperature Determination. - If the

volume of the product delivered is adjusted to the

volume at 15 EC (60 EF), 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 EC (60 EF) and shall also state the

product temperature used in making the adjustment.
3.30. Liquid-Measuring Devices



Liquid-Measuring Device Code Index

Acceptance ....................... 3-12, 3-13, 3-14

Adjustable element . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Advancement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3, 3-9

Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 3-6, 3-7

Agri-chemical .......................... 3-3, 3-13

Agri-chemical liquids .................... 3-3, 3-13

Antidrain means . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

Automatic . . . 3-7, 3-8, 3-9, 3-10, 3-11, 3-12, 3-13, 3-14,

3-16 Retail devices .............. 3-3, 3-4, 3-10, 3-11, 3-12

Automatic temperature compensating systems ..... 3-9,

3-11, 3-13 Retail motor-fuel dispensers .................. 3-10

Automatic temperature compensation . . . . . . . . . . . . 3-9

Automatic temperature compensators . . . . . . . . . . . . 3-9

Auxiliary elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Blend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 3-15

Clear interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Computing device . . . . . . . . . . . . . . . . . . . . . . . 3-5, 3-15

Directional flow valves . . . . . . . . . . . . . . . . . . . . . . . 3-7

Discharge hose . . . . . . . . . . . . . . . . . . . . 3-10, 3-13, 3-14

Discharge lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9

Discharge rate . . . . . . . . . . . . . . . 3-10, 3-11, 3-12, 3-14

Discharge rates ............................. 3-10

Diversion of liquid . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

Dry hose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

Fleet sales .......................... 3-5, 3-6, 3-15

Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5, 3-15

Graduations . . . . . . . . . . . . . . . . . . . . 3-4, 3-6, 3-7, 3-10

Gravity-discharge unit ....................... 3-10

Index of an indicator . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Indicating element ................... 3-3, 3-5, 3-15

Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Installation requirements ..................... 3-14

Interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8, 3-16

Invoices .................................. 3-16

Key-lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-15

Lubricant devices .................... 3-6, 3-9, 3-11

Maintenance . . . . . . . . . . . . . . . . . . . . . . 3-12, 3-13, 3-14

Marking requirements . . . . . . . . . . . . . . . . . . . . . . . 3-10

Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1, 3-3

Mass flow meters ......................... 3-1, 3-3

Measuring elements . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Money values-mathematical agreement . . . . . . . . . . 3-7

Money-value computation .................... 3-12

Money-value computations . . . . . . . . . . . . . . . . . . . . 3-5

Money-value divisions . . . . . . . . . . . . . . . . . . . . . 3-5, 3-6

Motor-fuel device ................. 3-13, 3-15, 3-16

Nonautomatic .............................. 3-16

Normal tests . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11, 3-14

Operating requirements . . . . . . . . . . . . . . . . . . . . 3-4, 3-7

Parallax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Power loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Price contract sales ................... 3-5, 3-6, 3-15

Primary indicating element ................ 3-3, 3-15

Printed ticket .......................... 3-15, 3-16

Product identity ..................... 3-5, 3-6, 3-15

Provision for sealing ...................... 3-7, 3-9

Pump-discharge unit ........................ 3-10

Quantity .......... 3-4, 3-5, 3-6, 3-7, 3-10, 3-11, 3-12

Recording element ................... 3-3, 3-6, 3-15

Repeatability .............................. 3-13

Retail motor-fuel device ................. 3-13, 3-16

Return to zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7, 3-8, 3-9, 3-10

Sealing ............................. 3-7, 3-8, 3-9

Security . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7, 3-9, 3-10

Selection of unit price . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Slow flow meters ........................ 3-4, 3-11

Special tests ................. 3-11, 3-12, 3-13, 3-14

Stop mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Temperature correction ...................... 3-12

Temperature determination ................ 3-9, 3-16

Test drafts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11

Tolerances . . . . . . . . . . . . . . . . . . . 3-7, 3-12, 3-13, 3-14

Total price ......................... 3-5, 3-6, 3-15

Totalizers ............................. 3-10, 3-15

Travel of indicator ........................ 3-6, 3-7

Truck refueling ..................... 3-5, 3-9, 3-15

Unit price . . . . . . . . . . . . . . . . . . . . . . 3-4, 3-5, 3-6, 3-15

User information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7, 3-9, 3-15

Vapor elimination . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

Wet-hose ................................. 3-10

Wholesale devices . 3-3, 3-7, 3-9, 3-10, 3-11, 3-12, 3-13

Zero-set-back interlock ................... 3-8, 3-16
3.31. Vehicle-Tank Meters



Sec. 3.31. Vehicle-Tank Meters

A. Application

A.1. - 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. - This code does not apply to the following devices:

(a) Devices used for dispensing liquefied petroleum gases

(for which see Sec. 3.32; Code for Liquefied

Petroleum Gas and Anhydrous Ammonia LiquidMeasuring Devices), or other liquids that do not

remain in a liquid state at atmospheric pressures and

temperatures.

(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 (for which see Sec.

4.40; Code for Vehicle Tanks Used as Measures).

(d) Mass flow meters (see Sec. 3.37. Code for Mass Flow

Meters)

(Added 1994)

A.3. - See also Sec. 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: Nonretroactive and effective January 1, 1995,

vehicle tank metering systems shall be equipped with

a ticket printer. To become retroactive as of January

1, 1999. See UR.2.2.]

(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 (gallons). Fractional parts of the liter

(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 (pounds) and decimal

kilograms (pounds). The weight value division

shall be a decimal multiple or submultiple of 1,

2, or 5. (See S.5.5.)

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 500 L/min (100 gal/min) or less

used for retail deliveries of liquid fuel, or

(c) 5 L (1 gal) on other meters.

(Amended 1989 and 1994)

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
3.31. Vehicle-Tank Meters



return of primary indicating elements, and of primary When the index of an indicator extends along the

recording elements if these are returnable to zero, entire length of a graduation, that portion of the index

beyond their correct zero position. of the indicator that may be brought into coincidence

S.1.2. Graduations.

S.1.2.1. Length. - Graduations shall be so varied in

length that they may be conveniently read. S.1.3.4. Clearance. - The clearance between the

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 S.1.3.5. Parallax. - Parallax effects shall be reduced

graduations, and the width of main graduations shall to the practicable minimum.

be not more than 50 percent 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. - these parts corresponding to the smallest indicated

The clear interval shall be not less than 2.5 mm value shall not be less than 5 mm (0.20 in).

(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.

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 and shall be accurately positioned. The value of each

indicator in relation to the series of graduations with graduated interval shall be 1 cent. On electronic

which it is used shall be not greater than devices with digital indications, the total price may be

(a) the width of the widest graduation, and the value of the smallest division indicated is equal to

(b) the width of the minimum clear interval between (Amended 1979, 1989)

graduations.

with the graduation shall be of the same width

throughout the length of the index that coincides with

the graduation.

index of an indicator and the graduations shall in no

case be more than 1.5 mm (0.06 in).

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

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 on the outside of the device, in a manner

clear to the operator and an observer, the unit price at

which the device is set to compute.

(Amended 1983)

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. - Moneyvalue 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

computed on the basis of the quantity indicated when

or less than 0.2 L (0.1 gal) or 0.2 kg (1 lb).

S.1.4.4. Money Values, Mathematical Agreement.

- Any digital money-value indication and any recorded
3.31. Vehicle-Tank Meters



money value on a computing-type device shall be in (b) the direction of flow for which the mechanism may

mathematical agreement with its associated quantity be set at any time is definitely and conspicuously

indication or representation to within 1 cent of money indicated.

value.

S.2. Design of Measuring Elements. unit, the discharge hose shall be of the wet-hose type

S.2.1. Vapor Elimination. - A metering system shall be discharge unit may be equipped also with a dry hose

equipped with an effective vapor or air eliminator or without a shutoff valve at its outlet end, but only if:

other automatic means to prevent the passage of vapor

and air through the meter. Vent lines from the air or (a) the dry hose is as short as practicable, and

vapor eliminator shall be made of metal tubing or some

other suitable rigid material. (b) there is incorporated in the discharge piping,

(Amended 1993) immediately adjacent to the meter, effective means

S.2.2. Provision for Sealing. - Except on devices for

metering milk, adequate provision shall be made for

applying security seals in such a manner that no adjustment may be made of:

(a) any measurement element, and charge unit, the discharge hose or equivalent pipe shall

(b) any adjustable element for controlling delivery rate end. The dry hose shall be of such stiffness and only of

when such rate tends to affect the accuracy of such length as to facilitate its drainage. The inlet end of

deliveries. the hose or of an equivalent outlet pipe shall be of such

S.2.2.1. Milk-Metering Systems. - Adequate

provision shall be made for applying security seals to

the adjustment mechanism and the register.

The adjusting mechanism shall be readily accessible for S.3.4. Discharge Hose. - A discharge hose shall be

purposes of affixing a security seal. adequately reinforced.

S.2.3. Directional Flow Valves. - Valves intended to S.3.5. Discharge Valve. - A discharge valve may be

prevent reversal of flow shall be automatic in operation. installed in the discharge line only if the device is of the

However, on equipment used exclusively for fueling wet-hose type, in which case such valve shall be at the

aircraft, such valves may be manual in operation. discharge end of the line. Any other shutoff valve on the

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 therefrom. However, two or more

delivery outlets may be installed if means is provided to S.3.6. Antidrain Valve. - In a wet-hose, pressure-type

insure that: device, an effective antidrain valve shall be incorporated

(a) liquid can flow from only one such outlet at one The antidrain valve shall function so as to prevent the

time, and drainage of the discharge hose. However, a device used

S.3.2. Pump-Discharge Unit. - On a pump-discharge

with a shutoff valve at its outlet end. However, a pumpto 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.

S.3.3. Gravity-Discharge Unit. - On a gravity-disbe of the dry-hose type with no shutoff valve at its outlet

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

insure the rapid and complete drainage.

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.

in the discharge valve or immediately adjacent thereto.

exclusively for fueling and defueling aircraft may be of

the pressure type without an antidrain valve.
3.31. Vehicle-Tank Meters



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 percent of the maximum discharge rate.

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.

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)

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).

(Part (b) 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.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.

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. shall be considered a special test. Special test

of a measuring system shall be made as follows:

(a) at a minimum discharge rate of 20 percent of the

marked maximum discharge rate or at the minimum
3.31. Vehicle-Tank Meters



discharge rate marked on the device whichever is installation, in which case this shall be fully effective and

less; automatic in operation.

(b) to develop operating characteristics of the measuring system during a split-compartment delivery.

(Amended 1978)

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.

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 Tables 1, 2, 3, and 4.

(Amended 1995)

T.3. Tolerance Values on Meters Used for the Measurement of Agri-Chemical Liquids. - The maintenance

tolerance on normal and special tests shall be 1 percent of

the indicated quantity. The acceptance tolerance on a normal test shall be 0.5 percent of the indicated quantity and on

special tests, 1 percent of the indicated quantity.

(Added 1985, Amended 1989)

T.4. Repeatability. - When multiple tests are conducted at

approximately the same flow rate, the range of the test

results for the flow rate shall not exceed 40 percent of the

applicable tolerance.

(Added 1992)

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

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.

UR.1.3. Intake Hose. - The intake hose in a milkmetering system shall be installed to permit complete

drainage and ensure that all available product is measured following each pickup.

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. - Vehiclemounted 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)
3.31. Vehicle-Tank Meters



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 sale 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.

Table 1.

Tolerances for Vehicle-Tank Meters Except for Vehicle-Mounted Milk Meters,

Agri-Chemical Meters, and Water Meters

Normal tests Special tests

Indication Acceptance tolerance Maintenance Maintenance and acceptance

tolerance tolerance

(Gallons) (Cubic inches) (Cubic inches) (Cubic inches)

50 50 25 50

Over 50 Add 1/2 cubic Add 1/4 cubic Add 1 cubic

inch per inch per inch per

indicated indicated indicated

gallon over 50 gallon over 50 gallon over 50
3.31. Vehicle-Tank Meters



Table 2. Tolerances for

Vehicle-Mounted 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)
3.31. Vehicle-Tank Meters



Table 3. Tolerances for Vehicle-Mounted Water Meters

Normal Tests

Meter size Rate of flow

(inches) (gal/min)

Maximum Rate

Meter indication Tolerance on over- and

under-registration gal ft3

5/8 15 50 5

3/4 25 50 5

1 40 100 10

1 1/2 80 300 40 1.5%

2 120 500 40

3 250 500 50

4 350 1 000 100

6 700 1 000 100

(Added 1995)

Table 4. Tolerances for Vehicle-Mounted Water Meters

Special Tests

Meter size Tolerance

(inches)

Intermediate rate Minimum rate

Rate of Rate of

flow flow

(gal/ (gal/

min) min)

Meter Meter

indication Tolerance on over- indication

and underregistration gal ft gal ft 3 3 Under- Overregistration registration

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

1 1/2 8 50 5 1.5% 1 1/2 10 1 5.0% 1.5%

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

(Added 1995)
3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices

6KVNGCOGPFGF 



Sec. 3.32. Liquefied Petroleum Gas and Anhydrous Ammonia

Liquid-Measuring Devices1

A. Application.

A.1. - 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. - 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. - See also Sec. 1.10; General Code requirements.

A.4. - This code does not apply to mass flow meters (see

Sec. 3.37. Code for Mass Flow Meters)

(Added 1994)

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 ticket printer as required by paragraph

UR.2.6.]

S.1.1.2. Units. - A device shall indicate, and record if

the device is equipped to record, its deliveries in terms

of gallons, quarts, pints, or binary-submultiple or

decimal subdivisions of the 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

(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 one cent of

money value; except that a stationary retail

computing-type device must compute and indicate to

the nearest 1 cent of money value (see Sec. 1.10., GS.5.5.).

(Amended 1984, 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, the

width of a graduation shall in no case be greater then

the width of the minimum clear interval between

graduations, and the width of main graduations shall

be not more than 50 percent greater than the width of
3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices



subordinate graduations. Graduations shall in no case

be less than 0.2 mm (0.008 in) width.

S.1.2.3. Clear Interval Between Graduations. - The nominal capacity of the device.

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 primary indicating elements, and of primary

be symmetrical with respect to the graduations, at least recording elements if these are returnable to

throughout that portion of its length associated with zero, beyond their correct zero position.

the graduations. (Amended 1990)

S.1.3.2. Length. - The index of an indicator shall S.1.5. For Stationary Retail Devices Only.

reach to the finest graduations with which it is used,

unless the indicator and the graduations are in the S.1.5.1. Display of Unit Price and Product

same plane, in which case the distance between the Identity. - In a device of the computing type, means

end of the indicator and the ends of the graduations, shall be provided for displaying on each face of the

measured along the line of graduations, shall be not device the unit price at which the device is set to

more than 1.0 mm (0.04 in). compute or to deliver as the case may be, and there

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

graduations. S.1.5.2. Money-Value Computations. - A

When the index of an indicator extends along the any single-purchase unit price (excluding fleet sales

entire length of a graduation, that portion of the index and other price contract sales) for which the product is

of the indicator that may be brought into coincidence offered for sale at any delivery possible within either

with the graduation shall be of the same width the measurement range of the device or the range of

throughout the length of the index that coincides with the computing elements, whichever is less. The

the graduation. analog money value indication shall not differ from 

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

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

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.

computing device shall compute the total sales price at
3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices



the mathematically computed money value (quantity x

unit price = sales price), for any delivered quantity, by

an amount greater than the values shown in Table 1.

(Amended 1995)

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-gallon intervals for

devices indicating in inch-pound units and 0.05

liter 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.1.6. 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 utilizes 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 applying security seals in such a manner that

no adjustment may be made of:

(a) any measurement element, 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.2.3. 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)

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 EC

(60 EF).

S.2.6.1. Provision for Deactivating. - On a device

equipped with an automatic temperature compensating

mechanism that will indicate or record only in terms

of liters compensated to 15 EC or gallons to 60 EF,

provision shall be made to facilitate the deactivation

of the automatic temperature compensating

mechanism so that the meter may indicate, and record
3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices



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¢ ± 2 1/2¢ ± 5¢

if it is equipped to record, in terms of the system to allow for repair and maintenance operations

uncompensated volume. shall be permitted. Effective means shall be provided to

(Amended 1972) prevent the passage of liquid through any such outlet

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.3.2. Delivery Hose. - The delivery hose of a retail

S.3. Design of Discharge Lines and Discharge Line

Valves. S.4. Marking Requirements.

S.3.1. Diversion of Measured Liquid. - No means shall S.4.1. Limitation of Use. - If a device is intended to

be provided by which any measured liquid can be measure accurately only products having particular

diverted from the measuring chamber of the meter or the properties, or to measure accurately only under specific

discharge line therefrom. However, two or more installation or operating conditions, or to measure

delivery outlets may be permanently installed if means accurately only when used in conjunction with specific

are provided to insure that: accessory equipment, these limitations shall be clearly

(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

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).

device shall be of the wet-hose type with a shutoff valve

at its outlet end.

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
3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices



(b) 20 percent of the marked maximum discharge rate both the compensated and uncompensated volume for

for other retail devices and for wholesale devices. each delivery, the tests in (a) and (b) may be

(Amended 1987) performed as a single test.

S.4.3. Temperature Compensation. - If a device is

equipped with an automatic temperature compensator, N.4.2. Special Tests. - "Special" tests, to develop the

the primary indicating elements, recording elements, and operating characteristics of a device and any special

recorded representation shall be clearly and elements and accessories attached to or associated with

conspicuously marked to show that the volume delivered the device, shall be made as circumstances require. Any

has been adjusted to the volume at 15 EC (60 EF). test except as set forth in N.4.1. shall be considered a

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 1 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

corrected to 15 EC (60 EF); 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

(Amended 1987)

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:

(a) the minimum discharge rate that can be

developed under the conditions of installation, or

(b) the 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 percent 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. shall be
3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices



determined by using the cone gear as a reference for automatic temperature compensating system activated shall

the total quantity delivered. The indicated delivered not exceed:

quantity shall agree with the cone gear representation

with the index of the indicator within the width of the (a) 1.0 percent for mechanical automatic temperature

graduation. The maximum allowable variation of the compensating systems; and

indicated sales price shall be as shown in Table 1.

N.4.3.2. Field Tests. - In the conduct of field tests to

determine compliance with paragraph S.1.5.2. the

maximum allowable variation in the indicated sales

price shall be as shown in Table 1.

(Added 1984)

N.5. 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.

T. Tolerances installed that the actual maximum discharge rate will not

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, UR.1.2. Length of Discharge Hose. - The length of the

whether or not a device is equipped with an automatic discharge hose on a stationary motor-fuel device shall

temperature compensator. not exceed 5.5 m (18 ft), measured from the outside of

T.2. Tolerance Values. - The maintenance and acceptance

tolerances for normal and special tests shall be:

#EEGRVCPEG

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(Amended 1988 and 1992)

T.3. Repeatability. -When multiple tests are conducted at

approximately the same flow rate, the range of the test

results for the flow rate shall not exceed 40 percent 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.

