**Chapter 3**

**Inspection**

# [Objectives]{.underline}

You will now begin a study of the Inspection portion of an official
examination of vehicle and axle-load scales. After studying this
chapter, you should be able to:

1\. Identify and describe the items of scale design, installation, and
operation that must be checked during the inspection, including:

-   Zero-Load Balance as Found

-   Marking

-   Indicating and Recording Elements

-   Installation

-   Weighing and Load-Receiving Elements

-   Approaches

-   Maintenance, Use, and Environmental Factors

-   Assistance

2\. Describe Handbook 44 requirements relating to these items that are
applicable in field examinations.

3\. Explain the meaning of the following terms:

Certificate of Conformance

damping

direct sale

multiple of a scale

overregistration and underregistration

parallax

performance requirements

primary indicating or recording elements

recorded representation

scale divisions, number of (n)

type

type evaluation

user requirement

These terms are printed in **bold type** when first introduced.

# [General Considerations]{.underline}

This chapter will describe the Inspection portion of an official field
examination of vehicle and axle-load scales, following the organization
of the EPOs (reproduced in their entirety in Appendix B). First,
however, you should be aware of several general considerations, which
may determine how you approach a particular inspection.

Handbook 44 (Scales Code, paragraph S.5.1.) specifies that scales
manufactured after January 1, 1986, that are to be used for commercial
purposes, shall be marked with an accuracy class designation as follows:
I, II, III, III L, or IIII. The accuracy class is designated by the
manufacturer, based upon guidelines established in the Scales Code; the
guidelines are based upon the weighing applications of various scales.
This topic will be covered in greater detail later.

The scales covered by this module, vehicle and axle-load scales, will
fall into accuracy class III L. In this module, and in Handbook 44, you
will find certain criteria that apply to scales marked III L, and
certain criteria for scales [not]{.underline} marked III L. The
references to scales not marked III L apply to scales manufactured
before 1986, which bear no accuracy class marking. It is important to be
alert to this distinction.

In the Inspection portion of the official examination, you will
determine the scale's compliance with specifications and other
requirements pertaining to design, installation, and operation. The
extent and emphasis of your inspection will depend on a number of
factors relating to the specific device being tested and the
circumstances under which it is being tested. Some of the more important
factors are:

-   your familiarity with the device,

-   the age and service history of the device,

-   whether or not the device is of a type that has been type evaluated,
    and

-   whether or not a complaint has been received.

Naturally, your previous experience with the particular device will
impact on the inspection process. If you are checking a device for the
first time, you may want to perform an extensive inspection that
includes a careful check of all applicable requirements in Handbook 44,
including those concerned with design and installation. If you are
checking a device with which you are familiar, one that has been in
service for some time, you may not need to spend much time on design and
installation requirements; however, you will want to look for such
things as fraudulent use or abuse of the equipment, and inappropriate
applications of the device.

The age and service history of the device are important because a number
of requirements in Handbook 44 are nonretroactive as of a certain date.
As a result, you will find that applicable requirements sometimes vary
with the age of the device. Nonretroactive requirements are enforceable
after the effective date for:

-   devices manufactured within a State after the effective date;

-   both new and used devices brought into the State after the effective
    date; and

-   devices that have been used in non-commercial applications and are
    being placed into commercial use after the effective date.

In this module, as in Handbook 44, nonretroactive requirements are
printed in italic type to distinguish them from fully retroactive
requirements, and the effective date is also given. Note that some
nonretroactive requirements become retroactive as of a specified date.
This is also indicated, where applicable.

In most cases, the scales you will be testing will be of a type that has
been evaluated under the National Type Evaluation Program (NTEP). NTEP
is a cooperative program among the National Conference on Weights and
Measures (NCWM), the States, the National Institute of Standards and
Technology (NIST), and representatives of scale manufacturers and users
for determining conformance of a weighing and measuring device
"**type**" or "model" with the relevant provisions of Handbook 44.
Manufacturers voluntarily submit models of their devices for evaluation
under the NTEP program. An NTEP-authorized State or Federal laboratory
conducts the evaluation.

When a device is found to meet all applicable technical requirements,
the NCWM issues a **Certificate of Conformance (CC)** for that device.
In some very limited cases, a provisional Certificate of Conformance may
be issued, making final approval contingent upon specified
modifications. The Certificate provides details of the evaluation
results and device characteristics necessary for use in commerce. Some
States require that new weighing and measuring devices receive a
Certificate of Conformance before they may be placed in commercial
service.

Before testing a new type of device, you should determine if a model of
the device has been type evaluated; and, if it has, you should review
the device's Certificate of Conformance to determine which features have
been evaluated. The NCWM posts all NTEP CCs on its website at
www.ncwm.net to help you determine if a particular device has been
evaluated. CCs are also available from the manufacturer of the weighing
or measuring device. If you are not familiar with NTEP CCs, your
instructor will explain their organization and content to you.

During the **type evaluation** process, extensive tests are performed in
laboratory and/or field settings to determine if a particular device
model meets all applicable requirements in Handbook 44. Some of these
tests are difficult to perform in the field; consequently, the existence
of a Certificate of Conformance can make your job easier --- during a
field inspection, you may not need to extensively examine certain design
criteria on a type evaluated device. But remember that type evaluation
means that [a model]{.underline} of a device has been examined, [not
each device]{.underline}; therefore, you should still review all
applicable requirements when inspecting a new device. The review may
simply consist of a brief visual check of an item.

In addition, it should be kept in mind that many scale system
components, such as load cells, are type evaluated. This may be an
important consideration if replacement parts have been installed: if
your determination regarding the extent of inspection is based upon type
evaluation, you should also consider the type evaluation status of any
replacement parts or modifications. Specific policy regarding
replacement parts is set forth in NCWM Publication 14, "NTEP
Administrative Policy" and in the NTEP Technical Checklists comprising
Publication 14.

Devices are designed with specific applications in mind. Some devices
are designed for a narrow range of applications, whereas others have a
multitude of features to satisfy many different applications. Not all
features are suitable for all applications. A Certificate of Conformance
will state the intended application of a device type, list its
selectable and non-selectable features, and describe the suitability of
the equipment and features for specific applications. (See the section
on **Marking** in this chapter for more information on Certificates of
Conformance.) If you encounter a new or unusual device or feature on a
device in an unusual application, it should be thoroughly tested to
determine its appropriateness and to assure that it does not facilitate
fraud.

Another factor that affects the nature and extent of the Inspection
portion of your examination is the existence of a complaint about a
particular device or the practices of a device owner or operator. You
may want to perform a more extensive inspection than usual if your
office has received complaints about a device or business.

Because of the above factors and others, it was difficult to select one
inspection approach to teach in this module. The approach taken has been
to assume that a routine inspection is being carried out on a device for
which a Certificate of Conformance has been issued.

EPO No. 13 and EPO No. 13‑E list major items to check during the
Inspection. The sequence in which these items are checked is not
critical. For the purposes of this module, we will discuss each item in
the order it is listed in the EPO. Your instructor will tell you if your
jurisdiction follows a different sequence.

# [Zero-Load Balance As Found]{.underline}

The first item to be inspected is the condition of zero-load balance of
a scale, that is, the balance condition with no load on the deck.
Handbook 44 requires that all scales be designed with a means to
indicate a zero-balance condition, and that automatic-indicating scales
have a means to indicate an out-of-balance condition that is either
above or below zero balance. In addition, scales must have a means of
adjusting the zero-load balance so that the scale is balanced and
indicates this condition when there is no load applied.

To inspect the scale for compliance, all load-counterbalance elements of
the scale, such as poises or unit weights, should be set to zero, and
the scale should indicate a zero balance condition.

If a scale is in an out-of-zero balance condition, you should ask the
operator to zero the scale. If the operator does not know how to zero
the scale, the owner (manager) should be requested to do so. Possible
reasons for the out-of-balance condition are:

-   the operator has not used the scale that day,

-   debris has accumulated on the scale,

-   the operator may not know how to balance the scale, tare was taken
    on the last weighing and not removed, or

-   carelessness.

+-----------------------------------------------------------------------+
| **S.1.1. Zero Indication.**                                           |
|                                                                       |
| \(a\) On a scale equipped with indicating or recording elements,      |
| provision shall be made to either indicate or record a zero-balance   |
| condition.                                                            |
|                                                                       |
| \(b\) On an automatic-indicating scale or balance indicator,          |
| provision shall be made to indicate or record an out of-balance       |
| condition on both sides of zero.                                      |
|                                                                       |
| \(c\) A zero-balance condition may be indicated by other than a       |
| continuous digital zero indication, provided that an effective        |
| automatic means is provided to inhibit a weighing operation or to     |
| return to a continuous digital indication when the scale is in an     |
| out-of-balance condition.                                             |
|                                                                       |
| (Added 1987)                                                          |
|                                                                       |
| (Amended 1987 and 1993)                                               |
|                                                                       |
| **S.2.1.1. General.** - A scale shall be equipped with means by which |
| the zero-load balance may be adjusted. Any loose material used for    |
| this purpose shall be enclosed so that it cannot shift in position    |
| and alter the balance condition of the scale.                         |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraphs S.1.1. and S.2.1.1.**     |
+-----------------------------------------------------------------------+

In accordance with the Scales Code (paragraph UR.4.1.), it is the
owner's responsibility to be sure that the scale is set at zero at all
times during use.

  -----------------------------------------------------------------------
  **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.

  **NIST Handbook 44, Scales Code, Paragraph U.R.4.1.**
  -----------------------------------------------------------------------

An out-of-balance condition should be noted on the report issued to the
owner (manager) in order that a history can be maintained. If an
out-of-balance condition is found regularly, it may be necessary to
resort to other enforcement action (a "warning letter," scale
condemnation, or, in extreme cases, prosecution) to convince the
operator or owner that it is his or her responsibility to maintain the
scale in zero balance.

Scales used in **direct sales** that have manual zero-setting
mechanisms, such as balance balls, must be so designed that the
mechanism is either enclosed in a cabinet or only operable by a separate
tool, such as a screwdriver. This requirement is intended to prevent
fraud by making it difficult for the owner or operator to move the scale
ahead of zero when making a weighing and then return the scale to zero
as the load is removed from the deck. Requiring the use of a tool, for
example, makes a zero adjustment obvious, and the excuse of an
accidental action is eliminated.

+-----------------------------------------------------------------------+
| **S.2.1.2. Scales used in Direct Sales. -** A manual zero setting     |
| mechanism (except on a digital scale with an analog zero adjustment   |
| mechanism with a range of not greater than one scale division) shall  |
| be operable or accessible only by a tool outside of and entirely      |
| separate from this mechanism, or it shall be enclosed in a cabinet.   |
| Except on Class I or II scales, a balance ball shall either meet this |
| requirement or not itself be rotatable.                               |
|                                                                       |
| A semiautomatic zero setting mechanism shall be operable or           |
| accessible only by a tool outside of and separate from this mechanism |
| or it shall be enclosed in a cabinet, or it shall be operable only    |
| when the indication is stable within:                                 |
|                                                                       |
| \(a\) plus or minus 3 scale divisions for scales of more than 2000 kg |
| (5000 lb) capacity in service prior to January 1, 1981, and for all   |
| axle load, railway track, and vehicle scales; or                      |
|                                                                       |
| \(b\) plus or minus 1 scale division for all other scales.            |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.2.1.2.**                 |
+-----------------------------------------------------------------------+

If the scale is equipped with a semi-automatic zero-setting mechanism
(push-button zero), it will be tested to determine if it operates only
when the indication is stable within plus or minus 3 scale divisions.
Details for performing this test will be covered in Chapter 6. A
semi-automatic zero-setting mechanism that resets the scale to zero when
the scale is not stable to within 3 scale divisions must meet the same
requirements as a manual zero-setting mechanism: it must be enclosed in
a cabinet or be operable or accessible only by means of a tool.

Many vehicle and axle-load scales with a weighbeam have a balance ball.
The balance ball is usually pinned so that it cannot rotate, but can
only move back and forth on a screw, which must be turned with a
screwdriver. This meets the requirements of S.2.1.2.

Electronic scales not intended to be used in direct sales applications
may be equipped with a combined zero/tare function key, provided that
the device is marked as described in Handbook 44 Scales Code paragraph
S.2.1.6.

+-----------------------------------------------------------------------+
| **S.2.1.6. Combined Zero-Tare (**\"**0/T**\"**) Key. -** Scales not   |
| intended to be used in direct sales applications may be equipped with |
| a combined zero and tare function key, provided that the device is    |
| clearly marked as to how the key functions. The device must also be   |
| clearly marked on or adjacent to the weight display with the          |
| statement "Not for Direct Sales."                                     |
|                                                                       |
| (Added 1998)                                                          |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.2.1.6.**                 |
+-----------------------------------------------------------------------+

**Weighbeam Scales**

The weighbeam of a scale must be in a horizontal position when the
balance condition is indicated. This assures that the indicator will
have equal distance for oscillation around the zero point.

  -----------------------------------------------------------------------
  **S.1.5.1. Normal Balance Position. -** The normal balance position of
  the weighbeam of a beam scale shall be horizontal.

  **NIST Handbook 44, Scales Code, Paragraph S.1.5.1**.
  -----------------------------------------------------------------------

On a beam scale with trig loop, a balance condition must be in the
center of the trig loop. On a beam scale with a balance indicator, a
balance condition is indicated by the tip of the indicator pointing to
the zero position.

**Dial Scales**

A dial scale is in zero-load balance when the indicator points to the
zero graduation, the line or marking associated with the numeral "zero"
on the dial. Any other position would indicate that the scale is out of
balance at zero load. If the scale has a printer, it must print "zero"
with no load on the platform, and it must be in agreement with any other
indicator. A dial indicator may have a screw adjustment for zero that
requires using a screwdriver or similar tool. This arrangement, too,
meets Handbook 44 requirements.

**Electronic Digital Indicating Scales**

You will find a variety of mechanisms used to zero vehicle and axle-load
scales with electronic digital indicators. On some scales, you will find
a knob that is turned to zero the scale (the knob must be enclosed to
satisfy S.2.1.2.). On other scales, a similar device is operated with a
screwdriver. A push-button may perform the same function. Because of the
"rounding" involved in generating digital signals, described in Chapter
1, the zero-balance indication of an electronic digital indicator can
represent a condition that is out of balance by as much as plus or minus
one-half of a scale division. Handbook 44 permits uncertainty only to
that degree. Some digital indicators are equipped with a "center of
zero" feature that provides greater sensitivity for the zero-balance
indication. For these devices, the uncertainty is limited to one-quarter
of a scale division. In addition, a digital indicating device must
either automatically maintain a center of zero condition to +/- ¼ scale
division or less or have an auxiliary or supplemental center-of-zero
indication as specified in paragraph S.1.1.1.

+-----------------------------------------------------------------------+
| **S.1.1.1. Digital Indicating Elements.**                             |
|                                                                       |
| \(a\) A digital zero indication shall represent a balance condition   |
| that is within ±½ the value of the scale division.                    |
|                                                                       |
| \(b\) A digital indicating device shall either automatically maintain |
| a \"center-of-zero\" condition to ±¼ scale *division or less, or have |
| an auxiliary or supplemental \"center-of-zero\" indicator that        |
| defines a zero‑balance condition to ±¼ of a scale division or less.*  |
|                                                                       |
| *\[Nonretroactive as of January 1, 1993\]*                            |
|                                                                       |
| (Amended 1992)                                                        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.1.1.1.**                 |
+-----------------------------------------------------------------------+

In addition, the scale indicator may have an electronic circuit, called
an **automatic zero-setting mechanism** (**AZSM**), that automatically
zeroes the scale under certain conditions. A special requirement applies
to this type of device.

+-----------------------------------------------------------------------+
| ***S.2.1.3. Scales Equipped with an Automatic Zero-Setting Mechanism. |
| ---** 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:*                                                      |
|                                                                       |
| *\* \* \**                                                            |
|                                                                       |
| *(b) For vehicle, axle-load, and railway track scales: 3.0 scale      |
| divisions.*                                                           |
|                                                                       |
| *\[Nonretroactive and enforceable as of January 1, 1981.\]*           |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.2.1.3.**                 |
+-----------------------------------------------------------------------+

If the scale has an AZSM, the mechanism must not rezero the scale if a
load of more than 3 scale divisions is placed on or removed from the
deck. The procedure for testing this feature will be described in
Chapter 6.

Finally, the General Code includes a requirement in paragraph
G-S.5.2.2.(d) that is intended to assure that a digital zero-load
indication is unambiguous. This requirement also applies to recorded
representations.

+-----------------------------------------------------------------------+
| **G-S.5.2.2.** **Digital Indication and Representation.** --- Digital |
| elements shall be so designed that:                                   |
|                                                                       |
| *(d) A digital zero indication includes the display of a zero for all |
| places that are displayed to the right of the decimal point and at    |
| least one place to the left. When no decimal values are displayed, a  |
| zero shall be displayed for each place of the displayed scale         |
| division. \[Nonretroactive as of January 1, 1986.\]*                  |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-S.5.2.2. (d)**          |
+-----------------------------------------------------------------------+

Vehicle and axle-load scales with electronic digital indicators
generally have scale divisions of no less than 10 lb and no more than 50
lb. Therefore, a digital indicator that displays in terms of pounds must
show zeroes for at least the first two digits at the right of the
display (one for each place of the displayed scale division), as
illustrated by the upper drawing in Figure 3-1. On the other hand, a
vehicle or axle-load scale with a scale division value of 0.01 ton would
require a zero indication of at least two zeroes to the right of the
decimal point plus one zero to the left, as shown in the lower drawing
in Figure 3-1.

  -----------------------------------------------------------------------
  ![](media/image1.png){width="3.838888888888889in"
  height="3.8881944444444443in"}

  **Figure 3-1. Digital Zero Indication**
  -----------------------------------------------------------------------

# [Marking]{.underline}

Basic information that identifies a weighing device is often needed by
device users, service personnel, and weights and measures officials for
maintenance, adjustment, and testing purposes. This basic information
includes items relating to the origin, type, capacities, application,
limitations, and special features or parameters of the device. Handbook
44 requires that specific information be permanently marked on devices,
so that it is available when needed.

Many scale systems, including vehicle and axle-load scales, consist of
several components, which may have been manufactured at different times
or even by different manufacturers, and which may also be physically
separate. To the degree that these components are distinct, Handbook 44
requires that they be marked separately with relevant identifying
information. Five distinct "categories" are identified in the Scales
Code:

-   weighing, load-receiving, and indicating element in the same housing
    or covered on the same CC -- applies to systems in which the
    weighing and indicating elements are housed within a single
    enclosure. Since the weighing elements of vehicle and axle-load
    scales are separate from the indicating element, this category is
    not applicable.

-   indicating element not permanently attached to weighing and
    load-receiving element or covered by a separate CC -- applies to
    indicating elements that are not permanently attached to a weighing
    element. For vehicle and axle-load scales, this could be a
    weighbeam, dial, or electronic digital indicator.

-   weighing and load receiving element not permanently attached to
    indicating element or covered by a separate CC -- applies to
    combined weighing and load-receiving elements that are not
    permanently attached to an indicating element. Vehicle and axle-load
    scales fall into this category.

-   load cell with CC -- applies to load cells which have been evaluated
    and received a Certificate of Conformance (CC) under NTEP after the
    Nonretroactive dates noted in Table S.6.3.b.

-   other equipment or device -- applies to equipment that is necessary
    to the weighing system but having no metrological effect, e.g.,
    auxiliary remote display, keyboard, etc.

The components and items of information that must be marked upon them
are specified in paragraphs G‑S.1. of the General Code and S.6.3. of the
Scales Code. Tables S.6.3.a. and S.6.3.b summarize all requirements by
component. These tables have been reproduced at the end of this chapter.
Refer to them as you read the following description of marking
requirements.

In summary, each individual component of a vehicle or axle-load scale
included in one of these five categories of Table S.6.3.a. must be
marked with the items listed for that category. Thus, a system must have
[separate]{.underline} markings on the indicating element and the
load-receiving/weighing elements, and on other equipment or devices and
load cells with CCs if so equipped. The specific items of information
that must be marked are described below, under the respective
categories.

One other important general consideration relating to the inspection of
required markings is that many of the requirements are nonretroactive,
and have different effective dates. This can be confusing. However, note
that Table S.6.3.b gives the effective dates; the EPOs also show the
effective date for each requirement.

