Technical Activities

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Updated  02/08/98

The following illustrations, text and photos are samples of the Technical Papers presented at the NISA Spring and Fall Technical Seminars.


National Institute of Standards & Technology

National Conference on Weights and Measures

NCWM Interim Meeting

NCWM Annual Meeting

NCWM is a Partnership

NCWM Membership Application

Handbook 44

National Type Evaluation Program

Examination Procedure Outlines

American Railway Engineering Association

AAR Scale Handbook



National Institute of Standards & Technology





National Conference on Weights and Measures

The National Conference on Weights and Measures is a national professional organization that develops consensus standards in such areas as weighing and measuring device regulation, commodity regulation, motor-fuel quality, and administration of regulatory weights and measures programs. Regulatory weights and measures activities are aimed at maintaining equity in the marketplace so that businesses can compete fairly and buyers and sellers can make informed decisions in trade. When you buy groceries, gasoline, heating fuel, or construction materials; when you ship a package, park in front of a parking meter, or use a laundromat, one thing is taken for granted: That the weight and measurement upon which the price of the product or service is based is accurate.

In 1905, the Director of the National Institute of Standards and Technology (NIST) (then named the National Bureau of Standards) called representatives of the weighing industry and directors of State weight and measures programs together. Since that first meeting, the NCWM has evolved from an annual forum to a year-round standards development, product testing, and training organization.

The Conference now operates the National Type Evaluation Program (NTEP) with a group of participating State and Federal Government laboratories to evaluate new measuring device designs against national performance standards. NIST still sponsors the NCWM, providing the secretariat to the Conference, technical support to its committees, and administration of Conference operations. NIST publishes Handbook 44, "Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices," Handbook 130, "Uniforms Laws and Regulations," and Handbook 133, "Checking the Net Contents of Packaged Goods." The NCWM National Training Program has developed training courses based on these handbooks and coordinates training and certification programs for weights and measures officials and training for industry personnel across the nation.

We welcome your participation in NCWM. Membership in the Conference is the only way to stay informed about fast-breaking developments and recommended standards that often become State law and regulation. All members receive quarterly newsletters, announcements, and reports of meetings throughout the year. So if you need to stay in touch with what is happening in weights and measures nationally and internationally, join your peers as a member of NCWM.

Organization of the National Conference on Weights and Measures

The NCWM is a standards development organization. Because of constantly evolving technologies (such as computer-interfaced supermarket checkout scales and in-motion systems used to weigh railroad cars) and new marketing practices such as "cash-discounts," "warehouse stores," and "buyers' clubs," the NCWM continuously reviews and updates its standards. This is accomplished annually through a feedback process involving regulated businesses and the officials who enforce the standards in the field. The NCWM is organized into the four standing committees listed below.

Executive Committee:

The policy-making and coordinating body for the Conference, with responsibility for the overall operation of the NCWM, also serving as Board of Governors for the National Type Evaluation Program.

Specifications & Tolerances (S&T) Committee:

Addresses specifications, tolerances, and technical requirements relating to commercial weighing and measuring devices, including interpretation and development of standards and testing and development of procedures for testing commercial equipment. The main product resulting from the continued work of the S&T Committee is NIST Handbook 44, "Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices".

Laws and Regulations (L&R) Committee:

Responsible for development and interpretation of uniform laws and regulations, and commodity inspection and regulation standards. Products of the L&R Committee include NIST Handbook 130, "Uniform Laws and Regulations," and NIST Handbook 133, "Checking the Net Contents of Packaged Goods." Handbook 130 includes a variety of recommendations for adoption by the States in areas of legal metrology, including motor-fuel quality. Standards for checking the net contents of package items including food, drugs, cosmetics, and other common packaged items available in office supply stores, hardware stores, discount houses, farm stores, and other non-food retail and wholesale businesses are contained in Handbook 133. The L&R Committee also addresses such current issues as the impact of the Nutrition Labeling and Education Act, product moisture loss, price verification procedures, and oversees the Petroleum Subcommittee and the Handbook 133 Working Group.