(Added 1992) (Amended 1997) 

T.4. Automatic Temperature Compensating Systems. -

The difference between the meter error (expressed as a

percentage) for results determined with and without the

(b) 0.5 percent 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

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.

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)

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.)

UR.2.3. Vapor-Return Line. - During any metered

delivery of liquefied petroleum gas from a supplier’s tank
3.32. LPG and Anhydrous Ammonia Liquid-Measuring Devices



to a receiving container, there shall be no vapor-return motion while on a public street, highway, or

line from the receiving container to the supplier’s tank: thoroughfare.

(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 EF.

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 at 15 EC or the United States gallon of 231 in3

at 60 EF.

(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 EC (60 EF).

(Amended 1984)

UR.2.4.4. Automated Temperature-Compensating

Systems. - Means for determining the temperature of

measured liquid in an automatic temperaturecompensating 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

UR.2.6. Ticket Printer; Customer Ticket. - Vehiclemounted 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.

(Added 1992)
3.33. Hydrocarbon Gas Vapor-Measuring Devices

6KVNGEJCPIGF 

3-35

Sec. 3.33. Hydrocarbon Gas Vapor-Measuring Devices1

A. Application

A.1. - 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, 1991)

A.2. - This code does not apply to:

(a) Liquid-measuring devices used for dispensing

liquefied petroleum gases in liquid form (for which

see Sec. 3.32; Code for Liquefied Petroleum Gas and

Anhydrous Ammonia Liquid-Measuring Devices).

(b) Natural, liquefied petroleum, and manufactured-gasvapor meters when these are operated in a public

utility system.

(c) Mass flow meters (see Sec. 3.37. Code for Mass Flow

Meters)

(Added 1994)

A.3. - See also Sec. 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 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, 1991)

S.1.1.3. Value of Smallest Unit. - VolumeMeasuring Devices: The value of the smallest unit of

indicated delivery, and recorded delivery if the device

is equipped to record, shall not exceed:

( 1 m (1000 dm ) (100 ft ) when the maximum 3 33

rated gas capacity is less than 100 m /h3

(10 000 ft /h); 3

( 10 m (1000 ft ) when the maximum rated gas 3 3

capacity is 280 m /h (10 000 ft /h) up to but not 3 3

including 1700 m /h (60 000 ft /h); 3 3

(c 100 m (10 000 ft ) when the maximum rated 3 3

gas capacity is 1700 m /h (60 000 ft /h) or more. 3 3

(Amended 1972, 1988, 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.

S.1.1.5. Proving Indicator. - Devices rated less than

280 m /h (10 000 ft /h) gas capacity shall be equipped 3 3

with a proving indicator measuring 0.025, 0.05, 0.1,

0.2, or 0.25 m per revolution, (1, 2, 5, or 10 ft per 3 3

revolution) for testing the meter. Devices with larger

capacities shall be equipped as follows:

(a) Devices rated 280 m (10 000 ft ) up to but not 3 3

including 1700 m /h (60 000 ft /h) gas capacity 3 3

shall be equipped with a proving indicator

measuring not greater than 1 m (100 ft ) per 3 3

revolution.

(b) Devices rated 1700 m /h (60 000 ft /h) gas 3 3

capacity or more shall be equipped with a

proving indicator measuring not more than 10 m3

(1000 ft ) per revolution. 3

The test circle of the proving indicator shall be

divided into 10 equal parts. Additional subdivisions

of one or more of such equal parts may be made.

(Amended 1973 and 1988)
82/ ' ##2 % )2

##2 % 0)2

3.33. Hydrocarbon Gas Vapor-Measuring Devices

3-36

S.1.2. Graduations. to the practicable minimum.

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 a retail motor fuel, the vapor should be measured at a

width of a graduation shall in no case be greater than normal gauge pressure (psig) of:

the width of the minimum clear interval between (Amended 1991)

graduations, and in no case should it exceed 1.0 mm

(0.04 in) for indicating elements and 0.5 mm (0.02 in) (a) 2740 Pa ± 685 Pa (11 in of water column

for proving circles. (0.40 psig) ± 2.75 in of water column (0.10 psig))

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:

(a) the width of the widest graduation, and

(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

S.2. Design of Measuring Elements.

S.2.1. Pressure Regulation. - Except when measured as

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:

Where

VPM = Volume pressure multiplier

AAP = Assumed atmospheric pressure in psia

GP = Gauge pressure in pascal or psig

NGP = Normal gauge pressure in pascal 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 percent.

(Amended 1980, 1984, 1991)

S.2.2. Provision for Sealing. - Adequate provision shall

be made for applying security seals in such a manner that

no adjustment 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.
3.33. Hydrocarbon Gas Vapor-Measuring Devices

3-37

Table 1.

Capacity of Low-Flow Test Rate Orifices

With Respect to Device Capacity

Metric Units Inch-Pound Units

Rated Capacity Low-Flow Test Rate Rated Capacity Low-Flow Test Rate

Up to and including

7 m /h3

0.007 m /h3 Up to and including 250

ft /h3

0.25 ft /h3

Over 7 m /h up to and 3

including 14 m /h3

0.014 m /h3 Over 250 ft /h up to and 3

including 500 ft /h3

0.50 ft /h3

Over 14 m /h3 0.1% of capacity rate Over 500 ft /h3 0.1% of capacity rate

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 EC (60 EF).

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.

S.4.2. Discharge Rates. - A volume-measuring 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 EC (2 EF) 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 m or 2 ft . All flow rates shall be controlled 3 3

by suitable outlet orifices.

(Amended 1973 and 1991)

N.4. Test Procedures. - If a device is equipped with an

automatic temperature compensator, the proving device

reading shall be corrected to 15 EC (60 EF), 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)
3.33. Hydrocarbon Gas Vapor-Measuring Devices

3-38

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 EC (60 EF).

N.4.2. Special Tests. - "Special" tests, to develop the

operating characteristics of a device, and any special

elements and accessories attached to or associated with

the device, shall be made as circumstances require. Any

test except as set forth in N.4.1. is a special test.

N.4.2.1. Slow Test. - The device shall be tested at a

rate not less than 20 percent 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, 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 vapormeasuring 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 hydrocarbon gas vapor-measuring

devices shall be 3 percent (1.03 proof) of the test draft on

underregistration and 1.5 percent (0.985 proof) of the test

draft on overregistration.

(Amended 1981)

 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 for other than motor fuel

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,
#%( ' )2 QH ICU % ##2

DCUG RTGUUWTG

3.33. Hydrocarbon Gas Vapor-Measuring Devices

3-39

service charges or a minimum charge for a (appropriately protected against freezing) shall be

minimum number of cubic meters (cubic feet). installed immediately up-stream of the meter.

(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 EC

(60 EF).

(Amended 1988, 1991)

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 or

2 shall be used. (The table is modified from NIST Handbook 117.)

(Amended 1988)

Elevation correction factors (ACF) were obtained by

using the following equation:

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

(Added 1990)
3.33. Hydrocarbon Gas Vapor-Measuring Devices

3-40

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
3.33. Hydrocarbon Gas Vapor-Measuring Devices

3-41

Table 2. Corrections for Altitude, Inch-Pound 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

1550 to

2100 to

2700 to

3300 to

3950 to

4550 to

5200 to

5850 to

6500 to

7200 to

7900 to

8600 to

9350 to

10 100 to

10 850 to

11 650 to

12 450 to

13 250 to

14 100 to

400

950

1550

2100

2700

3300

3950

4550

5200

5850

6500

7200

7900

8600

9350

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
3.34. Cryogenic Liquid-Measuring Devices

3-43

Sec. 3.34. Cryogenic Liquid-Measuring

Devices

A. Application

A.1. - 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. - This code does not apply to the following:

(a) Devices used for dispensing liquefied petroleum gases

(for which see Sec. 3.32; Code for Liquefied

Petroleum Gas and Anhydrous Ammonia LiquidMeasuring 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 (see Sec. 3.37. Code for Mass Flow

Meters)

(Added 1994)

A.3. - See also Sec. 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 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: 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 EC (70 EF) and

an absolute pressure of 101.325 kPa (14.696 psia); or

decimal subdivisions or multiples of the measured

units cited above.

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) 0.1 m of gas 3

(4) 10 ft of gas 3

(b) for large delivery devices

(1) 10 L

(2) 1 gal

(3) 1 m of gas 3

(4) 100 ft of gas 3

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
3.34. Cryogenic Liquid-Measuring Devices

3-44

be not more than 50 percent 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 value shall be not less than 0.5 mm (0.20 in).

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.

(See also S.1.3.6.)

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 indicated when the value of the smallest division

reach to the finest graduations with which it is used, indicated is equal to or less than the values specified

unless the indicator and the graduations are in the in S.1.1.3.

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 - Any digital money-value indication and any

not more than 1.0 mm (0.04 in). recorded money value on a computing type device

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 be equipped with an effective vapor eliminator or other

graduations. effective means to prevent the measurement of vapor that

When the index of an indicator extends along the (See Section T. Tolerances)

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 device.

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

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. - Moneyvalue 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

S.1.4.3. Money Values--Mathematical Agreement.

shall be in mathematical agreement with its associated

quantity indication or representation to within one

cent of money value.

S.2. Design of Measuring Elements.

S.2.1. Vapor Elimination. - A measuring system shall

will cause errors in excess of the applicable 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
3.34. Cryogenic Liquid-Measuring Devices

3-45

S.2.4. Automatic Temperature or Density S.4. Level Condition, On-Board Weighing Systems. -

Compensation. - A device shall be equipped with Provision shall be made for automatically inhibiting the

automatic means for adjusting the indication and/or delivery of a cryogenic liquid when the vehicle is out of

recorded representation of the measured quantity of the level beyond the limit required for the performance to be

product, to indicate and/or record in terms of: kilograms within applicable tolerance.

or pounds; liters or gallons of liquid at the normal boiling (Added 1986)

point of the specific cryogenic product; or the equivalent

cubic meters (cubic feet) of gas at a normal temperature

of 21 EC (70 EF) and an absolute pressure of

101.325 kPa (14.696 lb/in absolute). When a 2

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)

S.2.5. 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 element,

(b) any adjustable element for controlling delivery rate

when such rate tends to affect the accuracy of

deliveries, and

(c) any automatic temperature or density compensating

system.

Any adjusting mechanism shall be readily accessible for

purposes of affixing a security seal.

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.5. Marking Requirements.

S.5.1. 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.

S.5.2. Discharge Rates. - A meter shall be marked to

show its designed maximum and minimum discharge

rates.

S.5.3. 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.

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 precooled 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

two 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
3.34. Cryogenic Liquid-Measuring Devices

3-46

See Appendix D, Definitions. 1

thereof. When testing uncompensated volumetric meters or density compensator, the compensator shall be tested by

in a continuous recycle mode, appropriate corrections comparing the quantity indicated or recorded by the device

shall be applied if product conditions are abnormally (with the compensator connected and operating) with the

affected by this test mode. actual delivered quantity corrected to the normal boiling

(Amended 1976) point of the cryogenic product being measured or to the

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

following publication shall apply: "Thermophysical

Properties of Fluids. 1. Argon, Ethylene, Parahydrogen,

Nitrogen, Nitrogen Trifluoride, and Oxygen," published in

the Journal of Physical and Chemical Reference Data,

Volume 11, 1982, Supplement No. 1, and published by the

American Chemical Society and the American Institute of

Physics for the National Institute of Standards and

Technology.

(Amended 1986)

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.5.2. Special Tests. - Any test except as set forth in

N.5.1. 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 percent 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 as circumstances require.

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

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.

T.2.1. On Normal Tests. - The maintenance tolerance

on "normal" tests shall be two and one-half percent

(2.5%) of the indicated quantity. The acceptance

tolerance shall be one and one-half percent (1.5%) of the

indicated quantity.

T.2.2. On Special Tests. - The maintenance and

acceptance tolerance on "special" tests shall be two and

one-half percent (2.5%) of the indicated quantity.

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)
3.34. Cryogenic Liquid-Measuring Devices

3-47

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 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 (see references in N.4.) 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; or,

(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 cryogenic liquids shall be based on either

kilograms or pounds, liters or gallons at NBP , cubic 1

meters of gas or cubic feet of gas at NTP .1

(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 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.
3.34. Cryogenic Liquid-Measuring Devices

3-48

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 N.4.; 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)
3.35. Milk Meters



Sec. 3.35. Milk Meters

A. Application

A.1. - 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. - See also Sec. 1.10; General Code requirements.

A.3. - This code does not apply to mass flow meters (see

Sec. 3.37. Code for Mass Flow Meters).

(Added 1994)

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. (See S.4.5.)

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 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.

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.
3.35. Milk Meters



S.1.2.2. Width. - In any series of graduations, the S.1.3.5. Parallax. - Parallax effects shall be reduced

width of a graduation shall in no case be greater then to the practicable minimum.

the width of the minimum clear interval between

graduations, and the width of main graduations shall

be not more than 50 percent 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 graduated interval shall be 1 cent.

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

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.1.3.6. 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).

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. - Moneyvalue 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

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
3.35. Milk Meters



such a manner that the vapor eliminator cannot easily be cleaning purposes shall be clearly and permanently

emptied between uses. identified with a common serial number.

S.2.3. Provision for Sealing. - Adequate provision shall S.4.4. Flood Volume. - When applicable, the volume of

be made for applying security seals to the adjustment product (to the nearest minimum division of the meter)

mechanism and the register. necessary to flood the system when dry shall be clearly,

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,

(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. However, the minimum discharge rate shall not

exceed 20 percent of the maximum discharge rate.

S.4.3. Measuring Components. - All components that

affect the measurement of milk that are disassembled for

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 1000 lb).

(Amended 1989)

N.4. Testing Procedures.
3.35. Milk Meters



N.4.1. Normal Tests. - The "normal" test of a meter UR.1. Installation Requirements.

shall be made at the maximum discharge rate that may be

anticipated under the conditions of the installation. The UR.1.1. Plumb and Level Condition. - A device

"normal" test shall include a determination of the installed in a fixed location shall be installed plumb and

effectiveness of the air elimination system. level, and the installation shall be sufficiently strong and

N.4.2. Special Tests. - "Special" tests to develop the

operating characteristics of a meter and any special UR.1.2. Discharge Rate. - A meter shall be so installed

elements and accessories attached to or associated with that the actual maximum discharge rate will not exceed

the meter, shall be made as circumstances require. Any the rated maximum discharge rate. If necessary, means

test except as set forth in N.4.1. shall be considered a for flow regulation shall be incorporated in the

special test. installation, in which case this shall be fully effective and

N.4.3. System Capacity. - The test of a milk-metering

system shall include the verification of the volume of UR.1.3. Unit Price. - There shall be displayed on the face

product necessary to flood the system as marked on the of a device of the computing type the unit price at which the

air eliminator. device is set to compute.

 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.

(Amended 1989)

Table 1. Tolerances

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)

UR. User Requirements

rigid to maintain this condition.

automatic in operation.

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.
3.35. Milk Meters



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.
3.36. Water Meters



Sec. 3.36. Water Meters

A. Application

A.1. - This code applies to devices used for the

measurement of water; generally applicable to, but not

limited to, utilities type meters installed in homes or

business establishments and meters installed in batching

systems.

A.2. - This code does not apply to:

(a) water meters mounted on vehicle tanks (for which see

Sec. 3.31; Code for Vehicle-Tank Meters).

(b) mass flow meters (see Sec. 3.37. Code for Mass Flow

Meters)

(Added 1994)

A.3. - See also Sec. 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 water 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 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) on utility type meters,

(b) 0.2 L (1/10 gal) on batching meters delivering

less than 375 L/min (100 gal/min), or

(c) 5 L (1 gal) on batching meters delivering

375 L/min (100 gal/min) or more.

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.

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.1.2. 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 percent 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,
3.36. Water Meters



the width of the minimum clear interval between

graduations, and the width of main graduations shall

be not more than 50 percent 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 (a) any measurement elements, and

clear interval shall not be less than 1.0 mm (0.04 in).

If the graduations are not parallel, the measurement (b) any adjustable element for controlling delivery rate

shall be made: when such rate tends to affect the accuracy of

(a) along the line of relative movement between the

graduations at the end of the indicator, or The adjusting mechanism shall be readily accessible for

(b) if the indicator is continuous, at the point of

widest separation of the graduations.

S.1.3. Indicators. S.2.2.1. Air Elimination. - Batching meters shall be

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 not be greater than:

(a) the width of the widest graduation, and

(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.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 may be made of:

deliveries.

purposes of affixing a security seal.

S.2.2. Batching Meters Only.

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.

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 2 minutes and in no

case less than the amount delivered by the device in

1 minute at the actual maximum flow rate developed by the

installation. The test drafts shown in Table 1, next page,

shall be followed as closely as possible.

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 Table 1 values may be tested up to the

meter rating.

(Amended 1990)

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 2.
3.36. Water Meters



N.4.3. Batching Meter Tests. - Tests on batching UR.1.2. Siphon Breaker. - An automatic siphon

meters should be conducted at the maximum and breaker or other effective means shall be installed in the

intermediate rates only. discharge piping at the highest point of outlet, in no case

T. Tolerances

T.1. Tolerance Values. - Maintenance and acceptance

tolerances shall be as shown in Table 1 and Table 2.

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.

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.

Table 1. Tolerances for Water Meters

Normal Tests

Meter size Rate of flow

(inches) (gal/min)

Maximum Rate

Meter Tolerance on overindication and underregistration gal ft3

5/8 15 50 5

3/4 25 50 5

1 40 100 10

1 1/2 80 300 40 1.5%

2 120 500 40

3 250 500 50

4 350 1 000 100

6 700 1 000 100
3.36. Water Meters



Table 2. Tolerances for Water Meters

Special Tests

Meter size indication indication

(inches)

Intermediate Rate Minimum Rate

Rate of Tolerance on Rate of

flow over- and un- flow

(gal/ derregis- (gal/

min) tration min)

Meter Meter Tolerance

gal ft gal ft registra- regis- 3 3

Under- Overtion tration

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

1 1/2 8 50 5 1.5% 1 1/2 10 1 5.0% 1.5%

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
3.37. Mass Flow Meters

3-59

Sec. 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.

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" (see definitions).

(Added 1994)

S.1.3.2. Numerical Value of Quantity-Value

Divisions. - The value of a scale interval shall be

equal to: 

- 1, 2, or 5, or

- 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 be not greater than 0.2

percent of the minimum measured quantity.

(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.
3.37. Mass Flow Meters

3-60

(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. Nonresettable Indicator. - An instrument may

also be equipped with a nonresettable 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 moneyoperated 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)

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S.2.6. Money-Value Computations. - A computing

device shall compute the total sales price at any singlepurchase 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

money value 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,
3.37. Mass Flow Meters

3-61

Table S.3.5. 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. 

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.

[Category 2 applies to only devices

manufactured prior to January 1, 2005. 