+-----------------------------------------------------------------------+
| **S.6.3. Scales, Main Elements, and Components of Scales or Weighing  |
| Systems.** - Scales, main elements of scales when not contained in a  |
| single enclosure for the entire scale, load cells for which           |
| Certificates of Conformance (CC) have been issued under the National  |
| Type Evaluation Program, and other equipment necessary to a weighing  |
| system, but having no metrological effect on the weighing system,     |
| shall be marked as specified in Table S.6.3.a. and explained in the   |
| accompanying notes (Table S.6.3.b.)                                   |
|                                                                       |
| (Added 1990)                                                          |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.6.3.**                   |
+-----------------------------------------------------------------------+

+---------------------+---------+------------+-----------+----+------+
| **Table S.6.3.a.**  |         |            |           |    |      |
|                     |         |            |           |    |      |
| **Marking           |         |            |           |    |      |
| Requirements**      |         |            |           |    |      |
+=====================+=========+============+===========+====+======+
| To Be Marked With   | W       |            |           |    |      |
|                     | eighing |            |           |    |      |
|                     | Eq      |            |           |    |      |
|                     | uipment |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
|                     | We      | Indicating | Weighing  | Lo | O    |
|                     | ighing, | element    | and       | ad | ther |
|                     | l       | not        | load-     | ce | e    |
|                     | oad-rec | p          | receiving | ll | quip |
|                     | eiving, | ermanently | element   | wi | ­ment |
|                     | and     | attached   | not       | th | or   |
|                     | ind     | to         | pe        | CC | de   |
|                     | icating | weighing   | rmanent­ly |    | ­vice |
|                     | element | and        | attached  | \( |      |
|                     | in same | load       | to        | 11 | \(   |
|                     | housing | -receiving | i         | \) | 10\) |
|                     | or      | element or | ndicating |    |      |
|                     | covered | covered by | element   |    |      |
|                     | on the  | a separate | or        |    |      |
|                     | same    | CC         | covered   |    |      |
|                     | CC^1^   |            | by a      |    |      |
|                     |         |            | separate  |    |      |
|                     |         |            | CC        |    |      |
+---------------------+---------+------------+-----------+----+------+
| Manufacturer\'s ID  | x       | x          | x         | x  | x    |
| (1)                 |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Model Designation   | x       | x          | x         | x  | x    |
| and Prefix (1)      |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Serial Number and   | x       | x          | x         | x  | x    |
| Prefix (2)          |         |            |           |    | (16) |
+---------------------+---------+------------+-----------+----+------+
| Certificate of      | x       | x          | x         | x  | x    |
| Conformance Number  |         |            |           |    | (23) |
| (CC) (23)           |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Accuracy Class (17) | x       | x (8)      | x (19)    | x  |      |
+---------------------+---------+------------+-----------+----+------+
| Nominal Capacity    | x       | x          | x         |    |      |
| (3)(18)(20)         |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Value of Scale      | x       | x          |           |    |      |
| Division, \"d\" (3) |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Value of \"e\" (4)  | x       | x          |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Temperature Limits  | x       | x          | x         | x  |      |
| (5)                 |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Concentrated Load   |         | x          | x (9)     |    |      |
| Capacity (CLC)      |         |            |           |    |      |
| (12)(20)(22)        |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Special Application | x       | x          | x         |    |      |
| (13)                |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Maximum Number of   |         | x (8)      | x (19)    | x  |      |
| Scale Divisions     |         |            |           |    |      |
| (n~max~) (6)        |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Minimum             |         |            | x (19)    |    |      |
| Verification Scale  |         |            |           |    |      |
| Division (e~min~)   |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| \"S\" or \"M\" (7)  |         |            |           | x  |      |
+---------------------+---------+------------+-----------+----+------+
| Direction of        |         |            |           | x  |      |
| Loading (15)        |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Minimum Dead Load   |         |            |           | x  |      |
+---------------------+---------+------------+-----------+----+------+
| Maximum Capacity    |         |            |           | x  |      |
+---------------------+---------+------------+-----------+----+------+
| Safe Load Limit     |         |            |           | x  |      |
+---------------------+---------+------------+-----------+----+------+
| Load Cell           |         |            |           | x  |      |
| Verification        |         |            |           |    |      |
| Inter­val            |         |            |           |    |      |
|                     |         |            |           |    |      |
| (v~min~) (21)       |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| Section Capacity    |         | x          | x         |    |      |
| (14)(20)(22)        |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| **Note:** For       |         |            |           |    |      |
| applicable notes,   |         |            |           |    |      |
| see Table S.6.3.b.  |         |            |           |    |      |
|                     |         |            |           |    |      |
| ^1^Weighing/load    |         |            |           |    |      |
| receiving elements  |         |            |           |    |      |
| and indicators      |         |            |           |    |      |
| which are in the    |         |            |           |    |      |
| same housing or     |         |            |           |    |      |
| which are           |         |            |           |    |      |
| permanently         |         |            |           |    |      |
| attached will       |         |            |           |    |      |
| generally appear on |         |            |           |    |      |
| the same CC. If not |         |            |           |    |      |
| in the same         |         |            |           |    |      |
| housing, elements   |         |            |           |    |      |
| shall be hard wired |         |            |           |    |      |
| together or sealed  |         |            |           |    |      |
| with a physical     |         |            |           |    |      |
| seal or an          |         |            |           |    |      |
| electronic link.    |         |            |           |    |      |
| This requirement    |         |            |           |    |      |
| does not apply to   |         |            |           |    |      |
| peripheral          |         |            |           |    |      |
| equipment that has  |         |            |           |    |      |
| no input or effect  |         |            |           |    |      |
| on device           |         |            |           |    |      |
| calibrations or     |         |            |           |    |      |
| configurations.     |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+
| (Added 1990)        |         |            |           |    |      |
| (Amended 1992,      |         |            |           |    |      |
| 1999, 2000, 2001    |         |            |           |    |      |
| and 2002) (Footnote |         |            |           |    |      |
| 1 Added 2001)       |         |            |           |    |      |
+---------------------+---------+------------+-----------+----+------+

+-----------------------------------------------------------------------+
| **Table S.6.3.b., Notes For Table S.6.3.a.**                          |
+=======================================================================+
| 1.  Manufacturer\'s identification and model designation and *model   |
|     designation prefix\**.                                            |
|                                                                       |
| \**\[Nonretroactive as of January 1, 2003*\]                          |
|                                                                       |
| > (See also G-S.1.) *\[Prefix lettering may be initial capitals, all  |
| > capitals or all lower case\]*                                       |
|                                                                       |
| (Amended 2000)                                                        |
|                                                                       |
| 2.  *Serial number \[Nonretroactive as of January 1, 1968\] and       |
|     prefix \[Nonretroactive as of January 1, 1986\].* (See also       |
|     G-S.1.)                                                           |
|                                                                       |
| 3.  The nominal capacity *and value of the scale division shall be    |
|     shown together (e.g., 50 000 x 5 kg, 100 000 x 10 lb, 15 x 0.005  |
|     kg , or 30 x 0.01 lb) adjacent to the weight display when the     |
|     nominal capacity and value of the scale division are not          |
|     immediately apparent. Each scale division value or weight unit    |
|     shall be marked on multiple range or multi‑interval scales.       |
|     \[Nonretroactive as of January 1, 1983\]*                         |
|                                                                       |
| 4.  *Required only if different from \"d.\" \[Nonretroactive as of    |
|     January 1, 1986\]*                                                |
|                                                                       |
| 5.  *Required only on Class III, III L, and IIII devices if the       |
|     temperature range on the NTEP CC is narrower than and within      |
|     ‑10 C to 40 C (14 F to 104 F). \[Nonretroactive as of January 1,  |
|     1986\]*                                                           |
|                                                                       |
| 6.  *This value may be stated on load cells in units of 1000; e.g.,   |
|     n: 10 is 10 000 divisions. \[Nonretroactive as of                 |
|     January 1, 1988\]*                                                |
|                                                                       |
| 7.  *Denotes compliance for single or multiple load cell              |
|     applications. It is acceptable to use a load cell with the "S" or |
|     Single Cell designation in multiple load cell applications as     |
|     long as all other parameters meet applicable requirements. A load |
|     cell with the "M" or Multiple Cell designation can be used only   |
|     in multiple load cell applications.\[Nonretroactive as of January |
|     1, 1988\]*                                                        |
|                                                                       |
| > (Amended 1999)                                                      |
|                                                                       |
| 8.  *An indicating element not permanently attached to a weighing     |
|     element shall be clearly and permanently marked with the accuracy |
|     Class of I, II, III, III L, or IIII, as appropriate, and the      |
|     maximum number of scale divisions, n~max~ , for which the         |
|     indicator complies with the applicable requirement. Indicating    |
|     elements that qualify for use in both Class III and III L         |
|     applications may be marked III/III L and shall be marked with the |
|     maximum number of scale divisions for which the device complies   |
|     with the applicable requirements for each accuracy class.         |
|     \[Nonretroactive as of January 1, 1988\]*                         |
|                                                                       |
| 9.  *For vehicle and axle-load scales only. The CLC shall be added to |
|     the load-receiving element of any such scale not previously       |
|     marked at the time of modification. \[Nonretroactive as of        |
|     January 1, 1989\]*                                                |
|                                                                       |
| (Amended 2002)                                                        |
|                                                                       |
| 10. Necessary to the weighing system but having no metrological       |
|     effect, e.g., auxiliary remote display, keyboard, etc.            |
|                                                                       |
| 11. *The markings may be either on the load cell or in an             |
|     accompanying document; except that, if an accompanying document   |
|     is provided, the serial number shall appear both on the load cell |
|     and in the document. \[Nonretroactive as of January 1, 1988\] The |
|     manufacturer\'s name or trademark, the model designation, and     |
|     identifying symbols for the model and serial numbers as required  |
|     by paragraph G.-S.1. shall also be marked both on the load cell   |
|     and in any accompanying document. \[Nonretroactive as of January  |
|     1, 1991\]*                                                        |
|                                                                       |
| 12. Required on the indicating element *and the load-receiving        |
|     element* of vehicle and axle-load scales. *Such marking shall be  |
|     identified as \"concentrated load capacity\" or by the            |
|     abbreviation \"CLC.\"\**                                          |
|                                                                       |
| *\[\*Nonretroactive as of January 1, 1989\]*                          |
|                                                                       |
| (Amended 2002)                                                        |
|                                                                       |
| 13. *A scale designed for a special application rather than general   |
|     use shall be conspicuously marked with suitable words visible to  |
|     the operator and customer restricting its use to that             |
|     application, e.g., postal scale, prepack scale, weight            |
|     classifier, etc.\** *When a scale is installed with an            |
|     operational counting feature, the scale shall be marked on both   |
|     the operator and customer side with the statement \"The counting  |
|     feature is not legal for trade.\"* *\[\*Nonretroactive as of      |
|     January 1, 1986\]*                                                |
|                                                                       |
| (Amended 1994)                                                        |
|                                                                       |
| 14. *Required on livestock\* and railway track scales. When marked on |
|     vehicle and axle‑load scales manufactured before January 1, 1989, |
|     it may be used as the CLC. For livestock scales manufactured      |
|     between January 1, 1989 and January 1, 2003, required markings    |
|     may be either CLC or section capacity. \[\*Nonretroactive as of   |
|     January 1, 2003.*                                                 |
|                                                                       |
| (Amended 2002)                                                        |
|                                                                       |
| 15. *Required if the direction of loading the load cell is not        |
|     obvious. \[Nonretroactive as of January 1, 1988\]*                |
|                                                                       |
| 16. *Serial number \[Nonretroactive as of January 1, 1968\] and       |
|     prefix \[Nonretroactive as of January 1, 1986\].* (See also       |
|     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.                                                   |
|                                                                       |
| 17. *The accuracy Class of a device shall be marked on the device     |
|     with the appropriate designation as I, II, III, III L, or IIII.   |
|     \[Nonretroactive as of January 1, 1986\]*                         |
|                                                                       |
| 18. The nominal capacity shall be conspicuously marked as follows:    |
|                                                                       |
|     a.  on any scale equipped with unit weights or weight ranges;     |
|                                                                       |
|     b.  on any scale with which counterpoise or equal-arm weights are |
|         intended to be used;                                          |
|                                                                       |
|     c.  on any automatic-indicating or recording scale so constructed |
|         that the capacity of the indicating or recording element, or  |
|         elements, is not immediately apparent;                        |
|                                                                       |
|     d.  on any scale with a nominal capacity less than the sum of the |
|         reading elements; and                                         |
|                                                                       |
|     e.  *on the load-receiving element (weigh-bridge) of vehicle,     |
|         axle-load, and livestock scales.\**                           |
|                                                                       |
| *\[\*Nonretroactive as of January 1, 1989\]*                          |
|                                                                       |
| (Amended 1992)                                                        |
|                                                                       |
| 19. *\[Nonretroactive as of January, 1, 1988\]* (Amended 1992)        |
|                                                                       |
| 20. *Combination vehicle/railway track scales must be marked with     |
|     both the nominal capacity and CLC for vehicle weighing and the    |
|     nominal capacity and section capacity for railway weighing. All   |
|     other requirements relating to these markings will apply.         |
|     \[Nonretroactive as of January 1, 2000\]*                         |
|                                                                       |
| (Added 1999)                                                          |
|                                                                       |
| 21. The value of the load cell verification interval (v~min~) must be |
|     stated in mass units. In addition to this information, a device   |
|     may be marked with supplemental representations of v~min~.        |
|     *\[Nonretroactive as of January 1, 2001\]*                        |
|                                                                       |
| (Added 1999)                                                          |
|                                                                       |
| 22. *Combination vehicle/livestock scales must be marked with both    |
|     the CLC for vehicle weighing and the section capacity for         |
|     livestock weighing. All other requirements relative to these      |
|     markings will apply.*                                             |
|                                                                       |
| *\[Nonretroactive as of January 1, 2003\]*                            |
|                                                                       |
| (Added 2002)                                                          |
|                                                                       |
| 23. *Required only if a CC has been issued for the device or          |
|     equipment.*                                                       |
|                                                                       |
| *\[Nonretroactive as of January 1, 2003\]*                            |
|                                                                       |
| (G-S.1. Identification (f) Added 2001)                                |
+-----------------------------------------------------------------------+

**Basic Identification Information**

Paragraph G-S.1. of the General Code requires that all devices be marked
to identify the manufacturer or distributor. In addition, devices
manufactured or placed in service for the first time within the State
after January 1, 1968, must have a nonrepetitive serial number, which
identifies a device uniquely.

+-----------------------------------------------------------------------+
| **G-S.1. Identification.** - All equipment, except weights and        |
| separate parts necessary to the measurement process but not having    |
| any metrological effect, shall be clearly and permanently marked for  |
| the purposes of identification with the following information:        |
|                                                                       |
| > \(a\) the name, initials, or trademark of the manufacturer or       |
| > distributor;                                                        |
| >                                                                     |
| > \(b\) a model designation that positively identifies the pattern or |
| > design of the device;                                               |
| >                                                                     |
| > \(c\) *the model designation shall be prefaced by the term          |
| > \"Model,\" \"Type,\" or \"Pattern.\" These terms may be followed by |
| > the term \"Number\" or an abbreviation of that word. The            |
| > abbreviation for the word \"Number\" shall, as a minimum, begin     |
| > with the letter \"N\" (e.g., No or No.). The abbreviation for the   |
| > word "Model" shall be "Mod" or "Mod."*                              |
| >                                                                     |
| > *\[Nonretroactive January 1, 2003\]*                                |
| >                                                                     |
| > (Added 2000) (Amended 2001)                                         |
| >                                                                     |
| > *\[Note: Prefix lettering may be initial capitals, all capitals or  |
| > all lower case.\]*                                                  |
| >                                                                     |
| > *(d) except for equipment with no moving or electronic component    |
| > parts and not built-for-purpose, software-based devices, a          |
| > nonrepetitive serial number;*                                       |
| >                                                                     |
| > *\[Nonretroactive as of January 1, 1968\]*                          |
|                                                                       |
| (e) *for not built-for-purpose, software-based devices the current    |
|     software designation;*                                            |
|                                                                       |
| (f) *the serial number shall be prefaced by words, an abbreviation,   |
|     or a symbol, that clearly identifies the number as the required   |
|     serial number; and*                                               |
|                                                                       |
| *\[Nonretroactive as of January 1, 1986\]*                            |
|                                                                       |
| (g) *the serial number shall be prefaced by the words \"Serial        |
|     Number\" or an abbreviation of that term. Abbreviations for the   |
|     word \"Serial\" shall, as a minimum, begin with the letter \"S,\" |
|     and abbreviations for the word \"Number\" shall, as a minimum,    |
|     begin with the letter \"N\" (e.g., S/N, SN, Ser. No, and S No.).* |
|                                                                       |
| > *\[Nonretroactive as of January 1, 2001\]*                          |
|                                                                       |
| (h) *For devices that have an NTEP Certificate of Conformance (CC)    |
|     Number or a corresponding CC addendum number, the NTEP CC shall   |
|     be prefaced by the terms \"NTEP CC,\" \"CC,\" or \"Approval.\"    |
|     These terms may be followed by the term \"Number\" or an          |
|     abbreviation of that word. The abbreviation for the word          |
|     \"Number\" shall, as a minimum, begin with the letter \"N\"       |
|     (e.g., No or No.)*                                                |
|                                                                       |
| > *\[Nonretroactive as of January 1, 2003\]*                          |
|                                                                       |
| The required information shall be so located that it is readily       |
| observable without the necessity of the disassembly of a part         |
| requiring the use of any means separate from the device.              |
|                                                                       |
| (Amended 1985, 1991, 1999,2000, and 2003)                             |
|                                                                       |
| **G-UR.2.1.1. Visibility of Identification.** --- Equipment shall be  |
| installed in such a manner that all required markings are readily     |
| observable.                                                           |
|                                                                       |
| Added 1978                                                            |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraphs G-S.1. and G-UR.2.1.1.** |
+-----------------------------------------------------------------------+

According to G-S.1., the required markings must be observable without
disassembly that requires a tool. This requirement is intended to insure
that they are readily accessible. This requirement is supported by
another paragraph in the General Code (G-UR.2.1.1.), which states that
devices must be installed in such a way that required markings are
readily observable. However, the Scales Code contains an exception to
these requirements for some scales, including most vehicle and axle-load
scales. See the discussion of paragraph 3.6.2. below for more
information.

The information specified in G-S.1. must appear on the components or
groups of components shown in Table S.6.3.a, except that auxiliary
devices that do not have intelligence --- that is, do not have
processing capability --- and have no metrological effect, such as a
secondary weight display, and not built-for purpose, software-based
devices are not required to have a marked serial number. This is set
forth in Item 16 in Table S.6.3.b., and, in the case of not built for
purpose devices, in G-S.1.1. (see below). In addition, note that Item 11
states that required information for load cells may be presented in an
accompanying document, except that the information specified in G-S.1.
must be marked [both]{.underline} on the load cell and in the
accompanying document.

**Not Built-For-Purpose Devices, Software-Based**

Electronic vehicle scale weighing systems are generally comprised of a
weighing/load receiving element interfaced with an electronic indicator.
Many systems today use, in place of an electronic indicator dedicated to
and designed specifically for weighing operations, a computer system
with a CRT display. These systems typically use generic, "off the shelf"
computer hardware (central processing unit, computer display, and other
peripheral equipment) along with software that is specifically developed
for use in weighing applications.

NIST Handbook 44 General Code paragraph G-S.1.1. applies to these types
of software-based devices that were not built solely for use either as a
stand-alone weighing system or as an accessory to a weighing or
measuring system. These are referred to as "not built-for-purpose,
software-based" devices, and a definition for these devices appears in
Appendix D of Handbook 44.

[]{.mark}

Paragraph G-S.1.1. defines how the information required by G-S.1. is to
be marked or displayed by the system. Options are provided for marking
certain G-S.1. information on the device or displaying the information
either continuously or through a "help" menu on the device. Some G-S.1.
information such as the manufacturer or distributor and the model
designation must be continuously displayed or marked on the device.

For software-based systems, the functionality of the system and its
compliance with the performance and operational requirements of Handbook
44 are controlled by the software used in the system. In these systems,
a serial number is not relevant to positively identifying the device and
its capability to function as a weighing device under Handbook 44.
Consequently, a serial number is not required on "not built-for-purpose,
software-based devices." Instead, the manufacturer of the software must
display on the screen, the version of software used in the system. This
information can be used by the inspector to clearly identify the
manufacturer that is responsible for the weighing operation and
functionality of the system. The requirement for marking or displaying
the software designation also provides an effective way to determine if
a computer system is using a specific version of software that has been
evaluated as part of an NTEP evaluation.

Note that the manufacturer of the computer hardware (central processing
unit, computer display screen, and other peripheral equipment) may also
mark the hardware with identification and serial number information.