Administration and Public Affairs (A&P) Committee:

Administers NCWM programs dealing with the education and training of weights and measures officials and industry personnel, addresses consumer affairs and safety issues, and promotes weights and measures principles among the general public. The committee develops and maintains a series of training modules on inspection and testing of devices, package-checking, and weights and measures administration. It also oversees the Program Evaluation Work Group, which is working toward the establishment of a nationwide weights and measures network.

Identifying the Issues:

The NCWM standing committees may accept issues directly from any source; however, they prefer that issues be reviewed by regional weights and measures associations and receive thorough analysis prior to submission to the standing committee. Work Groups meet around the country throughout the year developing and refining proposed standards. Under this process, the standing committees have benefit of recommendations from the regional, know the preliminary positions of both the weights and measures officials and industry, and benefit from the advice of technical experts. Following their identification, the issues to be place on the agendas of the standing committees must be submitted to the Office of Weights and Measures (OWM), with an initial analysis, by November 1 of each year. OWM then assembles the submissions into an agenda for the NCWM Interim Meeting; the agenda is published and sent to NCWM members in December. Once the agendas are received and read, weights and measures officials, industry, device users, and consumers are invited to provide comments based on data and experience.

The NCWM Interim Meeting

The Interim Meeting of NCWM is held annually in January and is the main work session of the Conference. The standing committees review the issues, receive comments, and make decisions regarding recommendations to the Conference. Any Individual with an interest in a given issue should plan to attend and participate in the Interim Meeting. Following the Interim Meeting, the technical advisors draft committee reports for the review of committee members. The interim reports are published and sent to NCWM members in May. Thereafter, the NCWM constituency has the opportunity to provide further comment upon committee recommendations in preparation for the NCWM Annual Meeting in July.


The NCWM Annual Meeting

During the Annual Meeting: the standing committees meet to review all comments received since the Interim Meeting. They hold open hearings to receive oral comments on issues; committees make changes to their reports; then the final report, as amended, are made available for examination. The final reports are then presented, in open forum, to the weights and measures officials (the voting delegates) for vote. Following the Annual Meeting, adopted items are incorporated into annual additions of handbooks, published in November. NCWM members are mailed the handbooks they have selected immediately following publication. As a member of NCWM, you will be assured of having the handbooks you need in your work before new requirements take effect on January 1.


NCWM is a Partnership

NCWM relies on its partners in industry, in government weights and measures, and all concerned individuals in meeting its ultimate goal, "That Equity May Prevail." By joining NCWM you will have the opportunity to contribute to the work of the conference while staying abreast of critical issues. We look forward to welcoming you as a partner.



National Conference Membership Application

Use the following address to contact the Office of Weights and Measures and to join the National Conference of Weights and Measures.






Handbook 44

Handbook 44, 1997, "Specifications, Tolerances, and other Technical Requirements for Weighing and Measuring Devices" as adopted by the 81st National Conference on Weights and Measures.

Following the Annual Meeting, adopted items are incorporated into annual additions of handbooks, published in November and, in most cases, are accepted and become State law the following January. Following completion of the Membership Application and payment of annual dues, members should receive the new Handbook prior to January 1. The following should provide an introduction to using the Handbook.

1. Source. - The specifications, tolerances, and other technical requirements published in Handbook 44 comprise, in their latest form, all of the current codes as adopted by the National Conference on Weights and Measures (When sitting as a voting body, the National Conference on 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). The National Conference is sponsored by the National Institute of Standards and Technology (NIST), formally the National Bureau of Standards (NBS), 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 (Communications to this committee may be addressed as follows: Specification and Tolerances Committee Technical Advisor, National Conference on Weights and Measures, P.O. Box 4025, Gaithersburg, MD 20885), acting at the request of the Conference or upon its own initiative, with the cooperation of the National Institute of Standards and Technology, annually prepares proposed revisions, amendments, or additions to the material previously adopted by the Conference.  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 within Handbook 44 are recommended by the National Conference on Weights and Measures for official promulgation in and use by the several 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.

2. 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.