Devices with remote configuration capability

manufactured or in use after that date must

meet the sealing requirements outlined in

Category 3. Devices without remote

configuration capability manufactured after

that date will be required to meet the

minimum criteria outlined in Category 1].

[The hardware enabling access for remote communication

must be on-site. The hardware must be sealed using a

physical seal or 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.]*

[*Nonretroactive as of January 1, 1996]

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.

[Nonretroactive as of January 1, 2001]

Nonretroactive as of January 1, 2005, all

devices with remote configuration capability

must comply with the sealing requirements of

Category 3.

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 ten 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 and enforceable as of January 1, 1995]

(Table Added 1995)(Amended 1995, 1998, and 1999)

(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)

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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

measuring liquified gases shall be 5:1 or greater.
3.37. Mass Flow Meters

3-62

(b) The ratio of the maximum to minimum flow-rates when such rate tends to affect the accuracy of

specified by the manufacturer for devices deliveries; or

measuring other than liquified gases shall be 10:1

or greater. (c) the zero adjustment mechanism.

S.3.2. Adjustment Means. - An assembly shall be

provided with 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 percent.

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 liquidmeasuring 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 may be made of:

(a) any measurement element;

(b) any adjustable element for controlling delivery rate

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.3.5.

(Amended 1992 and 1995)

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.

[Nonretroactive as of January 1, 1995. To become

retroactive as of January 1, 1999.]

(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)

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
3.37. Mass Flow Meters

3-63

(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.

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 measuring system.

S.4.2. Pump-Discharge Unit. - A pump-discharge unit of time;

for liquids equipped with a flexible discharge hose shall

be of the wet-hose type. (g) maximum working pressure;

(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. (See N.1.)

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:

- by means of a tool (but not a pin) entirely separate from

the device, or

- by means of a security seal with which the valve is S.6. Printer. - When an assembly is equipped with means

sealed open. for printing the measured quantity, the following conditions

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.

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 designation 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.;*

(Added 1994)

(f) maximum and minimum flow rates in pounds per unit

(h) applicable range of temperature if other than -10 EC to

+50 EC;

(i) minimum measured quantity; and

(j) product limitations, if applicable.

[*Nonretroactive as of January 1, 1995.]

S.5.1. 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)

apply:

(a) the scale interval shall be the same as that of the

indicator;
3.37. Mass Flow Meters

3-64

(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;

(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.

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#FFGF

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. (See T.3.)

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.6.2. Special Tests. - Special tests to develop the

operating characteristics of a meter and any special

elements and accessories attached to or associated with

the device, shall be made as circumstances require. Any

test except as set forth in N.6.1. shall be considered a

special test. Special test of a measuring system shall be

made to develop operating characteristics of the

measuring systems during a split compartment delivery.

(See Table T.2.)

(Added 1999)

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.

(Amended 1994 and 1999)
3.37. Mass Flow Meters

3-65

Table T.2. Accuracy Classes for Mass Flow Meter Applications

Accuracy Class Application or Commodity Being Measured Acceptance

Tolerance

Maintenance

Tolerance

Special

Tolerance

0.3

Loading rack meters, vehicle-tank meters,

home heating oil, heated products (except

asphalt above 50 EC), asphalt below 50 EC,

milk and other food products, large capacity

motor-fuel dispensers (maximum discharge

flow rates greater than 100 L or 25 gallon

per minute), 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 above 50 EC 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

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)

T.3. Repeatability. - When multiple tests are conducted at

approximately the same flow rate, the range of the test

results for the flow rate shall not exceed:

(a) 0.2 percent for retail liquid motor fuel devices; and

(b) 40 percent of applicable tolerance for all other

devices listed in Table T.2.

(Amended 1992, 1994)

T.4. Type Evaluation Examinations for LiquidMeasuring 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]


#FFGF

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.
3.37. Mass Flow Meters

3-66

UR.2. Installation Requirements. 

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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 lowflow cut-off value.

(Added 1992)

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 EF.

(Added 1993)

UR.3.3. Ticket Printer; Customer Ticket. - Vehiclemounted 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. [Nonretroactive as of January 1, 1995. To

become retroactive as of January 1, 1999.]

(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. 'ZEGRVKQPUVQVJKU

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(Added 1995)(Amended 1997)
3.37. Mass Flow Meters

3-67

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)
3.38. Carbon Dioxide Liquid-Measuring Devices

3-69

Section 3.38. Carbon Dioxide 

Liquid-Measuring Devices - Tentative Code

This tentative code has only a trial or experimental status and is not intended to be enforced by weights and

measures officials. The requirements are designed for study prior to the development and adoption of a final

code for Carbon Dioxide Liquid-Measuring Devices. The tentative code is intended to be used by the National

Type Evaluation Program for type evaluation of carbon dioxide liquid-measuring devices. If upgraded to

become a permanent code, all requirements, except those for tolerances, will be nonretroactive as of the effective

date of the permanent code; tolerance requirements will apply retroactively as of the effective date of the

permanent code.

(Tentative Code Added 1996) (Amended 1998)

A. Application

A.1. This code applies to carbon dioxide liquid-measuring

devices used for the measurement of liquid carbon dioxide.

A.2. 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. See also, Sec. 1.10; General Code requirements.

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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.

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 percent

greater than the width of subordinate

graduations. Graduations shall in no case be less

than 0.2 mm (0.008 in) in width.
3.38. Carbon Dioxide Liquid-Measuring Devices

3-70

S.1.2.3. Clear Interval Between Graduations.

- The clear interval shall be not less than 1.0 mm to the smallest indicated value shall be no less

(0.04 in). If the graduations are not parallel, the than 5 mm (0.20 in).

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.

(See also S.1.3.6.)

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 The total price shall be computed on the basis of

it is used, unless the indicator and the the quantity indicated when the value of the

graduations are in the same plane, in which case smallest division indicated is equal to or less

the distance between the end of the indicator and than the value specified in S.1.1.3.

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 computing-type device shall be in mathematical

indicator in relation to the series of graduations agreement with its associated quantity indication

with which it is used shall be not greater than: or representation to within one cent of money

(a) the width of the widest graduation, and

(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

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 fullcomputing 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.

S.1.4.3. Money-Values, Mathematical

Agreement. - Any digital money-value

indication and any recorded money value on a

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
3.38. Carbon Dioxide Liquid-Measuring Devices

3-71

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 within the applicable tolerances.

shall be made for applying security seals in such a

manner that no adjustment or interchange may be

made of:

(a) any measurement element,

(b) any adjustable element for controlling delivery

rate when such rate tends to affect the accuracy

of deliveries, and

(c) any automatic temperature or density

compensating system.

Any adjusting mechanism shall be readily accessible

for purposes of affixing a security seal.

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.

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 percent of the maximum discharge rate.

S.5. Level Condition, On-Board Weighing Systems. -

Provision shall be made for automatically inhibiting the

delivery of liquid carbon dioxide when the vehicle is out of

level beyond the limit required for the performance to be

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 precooled 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 two 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 one

minute at 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.4.2. Special Tests. - Any test except as set forth in

N.4.1. 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 minimum rated capacity or 20

percent of the maximum rated discharge rate of

the device, whichever is less, or
3.38. Carbon Dioxide Liquid-Measuring Devices

3-72

(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 as circumstances require.

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 1.

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.

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.

T.2.1. On Normal Tests. - The maintenance

tolerance on "normal" tests shall be two and one-half

percent (2.5%) of the indicated quantity. The

acceptance tolerances shall be one and one-half

percent (1.5%) of the indicated quantity.

T.2.2. On Special Tests. - The maintenance and

acceptance tolerance on "special" tests shall be two

and one-half percent (2.5%) of the indicated quantity.

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

precooled to liquid temperatures before a "zero"

condition is established and 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.

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.
3.38. Carbon Dioxide Liquid-Measuring Devices

3-73

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.

D. Definitions

The terms defined here have a special and technical

meaning when used in the Code for Carbon Dioxide

Liquid-Measuring Devices.

automatic temperature or density compensation.

The use of integrated or ancillary equipment to obtain,

from the output of a volumetric meter, an equivalent

mass indication.

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.

large-delivery devices. Devices used primarily for

single deliveries greater than 1000 pounds or 500

kilograms.

small-delivery device. Any device other than a largedelivery device.

transfer standard. A measurement system designed

for use in proving and testing carbon dioxide liquidmeasuring devices.

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.

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.

wet-hose type. A type of device in which it is

intended that the discharge hose be completely filled

prior to each commercial delivery.
3.38. Carbon Dioxide Liquid-Measuring Devices

3-74

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG 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
3.38. Carbon Dioxide Liquid-Measuring Devices

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG lb/gal (lb-oz)/gal lb/cu ft lb/gal %

3-75

- 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

- 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
3.38. Carbon Dioxide Liquid-Measuring Devices

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG lb/gal (lb-oz)/gal lb/cu ft lb/gal %

3-76

- 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

- 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
3.38. Carbon Dioxide Liquid-Measuring Devices

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG lb/gal (lb-oz)/gal lb/cu ft lb/gal %

3-77

- 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

 - 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
3.38. Carbon Dioxide Liquid-Measuring Devices

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG lb/gal (lb-oz)/gal lb/cu ft lb/gal %

3-78

 - 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

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
3.38. Carbon Dioxide Liquid-Measuring Devices

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG lb/gal (lb-oz)/gal lb/cu ft lb/gal %

3-79

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
3.38. Carbon Dioxide Liquid-Measuring Devices

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG lb/gal (lb-oz)/gal lb/cu ft lb/gal %

3-80

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

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
3.38. Carbon Dioxide Liquid-Measuring Devices

Table 1

Temp Pressure Liquid Density Vapor Density Vapor

E F Displacement

PSIA PSIG lb/gal (lb-oz)/gal lb/cu ft lb/gal %

3-81

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
3.31. Vehicle-Tank Meters



Sec. 3.31. Vehicle-Tank Meters

A. Application

A.1. - 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. - This code does not apply to the following devices:

(a) Devices used for dispensing liquefied petroleum gases

(for which see Sec. 3.32; Code for Liquefied

Petroleum Gas and Anhydrous Ammonia LiquidMeasuring Devices), or other liquids that do not

remain in a liquid state at atmospheric pressures and

temperatures.

(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 (for which see Sec.

4.40; Code for Vehicle Tanks Used as Measures).

(d) Mass flow meters (see Sec. 3.37. Code for Mass Flow

Meters)

(Added 1994)

A.3. - See also Sec. 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: Nonretroactive and effective January 1, 1995,

vehicle tank metering systems shall be equipped with

a ticket printer. To become retroactive as of January

1, 1999. See UR.2.2.]

(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 (gallons). Fractional parts of the liter

(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 (pounds) and decimal

kilograms (pounds). The weight value division

shall be a decimal multiple or submultiple of 1,

2, or 5. (See S.5.5.)

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 500 L/min (100 gal/min) or less

used for retail deliveries of liquid fuel, or

(c) 5 L (1 gal) on other meters.

(Amended 1989 and 1994)

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
3.31. Vehicle-Tank Meters



return of primary indicating elements, and of primary When the index of an indicator extends along the

recording elements if these are returnable to zero, entire length of a graduation, that portion of the index

beyond their correct zero position. of the indicator that may be brought into coincidence

S.1.2. Graduations.

S.1.2.1. Length. - Graduations shall be so varied in

length that they may be conveniently read. S.1.3.4. Clearance. - The clearance between the

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 S.1.3.5. Parallax. - Parallax effects shall be reduced

graduations, and the width of main graduations shall to the practicable minimum.

be not more than 50 percent 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. - these parts corresponding to the smallest indicated

The clear interval shall be not less than 2.5 mm value shall not be less than 5 mm (0.20 in).

(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.

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 and shall be accurately positioned. The value of each

indicator in relation to the series of graduations with graduated interval shall be 1 cent. On electronic

which it is used shall be not greater than devices with digital indications, the total price may be

(a) the width of the widest graduation, and the value of the smallest division indicated is equal to

(b) the width of the minimum clear interval between (Amended 1979, 1989)

graduations.

with the graduation shall be of the same width

throughout the length of the index that coincides with

the graduation.

index of an indicator and the graduations shall in no

case be more than 1.5 mm (0.06 in).

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

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 on the outside of the device, in a manner

clear to the operator and an observer, the unit price at

which the device is set to compute.

(Amended 1983)

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. - Moneyvalue 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

computed on the basis of the quantity indicated when

or less than 0.2 L (0.1 gal) or 0.2 kg (1 lb).

S.1.4.4. Money Values, Mathematical Agreement.

- Any digital money-value indication and any recorded
3.31. Vehicle-Tank Meters



money value on a computing-type device shall be in (b) the direction of flow for which the mechanism may

mathematical agreement with its associated quantity be set at any time is definitely and conspicuously

indication or representation to within 1 cent of money indicated.

value.

S.2. Design of Measuring Elements. unit, the discharge hose shall be of the wet-hose type

S.2.1. Vapor Elimination. - A metering system shall be discharge unit may be equipped also with a dry hose

equipped with an effective vapor or air eliminator or without a shutoff valve at its outlet end, but only if:

other automatic means to prevent the passage of vapor

and air through the meter. Vent lines from the air or (a) the dry hose is as short as practicable, and

vapor eliminator shall be made of metal tubing or some

other suitable rigid material. (b) there is incorporated in the discharge piping,

(Amended 1993) immediately adjacent to the meter, effective means

S.2.2. Provision for Sealing. - Except on devices for

metering milk, adequate provision shall be made for

applying security seals in such a manner that no adjustment may be made of:

(a) any measurement element, and charge unit, the discharge hose or equivalent pipe shall

(b) any adjustable element for controlling delivery rate end. The dry hose shall be of such stiffness and only of

when such rate tends to affect the accuracy of such length as to facilitate its drainage. The inlet end of

deliveries. the hose or of an equivalent outlet pipe shall be of such

S.2.2.1. Milk-Metering Systems. - Adequate

provision shall be made for applying security seals to

the adjustment mechanism and the register.

The adjusting mechanism shall be readily accessible for S.3.4. Discharge Hose. - A discharge hose shall be

purposes of affixing a security seal. adequately reinforced.

S.2.3. Directional Flow Valves. - Valves intended to S.3.5. Discharge Valve. - A discharge valve may be

prevent reversal of flow shall be automatic in operation. installed in the discharge line only if the device is of the

However, on equipment used exclusively for fueling wet-hose type, in which case such valve shall be at the

aircraft, such valves may be manual in operation. discharge end of the line. Any other shutoff valve on the

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 therefrom. However, two or more

delivery outlets may be installed if means is provided to S.3.6. Antidrain Valve. - In a wet-hose, pressure-type

insure that: device, an effective antidrain valve shall be incorporated

(a) liquid can flow from only one such outlet at one The antidrain valve shall function so as to prevent the

time, and drainage of the discharge hose. However, a device used

S.3.2. Pump-Discharge Unit. - On a pump-discharge

with a shutoff valve at its outlet end. However, a pumpto 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.

S.3.3. Gravity-Discharge Unit. - On a gravity-disbe of the dry-hose type with no shutoff valve at its outlet

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

insure the rapid and complete drainage.

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.

in the discharge valve or immediately adjacent thereto.

exclusively for fueling and defueling aircraft may be of

the pressure type without an antidrain valve.
3.31. Vehicle-Tank Meters



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 percent of the maximum discharge rate.

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.

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)

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).

(Part (b) 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.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.

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. shall be considered a special test. Special test

of a measuring system shall be made as follows:

(a) at a minimum discharge rate of 20 percent of the

marked maximum discharge rate or at the minimum
3.31. Vehicle-Tank Meters



discharge rate marked on the device whichever is installation, in which case this shall be fully effective and

less; automatic in operation.

(b) to develop operating characteristics of the measuring system during a split-compartment delivery.

(Amended 1978)

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.

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 Tables 1, 2, 3, and 4.

(Amended 1995)

T.3. Tolerance Values on Meters Used for the Measurement of Agri-Chemical Liquids. - The maintenance

tolerance on normal and special tests shall be 1 percent of

the indicated quantity. The acceptance tolerance on a normal test shall be 0.5 percent of the indicated quantity and on

special tests, 1 percent of the indicated quantity.

(Added 1985, Amended 1989)

T.4. Repeatability. - When multiple tests are conducted at

approximately the same flow rate, the range of the test

results for the flow rate shall not exceed 40 percent of the

applicable tolerance.

(Added 1992)

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

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.

UR.1.3. Intake Hose. - The intake hose in a milkmetering system shall be installed to permit complete

drainage and ensure that all available product is measured following each pickup.

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. - Vehiclemounted 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)
3.31. Vehicle-Tank Meters



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 sale 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.

Table 1.

Tolerances for Vehicle-Tank Meters Except for Vehicle-Mounted Milk Meters,

Agri-Chemical Meters, and Water Meters

Normal tests Special tests

Indication Acceptance tolerance Maintenance Maintenance and acceptance

tolerance tolerance

(Gallons) (Cubic inches) (Cubic inches) (Cubic inches)

50 50 25 50

Over 50 Add 1/2 cubic Add 1/4 cubic Add 1 cubic

inch per inch per inch per

indicated indicated indicated

gallon over 50 gallon over 50 gallon over 50
3.31. Vehicle-Tank Meters



Table 2. Tolerances for

Vehicle-Mounted 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)
3.31. Vehicle-Tank Meters



Table 3. Tolerances for Vehicle-Mounted Water Meters

Normal Tests

Meter size Rate of flow

(inches) (gal/min)

Maximum Rate

Meter indication Tolerance on over- and

under-registration gal ft3

5/8 15 50 5

3/4 25 50 5

1 40 100 10

1 1/2 80 300 40 1.5%

2 120 500 40

3 250 500 50

4 350 1 000 100

6 700 1 000 100

(Added 1995)

Table 4. Tolerances for Vehicle-Mounted Water Meters

Special Tests

Meter size Tolerance

(inches)

Intermediate rate Minimum rate

Rate of Rate of

flow flow

(gal/ (gal/

min) min)

Meter Meter

indication Tolerance on over- indication

and underregistration gal ft gal ft 3 3 Under- Overregistration registration

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

1 1/2 8 50 5 1.5% 1 1/2 10 1 5.0% 1.5%

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

(Added 1995)
4.41. Liquid Measures



Sec. 4.41. Liquid Measures

A. Application

A.1. - 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. - The code does not apply to test measures or other

volumetric standards.

A.3. - See also Sec. 1.10; General Code requirements.

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 liquid pint, 1 liquid pint, 1 liquid quart, 1/2 gallon, 1-

1/4 gallon, 1-1/2 gallon, or a multiple of 1 gallon, and the

measure shall not be subdivided. However, 3-pint and 5-

pint brick molds and 2-1/2 gallon (10-quart) 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.

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.