+-----------------------------------------------------------------------+
| ***G-S.1.1. Not Built--For--Purpose Devices, Software-Based. -** For  |
| not built--for--purpose, software based devices, the following shall  |
| apply:*                                                               |
|                                                                       |
| *(a) the manufacturer or distributor and the model designation shall  |
| be continuously displayed or marked on the device (see note below),   |
| or*                                                                   |
|                                                                       |
| > *(b) the Certificate of Conformance (CC) Number shall be            |
| > continuously displayed or marked on the device (see note below),    |
| > or*                                                                 |
| >                                                                     |
| > *(c) all required information in G-S.1. Identification. (a), (b),   |
| > (c), (e), and (h) shall be continuously displayed. Alternatively, a |
| > clearly identified view only System Identification, G-S.1.          |
| > Identification, or Weights and Measures Identification shall be     |
| > accessible through the "Help" menu. Required information includes   |
| > that information necessary to identify that the software in the     |
| > device is the same type that was evaluated.*                        |
| >                                                                     |
| > *Note: Clear instructions for accessing the remaining required      |
| > G-S.1. information shall be listed on the CC. Required information  |
| > includes that information necessary to identify that the software   |
| > in the device is the same type that was evaluated.*                 |
|                                                                       |
| *\[Nonretroactive as of January 1, 2004\]*                            |
|                                                                       |
| \[Added 2003\]                                                        |
|                                                                       |
| > Definition, Handbook 44 Appendix D:                                 |
|                                                                       |
| **built-for-purpose device.** Any main device or element which was    |
| manufactured with the intent that it be used as, or part of, a        |
| weighing or measuring device or system.                               |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.6.3.**                   |
+-----------------------------------------------------------------------+

# Remanufactured Devices

In addition to the information specified in G-S.1., remanufactured
devices and remanufactured main elements must be clearly and permanently
marked with certain identification information regarding the
remanufacturer or the distributor of the equipment. These requirements
are outlined in General Code Paragraph G-S.1.2. Definitions for
terminology used in conjunction with remanufactured equipment can be
found in Appendix D of NIST Handbook 44.

+-----------------------------------------------------------------------+
| **G‑S.1.2. Remanufactured Devices and Remanufactured Main Elements.   |
| ‑** All remanufactured devices and remanufactured main elements shall |
| be clearly and permanently marked for the purposes of identification  |
| with the following information:                                       |
|                                                                       |
| *(a) the name, initials, or trademark of the last remanufacturer or   |
| distributor;*                                                         |
|                                                                       |
| > *(b) the remanufacturer\'s or distributor\'s model designation if   |
| > different than the original model designation.*                     |
|                                                                       |
| *\[Nonretroactive as of January 1, 2002\]*                            |
|                                                                       |
| (Added 2001)                                                          |
|                                                                       |
| **Note:** Definitions for "manufactured device," "repaired device,"   |
| and "repaired element" are also included (along with definitions for  |
| "remanufactured device" and "remanufactured element") in Appendix D,  |
| Definitions.                                                          |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-S.1.2.**                |
+-----------------------------------------------------------------------+

**Indicating Element Not Permanently Attached to Weighing and
Load-receiving Element or Covered by a Separate CC**

The following notes on the various types of markings (other than the
basic identification requirements of G‑S.1.) required for separate
indicating elements are intended to supplement the information in Table
S.6.3.b. Marking requirements that apply to weighing/load-receiving
elements will be described in the next section.

-   **accuracy class ---** indicating elements not permanently attached
    to a weighing element must be clearly and permanently marked with an
    accuracy class of I, II, III, III L, or IIII, as appropriate. This
    requirement is nonretroactive as of January 1, 1988. Vehicle and
    axle-load scales should be marked class III L. Note, however, that a
    separate indicating element may be marked for more than one class
    (for example, III/III L). If the indicator has a different number of
    scale divisions for the different classes marked, the maximum number
    of scale divisions must be marked for each class.

-   **nominal capacity ---** as designated by the manufacturer. However,
    the maximum nominal capacity is limited by the concentrated load
    capacity, as specified in S.6.1. Note that the nominal capacity *and
    scale division value must be marked together (e.g., 100,000 x 10 lb)
    immediately next to the weight display, unless these values are
    clear from the display*. \[Nonretroactive as of January 1, 1983\]

+-----------------------------------------------------------------------+
| ***S.6.1. Nominal Capacity; Vehicle and Axle‑Load Scales. ‑** For all |
| vehicle, axle‑load, scales, the marked nominal capacity shall not     |
| exceed the concentrated load capacity (CLC) times the quantity of the |
| number of sections in the scale minus 0.5.*                           |
|                                                                       |
| *As a formula, this is stated as: nominal capacity [\<]{.underline}   |
| CLC x (N ‑ 0.5)*                                                      |
|                                                                       |
| *where N = the number of sections in the scale.*                      |
|                                                                       |
| *(See N.1.3.4. and T.N.3.1.)*                                         |
|                                                                       |
| *\[Nonretroactive as of January 1, 1989\]*                            |
|                                                                       |
| \[**Note:** When the device is used in a combination railway track    |
| and vehicle weighing application, the above formula shall apply only  |
| to the vehicle scale application.\]                                   |
|                                                                       |
| (Added 1988) (Amended 1999 and 2002)                                  |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.6.1.**                   |
+-----------------------------------------------------------------------+

-   **value of scale division (d) ---** The value of the smallest
    graduated interval on an indicating device with graduations, or the
    smallest weight increment that is displayed on a digital indicator.

-   **value of "e" ---** The verification scale division, for indicating
    elements that are capable of indicating smaller divisions than those
    displayed (see definition in Appendix A for examples). For vehicle
    and axle-load scales, the value of "e" and the value of "d" are
    generally identical. Note that if "d" and "e" are the same, "e" need
    not be marked.

-   **temperature limits ---** Range of temperatures over which the
    device is designed to operate. For vehicle and axle-load scales,
    these limits need only be marked if outside the range of 14 to 104 F
    (-10 to 40 C). (See note 5 of Table S.6.3.b.)

-   **concentrated load capacity (CLC) ---** A capacity rating of a
    vehicle, axle-load scale, 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 as specified by the
    manufacturer. The concentrated load capacity rating is for both test
    and use.

-   **special application ---** See examples in Note 13. Generally not
    applicable to vehicle and axle-load scales.

-   **maximum number of scale divisions (n~max~) ---** Must not exceed
    limits specified in Table 3 (for scales marked with an accuracy
    class); Handbook 44 does not specify limits for scales that are not
    marked with an accuracy class.

-   **section capacity ---** The greatest live load that may be divided
    equally on the load pivots or load cells of a section without
    inducing stresses in any member in excess of the working stresses
    allowed for the load cells and materials involved. The section
    capacity was required to be marked on the indicating element of all
    vehicle scales manufactured prior to 1989. Table S.6.3.a now
    requires that the indicating element and the load-receiving element
    of vehicle and axle-load scales be marked with the CLC rather than
    the section capacity. For scales manufactured prior to 1989, the
    section capacity may be use as the CLC during testing.

**Weighing and Load-Receiving Element Not Permanently Attached to
Indicating Element or Covered by a Separate CC**

Many of the marking requirements pertaining to indicating elements not
permanently attached to a weighing or load receiving element also apply
to devices in this category. For example, as shown in Table S.6.3.a the
combined weighing/load-receiving elements of a vehicle or axle-load
scale must also be marked to show the basic identification specified in
G-S.1. (manufacturer's ID, model designation, and serial number).

In addition, the following markings are required for devices in this
category, as described in Table S.6.3.a. and in the accompanying notes
in Table S.6.3.b.

-   **accuracy class --** This requirement is nonretroactive as of
    January 1, 1988 for devices in this category.

-   **nominal capacity --** This requirement is nonretroactive as of
    January 1, 1989 for devices in this category, and the information
    must be marked on the load-receiving element (weighbridge) of the
    scale. See footnote 20 of Table S.6.3.b. for marking of combination
    vehicle/railroad track scales.

-   **temperature limits --** The application of this requirement is the
    same for indicating elements described above.

-   **concentrated load capacity --** The application of marking
    requirements are the same for indicating elements described above
    with one additional requirement - the CLC must be added to the
    load-receiving element of a scale not previously marked at time of
    modification. See above notes and footnote 9, Table S.6.3.b.

-   **special application --** The application of this requirement is
    the same for indicating elements described above.

-   **maximum number of scale divisions (n~max~) --** This requirement
    is nonretroactive as of January 1, 1988 for devices in this
    category.

-   **minimum verification scale division (e~min~) -** The e~min~ is the
    smallest scale division for which a weighing element complies with
    the influence factor requirements in the Scales Code of Handbook 44.
    This value must be less than or equal to the "e" or "d" value marked
    on the indicating element. This requirement is Nonretroactive as of
    January 1, 1988. A comparison among the various division/interval
    markings found on scales or their components is shown in Figure 3-2.

The required markings may be located on the weighing element or on the
load-receiving element, depending on how the scale has been installed.
On some vehicle and axle-load scales --- especially pit installations
--- the surface of the scale platform is the only portion of the
weighing and load-receiving elements that is above ground. Because this
surface is continuously exposed to traffic and the elements, conformance
with the requirements of G-S.1. that require markings be permanent
[and]{.underline} observable without disassembly requiring a tool is not
practicable. Paragraph S.6.2. of the Scales Code includes an exemption
from the latter requirement, provided that the information is easily
accessible.

+---------------+-----+-----------------+-----------------------------+
| **Marking**   | *   | **Location**    | **Definition**              |
|               | *Sy |                 |                             |
|               | mbo |                 |                             |
|               | l** |                 |                             |
+---------------+-----+-----------------+-----------------------------+
| Value of the  | d   | On scale or on  | The value of the displayed  |
| scale         |     | separate        | scale division.             |
| division      |     | indicating      |                             |
|               |     | element         |                             |
+---------------+-----+-----------------+-----------------------------+
| Verification  | e   | On scale or on  | The value by which the      |
| scale         |     | separate        | tolerance values and the    |
| division      |     | indicating      | accuracy class applicable   |
|               |     | element         | to the scale are            |
|               |     |                 | determined. "e" may be less |
|               |     |                 | than or equal to "d." If    |
|               |     |                 | "e" is equal to "d," it     |
|               |     |                 | does not have to be marked. |
+---------------+-----+-----------------+-----------------------------+
| Minimum       | e~m | On separate     | The smallest scale division |
| verification  | in~ | weighing        | for which a weighing        |
| scale         |     | /load-receiving | element complies with the   |
|               |     | element         | influence factor            |
|               |     |                 | requirements in Handbook    |
|               |     |                 | 44, including temperature   |
|               |     |                 | effect on zero. Similar to  |
|               |     |                 | v~min~ marking on load      |
|               |     |                 | cells.                      |
+---------------+-----+-----------------+-----------------------------+
| Load cell     | v~m | On load cell    | The smallest value for      |
| verification  | in~ |                 | which a load cell interval  |
|               |     |                 | complies with the           |
|               |     |                 | temperature effect on zero  |
|               |     |                 | requirements in Handbook    |
|               |     |                 | 44.                         |
+---------------+-----+-----------------+-----------------------------+
| ##            |     |                 |                             |
| # Figure 3-2. |     |                 |                             |
|  Division/Int |     |                 |                             |
| erval Marking |     |                 |                             |
| s on Scales a |     |                 |                             |
| nd Components |     |                 |                             |
+---------------+-----+-----------------+-----------------------------+

+-----------------------------------------------------------------------+
| **S.6.2. Location of Marking Information.** --- Scales that are not   |
| permanently attached to an indicating element, and for which the      |
| load-receiving element is the only part of the                        |
| weighing/load-receiving element visible after installation, may have  |
| the marking information required in G-S.1. of the General Code and    |
| S.6. of the Scales Code located in an area that is accessible only    |
| through the use of a tool; provided that the information is easily    |
| accessible (e.g., the information may appear on the junction box      |
| under an access plate). The identification information for these      |
| scales shall be located on the weighbridge (load-receiving element)   |
| near the point where the signal leaves the weighing element or        |
| beneath the nearest access cover.                                     |
|                                                                       |
| (Added 1989)                                                          |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.6.2.**                   |
+-----------------------------------------------------------------------+

For example, it would be permitted to put the information on a junction
box under the access plate that would have to be unfastened using a
screwdriver. The paragraph requires that the identification information
be located on the weighbridge near the point where the signal leaves the
weighing element or beneath the nearest access cover. For scales with a
lever system, some manufacturers put the markings on a ring inside the
manhole cover nearest the transverse lever. On an electronic scale, the
markings might be under an access cover or adjacent to the junction box
at which the cables carrying signals from the load cells are connected.

**Other Equipment or Device**

Auxiliary elements, such as a printer or a computer incorporated in the
weighing system, are only required to be marked with the basic
identification specified in G-S.1.

# Load Cell with CC

In addition to the basic identifications specified in G-S.1., load cells
manufactured after January 1, 1988, that have received an NTEP
Certificate of Conformance must also be marked to show the accuracy
class and the temperature limits as well as the following. These
requirements are nonretroactive as of January 1, 1988, except where
noted otherwise.

-   **maximum number of scale divisions (n~max~)** - This value may be
    stated on load cells in units of 1000; e.g., n: 10 is 10,000
    divisions.

-   **"S" or "M"** - indication of whether a load cell has received
    approval for **S**ingle or **M**ultiple load cell applications.*.*

-   **certificate of conformance number (CC) -** *Nonretroactive as of
    January 1, 2003.*

-   **direction of loading** --- required if the direction of loading of
    the cell is not obvious (see Table S.6.3.b., Note 15).

-   **minimum dead load** --- the minimum weight that will produce a
    zero output signal when applied to a load cell. Not used in field
    examinations of electronic vehicle and axle-load scales.

-   **maximum capacity** --- the capacity of the load cell

-   **safe load limit** --- the maximum weight that can be applied to a
    single load cell. Not used in field examinations of vehicle and
    axle-load scales.

-   **load cell verification interval** (**v~min~**) --- the minimum
    scale division for which the load cell was designed. Must be less
    than or equal to the verification scale division (e) of the
    indicator. Used to determine the appropriateness of a load cell for
    its application, as explained later in this chapter.

Note that in accordance with Table S.6.3.b. (Note 11), required markings
may be provided either on a load cell itself or in a separate document,
provided that the unique serial number of the load cell appears both on
the document and on the load cell (nonretroactive as of January 1,
1988). In addition, the manufacturer's name or trademark, the model
designation, and identifying symbol for the serial number also must
appear both on the load cell and in any accompanying document
(nonretroactive as of January 1, 1991). Consider, for example, the load
cell identification plate shown in Figure 3-3.

The identification plate in Figure 3-3 includes the following required
markings (read from the top down; however, note that the order of
presentation is not specified, and varies from one model to another):

-   model number (629R-R10-50K-30P5); in this example, the model number
    includes the capacity (50K, or 50,000 lb), which is also marked
    separately

-   accuracy Class (IIIL), n~max~ (10, representing 10,000), and
    multiple application (M)

-   v~min~ (4.8 lbs)

-   maximum capacity (50K lbs)

-   serial number (12345)

-   manufacturer's name (Load Cells, Inc.)

  -----------------------------------------------------------------------
  ![](media/image2.wmf)

  **Figure 3-3. Sample Load Cell Identification Plate**
  -----------------------------------------------------------------------

The plate shown in Figure 3-3 also includes the output of the cell,
which is not required by Handbook 44, but which may prove helpful. This
plate does [not]{.underline} include all of the following required
markings, including:

-   direction of loading (not required if obvious)

-   temperature limits (required only if other than that specified in
    T.N.8.1.1.)

-   minimum dead load

-   safe load limit

These markings, as applicable, would have to be marked on the device or
in an accompanying document. Note that the manufacturers name or
trademark and model designation and the applicable identifying symbols
for model and serial numbers must be marked on the load cell and, for
cells manufactured after January 1, 1991, in any accompanying document.

**Additional Marking Requirements**

In addition to the markings required by G‑S.1. and S.6.3., the General
Code has additional requirements relating to marking of controls and
features and readability and permanence of markings and instructions.

+-----------------------------------------------------------------------+
| **G-S.6. Marking Operational Controls, Indications, and Features. -** |
| All operational controls, indications, and features, including        |
| switches, lights, displays, push buttons, and other means, shall be   |
| clearly and definitely identified. The use of approved pictograms or  |
| symbols shall be acceptable.                                          |
|                                                                       |
| \[Nonretroactive as of January 1, 1977\]                              |
|                                                                       |
| (Amended 1978 and 1995)                                               |
|                                                                       |
| **G-S.7. Lettering.** --- All required markings and instructions      |
| shall be distinct and easily readable and shall be of such character  |
| that they will not tend to become obliterated or illegible.           |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraphs G-S.6. and G-S.7.**      |
+-----------------------------------------------------------------------+

Markings and lettering are considered permanent if they will withstand
wear and cleaning. Lettering is not permanent if it can be removed by
scraping the marking with a fingernail or if it would easily fade or be
washed away during cleaning. The markings may be placed on an
identification plate or a label. Be sure that the plate or label is
permanently attached to the device. An identification plate secured with
rivets would be acceptable; however, a plate secured with removable
screws would not. A pressure-sensitive label or badge is acceptable if
it can not be removed without being destroyed or distorted in appearance
so that it cannot be reused and would show obvious evidence that the
badge was removed. For example, if attempts to remove the badge results
in tears, permanent and extensive wrinkling, or repeated exposure of the
word "VOID", the permanence of the badge would be considered acceptable.
For devices evaluated under NTEP, specific tests are conducted to ensure
the permanence of badges and of required markings and lettering.

**Recording and Verification of Markings**

Because of the number and complexity of these marking requirements, it
is good practice to work with a checklist, like the ones included in the
EPOs. It is also a good idea to make a record of the marked items, which
will help you or another inspector determine at a subsequent inspection
whether parts have been replaced and whether the replacements are
appropriate. First identify the components, then locate the markings and
verify them for completeness, accessibility, permanence, and
readability.

If a scale system or component has been type-evaluated under NTEP,
markings found on the equipment should be compared to those shown on the
CC to determine that the device has the same capacities and parameters
as the model that was actually tested. (Instances have been found in
which a manufacturer has changed the listed capacities or parameters of
the model after the CC was issued.)

Consider the sample CC in Figures 3-4A and 3-4B, which was issued for a
"family" of load cells. (A single CC is often issued for a number of
devices of similar design and operating parameters that are produced by
a manufacturer, in this case, bending beam type load cells with
capacities ranging from 37,500 to 75,000 lb.) The required markings that
can be verified by comparing this CC with the actual markings on the
load cell are:

-   **manufacturer ---** printed in the box in the "Submitted by" box on
    the upper right of the first page of the CC.

-   **model number ---** printed in the "For" box on the upper left of
    page 1. Note that when a CC covers a family of devices, as in this
    case, the model number printed on the device may include additional
    numbers to designate the specific model. For example, a cell
    belonging to the model family covered by the sample CC might bear
    the number "12345-100K," with the additional numbers followed by the
    letter "K" indicating the capacity of that particular model (100,000
    lb).

-   **accuracy class ---** printed in the "For" box. Note that
    components of vehicle and axle-load scales may be marked with a dual
    accuracy class (III/III L) if they comply with Handbook 44
    requirements for both. In that case different values for n~max~ (the
    maximum number of scale divisions) relating to each class should
    also be marked.

-   **single or multiple application ---** also in the "For" box. Load
    cells approved for single cell applications (usually marked "S" on
    the load cell) may also be used in multiple cell applications, but
    that cells approved for multiple cell application (usually marked
    "M") may [not]{.underline} be used in single cell applications.

-   **n~max~ ---** also in the "For" box. In this example, 10,000 is the
    maximum number of scale divisions.

-   **temperature range ---** shown in the "Standard Features and
    Options" box. Note that the temperature range in the sample CC
    corresponds to the range specified in T.N.8.1.1. (and note 5 in
    Table S.6.3.b.), and that the load cell would therefore not be
    required to be marked with this particular item.

-   **v~min~ ---** the minimum verification scale division for the
    various capacities in this load cell family are presented in tabular
    form on page 1 of the CC. This appropriate value should be
    determined based upon the specific model being tested and then
    compared with the v~min~ marked on the load cell.

-   **minimum dead load ---** is also displayed for each capacity on
    page 1.

  -----------------------------------------------------------------------
  ![](media/image3.png){width="5.992361111111111in" height="7.75in"}

  **Figure 3-4A. Page 1 of a Sample NTEP Certificate of Conformance for a
  Load Cell**
  -----------------------------------------------------------------------

  -----------------------------------------------------------------------
  ![](media/image4.png){width="6.495833333333334in"
  height="8.102083333333333in"}

  **Figure 3-4B. Page 2 of a Sample NTEP Certificate of Conformance for a
  Load Cell**
  -----------------------------------------------------------------------

In the case of multiple scales used together to perform single-draft
weighings, each individual element must be marked as it would be if used
in a single system. However, elements that perform for the system as a
whole must be marked with aggregate capacities. For example, if a single
indicator is used to total the registrations of the separate weighing
elements, its nominal capacity and n~max~ must be based upon the total
capacity of the system and, at the same time, must meet the requirements
for III L scales in Handbook 44.