3. Handbook Amendments. - The Committee on Specifications and Tolerances of the National Conference on Weights and Measures provides the mechanism for consideration of amendments to the code provisions. Recommendations as to amendments and suggestions concerning investigations that might lead either to amendments or to new provisions should be directed to the Specifications and Tolerances Committee Technical Advisor, National Conference on Weights and Measures, Gaithersburg, MD 20885.

To be considered by the Committee for action during the upcoming Conference, proposals must be presented in writing to the Committee by November 1 prior to the Interim Meetings (usually the third week of January of each year).

Proposals should contain a concise statement of the problem and clearly outline the purpose and national need for its consideration.

Proposals should be accompanied by adequate background material, including test data, analysis of test data, or other appropriately researched and documented material from which the Committee will be able either to make a suitable judgment for a firm recommendation or to consider the need for further study. When possible, solutions to problems should be proposed and stated in specific language in amendment form to Conference documents.

Weights and measures officials are encouraged to utilize their regional associations for initial exploration of issues and to use the resources of all member States within that regional association to assist in the development of well documented proposals where applicable.

4. 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:

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

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

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

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

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

Sensitivity.  The sensitivity requirements, applicable only to nonautomatic-indicating scales, are performance requirements and are lettered with a T.

UR. User Requirement.  These paragraphs are directed particularly to the owner and operator of a device.  User requirements apply to the selection, installation, use, and maintenance of devices.

D. Definitions of Terms.  A definitions section appears in Appendix D to provide the definition of the terms having a special meaning.

The numerical designation after a letter follows the decimal system of paragraph identification that fixes both the relationship and the limitation of the requirements of the paragraph.  For example, in the Scales Code, under Specifications, the following numerical designations occur:

S.  Specifications

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

S.1.1. Zero Indication.

S.1.1.1. Digital Indicating Elements.

S.1.1.2. No-Load Reference Value.

S.1.2. Value of Scale Division Units.

S.1.2.1. Weight Units

S.1.3. Graduations.

S.1.3.1. Length.

S.1.3.2. Width.

In this example, Paragraphs S.1.1., S.1.2., and S.1.3. are directed and limited to paragraph S.1., which pertains to the design of indicating and recording elements and of recorded representations.  Paragraphs S.1.1.1., and S.1.1.2. are directly related to each other, but are limited to the design of zero indication.  Likewise, paragraphs S.1.3.1. and S.1.3.2. are directly related to each other, but are limited to the design of graduations.

5. Classification of Requirements. - The classification of requirements into "retroactive" and "nonretroactive" status is made in order that the requirements may be put into force and effect without unnecessary hardship and without wholesale condemnation of apparatus. Retroactive requirements are enforceable with respect to all equipment and are printed in upright roman type.  Nonretroactive requirements are those that, while clearly desirable, are not so vital that they should at once be enforced with respect to all apparatus.  Nonretroactive requirements are printed in italic type.

It is not expected that, after their promulgation in a given jurisdiction, nonretroactive requirements will always remain nonretroactive. It is entirely proper that a weights and measures official, following a careful analysis of existing conditions, fix reasonable periods for the continuance of the nonretroactive application of particular requirements, after which such requirements will become retroactive. These periods should be long enough to avoid undue hardship to the owners or operators of apparatus and, in the case of some requirements, should approximate the average useful life of the apparatus in question.

In order that all interested parties may have timely and ample notice of impending changes in the status of requirements, the following procedure is suggested for the official who plans to change the classification of requirements.  If sufficient data are at hand to make such action feasible, publish in combination with the codes themselves the date or dates at which nonretroactive requirements are to become retroactive.  In other cases, give equally effective notice at the earliest practicable date.

A nonretroactive requirement, in italic type, will indicate the year from which it should be enforced and, in some cases, the date the requirement shall be changed to retroactive status.  For example, [Nonretroactive as of 1978 and to become retroactive on January 1, 1985].  As a general rule, each nonretroactive requirement is reviewed after it has been in effect for 10 years to determine the appropriateness of its nonretroactive status.

6. 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.