 T. Tolerances

T.1. - Maintenance tolerances in excess and in deficiency

shall be as shown in Table 2. Acceptance tolerances shall

be one-half the maintenance tolerances.
4.41. Liquid Measures



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

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 pint or less 2.0 0.4 1.0 0.2

1 pint 3.0 0.7 1.5 0.3

1 quart 4.0 0.9 2.0 0.5

1/2 gallon 6.0 1.4 3.0 0.7

fluid

ounces

cubic

inches

fluid

drams

cubic

inches

1 and 1-1/4 gallons 1.0 1.8 4.0 0.9

1-1/2 gallons 1.5 2.7 6.0 1.4

fluid

ounces

cubic

inches

fluid

ounces

cubic

inches

2 gallons 2.0 3.5 1.0 1.8

3 and 4 gallons 4.0 7.0 2.0 3.6

5 gallons 6.0 11.0 3.0 5.4

10 gallons 10.0 18.0 5.0 9.0
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4.43. Measure-Containers



Sec. 4.43. Measure-Containers

A. Application

A.1. - 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. - 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. - See also Sec. 1.10; General Code requirements.

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 liquid pint 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 S.1.

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-liter (1-quart) 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)
4.43. Measure-Containers



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N.2.2.2. For Rectangular Prepackaged Measure--

container of Two Quarts or Two Liters or Greater.

- A rectangular prepackaged measure-container of

2-liter (2-quart) 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

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any side panel of the restraining form shall be 1.6 mm

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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.

T.2. Tolerance on Average Capacity. - The average

capacity on a random sample of ten 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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 Section 5

Page

5.50. Fabric-Measuring Devices 5-3

5.51. Wire- and Cordage-Measuring Devices 5-7

5.52. Linear Measures 5-9

5.53. Odometers 5-11

5.54. Taximeters 5-13

5.55. Timing Devices 5-17

5.56.(a) Grain Moisture Meters 5-21

5.56.(b) Grain Moisture Meters 5-29

5.57. Near-Infrared Grain Analyzers - Tentative Code 5-35

5.58. Multiple Dimension Measuring Devices - Tentative Code 5-41

5.50. Fabric-Measuring Devices



Sec. 5.50. Fabric-Measuring Devices

A. Application

A.1. - 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. - 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. - See also Sec. 1.10; General Code requirements.

S. Specifications

S.1. Units. - A fabric-measuring device shall indicate

lengths in terms of 10 cm (1/8 yd), 25 cm (1/4 yd), 50 cm

(1/2 yd), and meters (yd). In addition, lengths may be

indicated in terms of any or all of the following

subdivisions: 30 cm (1/3 yd), 6 cm (1/16 yd), meters and

centimeters (feet and inches). 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 percent 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-yard graduations), and 3 mm for 20-cm graduations (1/8 inch for

1-inch 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.

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 2-cent range by special graduations,

but these shall not be positioned in the clear intervals

between graduations of the regular series.
5.50. Fabric-Measuring Devices



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.

 T. Tolerances

T.1. Tolerance Values. - Maintenance and acceptance

tolerances shall be as shown in Table 1.

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.
5.50. 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 1-1/4 5/8 5/8 5/16

10 and 11 1-1/2 3/4 3/4 3/8

12 and 13 1-3/4 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
5.51. Wire- and Cordage-Measuring Devices



Sec. 5.51. Wire- and Cordage-Measuring Devices

A. Application

A.1. - 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. - See also Sec. 1.10; General Code requirements.

 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 percent 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.

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.
5.51. Wire- and Cordage-Measuring Devices



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

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

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 UR.2.2. Return to Zero. - The primary indicating

steel tape in order to assure that any marked interval is not elements of a wire- or cordage-measuring device shall be

in error by more than 1/3 of the tolerance of the device at returned to zero before each measurement.

that particular interval.

(Amended 1981)

N.2. Minimum Test. - Tests shall be conducted at a a manner as to cause slippage or inaccurate measminimum initial increment of 5 m (20 ft) and appropriate urement.

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.

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.2.3. Operation of Device. - A wire- or

cordage-measuring device shall not be operated in such

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.
5.52. Linear Measures



Sec. 5.52. Linear Measures

A. Application

A.1. - This code applies to any linear measure or measure of

length, whether flexible or inflexible, permanently installed

or portable.

A.2. - See also Sec. 1.10; General Code requirements.

 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

A 1-m 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-yd 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.

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. 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
5.52. Linear Measures



be as shown in Table 2. 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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5.54. Taximeters



 Sec. 5.54. Taximeters

A. Application

A.1. This code applies to taximeters; that is, to devices that

automatically calculate at a predetermined rate or rates and

indicate the charge for hire of a vehicle.

A.2. This code does not apply to odometers on vehicles

that are rented on a distance basis (for which see Sec. 5.53

Code for Odometers). (Amended 1977)

A.3. See also Sec. 1.10; General Code requirements.

 S. Specifications

S.1. Design of Indicating and Recording Elements.

S.1.1. General. - A taximeter shall be equipped with a

primary indicating element and may be equipped with a

recording element.

(Amended 1988)

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 1986, 1977, 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.1.4. 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 words or monetary signs. Means may be

provided to totalize the fare and extras if the totalized
5.54. Taximeters



amount returns to separate indications of fare and extras duplicate receipt shall be deactivated at the time the

within 5 seconds or less. meter is hired for the next fare.

(Amended 1988) [Nonretroactive as of January 1, 2000]

S.1.7.1. Nonuse of Extras. - If and when taximeter

extras are prohibited by legal authority or are S.2. Basis of Fare Calculations. - A taximeter shall

discontinued by a vehicle operator, the extras calculate fares only upon the basis of:

mechanisms shall be rendered inoperable or the extras

indications shall be effectively obscured by (a) distance traveled,

permanent means. 

(b) time elapsed, or

S.1.8. Protection of Indications. - Indications of fare

and extras shall be displayed through and entirely

protected by glass or other suitable transparent material

securely attached to the housing of the taximeter.

S.1.9. Recorded Representation. - A printed receipt

issued from a taximeter, whether through an integral or

separate recording element, shall include the following:

(a) date

(b) unique vehicle identification number, such as the

medallion number, taxi number, vehicle

identification number (VIN) or permit number*

(c) start and end time of trip*

(d) distance traveled, maximum increment of 0.1

kilometer (0.1 mile)*

(e) fare in $

(f) for multi-rate taximeters, each rate at which fare

was computed and the associated fare at that rate*

(g) additional charges where permitted such as extras,

surcharge, telephone use, tip and tax shall be

identified and itemized*

(h) total fare in $ (total charge)*

[Nonretroactive as of January 1, 1989.]

*[Nonretroactive as of January 1, 2000 ]

(Added 1988)(Amended 1999)

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

(Added 1999)

(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:

Seconds of Initial Time Interval =

Seconds per Non-Initial Time Interval

Distance of Initial Mileage Interval 

Distance per Non-Initial Mileage 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)
5.54. Taximeters



S.5. Provision for Security Seals. - Adequate provision N.1.2. Test Procedures. - The distance test of a

shall be made for affixing security seals to a taximeter and taximeter, whether a road test, a simulated-road test, or a

to other parts required for service operation of a complete fifth-wheel test, shall include at least duplicate runs of

installation on a vehicle, so that no adjustments, alterations, sufficient length to cover at least the third money drop or

or replacements affecting accuracy or indications of the 1 mile, whichever is greater, and shall be at a speed

device or the assembly can be made without mutilating the approximating the average speed traveled by the vehicle

seal or seals. The sealing means shall be such that it is not in normal service. In the case of metric-calibrated

necessary to disassemble or remove any part of the device taximeters, the test should cover at least the third money

or of the vehicle to apply or inspect the seals. drop or 2 km, whichever is greater.

(Amended 1988) (Amended 1977)

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.

[Effective and nonretroactive as of January 1, 1994.

Retroactive after January 1, 1999.]

(Added 1988)(Amended 1989 and 1990)

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.1.3. 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 odometer.

(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:
5.54. Taximeters



(a) On Overregistration: 1 percent of the interval

under test.

(b) On Underregistration: 4 percent 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 percent).

(b) On Underregistration: 9 seconds per minute

(15 percent) on the initial interval, and

6 seconds per minute (10 percent) on

subsequent intervals.

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 percent).

(b) On Underregistration: 3 seconds per minute

(5 percent).

(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 one percent 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)
5.55. Timing Devices



Sec. 5.55. Timing Devices

A. Application

A.1. - This code applies to devices used to measure time

during which services are being dispensed (such as vehicle

parking, laundry drying, and car washing).

A.2. - See also Sec. 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 timing device shall be equipped

with a primary indicating element, and may also be

equipped with a primary 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)

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 2 hours;

(b) six minutes on parking meters indicating time in

excess of 1 but not greater than 2 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. -

The in-service light indicator shall be operative only

during the time the device is in operation.

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 1 minute for times less than 1 hour and

not more than 2 minutes for times of 1 hour or more.

Convenient means shall be provided to indicate to the

purchaser the unexpired time. 

(Added 1975 and 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 percent 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.
5.55. Timing Devices



Table N.2.* Broadcast Times and Frequencies

Station Location,

Latitude,

Longitude

Frequency

(MHz)

Times of 

Transmission

(UTC)

WWV Fort Collins,

Colorado

40E41’ N

105E02’ W

2.5

5.0

10.0

15.0

Continuous

WWVH Kauai, Hawaii

21E59’ N

159E46’ W

2.5

5.0

15.0

Continuous

CHU Ottawa, Canada

45E18’ N

75E45’ W

3.330

7.335

14.670

Continuous

*From NIST Special Publication 559, "Time and Frequency Users’ Manual," 1979.

(Added 1988)

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. Printed Tickets. - 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.

(Amended 1983)

S.2. Marking Requirements, Operating Instructions. -

Operating instructions shall be clearly stated on the device.

 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 1 hour, the value of the minimum

division on the timepiece shall be not greater than 1 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.
5.55. Timing Devices



Table T.1.3.

Maintenance and Acceptance Tolerances

for Parking Meters

Maintenance and Acceptance Tolerances

Nominal time capacity On overregistration On underregistration

30 minutes or less

Over 30 minutes to and

 including 1 hour

Over 1 hour

No tolerance

No tolerance

No tolerance

10 seconds per minute, but not less

than 2 minutes

5 minutes plus 4 seconds per 

minute over 30 minutes

7 minutes plus 2 minutes per hour

over 1 hour

T. Tolerances UR. User Requirements

T.1. Tolerance Values. - Maintenance and acceptance UR.1. Statement of Rates. - The price in terms of money

tolerances for timing devices shall be as follows: per unit or units of time for the service dispensed and the

T.1.1. For Timing Devices Other Than Those

Specified in T.1.2. and T.1.3. - The maintenance and

acceptance tolerances shall be:

(a) On Overregistration: 5 seconds for any time UR.2. Time Representations. - Any time representation

interval of 1 minute or more; and shall be within plus or minus 2 minutes of the correct time

(b) On Underregistration: 6 seconds per indicated for "time out"; in addition, the time indication of the

minute. "time-out" clock shall be the same as or less than that of the

(Amended 1975 and 1986) "time-in" clock.

T.1.2. For Time Clocks and Time Recorders. - The

maintenance and acceptance tolerances on

overregistration and under registration shall be 3 seconds

per hour, but not to exceed 1 minute per day. 

 (Amended 1975) 

T.1.3. On Parking Meters. - The maintenance and

acceptance tolerances are shown in Table T.1.3.

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.

number of coins the device will accept and be activated by

at one time, shall be clearly, prominently, and

conspicuously displayed.

(Amended 1976)

in effect in the area, except on an individual clock used only

(Amended 1975)
5.56.(a) Grain Moisture Meters



Sec. 5.56.(a) Grain Moisture Meters

Section 5.56. has been reorganized into two sections. This Section, 5.56.(a), is applicable to all NTEP grain moisture

meters. It is also applicable to any grain moisture meter manufactured or placed into service after January 1, 1998.

(Code reorganized and renumbered 1996.) 

A. Application

A.1. 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.

A.2. 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 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. See also Sec. 1.10; General Code requirements.

 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, and calibration version

identification.

(d) A digital indicating element shall not display, and

a recording element shall not record, any moisture

content values before the end of the measurement

cycle.

(e) Moisture content results shall be displayed and

recorded as percent moisture content, wet basis.

Subdivisions of this unit shall be in terms of

decimal subdivisions (not fractions).

(f) A meter shall not display or record any moisture

content values when the moisture content of the

grain sample is beyond the operating range of the

device, unless the moisture representation includes

a clear error indication (and recorded error message

with the recorded representation).

(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)

(Added 1993)(Amended 1994 and 1995)

S.1.2. Grain or Seed Kind and Class Selection and

Recording. - Provision shall be made for selecting and

recording 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. Abbreviations for grain types

indicated on the meter must meet the minimum

acceptable abbreviations listed in Table S.1.2. Meters

shall have the capability (i.e., display capacity) of

indicating the grain type using a minimum of four

characters in order to accommodate the four-character

abbreviations listed in Table S.1.2. 

(Amended 1993 and 1995) 

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 EC to 30 EC. No

moisture value may be displayed when the temperature

range is exceeded. An appropriate error message shall
5.56.(a) Grain Moisture Meters



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be displayed when the temperature of the meter is error message shall be displayed when the

outside its specified operating range. difference in temperature between the meter and

(b) Temperature Range of each Grain or Seed. The (Added 1993)(Amended 1995)

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 EC to 40 EC. 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. A

moisture value may be displayed when the moisture

range is exceeded if accompanied by a clear

indication that the moisture range has been

exceeded.

(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 EC. No moisture value may be

displayed when the maximum allowable

temperature difference is exceeded. An appropriate

the sample exceeds the specified difference.

S.1.4. Value of Smallest Unit. - The display shall

permit constituent value determination to both 0.01

percent and 0.1 percent resolution. The 0.1 percent

resolution is for commercial transactions; the 0.01

percent resolution is for type evaluation and calibration

purposes only, not for commercial purposes.

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. -

Tolerance Values when operated in the temperature

range of 10 EC to 30 EC (50 EF to 86 EF) or within

the range specified by the meter manufacturer.
5.56.(a) Grain Moisture Meters



(c) If the manufacturer specifies a temperature range,

the range shall be at least 20 EC (36 EF).

(Added 1993)(Amended 1995 and 1996)

S.2. Design of Grain Moisture Meters constants. An error message must be displayed if

S.2.1. Minimum Sample Size. - Meters shall be (Added 1993)(Amended 1995)

designed to measure the moisture content of

representative-size 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)

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. - 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.

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 percent (approximately 3

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 determinations.

(Added 1993)(Amended 1995)

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

calibration constants have been electronically altered.

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 and effective 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.*) before

any change that affects the metrological integrity of the

device can be made to any mechanism.

[*Note: Table S.2.5. is Nonretroactive as of Jan, 1,

1999.]

[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.

(Added 1994)(Amended 1995)

S.3. Accessory Equipment - When the operating

instructions for a moisture meter require accessory

equipment separate from and external to the moisture meter,
5.56.(a) Grain Moisture Meters



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

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5.56.(a) Grain Moisture Meters



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5.56.(a) Grain Moisture Meters



Table S.2.5. Categories of Device and Methods of Sealing

Categories of Device Method of Sealing

Category 1: No remote configuration Seal by physical seal or two event counters: one for calibration

capability. 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 onsite device, the contents of the counters.

Category 2: Remote configuration The hardware enabling access for remote communication must be at

capability, but access is controlled by the device and sealed using a physical seal or two event counters;

physical hardware. one for calibration parameters (000 to 999) and one for

A device shall clearly indicate that it is in the counters, the device must be capable of displaying, or printing

remote configuration mode and shall not be through the device or through another on-site device, the contents of

capable of operating in the measure mode the counters.

while enabled for remote configuration.

configuration parameters (000 to 999.) If equipped with event

Category 3: Remote configuration capability An event logger is required in the device; it must include an event

access may be unlimited or controlled counter (000 to 999), the parameter ID, the date and time of the

through a software switch (e.g., password). change , and the new value of the parameter (for calibration changes

When accessed remotely for the purpose of information must be available through the device or through another

modifying sealable parameters, the device on-site device. The event logger shall have a capacity to retain

shall clearly indicate that it is in the records equal to twenty-five (25) times the number of sealable

configuration mode and shall not be capable parameters in the device, but not more than 1000 records are

of operating in the measuring mode. required. (Note: Does not require 1000 changes to be stored for

consisting of multiple constants, the calibration version number may

be used rather than the calibration constants). A printed copy of the

each parameter.)

Category 3a: No remote capability, but Same as Category 3 

operator is able to make changes that affect

the metrological integrity of the device (e.g.,

slope, bias, etc.) in normal operation.

Category 3b: No remote capability, but Same as Category 3 

 access to metrological parameters is

controlled through a software switch (e.g.,

password).

[Table Nonretroactive as of January 1, 1999.] (Amended 1998)
5.56.(b) Grain Moisture Meters



Sec. 5.56.(b) Grain Moisture Meters

Section 5.56. has been reorganized into two Sections. This Section, 5.56.(b) is applicable 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. - 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. - This code does not apply to devices used for

in-motion measurement of grain moisture content or seed

moisture content.

A.3. - See also Sec. 1.10; General Code requirements.

 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 percent 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.

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
5.56.(b) Grain Moisture Meters



graduation throughout the length of the index that coincides be used and still comply with the applicable

with the graduation. requirements;

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.

The operating range shall specify the following:

(a) the temperature range over which the meter may

(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.

(a) The value of the minimum indicated or recorded

moisture indication shall not be greater than

0.1 percent.

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
5.56.(b) Grain Moisture Meters



upright direction by up to 5 percent (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 EC to 40 EC (35 EF to

104 EF) or within the range specified by the meter

manufacturer.

(c) If the manufacturer specifies a temperature range,

the range shall be at least 10 EC (20 EF) 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 kind 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)

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. Complete

information concerning the accuracy, sensitivity, and use
5.56.(b) Grain Moisture Meters



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of accessory equipment (e.g., test weight per bushel 104 EF) with a maximum error of ±0.1 EC (0.2 EF).

equipment, thermometer, etc.) necessary in obtaining a Tests shall be conducted at two temperatures using liquid

moisture content shall be included. baths (e.g., ice water and room temperature water). The

two temperatures selected shall not exceed the range of

N. Notes

N.1. Testing Procedures.

N.1.1. Transfer Standards. - Official grain samples 1

shall be used as the official transfer standards with

moisture content values assigned by the reference T.1. To Underregistration and to Overregistration. -

methods. The reference methods shall be the oven The tolerances hereinafter prescribed shall be applied to

drying methods as specified by the USDA GIPSA. errors of under registration and errors of overregistration.

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:

(a) with samples (need not exceed three) of each grain

or seed for which the device is used, and

(b) with samples having at least two different moisture

content values within the operating range of the

device.

(Amended 1986, 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 EC (0.2 EF) subdivisions,

indicating over a range of from 0 EC to 40 EC (32 EF to

temperatures identified in the moisture meter operating

instructions.

(Amended 1988)

T. Tolerances2

T.2. Tolerance Values. - Maintenance and acceptance

tolerances shall be as shown in Table T.2. Tolerances are

expressed as a fraction of the percent moisture content of

the official grain sample, together with a minimum

tolerance.