Thus, if the individual elements have capacities of 100,000 lb, 100,000
lb, and 60,000 lb and scale divisions of 20 lb, the nominal capacity
marked on the totalizing indicator can be greater than any of the
individual units but could not be equal to the sum of the individual
capacities, because the number of scale divisions would not meet
Handbook 44 requirements for the maximum number of scale divisions
permitted on Class III L scales:

100,000 + 100,000 + 60,000 = 260,000 lb

260,000/20 = 13,000 scale divisions

An appropriate nominal capacity for this scale system would be 200,000
pounds, because the number of

scale divisions would meet Class III L requirements:

200,000 20 = 10,000 scale divisions

The totalizing indicator would also have to meet all other applicable
requirements. For example, it could not indicate values in excess of 105
percent of the marked nominal capacity of the system.

# [Determining the Suitability of System Components]{.underline}

As explained in the last section, marking requirements apply to the
separate major components of a vehicle or axle-load scale: the
indicating element, the weighing/load-receiving elements and, if the
system is so equipped, to load cells and/or other devices. Some vehicle
and axle-load scales are custom built for a specific set of service
requirements from separate components, and some scale systems currently
in service have been modified since their original installation. As a
result, the fact that the marking of a particular component is correct
and that the model has received an NTEP Certificate of Conformance does
not guarantee that the component is suitable for the specific
installation. You should, therefore, determine the suitability of the
components used in the system before proceeding to the inspection of
individual components. Note, however, that it is only possible to make
this determination for components that are marked.

In general, each of the capacities and parameters of the scale system as
a whole is limited by the corresponding feature of the individual
component of the system that is most limited. For example, if the
temperature ranges of the indicating element and the load cells are
different, the system as a whole is only suitable for use within the
narrowest temperature range.

Similarly, the number of scale divisions for the scale must be less than
or equal to the maximum number of scale divisions n~max~ for the
indicator or the load cells, whichever is less; for example, if the
indicator has an n~max~ of 10,000 and the load cells have an n~max~ of
5,000, then the scale may be used for up to 5,000 divisions.

The marked Accuracy Class of all components should also be checked. For
vehicle and axle-load scales, components marked for Class III or III L,
or those marked for dual application (III/III L) are suitable. Remember
that scale components marked for Accuracy Class III may also be used in
Class III L applications, but that components marked Class III L may not
be used in Class III applications.

It is especially important to verify the suitability of load cells used
in fully electronic and electromechanical scales. The EPO for vehicle
and axle-load scales equipped with electronic digital indicators (No.
13-E) specifies several determinations that are applicable to load cells
with NTEP CCs. These determinations are listed under the "Markings"
section of the EPO.

In addition to checking the n~max~ marked on the load cells to determine
the appropriate number of scale divisions for the scale system and
determining that the Accuracy Class is appropriate to the application,
as described above, two additional verifications are specified:

-   appropriate use in single versus multiple load cell application, and

-   conformance for field examination purposes with a requirement
    relating to temperature effect on zero-load balance.

Load cells with CCs must be marked to indicate whether the cell is
designed for single- or multiple- applications. Load cells approved for
single use (usually bearing an "S" marking) may also be employed in
multiple cell applications. However, cells marked for multiple use
(usually with the letter "M") cannot be used in single cell applications
(for example, in an electromechanical system that incorporates a single
load cell).

In accordance with T.N.8.1.3., on Class III L devices, including vehicle
and axle-load scales, zero-load indication may not vary by more than 3
scale divisions for every change in temperature of 9 F (5 C).

+-----------------------------------------------------------------------+
| **T.N.8.1.3. Temperature Effect on Zero-Load Balance. -** The         |
| zero-load indication shall not vary by more than:                     |
|                                                                       |
| \(a\) three divisions per 5 °C (9 °F) change in temperature for Class |
| III L devices; or                                                     |
|                                                                       |
| \(b\) one division per 5 °C (9 °F) change in temperature for all      |
| other devices.                                                        |
|                                                                       |
| (Amended 1990)                                                        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph T.N.8.1.3.**               |
+-----------------------------------------------------------------------+

It is not possible to test for conformance with requirements relating to
the effect of temperature on zero-load balance (T.N.8.1.3.) in the
field. However, as stated in EPO 13-E, a load cell may be considered to
meet this requirement for the purpose of a field examination if its
marked v~min~ does not exceed a calculated value as specified in NIST
Handbook 44 Scales Code paragraph S.5.4. and summarized below. Note that
the requirements in paragraph S.5.4. do not apply to complete scales and
weighing elements which satisfy certain criteria as specified in S.5.4.

-   for fully electronic systems employing more than one load cell, the
    v~min~ may not exceed the scale division (d) divided by the square
    root of the number of cells employed (N):

  -------------------------------------------------- --------------------
  v~min~                                             d

                                                     N
  -------------------------------------------------- --------------------

> A table including calculated values for a number of d and N values is
> provided at the end of EPO 13-E (Appendix A).

-   for electromechanical scales (lever systems employing a single load
    cell), the marked v~min~ may not exceed the scale division divided
    by the scale multiple (which can be determined from the ratios
    marked on the levers):

  ------------------------------ ----------------------------------------
  v~min~                         d

                                 Scale multiple
  ------------------------------ ----------------------------------------

Examples of both calculations are provided following the table in
Appendix A of the EPO. Note that the calculated limit for v~min~ will
vary for the same model cell when installed in scale systems with a
different number of sections or a different scale multiple. This
verification thus relates to the suitability of the load cell being
examined (with respect to temperature change on zero-load balance) for
use in the specific system in which it has been installed.

+-----------------------------------------------------------------------+
| ***S.5.4. Relationship of Load Cell Verification Interval Value to    |
| the Scale Division. -** The relationship of the value for the load    |
| cell verification scale interval, v~min~, to the scale division, d,   |
| for a specific scale installation shall be:*                          |
|                                                                       |
| *(a) where N is the number of load cells in the scale for scales      |
| without lever systems:* $v_{\text{min}} \leq \frac{d}{\sqrt{N}}$      |
|                                                                       |
| *and,*                                                                |
|                                                                       |
| *(b) for scales with lever systems:*                                  |
| $v_{                                                                  |
| \text{min}} \leq \frac{d}{\sqrt{N\text{ x }(\text{scale multiple})}}$ |
|                                                                       |
| *\[Nonretroactive as of January 1, 1994\]*                            |
|                                                                       |
| *\[Note: When the value of the scale division, d, is different than   |
| the verification scale division, e, for the scale, the value of e     |
| must be used in the formulae above\]*                                 |
|                                                                       |
| *This requirement does not apply to complete scales and weighing      |
| elements which satisfy the following criteria:*                       |
|                                                                       |
| *(1) The device has been evaluated for compliance with T.N.8.1.       |
| Temperature under the National Type Evaluation Program (NTEP);*       |
|                                                                       |
| *(2) The device has received an NTEP Certificate of Conformance; and* |
|                                                                       |
| *(3) The device must be equipped with an automatic zero-setting       |
| mechanism which cannot be made inoperative in the normal weighing     |
| mode. (A test mode which permits the disabling of the automatic       |
| zero-setting mechanism is permissible, provided the scale cannot      |
| function normally while in this mode.)*                               |
|                                                                       |
| (Added 1993) (Amended 1996)                                           |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph T.N.8.1.3.**               |
+-----------------------------------------------------------------------+

# [Indicating And Recording Elements]{.underline}

**Accuracy Class Designations**

Effective January 1, 1986, all scales must be designated with an
accuracy class as specified in NIST Handbook 44 Scales Code paragraph
S.5.1. Scales Code paragraph S.5.2. requires that the accuracy class of
a weighing device be designated by the manufacturer and that the device
comply with the parameters specified for the corresponding accuracy
class as shown in Table 3.

+-----------------------------------------------------------------------+
| ***S.5.1. Designation of Accuracy Class. -** Weighing devices are     |
| divided into accuracy classes and shall be desig­nated as I, II, III,  |
| III L, or IIII.*                                                      |
|                                                                       |
| *\[Nonretroactive as of January 1, 1986\]*                            |
|                                                                       |
| ***S.5.2. Parameters for Accuracy Class. -** The accuracy class of a  |
| weighing device is designated by the manufac­turer and shall comply    |
| with parameters shown in Table 3.*                                    |
|                                                                       |
| *\[Nonretroactive as of January 1, 1986\]*                            |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraphs S.5.1. and S.5.2.**       |
+-----------------------------------------------------------------------+

+-----------------------------------------------------------------------+
| +------------------------------------------------------------------+  |
| | ######### INCH‑POUND Units                                       |  |
| +------------------------------------------------------------------+  |
+-----------------------------------------------------------------------+
| #### NIST Handbook 44, Scales Code, Table 3                           |
+-----------------------------------------------------------------------+

**Scale Division: Value (d) and Number (n)**

The Scales Code requires that for all scales manufactured after January
1, 1986, the value of scale division units must be either 1, 2, or 5, a
decimal multiple or submultiple of 1, 2, or 5, or a binary submultiple
of a specific unit (e.g., ½ ounce, ¼ pound). That is, on vehicle or
axle-load scales, the scale divisions in pound units may be 10 lb, 20
lb, or 50 lb, but not 30 lb or 40 lb. This requirement is based on an
international requirement that was adopted to insure the use of
sequences of numbers with which people are most familiar and promote
logic in the tolerance structure.

In addition, all digital-indicating scales (except postal scales)
manufactured after January 1, 1989, are required to indicate weight
values using only a single unit of measure; for example, a digital
vehicle scale may not indicate in both pounds and ounces. Selection of
different weight units from an external key or switch is permitted,
however. The Scales Code also prohibits the digital representation of
common fractions such as 1/2 or 1/4.

+-----------------------------------------------------------------------+
| ***S.1.2. Value of Scale Division Units. -** Except for batching      |
| scales and weighing systems used exclusively for weighing in          |
| predetermined amounts, the value of a scale division \"d\" expressed  |
| in a unit of weight shall be equal to:*                               |
|                                                                       |
| *(a) 1, 2, or 5; or*                                                  |
|                                                                       |
| *(b) a decimal multiple or submultiple of 1, 2, or 5;*                |
|                                                                       |
| *(c) a binary submultiple of a specific unit of weight.*              |
|                                                                       |
| *Examples: scale divisions may be 0.01, 0.02, 0.05; 0.1, 0.2, or 0.5; |
| 1, 2, or 5; 10, 20, 50, or 100; or, scale divisions may be 1/2, 1/4,  |
| 1/8, 1/16, etc.*                                                      |
|                                                                       |
| *\[Nonretroactive as of January 1, 1986\]*                            |
|                                                                       |
| S.1.2.1. Weight Units. - Except for postal scales, a                  |
| digital-indicating scale shall indicate weight values using only a    |
| single unit of measure. Weight values shall be presented in a decimal |
| format with the value of the scale division expressed as 1, 2, or 5,  |
| or a decimal multiple or submultiple of 1, 2, or 5.                   |
|                                                                       |
| *\[Nonretroactive as of January 1, 1989\]*                            |
|                                                                       |
| (Added 1987)                                                          |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraphs S.1.2. and S.1.2.1.**     |
+-----------------------------------------------------------------------+

All scales must meet the basic requirement of suitability for their
application. Among other characteristics, the size and number of scale
divisions determine the suitability of a scale for a particular
application.

The Scales Code limits either the size or the number of scale divisions
that may be employed. The applicable requirement depends upon whether or
not the scale is marked with an accuracy class.

If the scale was manufactured before January 1, 1986, it will not be
marked with an accuracy class. In this case, a maximum scale division
size is specified in Table 7b of the Scales Code, which is referenced in
paragraph UR.1.1.(b).

+-----------------------------------------------------------------------+
| **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. ^1^             |
|                                                                       |
| ^1^ Purchasers and users of scales such as railway track, hopper, and |
| vehicle scales should be aware of possible additional requirements    |
| for the design and installation of such devices.                      |
|                                                                       |
| (Footnote Added 1995)                                                 |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraph UR.1.                        |
+-----------------------------------------------------------------------+

+-----------------------------------------------------------------------+
| +------------------------------+----------------------------------+   |
| | **Table 7b.**                |                                  |   |
| |                              |                                  |   |
| | **Applicable to Devices not  |                                  |   |
| | Marked With a Class          |                                  |   |
| | Designation**                |                                  |   |
| +------------------------------+----------------------------------+   |
| | Scale Type or De­sign         | Maximum Value of d               |   |
| +------------------------------+----------------------------------+   |
| | Retail Food Scales, 50‑lb    | 1 ounce                          |   |
| | capacity and less            |                                  |   |
| +------------------------------+----------------------------------+   |
| | Ani­mal Scales                | 1 pound                          |   |
| +------------------------------+----------------------------------+   |
| | Grain Hop­per Scales          | 10 pounds (not greater than 0.05 |   |
| |                              | % of c­apa­city)                   |   |
| | Ca­paci­ty up to and incl. 50  |                                  |   |
| | 000 lb                       | 20 pounds                        |   |
| |                              |                                  |   |
| | Ca­paci­ty over 50 000 lb      |                                  |   |
| +------------------------------+----------------------------------+   |
| | Crane Scales                 | not greater than 0.2 % of        |   |
| |                              | ca­pac­ity                         |   |
| +------------------------------+----------------------------------+   |
| | Vehi­cle and A­xle‑­Load Scales | 20 pounds                        |   |
| | Used in Combination          |                                  |   |
| |                              | 50 pounds                        |   |
| | Ca­paci­ty up to and in­clud­ing |                                  |   |
| | 200 000 lb                   |                                  |   |
| |                              |                                  |   |
| | Ca­paci­ty over 200 000 lb     |                                  |   |
| +------------------------------+----------------------------------+   |
| | Railway Track Scales         | 20 pounds                        |   |
| |                              |                                  |   |
| | With wei­gh­b­eam               | 100 pounds                       |   |
| |                              |                                  |   |
| | Au­to­mat­ic indi­cat­ing         |                                  |   |
| +------------------------------+----------------------------------+   |
| | Scales with ca­paci­ties       | 0.1 % capacity (but not greater  |   |
| | gre­ater than 500 lb ex­cept   | than 50 lb)                      |   |
| | oth­er­wise spe­ci­fied          |                                  |   |
| +------------------------------+----------------------------------+   |
| | Wh­eel‑­L­oad Wei­gh­ers          | 0.25 % capacity (but not great­er |   |
| |                              | than 50 lb)                      |   |
| +------------------------------+----------------------------------+   |
| | Note: For scales not         |                                  |   |
| | specified in this table,     |                                  |   |
| | G-UR.1.1. and UR.1. apply.   |                                  |   |
| |                              |                                  |   |
| | (Added 1985) (Amended 1989)  |                                  |   |
| +------------------------------+----------------------------------+   |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Table 7b                               |
+-----------------------------------------------------------------------+

According to this table, for a vehicle scale or for axle-load scales
used in combination that were manufactured before January 1, 1986 (and,
therefore, [not]{.underline} marked accuracy class III L), the value of
the scale division may not be greater than 20 lb if the capacity of the
scale is 200,000 lb or less. For scales with capacity over 200,000 lb,
the value of the scale division may not be greater than 50 lb.

In all likelihood, nearly all axle-load scales (used alone or in
combination) and many vehicle scales that you encounter will have
capacities of 200,000 lb (100 tons) or less and will have scale
divisions not greater than 20 lb. You may, however, encounter a few old
axle-load scales that are being used alone for enforcement purposes;
these scales should be subject to the requirement for "Scales with
capacities greater than 500 lb except otherwise specified" in Table 7b
and thus could have scale division values larger than 20 lb.

Scales manufactured on or after January 1, 1986, to be used for vehicle
or axle-load weighing will be marked III L. For these scales there is no
maximum size for the scale division, but the scale must meet the
requirements of an accuracy class III L scale: no fewer than 2,000 scale
divisions and no more than 10,000 scale divisions, with a minimum scale
division of 5 lb. This requirement is set forth in Table 3, which is
referenced in paragraph S.5.2.

To determine the number of scale divisions (n) on a scale, you need to
know the value of the scale division (d) and the scale capacity.

The value of the scale division (the smallest subdivision of the scale
for analog devices or the difference between two consecutively indicated
values for digital devices) is required to be marked on the device. It
frequently appears as part of the capacity statement, e.g., 200,000 20
lb (d = 20 lb).

To determine the number of scale divisions, divide scale capacity by the
scale division value,

n = [scale capacity]{.underline} = [200,000]{.underline} = 10,000
divisions

scale division value 20

The formula for determining the number of scale divisions that is given
in Handbook 44 indicates that the scale capacity should be divided by
the "verification scale division (e)," which is the value by which the
tolerance values and accuracy class for a device are determined. The
verification scale division (e) may be different from the displayed
scale division (d); however, they are usually the same in the case of
vehicle and axle-load scales.

In the above example, n corresponds to the maximum number of scale
divisions permitted for a Class III L scale. A scale with this capacity
could have as few as 2,000 divisions, but the divisions would have to be
100 lb. Since vehicle and axle-load scales typically have scale
divisions of 10 or 20 lb, this effectively limits their capacity to
100,000 and 200,000, respectively. Typical scale capacity values, scale
division values, and number of scale divisions found on vehicle and
axle‑load scales now in use are as shown in Figure 3-5.

+-----------------------------------------------------------------------+
|   ------------ -------------- ---------------- ---------------------  |
|   **Type**     **Capacity     **Scale Division **Number of Scale      |
|                (pounds)**     Value**          Divisions**            |
|                                                                       |
|   Vehicle      40 000         10               4 000                  |
|   scale                                                               |
|                                                                       |
|                50 000         10               5 000                  |
|                                                                       |
|                60 000         10               6 000                  |
|                                                                       |
|                100 000        10               10 000                 |
|                                                                       |
|                40 000         20               2 000                  |
|                                                                       |
|                50 000         20               2 500                  |
|                                                                       |
|                60 000         20               3 000                  |
|                                                                       |
|                100 000        20               5 000                  |
|                                                                       |
|                120 000        20               6 000                  |
|                                                                       |
|                150 000        20               7 500                  |
|                                                                       |
|                160 000        20               8 000                  |
|                                                                       |
|                200 000        20               10 000                 |
|                                                                       |
|   Axle-load    40 000         20               2 000                  |
|   scale                                                               |
|                                                                       |
|                60 000         20               3 000                  |
|   ------------ -------------- ---------------- ---------------------  |
+-----------------------------------------------------------------------+
| **Figure 3-5. Typical Scale Capacities, Scale Division Values, and**  |
|                                                                       |
| **Number of Scale Divisions for Vehicle and Axle-Load Scales**        |
+-----------------------------------------------------------------------+

An important question of interpretation arises with respect to the
application of the limitations on the number of scale divisions in
S.5.2. and Table 3 to multiple-weighing systems, that is, systems in
which a number of independent weighing devices are interfaced with a
totalizing indicating element and are used to perform single-draft
weighings of vehicles. Consider three axle-load scales with the
following capacities: 100,000 20 lb, 100,000 20 lb, and 60,000 20 lb.
When used simultaneously for single draft weighing, their separate
weight registrations are summed by a single indicator. If considered as
separate scales, they would each meet the requirements for n in Table 3,
since they have 5,000, 5,000, and 3,000 divisions, respectively.
However, if considered as a single scale, with a capacity of 260,000 lb
and a total of 13,000 scale divisions, the system would exceed the
maximum n for Class III L scales.

In 1990, the NCWM adopted a statement supporting the interpretation that
multiple weighing devices used together must be considered to be a
single system, and that Handbook 44 requirements must be met by each
scale separately [and]{.underline} by the system as a whole. A detailed
discussion of this interpretation and its implications for other design
and marking requirements, and for the application of tolerances, can be
found in Item 320-11of the "Report of the 75^th^ National Conference on
Weights and Measures." This topic will be discussed further in this
module under the various applicable requirements.

**Multi-Interval and Multiple Range Devices**

Some weighing devices may be used for multiple purposes. For example, a
combination vehicle and railway track scale is used to weigh both
highway vehicles and railroad cars. In order to ensure a suitable scale
division size and to meet minimum load and suitability requirements for
both weighing applications, a multi-interval scale will often be used. A
multi-interval scale is one in which a single weighing range is divided
into partial weighing ranges, each with a different scale interval. The
weighing range and corresponding division are determined automatically
according to the load applied to the scale. For example, a combination
vehicle/railway track scale may have the following intervals:

  ----------------------- ----------------------- -----------------------
  **Weighing Range        **"e" = verification    **n = number of
  (Capacity)**            scale division**        divisions**

  0 - 100 000 lb          \-                      5000

  100 000 - 200 000 lb    50                      4000

  200 000 - 400 000 lb    100                     4000
  ----------------------- ----------------------- -----------------------

The number of divisions, n, for each weighing range is determined by
dividing the scale capacity for each range by the verification scale
division, e, for each range. Paragraph S.5.3. requires that the value of
"e" be equal to the value of "d" for multi-interval and multiple range
scales.