It is not deemed advisable for a user to attempt to commit to memory tolerances or tolerance tables, even though these are used frequently.  For the Handbook to serve its purpose, it should be at hand when any of its requirements are to be applied.  Direct reference is the only sure way to apply a requirement properly and to check whether other requirements may be applicable.

It is the intention of this Handbook to supply criteria which 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)


National Type Evaluation Program



National Type Approval States





Examination Procedure Outlines

The Examination Procedure Outlines (EPOs) were developed by the Office of Weights and Measures of the National Institute of Standards and Technology (NIST).

Each outline contains: (1) Safety notes and safety key words or phrases; (2) an Inspection section, which covers design, installation, and user requirements that must be met; (3) a Pretest Determination section, which addresses the determination of tolerances and other factors that should be established prior to testing; (4) a Test Notes section, which covers actions to be taken throughout the test or testing information of a general nature; and (5) a Test section, which gives a step-by-step procedure for determining a device's compliance with applicable performance requirements.

All code citations in the EPOs refer to National Institute of Standards and Technology Handbook 44, Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices, 1992 Edition. A citation that begins with the letter "G" refers to the General Code; all others refer to the specific code noted at the beginning requirements.

In using the EPOs, it should be remembered that each outline describes what is considered a minimum examination preceding official action. Many factors influence the nature and extent of an examination. In some cases, such as the first examination of a device after it is placed into commercial service, a more extensive evaluation may be required. Consequently, users of these EPOs should thoroughly familiarize themselves with all of the requirements in Handbook 44.



American Railway Engineering Association

There are 22 working committees in the AREA, each of whom recommend and define engineering practice for a particular aspect of heavy haul railroading. Each committee maintains a manual of specifications as recommended practice. The Committees are:

1. Roadway and Ballast

2. Track Measuring Systems

3. Ties and Wood Preservation

4. Rail

5. Track

6. Building and Support Facilities

7. Timber Structures

8. Concrete Structures

10. Concrete Ties

11. Engineering Records and Property Accounting

12. Rail Transit

14. Yards and Terminals

15. Steel Structures

16. Economics of Plant, Equipment, and Operations

17. High Speed Rail

18. Light Density and Short Line Railways

24. Engineering Education

27. Maintenance of Work Equipment

28. Clearances

33. Electrical Energy Utilization

34. Scales

AREA Committees typically meet twice a year, in the Spring and Fall. Meeting are often enhanced by going on a field trip - one that showcases a new installation or an engineering procedure that is pertinent to that committees' charge. With downsizing of railroads and business in general, oftentimes it is difficult to spend a great deal of time working on subcommittee work during the workday, so many committees have a multiday meeting session; during the course of which, one day is spent in business meeting that includes a summary report of activity since the last committee meeting. As most of you are aware, the Scale Committee has spent the last few years, in a close affiliation with NISA. This relationship has been beneficial to both organizations, and the AREA Board of Direction encourages the symbiotic relationships to the extent that they increase knowledge level and "bring something of value" back to the participating railroads.

Committee 34 - Scales

There are currently 48 members of Committee 34. In breakdown, there are 36 voting members of which 29 are railroaders, with the other 7 being either regulatory in nature or some facet of industry that does not offer for sale weighing devices. There are 12 Associate members in the committee, and indeed the last group, which includes scale manufactures and scale service organizations, is certainly some of the most active and responsive with respect to helping the committee attain its goals.

There are currently 7 working subcommittees in the Scale Committee. Four subcommittees are "Standing" or ongoing teams that maintain the manual and evaluate the direction of the Scale Committee and make recommendations for new subcommittee investigation research projects.

The remaining 3 subcommittees are examples of investigative research projects that the scale committee has underway. Typically these projects should last 18 months or so, and culminate in an informal paper that is published in the AREA Technical Bulletin. Results of the Subcommittee assignments can also be published as "Recommended Practice" for the implementation into the AAR Scale Handbook.

Should you look in the AREA Manual for the work of Committee 34, you will find only one page that will refer you to the Association of American Railroads (AAR) Scale Handbook.



AAR Scale Handbook



Cover of the AAR Scale Handbook





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