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 0.193 kg/hL or

0.15 lb/bu. The test methods used shall be those specified

by the USDA GIPSA.

(Amended 1992)

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 EC (1 EF).

(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 percent.

Table T.2. Acceptance and Maintenance Tolerances for

Grain Moisture Meters

Type of grain Tolerance Minimum

or seed Tolerance
5.56.(b) Grain Moisture Meters



Corn, oats, 0.05 of the per- 0.8 percent in

rice, sorghum, cent moisture moisture

sunflower content content

All other cereal 0.04 of the per- 0.7 percent in

grains and oil cent moisture moisture

seeds content content

UR.1.2. See G-UR.1.2.

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.

UR.3.7. Location. - See G-UR.3.3. 

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 EC (20 EF).

(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)
5.57. Near-Infrared Grain Analyzers



Sec. 5.57. Near-Infrared Grain Analyzers - Tentative Code

This tentative code has only 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 for Near-Infrared Grain Analyzers. All

nonretroactive and effective dates have been changed to January 1, 2002. 

 (Tentative Code Added 1994.)

A. Application

A.1. - 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.

A.2. - This code does not apply to devices used for

in-motion measurement of grain constituent values.

A.3. Type Evaluation. - The National Type Evaluation

Program will accept for type evaluation only those devices

that comply with the nonretroactive requirements scheduled

to take effect on January 1, 2002. State enforcement will be

based upon the effective dates identified with each

requirement when specific dates are shown.

A.4. - See also Sec. 1.10; General Code requirements.

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, and calibration version

identification.

(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) Wheat protein content shall be recorded and

displayed as percent protein reported on a constant

moisture basis of 12 percent wet basis.

(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).

[Nonretroactive and effective as of January 1, 2002]

S.1.2. Selecting Grain Class and Constituent. -

Provision shall be made for selecting, and recording

the type or class of grain and the constituent(s) to be

measured. The means to select the grain type or

class and constituent(s) shall be readily visible and

the type or class of grain and constituent(s) selected

shall be clearly and definitely identified in letters

(such as HRWW, HRSW, etc. or PROT, etc.). A

symbol to identify the display of the type or class 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. Meters shall have the capability (i.e., display

capacity) of indicating the grain type using a

minimum of four characters in order to accommodate

the abbreviations listed in Table S.1.2.

[Nonretroactive and effective as of January 1, 2002]
5.57. Near-Infrared Grain Analyzers



Table S.1.2. Grain Types Considered for Type Evaluation

and Calibration

and Minimum Acceptable Abbreviations

Grain Type Minimum Acceptable Abbreviation

Durum Wheat

Hard Red Spring Wheat

Hard Red Winter Wheat

Hard White Wheat

Soft Red Winter Wheat

Soft White Wheat

DURW

HRSW

HRWW

HDWW

SRWW

SWW

[Nonretroactive and effective as of January 1, 2002]

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 EC to

30 EC. 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 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.

(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 EC to

30 EC. 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 EC. 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 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, 2002]

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 and effective as of January 1, 2002]

S.1.5. Value of Smallest Unit. - The display shall

permit constituent value determination to both 0.01

percent and 0.1 percent resolution. The 0.1 percent

resolution is for commercial transactions; the 0.01

percent resolution is for calibration purposes only, not

for commercial purposes.

[Nonretroactive and effective as of January 1, 2002]

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 and effective as of January 1, 2002]
5.57. Near-Infrared Grain Analyzers



S.2.2. Electric Power Supply.

S.2.2.1. Power Supply, Voltage and Frequency. - An S.2.5.2. Calibration Version. - An instrument must be

analyzer that operates using alternating current must capable of displaying either calibration constants, a

perform within tolerance requirements over the line unique calibration name, or a unique calibration

voltage range 100 V to 130 V and over the frequency version number for use in verifying that the latest

range of 59.5 Hz to 60.5 Hz. version of the calibration is being used to make

[Nonretroactive and effective as of January 1, 2002] constituent determinations.

S.2.2.2. Power Interruption. - A power interruption

shall not cause an indicating or recording element to S.2.5.3. Calibration Corruption. - If calibration

display or record any values outside the applicable constants are digitally stored in an electronically

tolerance limits. alterable form, the analyzer shall be designed to make

[Nonretroactive and effective as of January 1, 2002] automatic checks to detect corruption of calibration

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 S.2.6. Provision for Sealing. - An event logger is

from a level position into a position that is out of level in required in the device; it must include an event counter

any upright direction by up to 5 percent (approximately (000 to 999), the parameter ID, the date and time of the

3 degrees). The level-indicating means shall be readable change, and the new value of the parameter (for

without removing any instrument parts requiring a tool. calibration changes consisting of multiple constants, the

[Nonretroactive and effective as of January 1, 2002] calibration version number may be used rather than the

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 and effective as of January 1, 2002]

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.

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 S.4. Operating Instructions and Use Limitations. - The

under the conditions specified in UR.2.8. manufacturer shall furnish operating instructions for the

[Nonretroactive and effective as of January 1, device and accessories that include complete information

2002.] concerning the accuracy, sensitivity, and use of accessory

(Note added 1995) (Amended 1995)

[Nonretroactive and effective as of January 1, 2002].

constants. An error message must be displayed if

calibration constants have been electronically altered.

[Nonretroactive and effective as of January 1, 2002].

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 twenty-five (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 and effective as of January 1, 2002]

(Amended 1997)

S.3. Accessory Equipment. When the operating

instructions for a NIR analyzer require accessory

equipment separate from and external to the analyzer, such

equipment shall be appropriate and complete for the

measurement.

[Nonretroactive and effective as of January 1, 2002]

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 and effective as of January 1, 2002]
5.57. Near-Infrared Grain Analyzers



Table T.2. Acceptance and Maintenance Tolerances

for NIR Wheat Protein Analyzers

Type of Grain

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

0.60 0.40 0.40

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

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 and effective as of January 1, 2002]

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.

Wheat protein 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.

N.1.2. Standard Reference Samples, Wheat. -

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 wheat protein values

obtained using the GIPSA standard reference method

and an official GIPSA NIR wheat protein analyzer does

not exceed 0.3 for individual test samples or 0.15 for the

average of five samples.

T. Tolerances

T.1. To Underregistration and to Overregistration. -

The tolerances hereinafter prescribed shall be applied to

errors of under registration and errors of overregistration.

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.

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.

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."

UR.2.3. Printed Tickets. -

(a) Printed tickets shall be free from any previous

indication of constituent or grain type selected.
5.57. Near-Infrared Grain Analyzers



The printed ticket shall indicate constituent values cases of instrument failure and repair), and instrument

reported on a constant moisture basis. results after calibration adjustment or instrument repair.

(b) The customer shall be given a printed ticket Established error must be known.

showing the date, grain type or class, constituent (Amended 1995)

results, and calibration version identification. The

ticket shall be generated by the near-infrared grain

analyzer system.

[Nonretroactive and effective as of January 1, 2002]

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 1 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.

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. A written explanation and 1

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

1








Fundamental Considerations

A-1

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).
Fundamental Considerations

A-2

 See General Code, Section 1.10.; User Requirement G- 1

UR.4.3.

 The numerical values of the tolerances recommended by 2

the National Institute of Standards and Technology, for the

standards of length, mass, and capacity used by weights and

measures officials, may be obtained upon request from the

Office of Weights and Measures of the National Institute of

Standards and Technology.

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 3.1. Adequacy. - Tests can be made properly only if,

mechanical equipment is unattainable. Tolerances are among other things, adequate testing apparatus is available.

established, therefore, to fix the range of inaccuracy within Testing apparatus may be considered adequate

which equipment will be officially approved for commercial only when it is properly designed for its intended use, when

use. In the case of classes of equipment on which the it is so constructed that it will retain its characteristics for a

magnitude of the errors of value or performance may be reasonable period under conditions of normal use, when it

expected to change as a result of use, two sets of tolerances is available in denominations appropriate for a proper

are established: acceptance tolerances and maintenance determination of the value or performance of the

tolerances. commercial equipment under test, and when it is accurately

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 and measuring equipment be so established and maintained

that the permissible errors are sufficiently small that there is that the use of corrections is not necessary. Also, whenever

no serious injury to either the buyer or the seller of it can readily be done, it will be desirable to reduce the error

commodities, yet not so small as to make manufacturing or on a standard below the one-third point previously

maintenance costs of equipment disproportionately high. mentioned.

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

calibrated.

3.2. Tolerances for Standards. - The error in a standard 2

used by a weights and measures official should be known

and corrected for when the standard is used; or if the

standard is to be used without correction, its error should be

not greater than one-third of the smallest tolerance to be

applied when the standard is used. The reason for this is to

keep at a minimum the proportion of the tolerance on the

item tested that will be used up by the error of the standard.

Expressed differently, the reason is to give the item being

tested as nearly as practicable the full benefit of its own

tolerance.

Field testing operations are complicated to some degree

when corrections to standards are applied. Except for work

of relatively high precision, it is recommended that the

accuracy of standards used in testing commercial weighing

3.3. Accuracy of Standards. - Prior to the official use of

testing apparatus, its accuracy should invariably be verified.

Standards should be reverified as often as circumstances

require. By their nature, metal volumetric standards are
Fundamental Considerations

A-3

more susceptible to damage in handling than are standards requirements. But even a device of a type with which the

of some other types. A standard should be recalibrated official is thoroughly familiar and that he has previously

whenever damage is known or suspected to have occurred found to meet specification requirements should not be

or significant repairs have been made. In addition, accepted entirely on faith. Some part may have become

standards, particularly volumetric standards, should be damaged, or some detail of design may have been changed

recalibrated with sufficient frequency to affirm their by the manufacturer, or the owner or operator may have

continued accuracy, so that the official may always be in an removed an essential element or made an objectionable

unassailable position with respect to the accuracy of his addition. Such conditions may be learned only by

testing apparatus. Secondary standards, such as special inspection. Some degree of inspection is therefore an

fabric testing tapes, should be verified much more essential part of the official examination of every piece of

frequently than such basic standards as steel tapes or weighing or measuring equipment.

volumetric provers to demonstrate their constancy of value

or performance.

Accurate and dependable results cannot be obtained with

faulty or inadequate 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

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.

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 official to familiarize himself 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
Fundamental Considerations

A-4

See Sec. 1.10.; General Code and Appendix D. 3

Definitions.

manufacturers, from trained service persons and plant Only equipment that is correct should be sealed and

engineers, from observation of the operations performed by approved for commercial use.

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 deter

mined 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.

3

5. Correction of Commercial Equipment

5.1. Adjustable Elements. - Many types of weighing and

measuring instruments are not susceptible of 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.

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
Fundamental Considerations

A-5

the owner’s representative, the official should be confident On the other hand, rejection is clearly inappropriate for

that the problem is not due to faulty installation or a many items of measuring equipment. This is true for most

defective part, and that the adjustment will correct the linear measures, many liquid and dry measures, and

problem. The official should never undertake major graduates, measure-containers, milk bottles, lubricating-oil

repairs, or even minor corrections, if services of commercial bottles, and some scales. When such equipment is

agencies are readily available. The official should always "incorrect," it is either impractical or impossible to adjust or

be mindful of conflicts of interest before attempting to repair it, and the official has no alternative to outright conperform any services other than normal device examination demnation. When only a few such items are involved,

and testing duties. immediate destruction or confiscation is probably the best

(Amended 1995) procedure. If a considerable number of items are involved

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 7.2. Nonsealed and Noncommercial. - Rejection is not

destroy is necessary for adequate control of extreme appropriate if measuring equipment cannot be tested by the

situations, but seizure and destruction should be resorted to official at the time of his regular visit–for example, when

only when clearly justified. there is no gasoline in the supply tank of a

(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 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)
Fundamental Considerations

A-6

gasoline-dispensing device. Some officials affix to such officially approved for commercial use (with certain

equipment a nonsealed tag stating that the device has not exceptions to be pointed out later) be suitably marked or

been tested and sealed and that it must not be used sealed to show approval. This is done primarily for the

commercially until it has been officially tested and ap- benefit of the public to show that such equipment has been

proved. This is recommended whenever considerable time officially examined and approved. The seal of approval

will elapse before the device can be tested. should be as conspicuous as circumstances permit and

Where the official finds in the same establishment reasonably permanent. Uniformity of position of the seal

equipment that is in commercial use and also equipment on similar types of equipment is also desirable as a further

suitable for commercial use that is not presently in service, aid to the public.

but which may be put into service at some future time, he

may treat the latter equipment in any of the following ways: The official will need more than one form of seal to meet

a. Test and approve the same as commercial equipment quality, weather-resistant, water-adhesive, or presin use. sure-sensitive seals or decalcomania seals are recommended

b. Refrain from testing it and remove it from the taximeters, and most scales, because of their permanence

premises to preclude its use for commercial and good appearance. Steel stamps are most suitable for

purposes. liquid and dry measures, for some types of linear measures,

c. Mark the equipment nonsealed. etching ink, is excellent for steel tapes, and greatly

Where the official finds commercial equipment and practicable seal for a graduate is one marked with a

noncommercial equipment installed or used in close diamond or carbide pencil, or one etched with

proximity, he may treat the noncommercial equipment in glass-marking ink. For a vehicle tank, the official may wish

any of the following ways: to devise a relatively large seal, perhaps of metal, with

a. Test and approve the same as commercial equip- capacities, the whole to be welded or otherwise permanently

ment. attached to the shell of the tank. In general, the

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

should be of such a character and so applied that it will be

the requirements of different kinds of equipment. Good

for fabric-measuring devices, liquid-measuring devices,

and for weights. An etched seal, applied with suitable

preferable to a seal applied with a steel stamp. The only

provision for stamping data relative to compartment

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
Fundamental Considerations

A-7

desired. Such rounded-off values would be, respectively, these are not to be rounded off individually, but are to be

5000, 4700, 4740. Similarly, a value such as 47.382 can be rounded off as a group.] Thus, when rounding off 47.3499

rounded off to two decimal places, to one decimal place, or to the first decimal place, the result becomes 47.3. In

to the units place. The rounded-off figures in this example arriving at this result, the figures "499" are treated as a

would be, respectively, 47.38, 47.4, 47. group. Since the 4 next beyond the last figure to be retained

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 10.3. Rules for Reading of Indications. - An important

place retained is to be kept unchanged. When aspect of rounding off values is the application of these

rounding off 4738 to the nearest hundred, it is noted rules to the reading of indications of an inthat the figure 3 (next beyond the last figure to be dicator-and-graduated-scale combination (where the

retained) is less than 5. Thus the rounded-off value majority of the indications may be expected to lie somewould be 4700. Likewise, 47.382 rounded to two where between two graduations) if it is desired to read or

decimal places becomes 47.38. record values only to the nearest graduation. Consider a

b. When the figure next beyond the last figure or place indicator is between two graduations but is closer to one

to be retained is greater than 5, the figure in the last graduation than it is to the other adjacent graduation, the

place retained is to be increased by 1. When value of the closer graduation is the one to be read or

rounding off 4738 to the nearest thousand, it is recorded.

noted that the figure 7 (next beyond the last figure to

be retained) is greater than 5. Thus the rounded-off In the case where, as nearly as can be determined, the

value would be 5000. Likewise, 47.382 rounded to indicator is midway between two graduations, the

one decimal place becomes 47.4. odd-and-even rule is invoked, and the value to be read or rec. When the figure next beyond the last figure to be example, if the indicator lies exactly midway between two

retained is 5 followed by any figures other than graduations having values of 471 and 472, respectively, the

zero(s), treat as in (b) above; that is, the figure in indication should be read or recorded as 472, this being an

the last place retained is to be increased by 1. When even value. If midway between graduations having values

rounding off 4501 to the nearest thousand, 1 is of 474 and 475, the even value 474 should be read or

added to the thousands figure and the result recorded. Similarly, if the two graduations involved had

becomes 5000. values of 470 and 475, the even value of 470 should be read

d. When the figure next beyond the last figure to be

retained is 5 and there are no figures, or only zeros, A special case not covered by the foregoing paragraph is

beyond this 5, the figure in the last place to be that of a graduated scale in which successive graduations

retained is to be left unchanged if it is even (0, 2, 4, are numbered by two’s, all graduations thus having even

6, or 8) and is to be increased by 1 if it is odd (1, 3, values; for example, 470, 472, 474, etc. When, in this case,

5, 7, or 9). This is the odd and even rule, and may an indication lies midway between two graduations, the

be stated as follows: "If odd, then add." Thus, recommended procedure is to depart from the practice of

rounding off to the first decimal place, 47.25 would reading or recording only to the value of the nearest

become 47.2 and 47.15 would become 47.2. Also, graduation and to read or record the intermediate odd value.

rounded to the nearest thousand, 4 500 would For example, an indication midway between 470 and 472

become 4000 and 1500 would become 2000. should be read as 471.

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,

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.

vertical graduated scale and an indicator. Obviously, if the

corded is that of the graduation whose value is even. For

or recorded.

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
Fundamental Considerations

A-8

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 1-1/32, 1-2/32,

1-3/32, 1-4/32, 1-5/32, 1-6/32, 1-7/32, 1-8/32, 1-9/32.

Assume that these values are to be rounded off to the

nearest eighth (4/32). Then,

1-1/32 becomes 1. (1/32 is less than half of 4/32 and

accordingly is dropped.)

1-2/32 becomes 1. (2/32 is exactly one-half of 4/32; it is

dropped because it is round (down) to the "even" eighth,

which in this instance is 0/8.)

1-3/32 becomes 1-4/32 or 1-1/8. (3/32 is more than half

of 4/32,and accordingly is rounded "up" to 4/32 or 1/8).

1-4/32 remains unchanged, being an exact eighth (1-1/8).

1-5/32 becomes 1-4/32 or 1-1/8. (5/32 is 1/32 more than

an exact 1/8; 1/32 is less than half of 4/32 and

accordingly is dropped.)

1-6/32 becomes 1-2/8 or 1-1/4. (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.)

1-7/32 becomes 1-2/8 or 1-1/4. (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.)

1-8/32 remains unchanged, being an exact eighth (1-2/8

or 1-1/4.)