+-----------------------------------------------------------------------+
| **S.5.3. Multi-Interval and Multiple Range Scales, Division Value.    |
| -** On a multi-interval scale and multiple range scale, the value of  |
| \"e\" shall be equal to the value of \"d.\" ^1^                       |
|                                                                       |
| (Added 1986) (Amended 1995)                                           |
|                                                                       |
| ^1^ See Footnote 1 to Table 3 Parameters for Accuracy Classes.        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.5.3.**                   |
+-----------------------------------------------------------------------+

A similar type of scale is a [manual]{.underline} multi-interval scale.
This is a device in which the capacity and the value of the scale
division is changed by manual operation. Each manually-selected capacity
and scale division (weighing range) is considered to be an individual
scale and evaluated accordingly.

Another variation is a multiple-range scale. This instrument has two or
more weighing ranges with different maximum capacities and different
scale intervals for the same load-receiving element. However, each range
extends from zero to its maximum capacity. The weighing ranges maybe
either manually or automatically selected. Each weighing range is
considered to be an individual scale and evaluated accordingly.

**Rounding**

As said earlier, digital values, whether on an electronic indicator or
generated by a printer, will be a rounded value. The General Code
requires that indicated or recorded values must represent the registered
weight to the nearest minimum graduation. For scales, this means that
the weight increment should be divided evenly between successive
indicated or recorded increments.

+-----------------------------------------------------------------------+
| **G-S.5.2.2. Digital Indication and Representation. -** Digital       |
| elements shall be so designed that:                                   |
|                                                                       |
| ...                                                                   |
|                                                                       |
| \(c\) A digital value \"rounds off\" to the nearest minimum unit that |
| can be indicated or recorded.                                         |
|                                                                       |
| (Amended 1973 and 1985)                                               |
+-----------------------------------------------------------------------+
| NIST, Handbook 44 General Code, Paragraph G-S.5.2.2.(c)               |
+-----------------------------------------------------------------------+

Consider, for example, a 200,000-lb capacity vehicle scale with an
electronic digital indicator having 20-lb scale divisions. If a load of
120,505 lb is sensed by the weighing element, the indicator should
register 120,500 lb, since that is the closest indication to the weight;
if 10 pounds is added to the load, for a total of 120,515, the indicator
should read 120,520. A printed ticket would have to represent the same
values under these conditions. The indication and **recorded
representation** would change at exactly the midpoint of the scale
division, in this example, at 120,510 lb (within the limits of
sensitivity of the device).

Note that this is analogous to the correct method for reading values on
an analog device, as described in Handbook 44 (Appendix A, Fundamental
Considerations, section 10.3). This is obviously the most equitable
method. If values were always rounded to the next (higher) value, the
seller could charge for product not delivered up to a full scale
division, and would never be selling less than the registered amount; if
values were rounded to the previous (lower) value, the buyer would
benefit in the same way. Since actual quantities of product delivered
often fall more or less randomly between indicated amounts, rounding to
the nearer value should balance out over a number of transactions, and
the rounding in each transaction will be small enough that neither party
is materially affected.

**Manual Weight Entries**

Some electronic scales are equipped with a feature that permits the
operator to manually enter a weight value through a keyboard. As
specified in NIST Handbook 44 Scales Code paragraph S.1.12., a device
shall accept an entry of a manual weight value only when the scale is at
gross load zero and the scale indication is at zero in the gross weight
display mode. This helps to ensure that that the manual weight value
does not appear to be a result of a normal weighing operation. For
devices equipped with a printer capable of printing manual weight
values, the manual weight value must be identified and defined by
specific terms as specified in paragraph S.1.12. A related user
requirement, paragraph UR.3.9., only permits the use of manual weight
entries under very specific conditions. For vehicle scales, manual
weight entries are only permitted when the system generates a weight
ticket to correct an erroneous value.

+-----------------------------------------------------------------------+
| ***S.1.12. Manual Gross Weight Entries. -** A device shall accept an  |
| entry of a manual weight value only when the scale is at gross load   |
| zero and the scale indication is zero in the gross weights display    |
| mode. Recorded manual weight entries, except those on labels          |
| generated for packages of standard weights, shall identify the weight |
| value as a manual weight entry by one of the following terms:         |
| \"Manual Weight,\" \"Manual Wt,\" or \"MAN WT.\" The use of a symbol  |
| to identify multiple manual weight entries on a single document is    |
| permitted, provided that the symbol is defined on the same page on    |
| which the manual weight entries appear and the definition of the      |
| symbol is automatically printed by the recording element as part of   |
| the document.*                                                        |
|                                                                       |
| *\[Nonretroactive as of January 1, 1993\]*                            |
|                                                                       |
| (Added 1992)                                                          |
|                                                                       |
| **UR.3.9. Use of Manual Gross Weight Entries.** - Manual gross weight |
| entries are permitted for use in the following applications only: (1) |
| when credit is given for a weighed item on point-of-sale systems      |
| interfaced with scales; (2) when a device or system generates labels  |
| for standard weight packages; (3) when postal scales or weight        |
| classifiers generate manifests for packages to be picked up at a      |
| later time; or (4) when livestock and vehicle scale systems generate  |
| weight tickets to correct erroneous tickets.                          |
|                                                                       |
| (Added 1992) (Amended 2000)                                           |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraphs S.1.12. and UR.3.9.         |
+-----------------------------------------------------------------------+

**Tare Division Value and Tare Mechanism**

A nonretroactive requirement, effective as of January 1, 1983, specifies
that the tare division on a scale must be equal to the scale division.
For example, if the value of the scale division is 20 lb, the value of
the tare division must be 20 lb.

This same paragraph (S.2.3) also includes requirements that apply to the
tare mechanism. The function of a tare mechanism is to subtract the
weight of the empty vehicle from the total or gross load. However,
operation of the tare mechanism may not in any case cause a scale to
display a weight value that is more than the actual weight of the
product. You must, therefore, determine that tare operates only in the
direction of **underregistration** with respect to zero. This portion of
the requirement is fully retroactive, and applies to both mechanical and
digital scale systems.

+-----------------------------------------------------------------------+
| **S.2.3. Tare. -** *On any scale (except a monorail scale equipped    |
| with digital indications), the value of the tare division shall be    |
| equal to the value of the scale division.\** The tare mechanism shall |
| operate only in a backward direction (that is, in a direction of      |
| underregistration) with respect to the zero-load balance condition of |
| the scale. *A device designed to automatically clear any tare value   |
| shall also be designed to prevent the automatic clearing of tare      |
| until a complete transaction has been indicated.\**                   |
|                                                                       |
| *\[Note: On a computing scale, this requires the input of a unit      |
| price, the display of the unit price, and a computed positive total   |
| price at a readable equi­librium. Other devices require a complete     |
| weighing operation, including tare, net, and gross weight             |
| determination\]\**                                                    |
|                                                                       |
| *\[\*Nonretroactive as of January 1, 1983\]*                          |
|                                                                       |
| (Amended 1985)                                                        |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraph S.2.3.                       |
+-----------------------------------------------------------------------+

In direct sale situations, the customer must be able to verify the
amount of tare during the transaction. Some scales with electronic
digital indicators are designed to automatically clear the tare value at
the end of a transaction. For scales with this capability that are
subject to this portion of the requirement (nonretroactive as of January
1, 1983), the design must prevent the automatic clearing of tare until
[a complete transaction]{.underline} has been indicated. The complete
transaction might include tare, net, and gross weight determination. If
the scale you are examining is used for direct sales, you must verify
that an appropriate tare mechanism is used.

The performance of the tare mechanism will be verified as a part of the
Test portion of the scale examination, and will be covered in Chapter 6
of this module.

**Appropriateness of Design**

**General**

Many of the requirements relating to the appropriateness of indicating
and recording elements are set forth in the section G‑S.5. of the
General Code, and apply to all commercial weighing measuring devices
(except those specifically excluded). The most basic requirement states
that indicating and recording elements must be "appropriate in design
and adequate in amount," and that primary indications and recorded
representations must be clear, definite, accurate, and readable under
normal conditions of service.

  -----------------------------------------------------------------------
  **G-S.5.1. General.** - All weighing and measuring devices shall be
  provided with indicating or recording elements appropriate in design
  and adequate in amount. Primary indications and recorded
  representa­tions shall be clear, definite, accurate, and easily read
  under any conditions of normal operation of the device.

  NIST Handbook 44 General Code, Paragraph G-S.5.1.
  -----------------------------------------------------------------------

**Primary indicating and recording elements** are those that are used as
the basis for a commercial transaction. In the case of vehicle and
axle-load scales, this would include the indicator and a printer that
produces the record of the transaction (if the system is so equipped),
and any remote indicators if they are used by the operator to determine
the vehicle weight or the weight basis for charges. In multiple scale
applications, all indicating and recording elements for all scales used
to weigh single vehicles are considered to be primary elements of a
single system.

Inspect indicating and recording elements identified as primary to
verify that they are appropriate in design, adequate in amount, and easy
to read under normal operating conditions. Be particularly alert when
there have been replacements or modifications.

The general requirement in G-S.5. for analog indicators simply states
that graduations and a suitable indicator must be provided.

  -----------------------------------------------------------------------
  **G-S.5.2.1. Analog Indication and Representation. ** - Graduations and
  a suitable indicator shall be provided in connection with indica­tions
  designed to advance continuously.

  NIST Handbook 44, General Code, Paragraph G-S.5.2.1.
  -----------------------------------------------------------------------

Requirements for digital indications and recorded representations are
somewhat more detailed, and recognize the necessity of reconciling all
indications within a weighing system.

+-----------------------------------------------------------------------+
| **G-S.5.2.2. Digital Indication and Representation.** - Digital       |
| elements shall be so designed that:                                   |
|                                                                       |
| > \(a\) All digital values of like value in a system agree with one   |
| > an­other.                                                            |
| >                                                                     |
| > \(b\) A digital value coincides with its associated analog value to |
| > the nearest minimum graduation.                                     |
|                                                                       |
| (c) A digital value \"rounds off\" to the nearest minimum unit that   |
|     can be indicated or recorded.                                     |
|                                                                       |
| (d) *A digital zero indication includes the display of a zero for all |
|     places that are displayed to the right of the decimal point and   |
|     at least one place to the left. When no decimal values are        |
|     displayed, a zero shall be displayed for each place of the        |
|     displayed scale division.*                                        |
|                                                                       |
| *\[Nonretroactive as of January 1, 1986.\]*                           |
|                                                                       |
| (Amended 1973 and 1985)                                               |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-S.5.2.2.**              |
+-----------------------------------------------------------------------+

To summarize these requirements in terms of scales:

-   All digital values within the system must agree with one another.
    This means, for example, that the weight displayed on an electronic
    digital indicator, on a ticket printer used with that indicator and
    on a remote display that is part of the same system must agree
    exactly.

-   Any displayed digital value must agree with an associated analog
    value to the nearest scale division. For example, if the indicator
    on a mechanical dial scale stops between successive graduations, the
    value recorded on a printed ticket must be the same as the value of
    the graduation on the dial that is closest to the indicator.

-   Digital indications and recorded representations must be rounded to
    the nearest minimum scale division. (This requirement was discussed
    under Rounding, above.)

-   On vehicle and axle-load scales with digital indicating elements
    that do not display decimal values, a zero must be displayed for
    each digit in the displayed scale division. (This requirement was
    discussed under Zero-load Balance, above.)

Conformance with these requirements can only be determined when the
scale is in operation. The Test Notes section of the EPOs instructs the
inspector to check indications and recorded representations for
agreement repeatedly.

Three additional requirements relate to the size and character,
representation of values, and permanence of graduations, indications,
and recorded representations.

+-----------------------------------------------------------------------+
| **G-S.5.2.3. Size and Character.** - In any series of graduations,    |
| indications, or recorded representations, corresponding graduations   |
| and units shall be uniform in size and charac­ter. Graduations,        |
| indications, or recorded representations that are subordinate to, or  |
| of a lesser value than others with which they are associated, shall   |
| be appropriately portray­ed or designated. \[Made retroactive as of    |
| January 1, 1975.\]                                                    |
|                                                                       |
| **G-S.5.2.4. Values.** - If graduations, indications, or recorded     |
| representations are in­tended to have specific values, these shall be  |
| adequately defined by a sufficient number of figures, words, symbols, |
| or combinations thereof, uniformly placed with reference to the       |
| gradua­tions, indications, or recorded representations and as close    |
| thereto as practicable, but not so positioned as to interfere with    |
| the accuracy of reading.                                              |
|                                                                       |
| **G-S.5.2.5. Permanence.** - Graduations, indications, or recorded    |
| represen­tations and their defining figures, words, and symbols shall  |
| be of such character that they will not tend easily to become         |
| oblit­erated or illegible.                                             |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraphs G-S.5.2.3., G-S.5.2.4.,  |
| and G-S.5.2.5.**                                                      |
+-----------------------------------------------------------------------+

These requirements are intended to help insure that the meaning and
associated values of indications and recorded representations are clear
to the user.

According to paragraph G-S.5.3., the values assigned to graduated
intervals (the distance from the center of one graduation to the center
of the succeeding graduation) must be uniform within any series of
graduations.

  -----------------------------------------------------------------------
  **G-S.5.3. Values of Graduated Intervals or Increments.** - In any
  series of graduations, indications, or recorded representations, the
  values of the graduated intervals or increments shall be uniform
  throughout the series.

  **NIST Handbook 44, General Code, Paragraph G-S.5.3.**
  -----------------------------------------------------------------------

For example, on a dial scale with 20-lb and 100-lb graduations, the
values of the graduated intervals could not change to 10-lb and 50-lb
midway through the series of graduations. On an electronic scale with a
scale division value of 10 lb, the scale could not suddenly begin
indicating in 20-lb increments (unless the scale was identified as being
a multi-range scale --- in that case, the scale division values could
change at some point, but the would have to be uniform within the range
specified on the device.)

A subparagraph of G-S.5.3. relates this requirement to devices that
indicate or record in both inch-pound and metric units.

+-----------------------------------------------------------------------+
| **G-S.5.3.1. On Devices That Indicate or Record in More Than One      |
| Unit. -** On devices designed to indicate or record in more than one  |
| unit of measure­ment, the values indicated and recorded shall be       |
| iden­tified with an appropriate word, symbol, or ab­breviation.         |
|                                                                       |
| \[Made retroactive 1990\] (Amended 1978 and 1986)                     |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-S.5.3.1.**              |
+-----------------------------------------------------------------------+

It is a fundamental requirement of any weighing or measuring device that
it be capable of repeating its indications and recorded representations.
Failure to repeat the same indication for the same test load applied
under the same conditions generally indicates a worn or malfunctioning
component. The General Code states the basic requirement for
repeatability.

Performance requirements and test procedures relating to repeatability
will be described in Chapters 5 and 6.

  -----------------------------------------------------------------------
  **G-S.5.4. Repeatability of Indications.** - A device shall be capable
  of repeat­ing, within prescribed tolerances, its indications and
  recorded representa­tions. This requirement shall be met irrespective of
  repeated manipulation of any element of the device in a manner
  approximat­ing normal usage (including displacement of the indicating
  elements to the full extent allowed by the con­struction of the device
  and repeated operation of a locking or relieving mecha­nism) and of the
  repeated performance of steps or operations that are embraced in the
  testing proced­ure.

  **NIST Handbook 44, General Code, Paragraph G-S.5.4.**
  -----------------------------------------------------------------------

Most vehicle and axle-load scales are not equipped with computing-type
indicators. However, in applications in which a charge or fee is based
upon the weight of the vehicle contents, some systems have a computer
linked to the indicator, which computes the charges associated with the
registered weight and drives a printer that makes a permanent record.
Since these components provide the basis for the transaction, they are
considered to be primary elements, subject to all applicable
requirements. Specifically, the General Code includes a requirement
relating to recorded money values or [digital]{.underline} money value
indications produced by a computing device.

For example, if a shipping company's fee schedule for transporting a
commodity to a particular location is \$8.87 per hundredweight (100
pounds) and the vehicle scale, after taking tare, registers a net weight
of 38,690 lb, the total fee for the transaction, computed
mathematically, would be \$3,431.803 (38,690/100 x \$8.87). The
indication or recorded representation produced by the system would have
to be \$3,431.80.

+-----------------------------------------------------------------------+
| **G-S.5.5. Money Values, Mathematical Agreement.** - Any recorded     |
| money value and any digital money-value indication on a               |
| computing-type weighing or measuring device used in retail trade      |
| shall be in mathematical agreement with its associated quantity       |
| representation or indication to the nearest 1 cent of money value.    |
| This does not apply to auxiliary digital indications intended for the |
| operator's use only, when these indications are obtained from         |
| existing analog customer indications that meet this requirement.      |
|                                                                       |
| (Amended 1973)                                                        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-S.5.5.**                |
+-----------------------------------------------------------------------+

Another paragraph in the General Code states that requirements
applicable specifically to indicating and recording elements are also
applicable to recorded representations, when they are appropriate. This
paragraph also states, as mentioned above, that all recorded values must
be printed digitally. It would not, for example, be permissible to print
a representation of a dial face, with the printed arrow indicating the
value corresponding to the value indicated on the scale.

+-----------------------------------------------------------------------+
| **G-S.5.6. Recorded Representations.** - Insofar as they are          |
| appropriate, the require­ments for indicating and recording elements   |
| shall also apply to recorded represen­tations. All recorded values     |
| shall be printed digitally.                                           |
|                                                                       |
| \[Made retroactive 1990\] (Amended 1975)                              |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-S.5.6.**                |
+-----------------------------------------------------------------------+

A final requirement in this section makes it clear that all of the
requirements in Handbook 44 for indications and graduations apply to
indications and graduations that are magnified by an optical system. For
example, if a magnifier is used to make a dial indicator more easily
readable, the distance between the end of the indicator graduations [in
the magnified image]{.underline} could be no more than 0.06 inch
(S.1.4.4.)

  -----------------------------------------------------------------------
  **G-S.­5.7. Ma­g­nif­ied Gra­dua­tions and In­dica­tio­ns.** - All re­quir­e­me­nts
  for grad­ua­tions and in­dica­tions apply to a ser­ies of grad­ua­tions and an
  in­dicator mag­nified by an optical system or as mag­nified and projected
  on a screen.

  **NIST Handbook 44, General Code, Paragraph G-S.5.7**.
  -----------------------------------------------------------------------

**Weighbeams**

Requirements relating to weighbeams are set forth in paragraph S.1.5. of
the Scales Code. The various requirements under this paragraph will be
discussed separately in this section, except for subparagraph S.1.5.5,
which applies only to scales with nominal capacity of 30 lb or less,
which is far below the capacity of vehicle and axle-load scales.

A weighbeam on a vehicle or axle-load scale must be properly constructed
and must function properly. When at rest in the normal position, the
weighbeam must be horizontal.

  -----------------------------------------------------------------------
  **S.1.5.1. Normal Balance Position.** - The normal balance position of
  the weighbeam of a beam scale shall be horizontal.

  **NIST Handbook 44, Scales Code, Paragraph S.1.5.1.**
  -----------------------------------------------------------------------

When in motion, the tip of the beam must travel equal distances above
and below horizontal. A trig loop may be used to show a balanced
condition, with the edges of the trig loop stopping the travel of the
weighbeam tip. There may be other stops that limit travel of the
weighbeam. In either of these cases, the distance the weighbeam travels
between limiting stops must meet the minimums shown in Table 1.

  -----------------------------------------------------------------------
  **S.1.5.2. Travel.** - The weighbeam of a beam scale shall have equal
  travel above and below the horizontal. The total travel of the
  weigh­beam of a beam scale in a trig loop or between other limiting
  stops near the weigh­beam tip shall be not less than the minimum travel
  shown in Tables 1M and 1. When such limiting stops are not provided,
  the total travel at the weighbeam tip shall be not less than 8 percent
  of the distance from weighbeam fulcrum to the weighbeam tip.

  **NIST Handbook 44, Scales Code, Paragraph S.1.5.2.**
  -----------------------------------------------------------------------

+------------------+---------------+---+-----------------+--------------+
| **Table 1 M.**   |               |   | **Table 1.**    |              |
|                  |               |   |                 |              |
| **Minimum Travel |               |   | **Minimum       |              |
| of Weighbeam of  |               |   | Travel of       |              |
| Beam Scale**     |               |   | Weighbeam of    |              |
|                  |               |   | Beam Scale**    |              |
| **Between        |               |   |                 |              |
| Limiting Stops** |               |   | **Between       |              |
|                  |               |   | Limiting        |              |
|                  |               |   | Stops**         |              |
+------------------+---------------+---+-----------------+--------------+
| Distance from    | Minimum       |   | Distance from   | Minimum      |
| weighbeam        | travel        |   | weighbeam       | travel       |
| fulcrum to       | between       |   | fulcrum to      | between      |
| limiting stops   | limiting      |   | limiting stops  | limiting     |
| (centimeters)    | stops         |   | (inches)        | stops        |
|                  | (millimeters) |   |                 | (inches)     |
+------------------+---------------+---+-----------------+--------------+
| 30 or less       | 10            |   | 12 or less      | 0.4          |
+------------------+---------------+---+-----------------+--------------+
| 30+ to 50,       | 13            |   | 12+ to 20,      | 0.5          |
| inclusive        |               |   | inclusive       |              |
+------------------+---------------+---+-----------------+--------------+
| 50+ to 100,      | 18            |   | 20+ to 40,      | 0.7          |
| inclusive        |               |   | inclusive       |              |
+------------------+---------------+---+-----------------+--------------+
| Over 100         | 23            |   | Over 40         | 0.9          |
+------------------+---------------+---+-----------------+--------------+
| **NIST Handbook  |               |   |                 |              |
| 44, Scales Code, |               |   |                 |              |
| Tables 1M. and   |               |   |                 |              |
| 1.**             |               |   |                 |              |
+------------------+---------------+---+-----------------+--------------+

If a weighbeam has no limiting stops or trig loop, the tip of the
weighbeam must have freedom to travel at least 8 percent of the distance
from the weighbeam fulcrum to the weighbeam tip. This minimum travel
requirement assures that it is readily apparent whether the scale is
balanced or out of balance when a reading is taken. Note that this
minimum travel is considerably greater than that required in Table 1 for
weighbeams equipped with trig loops.

Conformance with the requirements of S.1.5.2. is extremely important
because it directly affects the **sensitivity** of the weighbeam, which
is a non-automatic-indicating device and therefore depends upon operator
judgment to determine the balance condition of the scale. Good
sensitivity is required to obtain accurate weight values on a beam
scale. As you will learn, specific **performance requirements** apply to
sensitivity of both automatic- and non-automatic-indicating scales.

Because weighbeams are seldom submitted for type evaluation, travel
should be checked on every weighbeam scale. (When type evaluations have
been conducted on weighbeams, this is a common violation.)

Weighbeams may employ customary graduation lines or the poise locating
notches may be used as graduations, with the center of the notch
corresponding to the graduation line. In some cases, a combination of
lines and notches may be used, with the notches representing
subdivisions of the intervals between graduation lines. In any case,
intervals must be uniform in size, shape, and arrangement. If notches
are used as graduations, they must be clearly and accurately marked.

  -----------------------------------------------------------------------
  **S.1.5.3. Subdivision.** - A subdivided weighbeam bar shall be
  subdivided by scale division graduations, notches, or a combination of
  both. Gradua­tions on a particular bar shall be of uniform width and
  per­pendicular to the top edge of the bar. Notches on a particular bar
  shall be uniform in shape and dimensions and per­pendicular to the face
  of the bar. When a combination of graduations and notches is employed,
  the gradua­tions shall be positioned in relation to the notches to
  indicate notch values clearly and accurately.

  **NIST Handbook 44, Scales Code, Paragraph S.1.5.3.**
  -----------------------------------------------------------------------

The weighbeam must also be designed so that values are easily and
accurately read. Even when a recorded representation can be made, as in
the case of a type-registering weighbeam, it must be possible to verify
this value from direct observation of the position of the poise on the
beam.

  -----------------------------------------------------------------------
  **S.1.5.4. Readability.** - A subdivided weighbeam bar shall be so
  subdivided and marked, and a weighbeam poise shall be so constructed,
  that the weight corre­sponding to any normal poise position can easily
  and accurately be read directly from the beam, whether or not provision
  is made for the optional recording of representations of weight.

  **NIST Handbook 44, Scales Code, Paragraph S.1.5.4.**
  -----------------------------------------------------------------------

The graduation lines and numbers, usually etched on the beam, must be
clear and distinct, and the index of the poise must be designed in such
a way that the graduations are indicated unambiguously, even if the
weighbeam is capable of producing a clear and unambiguous recorded
representation.

Finally, a stop must be provided to prevent the poise from crossing the
zero mark. This prevents a zero-balance adjustment that would have the
effect of causing the scale to underregister because the poise was
behind the zero graduation when the adjustment was made.

  -----------------------------------------------------------------------
  **S.1.5.6. Poise Stop.** - Except on a steelyard with no zero
  gradua­tion, a shoulder or stop shall be provided on each weighbeam bar
  to prevent a poise from traveling and remaining back of the zero
  graduation.

  **NIST Handbook 44, Scales Code, Paragraph S.1.5.6.**
  -----------------------------------------------------------------------

**Poises**

As mentioned above, poises are used on scales equipped with a weighbeam.
The poise counterbalances the load on the deck and provides a clear
indication of the weight of the load. Because the calibration of the
scale is based upon the poise weight, replacing the poise with one of a
different weight would affect the accuracy of the device. This could be
done deliberately to defraud the customer, especially if it were
possible to replace the poise used to zero the scale with another of
different weight during the transaction, or to remove or replace a part
of the poise, such as the locking screw, which would change the weight
of the poise. To prevent this, neither the poise nor any part of the
poise can be readily removable. Hanging poises must swing freely so that
the counterforce is always applied vertically.

  -----------------------------------------------------------------------
  **S.1.6.1. General.** - No part of a poise shall be readily detach­able.
  A locking screw shall be perpendicular to the longitudinal axis of the
  weigh­beam and shall not be removable. Except on a steelyard with no
  zero graduation, a poise shall not be readily removable from a
  weigh­beam. The knife edge of a hanging poise shall be hard and sharp
  and so constructed as to allow the poise to swing freely on the bearing
  surfaces in the weighbeam notches.

  **NIST Handbook 44, Scales Code, Paragraph S.1.6.1.**
  -----------------------------------------------------------------------

Material used for adjusting the weight of the poise must be in a
container and firmly fastened in place. Since adjusting weights are
often made of soft metal, and could lose material, and thus weight, by
sharp contact with a harder surface, adjusting material must not touch
the beam if it is softer than brass.

  -----------------------------------------------------------------------
  **S.1.6.2. Adjusting Material.** - The adjusting material in a poise
  shall be securely enclosed and firmly fixed in position; if softer than
  brass, it shall not be in contact with the weighbeam.

  **NIST Handbook 44, Scales Code, Paragraph S.1.6.2.**
  -----------------------------------------------------------------------

If the poise is used on a notched weighbeam and is not a hanging poise,
as is generally the case with vehicle and axle-load scales, it must have
a pawl to seat the poise firmly in the notches. The tip of the pawl
should be at least as wide as the notch.

  -----------------------------------------------------------------------
  **S.1.6.3. Pawl.** - A poise, other than a hanging poise, on a notched
  weigh­beam bar shall have a pawl that will seat the poise in a definite
  and correct position in any notch, wherever in the notch the pawl is
  placed, and hold it there firmly and without appreciable movement. The
  dimension of the tip of the pawl that is transverse to the longitudinal
  axis of the weighbeam shall be at least equal to the corresponding
  dimen­sion of the notches.

  **NIST Handbook 44, Scales Code, Paragraph S.1.6.3.**
  -----------------------------------------------------------------------

If the notches or the pawl have become so worn that the poise will not
seat in a definite position, indications for a given load will vary. You
can test the seating of the pawl by carefully positioning the tip inside
a notch but as close as possible to an edge. When you release the pawl,
it should pull into the center of the notch on its own and seat there
securely.

The reading edge of a poise should be sharply defined and parallel to
the beam's graduations, as in the example illustrated in Figure 1-10. If
this edge is damaged so that it is no longer sharply defined, or is
incorrectly aligned, an accurate reading may be difficult.

  -----------------------------------------------------------------------
  **S.1.6.4. Reading Edge or Indicator.** - The reading edge or indicator
  of a poise shall be sharply defined, and a reading edge shall be
  parallel to the graduations on the weighbeam.­

  **NIST Handbook 44 Scales Code, Paragraph S.1.6.4.**
  -----------------------------------------------------------------------

This requirement should also be considered as applying to the pointer on
a fractional bar, like the one shown in Figure 1-10.

**Dials and Balance Indicators**

The following inspection requirements apply to dial indicators, and also
to balance indicators with graduations having a specific weight value.
Balance indicators having a single line to indicate balance or a target
bar through which the oscillating pointer swings, are not covered. These
requirements, which are intended to help assure that graduations are
readable, are included in paragraph S.1.3. of the Scales Code.

+-----------------------------------------------------------------------+
| **S.1.3. Graduations.**                                               |
|                                                                       |
| > **S.1.3.1. Length. -** Graduations shall be so varied in length     |
| > that they may be conveniently read.                                 |
| >                                                                     |
| > **S.1.3.2. Width. -** In any series of graduations, the width of a  |
| > graduation shall in no case be greater than the width of the clear  |
| > space between graduations. The width of main graduations shall be   |
| > not more than 50 percent greater than the width of subordinate      |
| > graduations. Gradua­tions shall be not less than 0.2 mm (0.008 in)   |
| > wide.                                                               |
| >                                                                     |
| > **S.1.3.3. Clear Space Between Graduations. -** The clear space     |
| > between graduations shall be not less than 0.5 mm (0.02 in) for     |
| > graduations repre­senting money values, and not less than 0.75 mm    |
| > (0.03 in) for other gradua­tions. If the graduations are not         |
| > parallel, the measurement shall be made:                            |
| >                                                                     |
| > \(a\) along the line of relative movement between the gradu­ations   |
| > at the end of the indicator, or                                     |
| >                                                                     |
| > \(b\) if the indicator is continuous, at the point of widest        |
| > separation of the graduations.                                      |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.1.3.**                   |
+-----------------------------------------------------------------------+

To summarize, graduations on the dial must meet several requirements:

-   they must be varied in length so that they may be conveniently read;

-   they must be at least 0.2mm (0.008 in) wide, with main graduations
    not more than 50 percent greater in width than subordinate
    graduations, and may not be wider than the clear space between
    graduations;

-   the clear space between graduations must be at least 0.75mm (0.03
    in) for weight graduations.

It may not be practicable to verify the dimensions specified in
S.1.3.2., and S.1.3.3. during a field examination. Since these are
minimum dimensions, you may be able to evaluate them without taking a
measurement (for comparative purposes, 0.02 inch is the width of a
relatively fine mechanical pencil lead). If you have doubts, you may
consider requesting that the dial face be removed so that tests can be
made with appropriate measuring instruments. Dial indicators that have
been type evaluated will meet these basic requirements.

Specific requirements for indicators that are used on dial scales are
set forth in paragraph S.1.4. of the Scales Code. In particular, the
requirements apply to the **index** of the indicator, that part of the
indicator that points to the graduations and is used to make a reading.
To summarize these requirements:

-   The index of the indicator must be of the same shape as the
    graduations, and must reach to the finest graduation with which it
    is used if it is not on the same plane as the graduations. If it is
    on the same plane, it must reach to within 0.04 inch of the ends of
    the graduations (for example, in a case where the dial is inset to
    minimize parallax effects).

-   The index of the indicator may not be wider than the width of the
    narrowest graduation, and not more than the width of the clear space
    between graduations.

-   Parallax effects must be reduced to the practical minimum. The
    clearance between the index of the indicator and the graduations may
    not be more than 0.06 inch.

+-----------------------------------------------------------------------+
| **S.1.4. Indicators.**                                                |
|                                                                       |
| > **S.1.4.1. Symmetry.** - The index of an indicator shall be of the  |
| > same shape as the graduations, at least throughout that portion of  |
| > its length associated with the graduations.                         |
| >                                                                     |
| > **S.1.4.2. Length. -** The index of an indicator shall reach to the |
| > finest graduations with which it is used, unless the indicator and  |
| > the gradu­ations are in the same plane, in which case, the distance  |
| > between the end of the indicator and the ends of the graduations,   |
| > measured along the line of the graduations, shall be not more than  |
| > 1.0 mm (0.04 in).                                                   |
| >                                                                     |
| > **S.1.4.3. Width. -** The width of the index of an indicator in     |
| > relation to the series of graduations with which it is used shall   |
| > be not greater than:                                                |
| >                                                                     |
| > *(a) the width of the narrowest graduation,*                        |
| >                                                                     |
| > *\[Nonretroactive as of January 1, 2002\]*                          |
| >                                                                     |
| > *(b) the width of the clear space between weight gradua­tions, and*  |
| >                                                                     |
| > *(c) three-fourths of the width of the clear space between money    |
| > ­value graduations.*                                                 |
| >                                                                     |
| > When the index of an indicator extends along the entire length of a |
| > gradua­tion, that portion of the index of the indicator that may be  |
| > brought into coincidence with the graduation shall be of the same   |
| > width throughout the length of the index that coincides with the    |
| > graduation.                                                         |
| >                                                                     |
| > **S.1.4.4. Clearance. -** The clearance between the index of an     |
| > indicator and the graduations shall in no case be more than 1.5 mm  |
| > (0.06 in).                                                          |
| >                                                                     |
| > **S.1.4.5. Parallax. -** Parallax effects shall be reduced to the   |
| > practicable minimum.                                                |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.1.4.**                   |
+-----------------------------------------------------------------------+

As with requirements relating to graduations, a visual inspection of the
dial should be sufficient to determine conformance in most cases,
especially on a dial that has been type evaluated. The one dimension
that you may wish to check is the clearance between the index of the
indicator and the graduations, since this will have a major impact on
parallax effects. If the indicator is bent even by a small amount during
assembly (or re-assembly), this clearance may be significantly altered.
The scale face cover must be removed to make this check, but it can then
be easily accomplished, either with a conventional gap gauge or with a
special blade gauge that is used by scale service companies and
manufacturers.

Finally, a requirement in the Scales Code (S.1.7.) limits the indicating
or recording range of a weighing device to 105 percent of the scale
capacity. In addition, the total value of the applied counterforce from
units weights or weight ranges in place or in effect must be included in
any indicated or recorded value.

+-----------------------------------------------------------------------+
| **S.1.7. Capacity Indication, Weight Ranges, and Unit Weights.** -    |
|                                                                       |
| > \(a\) Gross Capacity. An indicating or recording element shall not  |
| > display nor record any values when the total platform load (not     |
| > counting the initial dead load that has been canceled by an initial |
| > zero-setting mechanism) is in excess of 105 percent of scale        |
| > capacity.                                                           |
| >                                                                     |
| > \(b\) Capacity Indication. Electronic computing scales (excluding   |
| > postal scales and weight classifiers) shall neither display nor     |
| > record a gross or net weight in excess of scale capacity plus 9 d.  |
|                                                                       |
| The total value of weight ranges and of unit weights in effect or in  |
| place at any time shall automatically be accounted for on the reading |
| face and on any recorded representation.                              |
|                                                                       |
| This requirement does not apply to: (1) single-revolution dial        |
| scales, (2) multi-revolution dial scales not equipped with unit       |
| weights, (3) scales equipped with two or more weighbeams, nor (4)     |
| devices that indicate mathematically derived totalized values.        |
|                                                                       |
| *\[Nonretroactive as of January 1, 1993\]*                            |
|                                                                       |
| (Amended 1990, 1992, and 1995)                                        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.1.7.**                   |
+-----------------------------------------------------------------------+

The first part of this requirement is intended to prevent the improper
use of a scale to weigh loads in excess of its nominal capacity (a
**user requirement**, UR.3.2., which states the basic limitation, will
be discussed further below). Though included in test procedures outlined
in Chapter 6, it is often not possible to test this design feature under
field conditions on vehicle scales because sufficient test weights are
not available.

The last part of the requirement has specific applicability to large
capacity scales with dial indicators. The unit weight or weight range
indication is generated separately from the dial indication, but is
necessary in order to make an accurate reading; therefore, the total
value of unit weights and weight ranges in place or in effect is
required to be accounted for on the reading face of the dial and on any
recorded representation.

**Damping Means**

Scales are required to have an effective means for limiting the number
of scale oscillations. Appropriate **damping** is typically 3 to 5
oscillations. On mechanical vehicle and axle-load scales, damping is
nearly always achieved by using a fluid dashpot.

  -----------------------------------------------------------------------
  **S.2.5. Damping Means.** - An automatic-indicating scale and a balance
  indicator shall be equipped with effective means to damp oscillations
  and to bring the indicating elements quickly to rest.

  NIST Handbook 44, Scales Code, Paragraph S.2.5.
  -----------------------------------------------------------------------

During the Increasing-Load Test of a dial scale, you will check the
scale at different points within its weighing range. During that test,
be sure that the dashpot is operating over the full range of indication.
Since dust and dirt will settle to the bottom of the dashpot, a scale
may work well for small loads but may bind when large loads are applied.
The scale is to be maintained in proper operating condition over its
entire weighing range.

If the dashpot is not working properly, you should ask the operator or
the owner to make the necessary adjustments. If the dashpot cannot be
properly adjusted, the scale cannot be approved until this condition is
corrected.

Electronic digital indicating vehicle and axle-load scales are either
mechanical scale systems with electronic digital indicators or are
totally electronic scale systems. Either of the two types must be
effectively damped to limit the number of oscillations before coming to
rest. This is most often achieved by use of electronic damping in the
indicator, and dashpot adjustment is not usually a concern.

+-----------------------------------------------------------------------+
| **S.2.5.1. Digital Indicating Elements.** - Digital indicating        |
| elements equipped with recording elements shall be equipped with      |
| effective means to permit the recording of weight values only when    |
| the indication is stable within:                                      |
|                                                                       |
| > \(a\) plus or minus 3 scale divisions for scales of more than 2000  |
| > kg (5000 lb) capacity in service prior to January 1, 1981, hopper   |
| > (other than grain hopper) scales with a capacity exceeding 22 000   |
| > kg (50 000 lb), and for all vehicle, axle load, livestock, and      |
| > railway track scales;                                               |
| >                                                                     |
| > \(b\) plus or minus 1 scale division for all other scales.          |
|                                                                       |
| The values recorded shall be within applicable tolerances.            |
|                                                                       |
| (Amended 1995)                                                        |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraph S.2.5.1.                     |
+-----------------------------------------------------------------------+

However, it is sometimes difficult to determine when the oscillation of
a digital indicator has become stable. To prevent a value being recorded
while the indication is still unstable, electronic devices equipped with
printers must have an automatic means to prevent printing of weight
values unless the indication is stable within plus or minus 3 scale
divisions for all vehicle and axle-load scales. During the Test section
of this module, you will test to determine that the printer does not
operate unless the scale is stable. The method of conducting that test
will be described in Chapter 6.

**Suitability**

It is the scale owner's responsibility to choose a legal and suitable
device for a given commercial application, particularly with regard to
the indicating and recording elements that are the primary basis for a
commercial transaction. You have already learned about the general
requirement relating to this responsibility, which is set forth in UR.1.
(described under **Scale Divisions**, above).

A subparagraph of UR.1., UR.1.1.(a), includes a table (Table 7a), which
associates types of scales and scale applications with the accuracy
classes that are required to be designated on all scales manufactured
after January 1, 1986. Requirements for scale divisions on unmarked
scales are addressed under UR.1.1.(b) and Table 7b, which were discussed
earlier in this chapter.