1-9/32 becomes 1-2/8 or 1-1/4. (9/32 is 1/32 more than

an exact 1/8; 1/32 is less than half of 4/32 and

accordingly is dropped.)
Units and Systems

B-1

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 half 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 and 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 1 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 in

order to have a length of 1 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 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.
Units and Systems

B-2

Our present knowledge of early weights and measures cubit. In any case, the foot was inherited from the Egypcomes from many sources. Some rather early standards tians by the Greeks and Romans. The Roman foot was

have been recovered by archaeologists and preserved in divided into both 12 unciae (inches) and 16 digits. The

museums. The comparison of the dimensions of Romans also introduced the mile of 1000 paces or double

buildings with the descriptions of contemporary writers steps, the pace being equal to 5 Roman feet. The Roman

is another source of information. An interesting example mile of 5000 feet was introduced into England during the

of this is the comparison of the dimensions of the Greek occupation. Queen Elizabeth, who reigned from 1558 to

Parthenon with the description given by Plutarch from 1603, changed, by statute, the mile to 5280 feet or 8 furwhich a fairly accurate idea of the size of the Attic foot longs, a furlong being 40 rods of 5-1/2 yards each.

is obtained. In some cases, we have only plausible

theories and we must sometimes decide on the The introduction of the use of the yard as a unit of length

interpretation to be given to the evidence. came later, but its origin is not definitely known. Some

For example, does the fact that the length of the it originated from cubic measure. Regardless of its

double-cubit of early Babylonia was equal (within two origin, the early yard was divided by the binary system

parts per thousand) to the length of the seconds into 2, 4, 8, and 16 parts called the half-yard, span,

pendulum at Babylon indicate a scientific knowledge of finger, and nail. The association of the yard with the

the pendulum at a very early date, or do we merely have "gird" or circumference of a person’s waist or with the

a curious coincidence? By studying the evidence given distance from the tip of the nose to the end of the thumb

by all available sources, and by correlating the relevant of Henry I are probably standardizing actions, since

facts, we obtain some idea of the origin and development several yards were in use in Great Britain.

of the units. We find that they have changed more or less

gradually with the passing of time in a complex manner The point, which is a unit for measuring print type, is

because of a great variety of modifying influences. We recent. It originated with Pierre Simon Fournier in 1737.

find the units modified and grouped into measurement It was modified and developed by the Didot brothers,

systems: The Babylonian system, the Egyptian system, Francois Ambroise and Pierre Francois, in 1755. The

the Phileterian system of the Ptolemaic age, the Olympic point was first used in the United States in 1878 by a

system of Greece, the Roman system, and the British Chicago type foundry (Marder, Luse, and Company).

system, to mention only a few. Since 1886, a point has been exactly 0.3514598

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

believe the origin is the double cubit, others believe that

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 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

1/144 ounce and then 0.2 gram.
Units and Systems

B-3

Goods of commerce were originally traded by number or The adoption of the system in France was slow, but its

volume. When weighing of goods began, units of mass desirability as an international system was recognized by

based on a volume of grain or water were developed. For geodesists and others. On May 20, 1875, an international

example, the talent in some places was approximately treaty known as the International Metric Convention or

equal to the mass of one cubic foot of water. Was this a the Treaty of the Meter was signed by 17 countries

coincidence or by design? The diverse magnitudes of including the United States. This treaty established the

units having the same name, which still appear today in following organizations to conduct international activities

our dry and liquid measures, could have arisen from the relating to a uniform system for measurements:

various commodities traded. The larger avoirdupois

pound for goods of commerce might have been based on 1) The General Conference on Weights and Measures

volume of water which has a higher bulk density than (French initials: CGPM), an intergovernmental

grain. For example, the Egyptian hon was a volume unit conference of official delegates of member nations

about 11 percent larger than a cubic palm and and the supreme authority for all actions;

corresponded to one mina of water. It was almost

identical in volume to the present U.S. pint. 2) The International Committee of Weights and MeaThe stone, quarter, hundredweight, and ton are larger scientists and metrologists, which prepares and

units of mass still used in Great Britain. The present executes the decisions of the CGPM and is responstone is 14 pounds, but an earlier unit appears to have sible for the supervision of the International Bureau

been 16 pounds. The other units are multiples of 2, 8, of Weights and Measures;

and 160 times the stone, or 28 112, and 2240 pounds.

The hundredweight is approximately equal to 2 talents. 3) The International Bureau of Weights and Measures

In the United States the ton of 2240 pounds is known as (French initials: BIPM), a permanent laboratory and

the long ton. The short ton is equal to 2000 pounds. world center of scientific metrology, the activities of

Units of time and angle: The division of the circle into dards and scales of the principal physical quantities

360 degrees and the day into hours, minutes, and seconds and maintenance of the international prototype

can be traced to the Babylonians who had a sexagesimal standards.

system of numbers. The 360 degrees may have been

related to a year of 360 days. The National Institute of Standards and Technology

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 2.2.2. International System of Units. - At the end of

systems were based on the meter, kilogram, and second World War II, a number of different systems of mea-

(mks) to improve the value of the units for practical surement still existed throughout the world. Some of

applications. The present metric system is the these systems were variations of the metric system, and

International System (SI) of units; it is also based on the others were based on the customary inch-pound system

meter, kilogram and second as well as additional base of the English-speaking countries. It was recognized that

units for temperature, electricity, radiation, and the additional steps were needed to promote a worldwide

quantity of substance that enters into chemical reactions. measurement system. As a result, in 1948, the 9th

the International System of units is often called the General Conference on Weights and Measures asked the

modernized metric system. International Committee of Weights and Measures to

sures (French initials: CIPM), consisting of selected

which include the establishment of the basic stanprovides 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. 

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.
Units and Systems

B-4

conduct an international study of the measurement needs traveled by light in a vacuum during a time interval of

of the scientific, technical, and educational communities. 1/299 792 458 of a second. 

On the basis of the findings of this study, the 10th

General Conference in 1954 decided that an international The kilogram, previously defined as the mass of one

system should be derived from six base units in order to cubic decimeter of water at the temperature of maximum

provide for the measurement of temperature and optical density, was known as the Kilogram of the Archives. It

radiation in addition to mechanical and electromagnetic was replaced after the International Metric Convention in

quantities. The six base units recommended were the 1875 by the International Prototype Kilogram which

meter, kilogram, second, ampere, Kelvin degree (which became the unit of mass without reference to the mass of

later was renamed the kelvin), and the candela. a cubic decimeter of water or to the Kilogram of the

In 1960, the 11th General Conference of Weights and International Metric Convention was assigned one or

Measures named the system based on the six base quan- more copies of the international standards; these are

tities the International System of Units. The generally known as National Prototype Meters and Kilograms.

adopted abbreviation, SI, is taken from the French name:

Le Système International D'Unités. The SI metric system The liter is a unit of capacity or volume. In 1964, the

is now either obligatory or permissible throughout the 12th General Conference on Weights and Measures redeworld. fined the liter as being one cubic decimeter. By its previ2.2.3. 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, as well as 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 1 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 it was found by precise measurements 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 2.2.4. The International Bureau of Weights and Meaequal to 1 650 763.73 wavelengths in vacuum of the sures. - The International Bureau of Weights and Mearadiation corresponding to the transition between the sures was established at Sèvres, a suburb of Paris,

specified energy levels of the krypton 86 atom. Since France, in accordance with the International Metric

1983 the meter has been defined as the length of the path Convention of May 20, 1875. At the Bureau there are

Archives. Each of the countries that subscribed to the

ous definition as being the volume occupied, under

standard conditions, by a quantity of pure water having

a mass of 1 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 modernized metric system (SI) includes three classes

of units:

base units for length, mass, time, temperature,

electricity, radiation and amount of substance;

supplementary units for plane angle and solid

angle; and

derived units for all other quantities (e.g., work,

force, power) expressed in terms of the nine

base units and supplementary units.

For details, see NIST Special Publication 330 (1991),

The International System of Units (SI) and NIST Special

Publication 811, Guide for the Use of the International

System of Units (available from the Superintendent of

Documents, U.S. Government Printing Office, Washington, DC 20402).

kept the International Prototype Kilogram, many sec-
Units and Systems

B-5

ondary standards, and equipment for comparing United States to encourage educational agencies and

standards and making precision measurements. The institutions to prepare students to use the metric system

Bureau, funded by assessment of the signatory govern- of measurement as part of the regular education program.

ments, is truly international. In recent years the scope of Under both this act and the Metric Conversion Act of

the work at the International Bureau has been 1975, the "metric system of measurement" is defined as

considerably broadened. It now carries on researches in the International System of Units as established in 1960

the fields of electricity, photometry and radiometry, by the General Conference on Weights and Measures and

ionizing radiations, and time and frequency in addition to interpreted or modified for the United States by the

its work in mass, length, and thermometry. Secretary of Commerce (sec. 4(4), Pub. L. 94-168; sec.

2.2.5. Present 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 aquired 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 BIPM. The prototype meter has been replaced by

modern stabilized lasers in accordance with the most

recent definition of the meter.

From 1893 until 1959, the yard was defined as being

equal exactly to 3 600/3 937 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, the yard is defined as being 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 1 200/3 937 meter). This foot is called 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 also acres should therefore be

converted to the corresponding metric values by using

pre-1959 conversion factors if more than five significant

figure accuracy is involved.

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

December 20, 1990.

Section 403 of Public Law 93-380, the Education 2.3. British and United States Systems of MeasureAmendment of 1974, states that it is the policy of the ment. - In the past, the customary system of weights and

403(a)(3), Pub. L. 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 of the latter 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

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 most recent revision of 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.)
Units and Systems

B-6

measures in the British Commonwealth countries and that in the U.S. system because a U.S. gallon of water at 62 EF

in the United States were very similar; however, the SI weighs about 8-1/3 pounds, or 133-1/3 avoirdupois ounces,

metric system is now the official system of units in the and the U.S. gallon is equivalent to 4 x 32, or 128 fluid

United Kingdom, while the customary units are still ounces.

predominantly used in the United States. Because

references to the units of the old British customary system 1 U.S. fluid ounce = 1.041 British fluid ounces

are still found, the following discussion describes the 1 British fluid ounce = 0.961 U.S. fluid ounce

differences between the U.S. and British customary systems 1 U.S. gallon = 0.833 British Imperial gallon

of units. 1 British Imperial gallon = 1.201 U.S. gallons

After 1959, the U.S. and the British inch were defined Among other differences between the customary British and

identically for scientific work and were identical in the United States measurement systems , it should be noted

commercial usage. A similar situation existed for the U.S. that the use of the troy pound was abolished in England

and the British pound, and many relationships, such as 12 January 6, 1879, only the troy ounce and its subdivisions

inches = 1 foot, 3 feet = 1 yard, and 1760 yards = 1 being retained, whereas the troy pound is still legal in the

international mile, were the same in both countries; but United States, although it is not now greatly used. The

there were some very important differences. common use in England of the stone of 14 pounds should be

In the first place, the U.S. customary bushel and the U.S. States, although its influence was shown in the practice until

gallon, and their subdivisions differed from the World War II of selling flour by the barrel of 196 pounds

corresponding British Imperial units. Also the British ton (14 stones). In the apothecaries system of liquid measure

is 2240 pounds, whereas the ton generally used in the Unit- the British insert a unit, the fluid scruple, equal to one third

ed States is the short ton of 2000 pounds. The American of a fluid drachm (spelled dram in the United States)

colonists adopted the English wine gallon of 231 cubic between their minim and their fluid drachm. In the United

inches. The English of that period used this wine gallon States, the general practice now is to sell dry commodities,

and they also had another gallon, the ale gallon of 282 cubic such as fruits and vegetables, by their mass.

inches. In 1824, these two gallons were abandoned by the

British when they adopted the British Imperial gallon,

which is defined as the volume of 10 pounds of water, at a

temperature of 62 EF, which, by calculation, is equivalent to

277.42 cubic inches. At the same time, the bushel was

redefined 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; the bushel, with its

subdivisions, is used in the measurement of certain dry

commodities. The U.S. gallon is divided into 4 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 the foregoing it is seen that in the customary British

system an avoirdupois ounce of water at 62 EF has a volume

of 1 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

mentioned, this being a unit now unused in the United

2.4. Subdivision of Units. - In general, units are subdivided by one of three systems: (a) decimal, that is into

tenths; (b) duodecimal, into twelfths; or (c) binary, into

halves. Usually the subdivision is continued by the use of

the same system. 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 4-3/8 inches. However, if

these measured lengths are to be subsequently used in

calculations of 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 on

the basis of convenience to the user. The fact that units
Units and Systems

B-7

 See Federal Register for July 1, 1959. See also next to last 1

paragraph of 2.2.5.

have commonly been sub divided into certain subunits for arithmetical systems of numbers. The systems of units

centuries does not preclude their also having another mode used in this country for commercial and scientific work,

of subdivision in some frequently used cases where having many origins as has already been shown, naturally

convenience indicates the value of such other method. show traces of the various number systems associated with

Thus, the gallon is usually subdivided into quarts and pints, their origins and developments. Thus, (a) the binary subbut the majority of gasoline-measuring pumps of the division has come down to us from the Hindus, (b) the

price-computing type are graduated to show tenths of a duodecimal system of fractions from the Romans, (c) the

gallon. decimal system from the Chinese and Egyptians, some

Although the mile has for centuries been divided into rods, sexagesimal system (division by 60) now illustrated in the

yards, feet, and inches, the odometer part of an automobile subdivision of units of angle and of time, from the ancient

speedometer indicates tenths of a mile. Although our dollar Babylonians. The use of decimal numbers in measurements

is divided into 100 parts, we habitually use and speak of is becoming the standard practice.

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, 1-1/2, and 3 inches, respectively,

represent 1 foot full scale, as well as 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. Elevations of land

above sea level are given in feet even though 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

developments having been made by the Hindus, and (d) the

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 vacuum, is the unit on

which all length measurements are based. 

The yard is defined as follows: 1

1 yard = 0.914 4 meter

and the inch is exactly equal to 25.4 millimeters.

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. Calibrations are made in accordance with

fee schedules, copies of which may be obtained by

application to NIST.

NIST does not calibrate carpenters rules, machinists

scales, draftsman scales, and the like. Such apparatus, if

calibration is required, should be submitted to State or

local weights and measures officials.

3.2. Standards of Mass. - The primary standard of mass
Units and Systems

B-8

 See Federal Register for July 1, 1959. 2

for this country is United States Prototype Kilogram 20, same location (where both masses are acted upon by the

which is a platinum-iridium cylinder kept at NIST. The same g) will be affected in the same manner and by the

value of this mass standard is known in terms of the same amount by any change in the value of g, the two

International Prototype Kilogram, a platinum-iridium objects will balance each other under any value of g.

standard which is kept at the International Bureau of

Weights and Measures. However, on a spring balance the mass of a body is not

In colonial times the British standards were considered to be gravitational force on the body is balanced by the

the primary standards of the United States. Later, the U.S. restoring force of a spring. Therefore, if a very sensitive

avoirdupois pound was defined in terms of the Troy Pound spring balance is used, the indicated mass of the body

of the Mint, which is a brass standard kept at the United would be found to change if the spring balance and the

States Mint in Philadelphia. In 1911, the Troy Pound of the body were moved from one locality to another locality

Mint was superseded, for coinage purposes, by the Troy with a different acceleration of gravity. But a spring balPound of the Institute. ance is usually used in one locality and is adjusted or

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 1/7 000 of the avoirdupois pound and is

identical in the avoirdupois, troy, and apothecaries systems.

The troy ounce and the apothecaries ounce differ from the

avoirdupois ounce but are equal to each other, and equal to

480 grains. The avoirdupois ounce is equal to 437 1/2

grains.

3.2.1. Mass and Weight. - The mass of a body is a er body.

measure of its inertial property or the amount of matter it

contains. The weight of a body is a measure of the force The greater the difference in volume, and the greater the

exerted on it by gravity or the force needed to support it. density of the air in which the comparison weighing is

Gravity on earth gives a body a downward acceleration made, the greater will be the apparent difference in

of about 9.8 m/s . (In common parlance, weight is often mass. For that reason, in assigning a precise numerical 2

used as a synonym for mass as in weights and measures.) value of mass to a standard, it is necessary to base this

The incorrect use of weight in place of mass should be value on definite values for the air density and the

phased out, and the term mass used when mass is meant. density of the mass standard of reference.

Standards of mass are ordinarily calibrated by com- The apparent mass of an object is equal to the mass of

parison to a reference standard of mass. If two objects just enough reference material of a specified density (at

are compared on a balance and give the same balance 20 EC) that will produce a balance reading equal to that

indication, they have the same "mass" (excluding the produced by the object if the measurements are done in

effect of air buoyancy). The forces of gravity on the two air with a density of 1.2 mg/cm at 20 EC. The original

objects are balanced. Even though the value of the basis for reporting apparent mass is apparent mass versus

acceleration of gravity, g, is different from location to brass. The apparent mass versus a density of 8.0 g/cm

location, because the two objects of equal mass in the is the more recent definition, and is used extensively

balanced against the mass of another body. Instead, the

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 small3

3

throughout the world. The use of apparent mass versus

8.0 g/cm is encouraged over apparent mass versus 3
Units and Systems

B-9

brass. The difference in these apparent mass systems is temperature. More important is the care to prevent any

insignificant in most commercial weighing applications. damage to the standard because of careless handling.

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, standards of capacity have been

made and distributed to the several States. Other standards

of capacity have been verified by calibration for a wide

variety of uses in science, technology, and commerce.

3.3.1. Calibrations of Standards of Capacity. - Calibrations are made by NIST 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. Furthermore, NIST calibrates precision grade

volumetric glassware which is normally in metric units.

Calibrations are made in accordance with fee schedules,

copies of which may be obtained by application to 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 also to realize all the other base units. It 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

4. Specialized use of the Terms

"Ton" and "Tonnage" 

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 use has 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,
Units and Systems

B-10

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 on account of 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

that are deducted are those totally unavailable for

carrying cargo, such as the engine room, coal bunkers,

crews quarters, chart and instrument room, etc. The net

tonnage is used in computing the amount of 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.

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.
General Tables of Units of Measurement

C-1

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, thus 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 1 000, 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 1 000 and

for subdivisions smaller than one-thousandth. Accordingly, the following prefixes have been introduced and these are

now generally recognized:

yotta, (Y) meaning 10 deci, (d), meaning 10 24 -1

zetta, (Z), meaning 10 centi, (c), meaning 10 21 -2

exa, (E), meaning 10 milli, (m), meaning 10 18 -3

peta, (P), meaning 10 micro, (μ), meaning 10 15 -6

tera, (T), meaning 10 nano, (n), meaning 10 12 -9

giga, (G), meaning 10 pico, (p), meaning 10 9 -12

mega, (M), meaning 10 femto, (f), meaning 10 6 -15

kilo, (k), meaning 10 atto, (a), meaning 10 3 -18

hecto, (h), meaning 10 zepto, (z), meaning 10 2 -21

deka, (da), meaning 10 yocto, (y), meaning 10 1 -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
General Tables of Units of Measurement

 By action of the 12th General Conference on Weights and Measures (1964) the liter is a special name for the cubic 1

decimeter. 

C-2

Units of Area

100 square millimeters (mm ) = 1 square centimeter (cm ) 2 2

100 square centimeters = 1 square decimeter (dm )2

100 square decimeters = 1 square meter (m )2

100 square meters = 1 square dekameter (dam ) = 1 are 2

100 square dekameters = 1 square hectometer (hm ) = 1 hectare (ha) 2

100 square hectometers = 1 square kilometer (km )2

Units of Liquid Volume

10 milliliters (mL) = 1 centiliter (cL)

10 centiliters = 1 deciliter (dL) = 100 milliliters

10 deciliters = 1 liter = 1000 milliliters 1

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 (mm ) = 1 cubic centimeter (cm ) 3 3

1000 cubic centimeters = 1 cubic decimeter (dm )3

= 1 000 000 cubic millimeters

1000 cubic decimeters = 1 cubic meter (m )3

= 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)
General Tables of Units of Measurement

 This section lists units of measurement that have traditionally been used in the United States. In keeping with the 2

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.