+-----------------------------------------------------------------------+
| **UR.1.1. General.**                                                  |
|                                                                       |
| > \(a\) For devices marked with a class designation, the typical      |
| > class or type of device for particular weighing applications is     |
| > shown in Table 7a.                                                  |
|                                                                       |
| For devices not marked with a class designation, Table 7b applies.    |
|                                                                       |
| +------+----------------------------------------------------------+   |
| | **T  |                                                          |   |
| | able |                                                          |   |
| | 7    |                                                          |   |
| | a.** |                                                          |   |
| |      |                                                          |   |
| | *    |                                                          |   |
| | *Typ |                                                          |   |
| | ical |                                                          |   |
| | C    |                                                          |   |
| | lass |                                                          |   |
| | or   |                                                          |   |
| | Type |                                                          |   |
| | of   |                                                          |   |
| | De   |                                                          |   |
| | vice |                                                          |   |
| | for  |                                                          |   |
| | Weig |                                                          |   |
| | hing |                                                          |   |
| | Oper |                                                          |   |
| | atio |                                                          |   |
| | ns** |                                                          |   |
| +------+----------------------------------------------------------+   |
| | C    | Weighing Application or Scale Type                       |   |
| | lass |                                                          |   |
| +------+----------------------------------------------------------+   |
| | I    | Precision laboratory weighing                            |   |
| +------+----------------------------------------------------------+   |
| | II   | Laboratory weighing, precious metals and gem weighing,   |   |
| |      | grain test scales                                        |   |
| +------+----------------------------------------------------------+   |
| | III  | All commercial weighing not otherwise specified, grain   |   |
| |      | test scales, retail pre­cious met­als and semi-precious    |   |
| |      | gem weighing, animal scales, postal scales, scales used  |   |
| |      | to deter­mine laun­dry charges, and vehicle on-board       |   |
| |      | weighing systems                                         |   |
| +------+----------------------------------------------------------+   |
| | III  | Vehicle, axle‑load, livestock, railway track scales,     |   |
| | L    | crane, hopper (other than grain hop­per) scales, and      |   |
| |      | vehicle on-board weighing systems                        |   |
| +------+----------------------------------------------------------+   |
| | IIII | Wheel-load weighers and portable axle-load weighers used |   |
| |      | for highway weight enforcement                           |   |
| +------+----------------------------------------------------------+   |
| | N    |                                                          |   |
| | ote: |                                                          |   |
| | A    |                                                          |   |
| | s    |                                                          |   |
| | cale |                                                          |   |
| | with |                                                          |   |
| | a    |                                                          |   |
| | hi   |                                                          |   |
| | gher |                                                          |   |
| | accu |                                                          |   |
| | racy |                                                          |   |
| | c    |                                                          |   |
| | lass |                                                          |   |
| | than |                                                          |   |
| | that |                                                          |   |
| | s    |                                                          |   |
| | peci |                                                          |   |
| | fied |                                                          |   |
| | as   |                                                          |   |
| | \"t  |                                                          |   |
| | ypic |                                                          |   |
| | al\" |                                                          |   |
| | may  |                                                          |   |
| | be   |                                                          |   |
| | u    |                                                          |   |
| | sed. |                                                          |   |
| |      |                                                          |   |
| | (Ame |                                                          |   |
| | nded |                                                          |   |
| | 1    |                                                          |   |
| | 985, |                                                          |   |
| | 1    |                                                          |   |
| | 986, |                                                          |   |
| | 1    |                                                          |   |
| | 987, |                                                          |   |
| | 1    |                                                          |   |
| | 988, |                                                          |   |
| | 1    |                                                          |   |
| | 992, |                                                          |   |
| | and  |                                                          |   |
| | 1    |                                                          |   |
| | 995) |                                                          |   |
| +------+----------------------------------------------------------+   |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraph UR.1.1. and Table 7a         |
+-----------------------------------------------------------------------+

As explained earlier in this chapter (under **Scale Divisions**), the
Scales Code paragraph S.5.2. and Table 3 specify the maximum and minimum
number of scale divisions for scales marked with an accuracy class. In
order to be suitable, a vehicle or axle-load scale marked accuracy class
III L must have no less than 2,000 scale divisions and no more than
10,000 scale divisions.

A wide variety of indicating and recording devices have been developed
to meet the needs of the device user. The device manufacturer has
considerable latitude to incorporate various device features or
capabilities, provided the customer is given information necessary to
understand a transaction, and provided the features do not facilitate
fraud.

A device must not only be suitable for its application based upon the
accuracy class, the scale capacity, and the division size; the features
that are operational on the device must also be appropriate for the
application. Although it is not possible to give a comprehensive list of
specific applications and associated features that are suitable or not
suitable, some of the following common examples should illustrate the
basic approach to assessing suitability.

-   If the system has a "training mode," in which tickets can be issued,
    an indication should appear on the tickets printed in that mode that
    they are not valid weigh tickets.

-   Neither push-button tare nor keyboard tare features should interact
    with a weigh-in/weigh-out feature on a vehicle scale. This prevents
    tare from effectively being taken twice or changed manually after
    the weigh-in/weigh-out feature is used. With a weigh-in/weigh-out
    feature, vehicle weight before loading or unloading is stored in
    computer memory and then recalled when the vehicle is weighed again
    and used to determine the net weight. If the weigh-in/weigh-out
    feature is operated through a computer that is linked to the
    indicating element of the scale, the scale indicator (and any
    recording device that is not linked to the computer) should register
    only gross weight values.

-   Unattended vehicle scales:

    -   must indicate the zero balance condition;

    -   may indicate plus or minus a few hundred pounds to make it
        possible for the driver to tell if the scale is in a zero
        balance condition prior to use and then blank the display to
        prevent the scale from being used to get a vehicle weight
        without payment or authorization;

    -   must have a weight display for the vehicle driver;

    -   must be equipped with a push-button zero feature that allows the
        driver to zero the scale;

    -   may go through the zero-setting process automatically when the
        vehicle driver inserts a card into a card reader or makes
        payment; and

    -   if equipped with printers, must either make the ticket available
        at the scale or provide instructions at the scale describing how
        the ticket can be obtained.

When assessing the appropriateness or suitability of a specific device
for a particular application, ask yourself:

-   Does this scale make sense in this situation?

-   Does the device meet the requirements of this use?

-   Is the environment appropriate for this scale?

Remember that human operators, other personnel, buyers, sellers, and
others are part of the environment in which the device is operated.

Three additional user requirements (UR.3.1., UR.3.2., and UR.3.3.)
relate specifically to the suitability of a scale. As with other user
requirements, it is often not possible to determine whether there is
strict conformance during a field examination. However, these
requirements provide guidelines that can be used in assessing
suitability. For example, a scale used to weigh loads that exceed its
nominal capacity is obviously not suitable for its application.
Paragraph UR 3.2. of the Scales Code specifically prohibits this
practice, and thereby establishes a criterion of suitability.

NIST Handbook 44 paragraph UR.3.2.1. includes additional limitations on
the maximum loading for a vehicle scale. This paragraph prohibits a
vehicle scale from being used to weigh loads that exceed the maximum
load capacity of the scale's span. These maximums are specified in an
accompanying table, Table UR.3.2.1. according to the scale's
concentrated load capacity (CLC) and the number of axles on the vehicle
being weighed in a given span. Step-by-step instructions are included at
the beginning of Table UR.3.2.1. explaining how to determine whether or
not a scale is suitable for use in weighing a specific vehicle.

+-----------------------------------------------------------------------+
| **UR.3.2. Maximum Load.** ‑ A scale shall not be used to weigh a load |
| of more than the nominal capacity of the scale.                       |
|                                                                       |
| **UR.3.2.1. Maximum Loading for Vehicle Scales. -** A vehicle scale   |
| shall not be used to weigh loads exceeding the maximum load capacity  |
| of its span as specified in Table UR.3.2.1.                           |
|                                                                       |
| (Added 1996)                                                          |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraphs UR.3.2. and UR.3.2.1.       |
+-----------------------------------------------------------------------+

+------------+------+------+------+------+------+------+------+------+
| **Table    |      |      |      |      |      |      |      |      |
| U          |      |      |      |      |      |      |      |      |
| R.3.2.1.** |      |      |      |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
| **Span     |      |      |      |      |      |      |      |      |
| Maximum    |      |      |      |      |      |      |      |      |
| Load**     |      |      |      |      |      |      |      |      |
+============+======+======+======+======+======+======+======+======+
| **Distance | **R  |      |      |      |      |      |      |      |
| in feet    | atio |      |      |      |      |      |      |      |
| between    | of   |      |      |      |      |      |      |      |
| the        | CLC  |      |      |      |      |      |      |      |
| extremes   | to   |      |      |      |      |      |      |      |
| of any two | max  |      |      |      |      |      |      |      |
| or more    | imum |      |      |      |      |      |      |      |
| c          | Load |      |      |      |      |      |      |      |
| onsecutive | ("r" |      |      |      |      |      |      |      |
| axles**    | fac  |      |      |      |      |      |      |      |
|            | tor) |      |      |      |      |      |      |      |
|            | car  |      |      |      |      |      |      |      |
|            | ried |      |      |      |      |      |      |      |
|            | on   |      |      |      |      |      |      |      |
|            | a    |      |      |      |      |      |      |      |
|            | ny** |      |      |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
|            | **g  |      |      |      |      |      |      |      |
|            | roup |      |      |      |      |      |      |      |
|            | of 2 |      |      |      |      |      |      |      |
|            | or   |      |      |      |      |      |      |      |
|            | more |      |      |      |      |      |      |      |
|            | con  |      |      |      |      |      |      |      |
|            | secu |      |      |      |      |      |      |      |
|            | tive |      |      |      |      |      |      |      |
|            | axle |      |      |      |      |      |      |      |
|            | s.** |      |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
|            | **2  | **3  | **4  | **5  | **6  | **7  | **8  | **9  |
|            | axl  | axl  | axl  | axl  | axl  | axl  | axl  | axl  |
|            | es** | es** | es** | es** | es** | es** | es** | es** |
+------------+------+------+------+------+------+------+------+------+
| 4**^1^**   | 1    |      | I    |      |      |      |      |      |
|            | .000 |      | NSTR |      |      |      |      |      |
|            |      |      | UCTI |      |      |      |      |      |
|            |      |      | ONS: |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
|            |      |      | 1\.  |      |      |      |      |      |
|            |      |      | D    |      |      |      |      |      |
|            |      |      | eter |      |      |      |      |      |
|            |      |      | mine |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | sca  |      |      |      |      |      |
|            |      |      | le's |      |      |      |      |      |
|            |      |      | CLC. |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
|            |      |      | 2\.  |      |      |      |      |      |
|            |      |      | C    |      |      |      |      |      |
|            |      |      | ount |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | nu   |      |      |      |      |      |
|            |      |      | mber |      |      |      |      |      |
|            |      |      | of   |      |      |      |      |      |
|            |      |      | a    |      |      |      |      |      |
|            |      |      | xles |      |      |      |      |      |
|            |      |      | on   |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | veh  |      |      |      |      |      |
|            |      |      | icle |      |      |      |      |      |
|            |      |      | in a |      |      |      |      |      |
|            |      |      | g    |      |      |      |      |      |
|            |      |      | iven |      |      |      |      |      |
|            |      |      | span |      |      |      |      |      |
|            |      |      | and  |      |      |      |      |      |
|            |      |      | d    |      |      |      |      |      |
|            |      |      | eter |      |      |      |      |      |
|            |      |      | mine |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | dist |      |      |      |      |      |
|            |      |      | ance |      |      |      |      |      |
|            |      |      | in   |      |      |      |      |      |
|            |      |      | feet |      |      |      |      |      |
|            |      |      | bet  |      |      |      |      |      |
|            |      |      | ween |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | f    |      |      |      |      |      |
|            |      |      | irst |      |      |      |      |      |
|            |      |      | and  |      |      |      |      |      |
|            |      |      | last |      |      |      |      |      |
|            |      |      | axle |      |      |      |      |      |
|            |      |      | in   |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | s    |      |      |      |      |      |
|            |      |      | pan. |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
|            |      |      | 3\.  |      |      |      |      |      |
|            |      |      | Mult |      |      |      |      |      |
|            |      |      | iply |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | CLC  |      |      |      |      |      |
|            |      |      | by   |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | c    |      |      |      |      |      |
|            |      |      | orre |      |      |      |      |      |
|            |      |      | spon |      |      |      |      |      |
|            |      |      | ding |      |      |      |      |      |
|            |      |      | mu   |      |      |      |      |      |
|            |      |      | ltip |      |      |      |      |      |
|            |      |      | lier |      |      |      |      |      |
|            |      |      | in   |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | tabl |      |      |      |      |      |
|            |      |      | e\*. |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
|            |      |      | 4\.  |      |      |      |      |      |
|            |      |      | The  |      |      |      |      |      |
|            |      |      | r    |      |      |      |      |      |
|            |      |      | esul |      |      |      |      |      |
|            |      |      | ting |      |      |      |      |      |
|            |      |      | nu   |      |      |      |      |      |
|            |      |      | mber |      |      |      |      |      |
|            |      |      | is   |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | scal |      |      |      |      |      |
|            |      |      | e\'s |      |      |      |      |      |
|            |      |      | max  |      |      |      |      |      |
|            |      |      | imum |      |      |      |      |      |
|            |      |      | conc |      |      |      |      |      |
|            |      |      | entr |      |      |      |      |      |
|            |      |      | ated |      |      |      |      |      |
|            |      |      | load |      |      |      |      |      |
|            |      |      | for  |      |      |      |      |      |
|            |      |      | a    |      |      |      |      |      |
|            |      |      | si   |      |      |      |      |      |
|            |      |      | ngle |      |      |      |      |      |
|            |      |      | span |      |      |      |      |      |
|            |      |      | b    |      |      |      |      |      |
|            |      |      | ased |      |      |      |      |      |
|            |      |      | on   |      |      |      |      |      |
|            |      |      | the  |      |      |      |      |      |
|            |      |      | veh  |      |      |      |      |      |
|            |      |      | icle |      |      |      |      |      |
|            |      |      | co   |      |      |      |      |      |
|            |      |      | nfig |      |      |      |      |      |
|            |      |      | urat |      |      |      |      |      |
|            |      |      | ion. |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
|            |      |      | \    |      |      |      |      |      |
|            |      |      | *See |      |      |      |      |      |
|            |      |      | note |      |      |      |      |      |
|            |      |      | and  |      |      |      |      |      |
|            |      |      | for  |      |      |      |      |      |
|            |      |      | mula |      |      |      |      |      |
|            |      |      | on   |      |      |      |      |      |
|            |      |      | next |      |      |      |      |      |
|            |      |      | p    |      |      |      |      |      |
|            |      |      | age. |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 5**^1^**   | 1    |      |      |      |      |      |      |      |
|            | .000 |      |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 6**^1^**   | 1    |      |      |      |      |      |      |      |
|            | .000 |      |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 7**^1^**   | 1    |      |      |      |      |      |      |      |
|            | .000 |      |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 8 and      | 1    | 1    |      |      |      |      |      |      |
| l          | .000 | .000 |      |      |      |      |      |      |
| ess**^1^** |      |      |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| More than  | 1    | 1    |      |      |      |      |      |      |
| 8**^1^**   | .118 | .235 |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 9          | 1    | 1    |      |      |      |      |      |      |
|            | .147 | .257 |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 10         | 1    | 1    |      |      |      |      |      |      |
|            | .176 | .279 |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 11         | 1    | 1    |      |      |      |      |      |      |
|            | .206 | .301 |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 12         | 1    | 1    | 1    | 1    |      |      |      |      |
|            | .235 | .324 | .471 | .632 |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 13         | 1    | 1    | 1    | 1    |      |      |      |      |
|            | .265 | .346 | .490 | .651 |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 14         | 1    | 1    | 1    | 1    |      |      |      |      |
|            | .294 | .368 | .510 | .669 |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 15         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .324 | .390 | .529 | .688 | .853 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 16         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .353 | .412 | .549 | .706 | .871 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 17         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .382 | .434 | .569 | .724 | .888 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 18         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .412 | .456 | .588 | .743 | .906 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 19         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .441 | .478 | .608 | .761 | .924 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 20         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .471 | .500 | .627 | .779 | .941 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 21         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .500 | .522 | .647 | .798 | .959 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 22         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .529 | .544 | .667 | .816 | .976 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 23         | 1    | 1    | 1    | 1    | 1    |      |      |      |
|            | .559 | .566 | .686 | .835 | .994 |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| 24         | 1    | 1    | 1    | 1    | 2    | 2    |      |      |
|            | .588 | .588 | .706 | .853 | .012 | .176 |      |      |
+------------+------+------+------+------+------+------+------+------+
| 25         | 1    | 1    | 1    | 1    | 2    | 2    |      |      |
|            | .618 | .610 | .725 | .871 | .029 | .194 |      |      |
+------------+------+------+------+------+------+------+------+------+
| 26         |      | 1    | 1    | 1    | 2    | 2    |      |      |
|            |      | .632 | .745 | .890 | .047 | .211 |      |      |
+------------+------+------+------+------+------+------+------+------+
| 27         |      | 1    | 1    | 1    | 2    | 2    |      |      |
|            |      | .654 | .765 | .908 | .065 | .228 |      |      |
+------------+------+------+------+------+------+------+------+------+
| 28         |      | 1    | 1    | 1    | 2    | 2    | 2    |      |
|            |      | .676 | .784 | .926 | .082 | .245 | .412 |      |
+------------+------+------+------+------+------+------+------+------+
| 29         |      | 1    | 1    | 1    | 2    | 2    | 2    |      |
|            |      | .699 | .804 | .945 | .100 | .262 | .429 |      |
+------------+------+------+------+------+------+------+------+------+
| 30         |      | 1    | 1    | 1    | 2    | 2    | 2    |      |
|            |      | .721 | .824 | .963 | .118 | .279 | .445 |      |
+------------+------+------+------+------+------+------+------+------+
| 31         |      | 1    | 1    | 1    | 2    | 2    | 2    |      |
|            |      | .743 | .843 | .982 | .135 | .297 | .462 |      |
+------------+------+------+------+------+------+------+------+------+
| 32         |      | 1    | 1    | 2    | 2    | 2    | 2    | 2    |
|            |      | .765 | .863 | .000 | .153 | .314 | .479 | .647 |
+------------+------+------+------+------+------+------+------+------+
| 33         |      |      | 1    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .882 | .018 | .171 | .331 | .496 | .664 |
+------------+------+------+------+------+------+------+------+------+
| 34         |      |      | 1    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .902 | .037 | .188 | .348 | .513 | .680 |
+------------+------+------+------+------+------+------+------+------+
| 35         |      |      | 1    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .922 | .055 | .206 | .365 | .529 | .697 |
+------------+------+------+------+------+------+------+------+------+
| 36         |      |      | 2.00 | 2    | 2    | 2    | 2    | 2    |
|            |      |      | 0^2^ | .074 | .224 | .382 | .546 | .713 |
+------------+------+------+------+------+------+------+------+------+
| 37         |      |      | 2.00 | 2    | 2    | 2    | 2    | 2    |
|            |      |      | 0^2^ | .092 | .241 | .400 | .563 | .730 |
+------------+------+------+------+------+------+------+------+------+
| 38         |      |      | 2.00 | 2    | 2    | 2    | 2    | 2    |
|            |      |      | 0^2^ | .110 | .259 | .417 | .580 | .746 |
+------------+------+------+------+------+------+------+------+------+
| 39         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .000 | .129 | .276 | .434 | .597 | .763 |
+------------+------+------+------+------+------+------+------+------+
| 40         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .020 | .147 | .294 | .451 | .613 | .779 |
+------------+------+------+------+------+------+------+------+------+
| 41         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .039 | .165 | .312 | .468 | .630 | .796 |
+------------+------+------+------+------+------+------+------+------+
| 42         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .059 | .184 | .329 | .485 | .647 | .813 |
+------------+------+------+------+------+------+------+------+------+
| 43         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .078 | .202 | .347 | .502 | .664 | .829 |
+------------+------+------+------+------+------+------+------+------+
| 44         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .098 | .221 | .365 | .520 | .681 | .846 |
+------------+------+------+------+------+------+------+------+------+
| 45         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .118 | .239 | .382 | .537 | .697 | .862 |
+------------+------+------+------+------+------+------+------+------+
| 46         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .137 | .257 | .400 | .554 | .714 | .879 |
+------------+------+------+------+------+------+------+------+------+
| 47         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .157 | .276 | .418 | .571 | .731 | .895 |
+------------+------+------+------+------+------+------+------+------+
| 48         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .176 | .294 | .435 | .588 | .748 | .912 |
+------------+------+------+------+------+------+------+------+------+
| 49         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .196 | .313 | .453 | .605 | .765 | .928 |
+------------+------+------+------+------+------+------+------+------+
| 50         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .216 | .331 | .471 | .623 | .782 | .945 |
+------------+------+------+------+------+------+------+------+------+
| 51         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .235 | .349 | .488 | .640 | .798 | .961 |
+------------+------+------+------+------+------+------+------+------+
| 52         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .255 | .368 | .506 | .657 | .815 | .978 |
+------------+------+------+------+------+------+------+------+------+
| 53         |      |      | 2    | 2    | 2    | 2    | 2    | 2    |
|            |      |      | .275 | .386 | .524 | .674 | .832 | .994 |
+------------+------+------+------+------+------+------+------+------+
| 54         |      |      | 2    | 2    | 2    | 2    | 2    | 3    |
|            |      |      | .294 | .404 | .541 | .691 | .849 | .011 |
+------------+------+------+------+------+------+------+------+------+
| 55         |      |      | 2    | 2    | 2    | 2    | 2    | 3    |
|            |      |      | .314 | .423 | .559 | .708 | .866 | .028 |
+------------+------+------+------+------+------+------+------+------+
| 56         |      |      | 2    | 2    | 2    | 2    | 2    | 3    |
|            |      |      | .333 | .441 | .576 | .725 | .882 | .044 |
+------------+------+------+------+------+------+------+------+------+
| 57         |      |      | 2.35 | 2    | 2    | 2    | 2    | 3    |
|            |      |      | 3^3^ | .460 | .594 | .742 | .899 | .061 |
+------------+------+------+------+------+------+------+------+------+
| 58         |      |      |      | 2    | 2    | 2    | 2    | 3    |
|            |      |      |      | .478 | .612 | .760 | .916 | .077 |
+------------+------+------+------+------+------+------+------+------+
| 59         |      |      |      | 2    | 2    | 2    | 2    | 3    |
|            |      |      |      | .496 | .629 | .777 | .933 | .094 |
+------------+------+------+------+------+------+------+------+------+
| 60         |      |      |      | 2    | 2    | 2    | 2    | 3    |
|            |      |      |      | .515 | .647 | .794 | .950 | .110 |
+------------+------+------+------+------+------+------+------+------+
| \*Note:    |      |      |      |      |      |      |      |      |
| This table |      |      |      |      |      |      |      |      |
| was        |      |      |      |      |      |      |      |      |
| developed  |      |      |      |      |      |      |      |      |
| based upon |      |      |      |      |      |      |      |      |
| the        |      |      |      |      |      |      |      |      |
| following  |      |      |      |      |      |      |      |      |
| formula.   |      |      |      |      |      |      |      |      |
| Values may |      |      |      |      |      |      |      |      |
| be rounded |      |      |      |      |      |      |      |      |
| in some    |      |      |      |      |      |      |      |      |
| cases for  |      |      |      |      |      |      |      |      |
| ease of    |      |      |      |      |      |      |      |      |
| use.       |      |      |      |      |      |      |      |      |
| $          |      |      |      |      |      |      |      |      |
| W = r \tim |      |      |      |      |      |      |      |      |
| es \text{5 |      |      |      |      |      |      |      |      |
| 00}\left\l |      |      |      |      |      |      |      |      |
| brack \lef |      |      |      |      |      |      |      |      |
| t( \frac{\ |      |      |      |      |      |      |      |      |
| text{LN}}{ |      |      |      |      |      |      |      |      |
| N - 1} \ri |      |      |      |      |      |      |      |      |
| ght)\text{ |      |      |      |      |      |      |      |      |
|   } + \tex |      |      |      |      |      |      |      |      |
| t{  }\text |      |      |      |      |      |      |      |      |
| {12}N\text |      |      |      |      |      |      |      |      |
| {  } + \te |      |      |      |      |      |      |      |      |
| xt{  }\tex |      |      |      |      |      |      |      |      |
| t{36} \rig |      |      |      |      |      |      |      |      |
| ht\rbrack$ |      |      |      |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
| ^1^ Tandem |      |      |      |      |      |      |      |      |
| Axle       |      |      |      |      |      |      |      |      |
| Weight.    |      |      |      |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
| ^2^        |      |      |      |      |      |      |      |      |
| E          |      |      |      |      |      |      |      |      |
| xception - |      |      |      |      |      |      |      |      |
| These      |      |      |      |      |      |      |      |      |
| values in  |      |      |      |      |      |      |      |      |
| the third  |      |      |      |      |      |      |      |      |
| column     |      |      |      |      |      |      |      |      |
| correspond |      |      |      |      |      |      |      |      |
| to the     |      |      |      |      |      |      |      |      |
| maximum    |      |      |      |      |      |      |      |      |
| loads in   |      |      |      |      |      |      |      |      |
| which the  |      |      |      |      |      |      |      |      |
| inner      |      |      |      |      |      |      |      |      |
| bridge     |      |      |      |      |      |      |      |      |
| dimensions |      |      |      |      |      |      |      |      |
| of 36, 37, |      |      |      |      |      |      |      |      |
| and 38     |      |      |      |      |      |      |      |      |
| feet are   |      |      |      |      |      |      |      |      |
| considered |      |      |      |      |      |      |      |      |
| to be      |      |      |      |      |      |      |      |      |
| equivalent |      |      |      |      |      |      |      |      |
| to 39      |      |      |      |      |      |      |      |      |
| feet. This |      |      |      |      |      |      |      |      |
| allows a   |      |      |      |      |      |      |      |      |
| weight of  |      |      |      |      |      |      |      |      |
| 68 000 lb  |      |      |      |      |      |      |      |      |
| on axles 2 |      |      |      |      |      |      |      |      |
| through 5. |      |      |      |      |      |      |      |      |
|            |      |      |      |      |      |      |      |      |
| ^3^        |      |      |      |      |      |      |      |      |
| C          |      |      |      |      |      |      |      |      |
| orresponds |      |      |      |      |      |      |      |      |
| to the     |      |      |      |      |      |      |      |      |
| Interstate |      |      |      |      |      |      |      |      |
| Gross      |      |      |      |      |      |      |      |      |
| Weight     |      |      |      |      |      |      |      |      |
| Limit.     |      |      |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+
| NIST       |      |      |      |      |      |      |      |      |
| Handbook   |      |      |      |      |      |      |      |      |
| 44, Scales |      |      |      |      |      |      |      |      |
| Code,      |      |      |      |      |      |      |      |      |
| Table      |      |      |      |      |      |      |      |      |
| UR.3.2.1.  |      |      |      |      |      |      |      |      |
+------------+------+------+------+------+------+------+------+------+