 Squares and cubes of customary but not of metric units are sometimes expressed by the use of abbreviations rather than 3

symbols. For example, sq ft means square foot, and cu ft means cubic foot.

C-3

2. TABLES OF U.S. 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 (see Section 2.2.4.).

Units of Length

12 inches (in) = 1 foot (ft)

3 feet = 1 yard (yd)

16-1/2 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 = 6076.115 49 feet (approximately)

= 1 international nautical mile

Units of Area3

144 square inches (in ) = 1 square foot (ft ) 2 2

9 square feet = 1 square yard (yd )2

= 1296 square inches

272-1/4 square feet = 1 square rod (sq rd)

160 square rods = 1 acre = 43 560 square feet

640 acres = 1 square mile (mi )2

1 mile square = 1 section of land

6 miles square = 1 township

= 36 sections = 36 square miles

Units of Volume3

1728 cubic inches (in ) = 1 cubic foot (ft ) 3 3

27 cubic feet = 1 cubic yard (yd )3

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
General Tables of Units of Measurement

 When necessary to distinguish the liquid pint or quart from the dry pint or quart, the word "liquid" or the abbreviation 4

"liq" should be used in combination with the name or abbreviation of the liquid unit.

 When necessary to distinguish dry pint or quart from the liquid pint or quart, the word "dry" should be used in 5

combination with the name or abbreviation of the dry unit.

C-4

Units of Liquid Volume4

4 gills (gi) = 1 pint (pt)= 28.875 cubic inches

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 (min or ) = 1 fluid dram (fl dr or ƒ )

= 0.225 6 cubic inch

8 fluid drams = 1 fluid ounce (fl oz or ƒ )

 = 1.804 7 cubic inches

16 fluid ounces = 1 pint (pt or )

= 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

Units of Dry Volume5

2 pints (pt) = 1 quart (qt) = 67.200 6 cubic inches

8 quarts = 1 peck (pk) = 537.605 cubic inches 

= 16 pints

4 pecks = 1 bushel (bu) = 2150.42 cubic inches

= 32 quarts
General Tables of Units of Measurement

 When necessary to distinguish the avoirdupois dram from the apothecaries dram, or to distinguish the avoirdupois dram 6

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.

 When the terms "hundredweight" and "ton" are used unmodified, they are commonly understood to mean the 100- 7

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.

C-5

Avoirdupois Units of Mass6

[The "grain" is the same in avoirdupois, troy, and apothecaries units of mass.

27-11/32 grains = 1 dram (dr)

16 drams = 1 ounce (oz)

= 437-1/2 grains

16 ounces = 1 pound (lb)

= 256 drams

= 7000 grains

100 pounds = 1 hundredweight (cwt)7

20 hundredweights = 1 ton

= 2000 pounds7

In "gross" or "long" measure, the following values are recognized:

112 pounds = 1 gross or long hundredweight 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 = 1 pennyweight (dwt)

20 pennyweights = 1 ounce troy (oz t)= 480 grains

12 ounces troy = 1 pound troy (lb t)

= 240 pennyweights = 5760 grains

Apothecaries Units of Mass

[The "grain" is the same in avoirdupois, troy, and apothecaries units of mass.

20 grains = 1 scruple (s ap or )

3 scruples = 1 dram apothecaries (dr ap or )

= 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
General Tables of Units of Measurement

C-6

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 percent and 3 percent 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)
General Tables of Units of Measurement

 One international foot = 0.999 998 survey foot (exactly) 8

 One international mile = 0.999 998 survey mile (exactly)

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)

C-7

4. TABLES OF UNITS OF MEASUREMENT

(all underlined figures are exact)

Units of Length - International Measure8

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 Measure8

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
General Tables of Units of Measurement

 One square survey foot = 1.000 004 square international feet 9

 One square survey mile = 1.000 004 square international miles

C-8

 Units of Area - International Measure9

 (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 = 1296 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

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 Measure9

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 = 4356 16 1 0.1

1 acre = 43 560 160 10 1

1 square mile = 27 878 400 102 400 6400 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
General Tables of Units of Measurement

C-9

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

 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 = 1728 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 Liters Cubic Meters

(Cubic Centimeters) (Cubic Decimeters)

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 = 1000 1 0.001

1 cubic meter = 1 000 000 1000 1
General Tables of Units of Measurement

C-10

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

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 07 0.035 239 07

1 cubic inch = 1 0.000 578 703 7 0.016 387 06 0.000 016 387 06

1 cubic foot = 1728 1 28.316 85 0.028 316 85

1 liter = 61.023 74 0.035 314 67 1 0.001

1 cubic meter = 61 023.74 35.314 67 1000 1
General Tables of Units of Measurement

C-11

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 = 1920 32 4 1

1 liquid pint = 7680 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 1728

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
General Tables of Units of Measurement

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 3785.412 3.785 412

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 1000 1

 Units of Mass Not Less Than Avoirdupois Ounces

 (all underlined figures are exact)

Units Avoirdupois Avoirdupois Short Hundred- Short tons

Ounces Pounds weights

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 1600 100 1 0.05

hundredweight =

1 short ton = 32 000 2000 20 1

1 long ton = 35 840 2240 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 1000 1
General Tables of Units of Measurement

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= 5760 288 240 210.651 4

1 avdp. pound = 7000 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 Apothecaries or Troy

Ounces 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
General Tables of Units of Measurement

 The angstrom is basically defined as 10 meter. 10 -10

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 1295.978 2 1.295 978 2 0.001 295 978 2

1 pennyweight = 0.003 428 571 1555.173 84 1.555 173 84 0.001 555 173 84

1 avdp. dram = 0.003 906 25 1771.845 195 312 5 1.771 845 195 312 5 0.001 771 845 195 312 5

1 apoth. dram = 0.008 571 429 3887.934 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 0.068 571 43 31 103.476 8 31.103 476 8 0.031 103 476 8

ounce =

1 apoth. or troy 0.822 857 1 373 241.721 6 373.241 721 6 0.373 241 721 6

pound =

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 1000 1 0.001

1 kilogram = 2.204 623 1 000 000 1000 1

5. TABLES OF EQUIVALENTS

In these tables it is necessary to differentiate between the "international foot" and the "survey foot" (see Section 2.2.4.);

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

0.1 nanometer (exactly).

0.000 1 micrometer (exactly).

angstrom (D) ----------------------- 0.000 000 1 millimeter (exactly). 10

0.000 000 004 inch.

120 fathoms (exactly).

1 cable’s length----------------------- 720 feet (exactly).

219 meters.

1 centimeter (cm)---------------------- 0.393 7 inch.

1 chain (ch)--------------------------- 66 feet (exactly). 
General Tables of Units of Measurement

 The term "statute mile" originated with Queen Elizabeth I who changed the definition of the mile from the Roman 11

mile of 5000 feet to the statute mile of 5280 feet (see 2.1.3.). 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).

C-15

 (Gunter’s or surveyors) 

20.116 8 meters.

1 decimeter (dm)----------------------- 3.937 inches.

1 dekameter (dam)---------------------- 32.808 feet.

6 feet (exactly).

1 fathom------------------------------- 1.828 8 meters.

1 foot (ft)---------------------------- 0.304 8 meter (exactly).

 

10 chains (surveyors) (exactly).

1 furlong (fur)------------------------ 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.

0.66 foot (exactly).

1 link (li) (Gunter’s or surveyors)---- 0.201 168 meter.

1 meter (m)---------------------------- 39.37 inches.

1.094 yards.

1 micrometer--------------------------- 0.001 millimeter (exactly).

0.000 039 37 inch.

0.001 inch (exactly).

1 mil---------------------------------- 0.025 4 millimeter (exactly).

1 mile (mi) (U.S. statute) ---------- 5280 feet (exactly). 11

1.609 kilometers.

1 mile (mi) (international)------------ 5280 feet (exactly).
43560 ' 208.710%

General Tables of Units of Measurement

 The international nautical mile of 1 852 meters (6 076.115 49...feet) was adopted effective July 1, 1954, for use in 12

the United States. The value formerly used in the United States was 6 080.20 feet = 1 nautical (geographical or sea)

mile.

 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 13

square feet. It is not necessarily square, or even rectangular. But, if it is square, then the length of a side is equal to

 feet.

C-16

1 mile (mi) (international nautical) 1.852 kilometers (exactly). 12

1.151 survey miles.

1 millimeter (mm)---------------------- 0.039 37 inch.

 0.001 micrometer (exactly).

1 nanometer (nm)----------------------- 0.000 000 039 37 inch.

 

0.013 837 inch (exactly).

1 Point (typography)------------------- 1/72 inch (approximately).

0.351 millimeter.

1 rod (rd), pole, or perch------------- 16 1/2 feet (exactly).

5.029 2 meters.

1 yard (yd)---------------------------- 0.914 4 meter (exactly).

UNITS OF AREA

43 560 square feet (exactly).

1 acre ---------------------------- 0.405 hectare. 13

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 (dm )------------ 15.500 square inches. 2

1 square foot (ft )----------------- 929.030 square centimeters. 2

1 square inch (in )----------------- 6.451 6 square centimeters (exactly). 2

1 square kilometer (km )------------ 247.104 acres. 2

 0.386 square mile.

1 square meter (m )----------------- 1.196 square yards. 2

 10.764 square feet.
General Tables of Units of Measurement

 There are a variety of "barrels" established by law or usage. For example, Federal taxes on fermented liquors are 14

based on a barrel of 31 gallons; many State laws fix the "barrel for liquids" as 31-1/2 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. 

 Frequently recognized as 1-1/4 bushels, struck measure. 15

C-17

1 square mile (mi )----------------- 258.999 hectares. 2

1 square millimeter (mm )----------- 0.002 square inch. 2

1 square rod (rd ), sq pole, 2

 or sq perch----------------------- 25.293 square meters. 

1 square yard (yd )----------------- 0.836 square meter. 2

UNITS OF CAPACITY OR VOLUME

1 barrel (bbl), liquid----------------- 31 to 42 gallons.14

1 barrel (bbl), standard for fruits, 7056 cubic inches.

 vegetables, and other dry------------ 105 dry quarts.

 commodities, except cranberries 3.281 bushels, struck measure.

5 826 cubic inches.

1 barrel (bbl), standard, cranberry---- 86 45/64 dry quarts.

 2.709 bushels, struck measure.

2150.42 cubic inches (exactly).

1 bushel (bu) (U.S.) struck measure---- 35.239 liters.

2 747.715 cubic inches.

[1 bushel, heaped (U.S.)]-------------- 1.278 bushels, struck measure.15

[1 bushel (bu) (British Imperial)

1.032 U.S. bushels, struck measure 

(struck measure)]---------------------- 2219.36 cubic inches. 

1 cord (cd) (firewood)----------------- 128 cubic feet (exactly).

1 cubic centimeter (cm )--------------- 0.061 cubic inch. 3

1 cubic decimeter (dm )---------------- 61.024 cubic inches. 3

1 cubic foot (ft )--------------------- 7.481 gallons. 3

28.316 cubic decimeters. 

 0.554 fluid ounce.

1 cubic inch (in )------------------------ 4.433 fluid drams. 3

 16.387 cubic centimeters.
General Tables of Units of Measurement

C-18

1 cubic meter (m )--------------------- 1.308 cubic yards. 3

1 cubic yard (yd )--------------------- 0.765 cubic meter. 3

8 fluid ounces (exactly).

1 cup, measuring----------------------- 237 milliliters.

 1/2 liquid pint (exactly).

1 dekaliter (daL)---------------------- 2.642 gallons.

 1.135 pecks.

 1/8 fluid ounce (exactly).

1 dram, fluid (or liquid) (fl dr 0.226 cubic inch.

or ƒ ) (U.S.)------------------------ 3.697 milliliters.

 1.041 British fluid drachms.

 0.961 U.S. fluid dram.

[1 drachm, fluid (fl dr) (British)]---- 0.217 cubic inch. 

 3.552 milliliters.

 231 cubic inches (exactly). 

3.785 liters.

1 gallon (gal) (U.S.)------------------ 0.833 British gallon. 

 128 U.S. fluid ounces (exactly).

 277.42 cubic inches. 

 1.201 U.S. gallons.

[1 gallon (gal) (British Imperial)]---- 4.546 liters. 

 160 British fluid ounces (exactly).

 7.219 cubic inches.

1 gill (gi)---------------------------- 4 fluid ounces (exactly). 

0.118 liter.

1 hectoliter (hL)---------------------- 26.418 gallons.

 2.838 bushels.

1.057 liquid quarts.

1 liter (1 cubic decimeter exactly)---- 0.908 dry quart. 

 61.025 cubic inches 

 0.271 fluid dram.

1 milliliter (mL)---------------------- 16.231 minims. 

 0.061 cubic inch.

1 ounce, fluid (or liquid) (fl oz 1.805 cubic inches.

or ƒ )(U.S.)------------------------- 29.573 milliliters.

 1.041 British fluid ounces.

0.961 U.S. fluid ounce.

[1 ounce, fluid (fl oz) (British)]----- 1.734 cubic inches. 

 28.412 milliliters.

1 peck (pk)---------------------------- 8.810 liters. 
General Tables of Units of Measurement

 The equivalent "1 teaspoon = 1-1/3 fluid drams" has been found by the Bureau to correspond more closely with the 16

actual capacities of "measuring" and silver teaspoons than the equivalent "1 teaspoon = 1 fluid dram," which is given

by a number of dictionaries.

 Used in assaying. The assay ton bears the same relation to the milligram that a ton of 2000 pounds avoirdupois bears 17

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.

C-19

33.600 cubic inches.

1 pint (pt), dry----------------------- 0.551 liter.

 28.875 cubic inches exactly.

1 pint (pt), liquid-------------------- 0.473 liter.

 67.201 cubic inches.

1 quart (qt), dry (U.S.)--------------- 1.101 liters.

 0.969 British quart.

57.75 cubic inches (exactly).

1 quart (qt), liquid (U.S.)------------ 0.946 liter.

 0.833 British quart.

 69.354 cubic inches.

[1 quart (qt) (British)]--------------- 1.032 U.S. dry quarts. 

 1.201 U.S. liquid quarts. 

 3 teaspoons (exactly).

1 tablespoon, measuring---------------- 15 milliliters.

 4 fluid drams.

 1/2 fluid ounce (exactly).

1/3 tablespoon (exactly).

1 teaspoon, measuring------------------ 5 milliliters.

1-1/3 fluid drams.16

270.91 U.S. gallons.

1 water ton (English)------------------ 224 British Imperial gallons.

(exactly).

UNITS OF MASS

1 assay ton (AT)--------------------- 29.167 grams. 17

200 milligrams (exactly).

1 carat (c)---------------------------- 3.086 grains.

1 dram apothecaries (dr ap or )----- 60 grains (exactly).

3.888 grams.

1 dram avoirdupois (dr avdp)----------- 27-11/32 (= 27.344) grains.

1.777 grams.
General Tables of Units of Measurement

 The gross or long ton and hundredweight are used commercially in the United States to only a very limited extent, 18

usually in restricted industrial fields. The units are the same as the British "ton" and "hundredweight."

C-20

1 gamma ( )--------------------------- 1 microgram (exactly).

1 grain-------------------------------- 64.798 91 milligrams (exactly).

1 gram (g)----------------------------- 15.432 grains.

0.035 ounce, avoirdupois.

1 hundredweight, gross or long 112 pounds (exactly). 18

 (gross cwt)-------------------------- 50.802 kilograms.

1 hundredweight, gross or short 100 pounds (exactly).

 (cwt or net cwt)--------------------- 45.359 kilograms.

1 kilogram (kg)------------------------ 2.205 pounds.

1 microgram (μg) [the Greek letter mu

 in combination with the letter g]--- 0.000 001 gram (exactly).

1 milligram (mg)----------------------- 0.015 grain.

437.5 grains (exactly).

1 ounce, avoirdupois (oz avdp)--------- 0.911 troy or apothecaries ounce.

28.350 grams.

1 ounce, troy or apothecaries 480 grains (exactly).

(oz t or oz ap or )---------------- 1.097 avoirdupois ounces.

31.103 grams.

1 pennyweight (dwt)-------------------- 1.555 grams.

1 point-------------------------------- 0.01 carat.

2 milligrams.

7000 grains (exactly).

1 pound, avoirdupois (lb avdp)--------- 1.215 troy or apothecaries pounds.

453.592 37 grams (exactly).

1 pound, troy or apothecaries 5760 grains (exactly).

 (lb t or lb ap)---------------------- 0.823 avoirdupois pound.

373.242 grams.

1 scruple (s ap or )---------------- 20 grains (exactly).

1.296 grams.
General Tables of Units of Measurement

 The gross or long ton and hundredweight are used commercially in the United States to a limited extent only, usually 19

in restricted industrial fields. These units are the same as the British "ton" and "hundredweight."

C-21

2240 pounds (exactly).

1 ton, gross or long ----------------- 1.12 net tons (exactly). 19

1.016 metric tons.

2204.623 pounds.

1 ton, metric (t)---------------------- 0.984 gross ton.

1.102 net tons.

2000 pounds (exactly).

1 ton, net or short-------------------- 0.893 gross ton.

0.907 metric ton.
Definitions

D-1

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.[4.43]

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.")[1.10]

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/cm . The apparent mass 3

of an object versus 8.0 g/cm is the mass of material of 3

density 8.0 g/cm that produces exactly the same 3

balance reading as the object when the comparison is

made in air with a density of 1.2 mg/cm at 3

20 EC.[3.30, 3.32]

approval seal. A label, tag, stamped or etched

impression, or the like, indicating official approval of

a device. (Also see "security seal.")[1.10]

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, 3.30] (Added 1993)

automatic zero-setting mechanism. Automatic

means provided to maintain zero balance indication

without the intervention of an operator.[2.20]

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.[2.20]

automatic hopper scale. One adapted to the

automatic weighing of bulk commodity in successive

drafts of predetermined amounts. (This is not an "automatic-indicating scale" defined below.)[2.20]

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 a normal

temperature of 70 EF and absolute pressure of

14.696 lb/in absolute.[3.34] 2

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]

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]
Definitions

D-2

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 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]

basic distance rate. The charge for distance for all

intervals except the initial interval.[5.54]

batching meter. A device used for the purpose of

measuring quantities of water to be used in a batching

operation.[3.36]

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]

beam. See "weighbeam."[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]

bench scale. See "counter scale."[2.20]

binary submultiples. Fractional parts obtained by

successively dividing by the number 2. Thus, one-half,

one-fourth, one-eighth, one-sixteenth, and so on, are

binary submultiples.[1.10]

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, 3.30] (Added 1993)

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]

chart recorder. An element used with a belt-conveyor

scale that continuously records the rate-of-flow of bulk

material over the scale.[2.21]

check rate. A rate of flow usually 20 percent of the

capacity rate.[3.33]

checkweighing scale. One used to verify

predetermined weight within prescribed limits.[2.20]
Definitions

D-3

class of grain. Hard Red Winter Wheat as

distinguished from Hard Red Spring Wheat as

distinguished from Soft Red Winter Wheat, etc.[5.56]

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] contract sale. A sale where there is a written

coal-mine scale. One used at a coal mining operation

for determining the basic wages of miners on a

production basis.[2.20]

cold-tire pressure. The pressure in a tire at ambient

temperature.[5.53, 5.54]

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]

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]

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). A capacity rating

of a vehicle, axle-load, or livestock scale, specified by

the manufacturer, defining the maximum load

concentration for which the weighbridge is designed.

In the case of vehicle and axle-load scales, it is the

maximum axle-load concentration (for a group of two

axles with a centerline spaced 4 feet apart and an axle

width of 8 feet) for which the weighbridge is designed correct. A piece of equipment is "correct" when, in

as specified by the manufacturer. The concentrated addition to being accurate, it meets all applicable

load capacity rating is for both test and use.[2.20] specification requirements. Equipment that fails to

(Added 1988)(Amended 1991, 1994) meet any of the requirements for correct equipment is

configuration parameter. Any adjustable or

selectable parameter for a device feature that can affect counter scale. One that, by reason of its size,

the accuracy of a transaction or can significantly arrangement of parts, and moderate nominal capacity,

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, 3.30] (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-material hopper scale. A scale adapted

to weighing construction materials such as sand, gravel,

cement, and hot oil.[2.20]

agreement stating the price as either a fixed price, a

price above cost, or an adjustment from the posted

price. [3.30] (Added 1993)

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]

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]

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]

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]

"incorrect." (Also see "accurate.")[1.10]
Definitions

D-4

is adapted for use on a counter or bench. Sometimes that partially surrounds the gauge glass in the upper

called "bench scale."[2.20] neck.[3.33]

counterbalance weight. One intended for application cubic foot, gas. The amount of a cryogenic liquid in

near the butt of a weighbeam for zero-load balancing the gaseous state at a temperature of 70 EF and under

purposes.[2.20] a pressure of 14.696 lb/in absolute that occupies one

counterpoise weight. A slotted or "hanger" weight

intended for application near the tip of the weighbeam

of a scale having a multiple greater than 1.[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]

(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, trackmounted

crane.[2.20]

cryogenic liquid-measuring device. A system

including a mechanism or machine of (a) the meter or

mass flow type, or (b) a weighing type of device

mounted on a vehicle, designed to measure and deliver

cryogenic liquids in the liquid state. Means may be

provided to indicate automatically, for one of a series

of unit prices, the total money value of the liquid

measured.[3.34]

(Amended 1986)

cryogenic liquids. Fluids whose normal boiling point

is below 120 kelvin (-243 EF).[3.34]

cubic foot, standard. That quantity of gas that

occupies a volume of one cubic foot when under a

pressure of 14.73 lb/in absolute and at a temperature 2

of 60 EF.[3.33]

cubic foot, metered. That quantity of gas that

occupies one cubic foot when under pressure and

temperature conditions existing in the meter.[3.33]

cubic-foot bottle. A metal bottle open at the lower end

and so supported that it may be easily raised or lowered

in a tank that contains a sealing medium. With the

level of the sealing medium properly adjusted, the

bottle, when lowered, will displace exactly one cubic

foot of air upon coming to rest on the bottom of the

tank. The marks on the bottle defining the cubic foot

are the bottom of the lower neck and the gauge mark

2

cubic foot. (See NTP.)[3.34]

D

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]

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]

(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]

direct sale. A sale in which both parties in the

transaction are present when the quantity is being

determined. An unattended automated or customeroperated weighing or measuring system is considered

to represent the device/business owner in transactions

involving an unattended device. [1.10] (Amended

1993)

discharge line. A rigid pipe connected to the outlet of

a measuring device. [3.30]

(Added 1987)

discharge hose. A flexible hose connected to the

discharge outlet of a measuring device or its discharge

line. [3.30]

(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]

dispenser. See motor-fuel device.[3.30]

distributed-car test train. A train consisting of cars

weighed first on a reference scale, cars coupled
Definitions

D-5

consecutively in groups at different locations within the was changed, and the new value of the parameter.

train, then run over the coupled-in-motion railway track [2.20, 3.30]

scale under test. The groups are typically placed at the (Added 1993)

front, middle, and rear of the train.[2.20]

(Added 1990)

dry-hose type. A type of device in which it is can be determined, its error is said to be "in excess" or

intended that the discharge hose be completely drained "in deficiency," depending upon whether its actual

following the mechanical operations involved in each value is, respectively, greater or less than its nominal

delivery. [See "dry hose."] [3.30, 3.34] value. (See "nominal.") Examples of instruments

dry hose. A discharge hose intended to be completely

drained at the end of each delivery of liquid. [See

"dry-hose type."][3.30]

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 a 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

equal-arm scale. A scale having only a single lever

with equal arms (that is, with a multiple of 1), 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]

e (minimum verification scale division). min The

smallest scale division for which a weighing element

complies with the applicable requirements.[2.20, 2.21,

2.24] 

(Added 1997) 

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, 3.30]

(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

excess and deficiency. When an instrument or device

is of such a character that it has a value of its own that

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 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]

feeding mechanism. The means for depositing

material to be weighed on the belt conveyor. [2.21]
Definitions

D-6

fifth wheel. A commercially-available distancemeasuring 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] grain hopper scale. One adapted to the weighing of

fifth-wheel test. A distance test similar to a road test,

except that the distance traveled by the vehicle under grain moisture meter. Any device indicating either

test is determined by a mechanism known as a "fifth- directly or through conversion tables and/or correction

-wheel" that is attached to the vehicle and that indepen- tables the moisture content of cereal grains and oil

dently measures and indicates the distance.[5.53, 5.54] seeds. Also termed "moisture meter."[5.56]

flag. A plate at the end of the lever arm or similar part grain sample. That portion of grain or seed taken

by which the operating condition of a taximeter is from a bulk of grain or seed to be bought or sold and

controlled and indicated.[5.54] used to determine the moisture content of the

fractional bar. A weighbeam bar of relatively small

capacity for obtaining indications intermediate between grain-test scale. A scale adapted to weighing grain

notches or graduations on a main or tare bar.[2.20] samples used in determining moisture content, dockage,

ft /h. Cubic feet per hour.[3.33] 3

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.[4.43]

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.[4.43]

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]

individual loads of varying amounts of grain.[2.20]

bulk.[5.56]

weight per unit volume, etc.[2.20, 5.56]

gravity type. A type of device designed for discharge

by gravity.[3.30]

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]

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-material 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
Definitions

D-7

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]

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 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)

initial distance or time interval. The interval

corresponding to the initial money drop.[5.54]

interval, graduated. See "graduated interval."[1.10]

interval, clear, between graduations. See "clear

interval between graduations."[1.10]

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]

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]

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 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 naturaland manufactured-gas meters.[3.32]

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.[3.32, 3.33]

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)

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
Definitions

D-8

deliveries corresponding to specific money values at a

definite unit price.[3.30]

liquid fuel. Any liquid used for fuel purposes, that is,

as a fuel, including motor fuel.[3.30]

livestock scale. A scale equipped with stock racks substantially altered or rebuilt.[1.10]

and gates and adapted to weighing livestock standing

on the scale platform.[2.20]

(Amended 1989)

load-receiving element. That element of a scale that effects of mass on the sensing unit or may be inferred

is designed to receive the load to be weighed; for by measuring the properties of the product, such as the

example, platform, deck, rail, hopper, platter, plate, volume, density, temperature, or pressure, and

scoop.[2.20] displaying the quantity in mass units.[3.30, 3.32]

load cell. A device, whether electric, hydraulic, or master meter test method. A method of testing milk

pneumatic, that produces a signal proportional to the tanks that utilizes an approved master meter system for

load applied.[2.20] measuring test liquid removed from or introduced into

load cell verification interval (v). The load cell

interval, expressed in units of mass, used in the test of master weight totalizer. An indicating element used

the load cell for accuracy classification.[2.20, 2.21] with a belt conveyor scale to indicate the weight of

(Added 1996) material that was passed over the scale. The master

loading point. The location at which material to be

conveyed is applied to the conveyor.[2.21]

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

m /h. Cubic meters per hour.[3.33] 3

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]

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]

manual zero-setting mechanism. Nonautomatic

means provided to attain a zero balance indication by

the direct operation of a control.[2.20]

manufactured device. Any new device or any other

device that has been removed from service and

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

the tank.[4.43]

weight totalizer is a primary indicating element of the

belt-conveyor scale.[2.21]

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 percent.[2.21]

(Amended 1989)

maximum capacity. The largest load that may be

accurately weighed. [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]

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
Definitions

D-9

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 (Added 1995) [2.20]

accurately weighed. The weighing results may be

subject to excessive error if used below this value.

[2.24]

(Added 1999)

minimum totalized load. The least amount of weight

for which the scale is considered to be performing

accurately.[2.21]

minimum tolerances. Minimum tolerances are the application load cell is designated with the letter "M"

smallest tolerance values that can be applied to a scale. or the term "Multiple." (See also “single cell

Minimum tolerances are determined on the basis of the application load cell”) [2.20]

value of the minimum graduated interval or the nominal (Added 1999)

or reading face capacity of the scale. (See also

definition for basic tolerances.)[2.20]

minimum clear interval. The shortest distance elements. (On a beam scale, the multiple of the scale is

between adjacent graduations when the graduations are the number of pounds on the load-receiving element

not parallel. (Also see "clear interval.")[3.30] that will be counterpoised by 1 pound applied to the tip

minimum delivery. The least amount of weight that

is to be delivered as a single weighment by a multiple range scale. A scale having two or more

belt-conveyor scale system in normal use.[2.21] weighing ranges with different maximum capacities

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]

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 multiple. An integral multiple; that is, a result

of product.[1.10] obtained by multiplying by a whole number. (Also see

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]

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 (see definition of "retail

device").[3.30]

motor fuel. Liquid used as fuel for internalcombustion engines.[3.30]

multi-interval scale. A scale having one weighing

range which is divided into partial weighing ranges,

each with different scale intervals, with the weighing

range determined automatically according to the load

applied, both on increasing and decreasing loads.

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 cell application load cell. A load cell

intended for use in a weighing system which

incorporates more than one load cell. A multiple cell

multiple of a scale. In general, the multiplying power

of the entire system of levers or other basic weighing

pivot of the weighbeam.)[2.20]

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]

"multiple of a scale.")[1.10]

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/in absolute.[3.34] 2

n (maximum number of scale divisions). max The

maximum number of scale divisions for which a main

element or load cell complies with the applicable
Definitions

D-10

requirements. The maximum number of scale divisions greater or lesser. (See nominal capacity of a

permitted for an installation is limited to the lowest n s max cale)[1.10]

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 1. devices manufactured within a State after the

indication with no load in the load-receiving element effective date;

(hopper) of the scale. (Used with automatic

bulk-weighing systems and certain single-draft, 2. both new and used devices brought into a State after

manually-operated receiving hopper scales installed the effective date; and

below grade and used to receive grain.)[2.20]

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 2-1/2 percent of nose-iron. A slide-mounted, manually-adjustable pivot

the sum of the capacities of the remaining reading assembly for changing the multiple of a lever.[2.20]

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 measures officials.[1.10]

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]

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

nonretroactive. "Nonretroactive" requirements are

enforceable after the effective date for:

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)

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

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]

NTP. Normal temperature of 21 EC (70 EF) and

pressure of 101.325 kPa (14.696 lb/in absolute) 2

respectively.[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]
Definitions

D-11

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) point-of-sale system. An assembly of elements

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 portable cubic-foot standard. A gasometer of the

over-and-under indicator is classed as an auto- annular type, the bell being sealed with a light oil, the

matic-indicating scale.)[2.20] amount of its rise (and consequently of the volume of

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, postal scale. A scale (usually a computing scale)

its error is said to be in the direction of over designed for use to determine shipping weight or

registration or underregistration, depending upon delivery charges for letters or parcels delivered by the

whether the indications are, respectively, greater or less U.S. Postal Service or private shipping companies. A

than they should be. Examples of devices having errors weight classifier may be used as a postal scale.[2.20]

of "overregistration" are: a fabric-measuring device (Added 1987)

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]

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). (See definitions for "tolerance" and

"sensitivity requirement.")[1.10]

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]

(Added 1986) (Amended 1997)

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]

air or gas being measured) being under absolute control

so that an exact cubic foot can be delivered.[3.33]

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]

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
Definitions

D-12

meters or scales so equipped.) The term "primary" is weights substituted in all cases for the weights

not applied to such auxiliary elements as, for example, commercially used on the scale. (It is appropriate to

the totalizing register or predetermined-stop mechanism use this test for some scales not employing

on a meter or the means for producing a running record counterpoise weights.)[2.20]

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]

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 graduations or may present values digitally, and may

proving or leak-test circle on the meter register or also provide money-value indications.[1.10]

index.[3.33]

prover test method. A method of testing milk tanks other representation that is recorded as a quantity by a

that utilizes approved volumetric prover(s) for weighing or measuring device.[1.10]

measuring the test liquid removed from or introduced

into the tank.[4.43]

R

T HCEVQT#EQORWVCVKQPHQTFGVGTOKPKPIVJG

UWKVCDKNKV[QHCXGJKENGUECNGHQTYGKIJKPIXGJKENGU

YKVJXCT[KPICZNGEQPHKIWTCVKQPU6JGHCEVQTYCU

FGTKXGFD[FKXKFKPIVJGYGKIJVUKP(*9#(GFGTCN

*KIJYC[$TKFIG)TQUU9GKIJV6CDNG$D[

NDU
6JGTGUWNVCPVHCEVQTUEQPVCKPGFKP6CDNG

74=?

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]

ranges, weight. See "weight ranges."[2.20]

rated scale capacity. That value representing the

weight that can be delivered by the device in one hour.-

[2.21]

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]

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

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]

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

recorded representation. The printed, embossed, or

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 railroad car weighed on a

scale for temporary use as a mass standard over a short

period of time (typically, the time required to test one

scale) as part of a test train.

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)

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, 3.30]

(Added 1993)

retail device. A device used for single deliveries of

less than 378 L (100 gal), retail deliveries of motor

fuels to individual highway vehicles, or
n ' Capacity

e

Definitions

D-13

single deliveries of liquefied petroleum gas for 

domestic use and liquified petroleum gas or liquid

anhydrous ammonia for nonresale use.

(Amended 1987)[3.32]

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 weighing or measuring device for protection against or

a complete taximeter assembly when installed on a indication of access to adjustment. (Also see "approval

vehicle, the mechanism being actuated as a result of seal.")[1.10]

vehicle travel.[5.53] (Amended 1994)

rolling circumference. The rolling circumference is selector-type. A system of indication or recording in

the straight line distance traveled per revolution of the which the mechanism selects, by means of a

wheel (or wheels) that actuates the taximeter or ratchet-and-pawl combination or by other means, one

odometer. If more than one wheel actuates the or the other of any two successive values that can be

taximeter or odometer, the rolling circumference is the indicated or recorded.[1.10]

average distance traveled per revolution of the

actuating wheels.[5.53, 5.54]

S

scale division, number of (n). Quotient of the

capacity divided by the value of the verification scale

division:[2.20]

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]

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]

scale. See specific type of scale.[2.20]

seal. See "approval seal," "security seal."[1.10]

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

semi-automatic zero-setting mechanism. Automatic

means provided to attain a direct zero balance

indication requiring a single initiation by an

operator.[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]

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]

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)

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]
Definitions

D-14

simulated test. A test using artificial means of loading surface gauge. A combination of (1) a stationary

the scale to determine the performance of a indicator, and (2) a movable, graduated element

belt-conveyor scale.[2.21] designed to be brought into contact with the surface of

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."

(See also “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 4 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]

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]

the liquid from above.[4.43]

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-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]

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 netweight

determinations.[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]

testing. An operation consisting of a series of

volumetric determinations made to verify the accuracy

of the volume chart that was developed by

gauging.[4.43]

test liquid. The liquid used during the test of a

device.[3.30]

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 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
Definitions

D-15

weight car may be one of the following types: a self- a unit weight will increase the range of automatic

contained composite car, a self-propelled car, or a indication, normally in increments equal to the

standard rail car.[2.20] reading-face capacity.[2.20]

(Added 1991)

time recorder. A clock-operated mechanism designed contiguous cars carrying a single commodity from one

to record the time of day. Examples of time recorders consignor to one consignee. The number of cars is

are those used in parking garages to record the "in" and determined by agreement among the consignor,

"out" time of day for parked vehicles.[5.55] consignee, and the operating railroad.[2.20]

timing device. A device used to measure the time user requirement. A requirement dealing with the

during which a particular paid-for service is dispensed. selection, installation, use, or maintenance of a

Examples of timing devices are laundry driers, weighing or measuring device. User requirements are

car-wash timers, parking meters, and parking-garage directed primarily to the users of devices.[1.10]

clocks and recorders.[5.55]

tolerance. A value fixing the limit of allowable error in practice or in the normal course of events and in

or departure from true performance or value. (See also accordance with established practices.[1.10]

"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.[3.34]

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 verification scale division, value of (e). A value,

(i.e., the weighing element, the load-receiving element, expressed in units of weight (mass) and specified by

and the indicating element with its software), and (3) the manufacturer of a device, by which the tolerance

the exit trackage which permit the weighing of railroad values and the accuracy class applicable to the device

cars uncoupled in motion. [2.20] (Added 1993) are determined. The verification scale division is

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.[3.30]

(Added 1992)

unit weight. One contained within the housing of an

automatic-indicating scale and mechanically applied to

and removed from the mechanism. The application of

unit train. A unit train is defined as a number of

usual and customary. Commonly or ordinarily found

V

value of minimum graduated interval. The value

represented by the interval from the center of one

graduation to the center of the succeeding graduation.

Also, the increment between successive recorded

values. (Also see "graduated interval.")[1.10]

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]

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]
Definitions

D-16

v (minimum load cell verification interval). min The wing pulley. A pulley made of widely spaced metal

smallest load cell verification interval, expressed in bars in order to set up a vibration to shake loose

units of mass* into which the load cell measuring range material off the underside (return side) of the

can be divided. [2.20, 2.21, 2.24] belt.[2.21]

[*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]

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]

(Added 1988)

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]

wet hose. A discharge hose intended to be full of

liquid at all times. [See "wet-hose type."][3.30]

wet-hose type. A type of device designed to be

operated with the discharge hose full of liquid at all

times. [See "wet hose."][3.30]

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. [See "retail device."][3.30, 3.32] 

Z

zero-load balance. A correct weight indication or

representation of zero when there is no load on the

load-receiving element. (See also "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-setting mechanism. Means provided to attain a

zero balance indication with no load on the

load-receiving element. Three types of these

mechanisms are:[2.20]

 

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]

automatic zero-setting mechanism. Automatic

means provided to maintain zero balance

indication without the intervention of an

operator.[2.20]
Definitions

D-17

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]