It is also an inappropriate use of a scale to regularly weigh loads that
are lighter than those for which the scale was designed. This practice
can produce large errors. Handbook 44 recommends that scales marked
accuracy class III L not be used to weigh loads of less than 50 scale
divisions. For example, if a scale marked class III L has a scale
division value of 20 lb, the minimum recommended load is 50 d x 20 lb =
1,000 lb. If the scale has a scale division value of 50 lb, the minimum
recommended load is 2,500 lb (50 d x 50 lb).

+-----------------------------------------------------------------------+
| **UR.3.1. Recommended Minimum Load.** ‑ A recommended minimum load is |
| specified in Table 8 since the use of a device to weigh light loads   |
| is likely to result in relatively large errors.                       |
|                                                                       |
| +-------------------+---------------------+----------------------+    |
| | **Table 8.**      |                     |                      |    |
| |                   |                     |                      |    |
| | **Recommended     |                     |                      |    |
| | Minimum Load**    |                     |                      |    |
| +-------------------+---------------------+----------------------+    |
| | Class             | Value of scale      | Re­com­men­ded mini­mum  |    |
| |                   | divi­sion            | load                 |    |
| |                   |                     |                      |    |
| |                   | (d or e\*)          | (d or e\*)           |    |
| +-------------------+---------------------+----------------------+    |
| | I                 | equal to or gre­ater | 100                  |    |
| |                   | than 0.001 g        |                      |    |
| +-------------------+---------------------+----------------------+    |
| | II                | 0.001 g to 0.05 g,  | 20                   |    |
| |                   | in­clu­sive           |                      |    |
| +-------------------+---------------------+----------------------+    |
| |                   | equal to or gre­ater | 50                   |    |
| |                   | than 0.1 g          |                      |    |
| +-------------------+---------------------+----------------------+    |
| | III               | All\*\*             | 20                   |    |
| +-------------------+---------------------+----------------------+    |
| | III L             | All                 | 50                   |    |
| +-------------------+---------------------+----------------------+    |
| | IIII              | All                 | 10                   |    |
| +-------------------+---------------------+----------------------+    |
| | \*For Class I and |                     |                      |    |
| | II devices        |                     |                      |    |
| | equipped with     |                     |                      |    |
| | auxiliary read­ing |                     |                      |    |
| | means (i.e., a    |                     |                      |    |
| | rider, a vernier, |                     |                      |    |
| | or a least        |                     |                      |    |
| | signifi­cant       |                     |                      |    |
| | decimal           |                     |                      |    |
| | dif­ferentiated by |                     |                      |    |
| | size, shape or    |                     |                      |    |
| | color), the value |                     |                      |    |
| | of the            |                     |                      |    |
| | verifi­ca­tion      |                     |                      |    |
| | scale division    |                     |                      |    |
| | \"e\" is the      |                     |                      |    |
| | value of the      |                     |                      |    |
| | scale divi­sion    |                     |                      |    |
| | im­medi­ately       |                     |                      |    |
| | preceding the     |                     |                      |    |
| | auxil­ia­ry means.  |                     |                      |    |
| | For Class III and |                     |                      |    |
| | IIII devices the  |                     |                      |    |
| | value of \"e\" is |                     |                      |    |
| | speci­fied by the  |                     |                      |    |
| | man­ufac­turer as   |                     |                      |    |
| | marked on the     |                     |                      |    |
| | device; \"e\"     |                     |                      |    |
| | must be less than |                     |                      |    |
| | or equal to       |                     |                      |    |
| | \"d.\"            |                     |                      |    |
| |                   |                     |                      |    |
| | \*\*A minimum     |                     |                      |    |
| | load of 10 d is   |                     |                      |    |
| | recommended for a |                     |                      |    |
| | weight classifier |                     |                      |    |
| | marked in         |                     |                      |    |
| | accordance with a |                     |                      |    |
| | statement         |                     |                      |    |
| | identifying its   |                     |                      |    |
| | use for special   |                     |                      |    |
| | applications.     |                     |                      |    |
| |                   |                     |                      |    |
| | (Amended 1990)    |                     |                      |    |
| +-------------------+---------------------+----------------------+    |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraph UR3.1. and Table 8           |
+-----------------------------------------------------------------------+

For example, if a scale marked class III L has a scale division value of
20 lb, the minimum recommended load is 50 d x 20 lb =1,000 lb. In
contrast, if the scale has a scale division value of 50 lb, the minimum
recommended load is 2,500 lb (50 d x 50 lb).

Note that a separate requirement, UR.3.7., discussed below under
**Maintenance, Use, and Environmental Factors**, makes the
50-scale-division minimum net load a requirement on vehicle scales other
than those used to weigh scrap metal for recycling, in which case a
minimum net load of 10d is required. Another requirement, UR.3.8., also
discussed in that section, prohibits the use of a scale with a scale
division of 5 lb or less for weighing net loads smaller that 500d (this
requirement applies to scales used to measure livestock).

As has been said, the practice of split weighing, that is, determining
the gross weight of a vehicle by using an axle-load scale to
successively weigh each axle and then summing the separate weighings, is
inappropriate, and can result in large errors in measurement. The Scales
Code specifically requires single-draft weighing of vehicles.

+-----------------------------------------------------------------------+
| **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 determined by      |
| > uncoupling the various elements (tractor, semitrailer, trailer),    |
| > 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.                                                     |
|                                                                       |
| **Note:** This paragraph does not apply to highway-law-enforcement    |
| scales and scales used for the collection of statistical data.        |
|                                                                       |
| (Added 1992)                                                          |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraph UR.3.3.                      |
+-----------------------------------------------------------------------+

Note that a coupled vehicle may be uncoupled and a gross weight
determined by summing the separate weights of the components, provided
that each component is weighed as a single draft. In addition,
subparagraph (b) recognizes multi-scale weighing as an appropriate
method.

**Customer Readability --- If Applicable**

Vehicle scales are sometimes used in direct sales, where both buyer and
seller are present when the weight of the vehicle is determined. In a
direct sale situation, the customer must be provided with enough
information to understand the transaction and to detect accidental or
intentional errors that might occur. The customer's presence limits the
opportunities for some fraudulent practices, but it is also the
customer's responsibility to observe the measurement process.

The customer must be able to verify:

-   that the scale is at zero before weighing;

-   that the scale deck is empty before vehicles are placed on the
    scale; and

-   that the weighing elements are not being manipulated in any
    fraudulent way by the scale operator.

The General Code requires that a weighing device be positioned in such a
way as to facilitate to the greatest practicable extent customer
verification of the weighing.

+-----------------------------------------------------------------------+
| **G-UR.3.3. Position of Equipment.** - A device or system equipped    |
| with a primary indicating element and used in direct sales, except    |
| for prescription scales, shall be positioned so that its indications  |
| may be accurately read and the weighing or measur­ing operation may be |
| ob­served from some reasonable \"customer\" and "operator" position.   |
| The per­missible distance between the equipment and a reason­able       |
| customer and operator position shall be determined in each case upon  |
| the basis of the indivi­dual cir­cumstances, particu­larly the size and  |
| character of the indicating element.                                  |
|                                                                       |
| (Amended 1974 and 1998)                                               |
+-----------------------------------------------------------------------+
| NIST Handbook 44, General Code, Paragraph G-UR.3.3.                   |
+-----------------------------------------------------------------------+

The customer must be able to accurately read the scale from a reasonable
position. Customers must be able to fulfill their responsibility of
observing the weight determination of the vehicle in order to benefit
from the requirements in Handbook 44 concerning customer readability. If
the customer has no direct access to the device's indicating element, a
remote display may be required to permit the customer to read the
scale's indications.

Before any vehicles are brought onto the scale, the operator must ensure
that the scale indication is on zero and the scale deck is empty. The
operator must also be able to clearly and accurately read the final
weight indication on the scale. Consequently, it is equally important
that the operator be able to accurately read the scale from a reasonable
operator position.

**Adjustable Components**

To prevent accidental resetting of adjustments that could affect
measurement, or deliberate abuses, the Scales Code requires that all
adjustable components of indicating and recording elements, except for
the zero-load balance mechanism, be enclosed within the housing of the
device.

+-----------------------------------------------------------------------+
| **S.1.10. Adjustable Components.** - An adjustable component such as  |
| a pendulum, spring, or potentiometer shall be held securely in        |
| adjustment and, except for a zero-load balance mechanism, shall be    |
| located within the housing of the element.                            |
|                                                                       |
| (Added 1986)                                                          |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.1.10.**                  |
+-----------------------------------------------------------------------+

**Provision for Sealing**

Adjustable elements that can affect the measurement of electronic
devices require further protection from tampering. NIST Handbook 44
Scales Code paragraph S.1.11. and the accompanying table require that
indicating and recording elements be designed with provision for sealing
these adjustments.

A seal cannot actually *prevent* tampering, but leaves evidence that
tampering has occurred. This requirement (and its corresponding
paragraph in the General Code, G‑S.8) recognizes two general methods of
sealing, either or both of which may be used to effectively seal the
device.

The first, more traditional method involves the use of physical seals,
such as lead-and-wire, plastic wire, or pressure sensitive seals, which
must be broken or deformed in order to gain access to or operate an
adjustment. For example, if an adjustment is enclosed within a cabinet,
inside a box, or behind a door or plate, a lead-and-wire seal can be
threaded through a latch, or through a screw that fastens the closure;
in order to open the closure to make an adjustment, the wire and/or lead
seal must first be broken.

+-----------------------------------------------------------------------+
| ***S.1.11. Provision for Sealing.***                                  |
|                                                                       |
| > *(a) Except on Class I scales, provision shall be made for apply­ing |
| > a security seal in a manner that requires the security seal to be   |
| > broken before an adjustment can be made to any component affecting  |
| > the performance of an electronic device.*                           |
| >                                                                     |
| > *\[Nonretroactive as of January 1, 1979\]*                          |
| >                                                                     |
| > *(b) Except on Class I scales, a device shall be designed with      |
| > provision(s) for applying a security seal that must be broken, or   |
| > for using other approved means of providing security (e.g., data    |
| > change audit trail available at the time of inspection), before any |
| > change that detrimentally affects the metrologi­cal integrity of the |
| > device can be made to any electronic mechanism.*                    |
|                                                                       |
| *\[Nonretroactive as of January 1, 1990\]*                            |
|                                                                       |
| > *(c) Except on Class I scales, audit trails shall use the format    |
| > set forth in Table S.1.11.*                                         |
| >                                                                     |
| > *\[Nonretroactive as of January 1, 1995\]*                          |
|                                                                       |
| A device may be fitted with an automatic or a semi-automatic          |
| calibration mechanism. This mechanism shall be incorporated inside    |
| the device. After sealing, neither the mechanism nor the calibration  |
| process shall facilitate fraud.                                       |
|                                                                       |
| (Amended 1989, 1991 and 1993)                                         |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.1.11.**                  |
+-----------------------------------------------------------------------+

  -----------------------------------------------------------------------

  **NIST Handbook 44, Scales Code, Table S.1.11.**
  -----------------------------------------------------------------------

This method is effective when the adjustable element does not need to be
used during normal operation. However, many electronic indicators are
designed to permit calibration type adjustments to be made through the
same keyboard or keypad module that is used for data entry during normal
service. In this case, a physical seal would not be appropriate;
consequently, the Handbook provides for the use of other approved means
of providing security.

One such means that has been developed involves the maintenance of an
automatic and permanent record of each time the adjustment mode, or the
region of electronic memory where adjustment factors are stored, is
accessed. This technique is commonly referred to as an **audit trail**.
The audit trail must be continuously and automatically maintained, even
during power failures, must itself be tamperproof, and must be
accessible to the weights and measures official when requested.

Note that S.1.11. refers to "other [approved]{.underline} means." Table
S.1.11. outlines categories of devices and the required methods of
sealing for each category. There are three basic categories of devices,
which are categorized according to the way in which metrologically
significant changes can be made on the device. A Category 1 device
describes the simplest device; one that has no remote configuration
capability. That is, changes to metrological features such as
calibration can only be made at the device itself, not through a remote
device. Category 2 and 3 devices [do]{.underline} have remote
configuration capability. That is, metrologically significant
adjustments can be made to these devices through a remote device such as
a console or controller. The key different between the Category 2 and
the Category 3 device is that the Category 3 device has unlimited remote
access (or access controlled through a software switch such as a
password), whereas remote access to the configuration mode in a Category
2 device is controlled by physical hardware.

Table S.1.11. lists the minimum methods for sealing each category of
device. Note that "lower" category devices may use a more advanced
method of sealing and still satisfy the requirements. For example, a
Category 1 device may use an event logger as outlined for a Category 3
device.

If a device has been type evaluated, the NTEP Certificate of Conformance
will describe the provision for sealing, and whether it is acceptable.
For devices that have not been type evaluated, you must first identify
all elements that require sealing and then assess the sealing technique
used. This may necessitate reviewing technical manuals or contacting the
scale manufacturer to verify the adequacy of the security and to check
that all adjustments are currently secure.

When inspecting a device sealed through an audit trail, pertinent
information from the audit trail such as the values of the event
counters, should be recorded on the inspection report. By comparing
information currently displayed on an audit trail with the information
from the last inspection, you will be able to assess the number and
types of changes that have been made to the device's calibration and
configuration settings. A significant number of changes may indicate
that further investigation of the device is warranted. If you find such
a situation, you should consult your supervisor for further guidance or
follow your jurisdiction's policies.

The General Code makes it the responsibility of the device owner to make
sure that seals are correctly installed and that they remain effective.

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

  **NIST Handbook 44, General Code, Paragraph G-UR.4.5.**
  -----------------------------------------------------------------------

This requirement should also be construed as applying to all sealing
methods, including audit trails. For the seal to remain effective, it
must either be maintained continuously intact or, when an adjustment is
made, it must be fully documented.

# [Installation]{.underline}

All weighing and measuring devices must be installed in accordance with
the manufacturer's instructions, in a manner that will not adversely
affect its accuracy, obscure markings or indications, or inhibit
operation or monitoring based upon either direct or indirect observation
of the weighing. In addition, devices must be installed so that they are
accessible for examination purposes. Some States have "Pit Laws," which
specify construction details for scale pits. If your State has such a
law, you will need to check to make sure that its requirements have been
met.

+-----------------------------------------------------------------------+
| **G-UR.2. Installation Requirements.**                                |
|                                                                       |
| > **G-UR.2.1. Installation.** - A device shall be installed in        |
| > accordance with the manufac­turer\'s instructions, including any     |
| > instructions marked on the device. A device installed in a fixed    |
| > location shall be installed so that neither its opera­tion nor its   |
| > performance will be ad­versely affected by any characteristic of the |
| > founda­tion, supports, or any other detail of the installa­tion.      |
| >                                                                     |
| > **G-UR.2.1.1. Visibility of Identification.** - Equip­ment shall be  |
| > in­stalled in such a manner that all required markings are readily   |
| > observable.                                                         |
| >                                                                     |
| > (Added 1978)                                                        |
| >                                                                     |
| > **G-UR.2.2. Installation of Indicating or Recording Element.** - A  |
| > device shall be so installed that there is no obstruction between a |
| > primary indicating or recording element and the weighing or         |
| > measuring element; otherwise there shall be convenient and          |
| > per­manently installed means for direct communication, oral or       |
| > visual, between an individual located at a primary indicating or    |
| > recording element and an individual located at the weigh­ing or      |
| > measuring ele­ment. \[See also G-UR.3.3.\]                           |
| >                                                                     |
| > **G-UR.2.3. Accessibility for Inspection, Testing, and Sealing      |
| > Purposes.** - A device shall be located, or such facilit­ies for     |
| > normal access thereto shall be provided, to permit:                 |
| >                                                                     |
| > \(a\) inspecting and testing the device;                            |
| >                                                                     |
| > \(b\) inspecting and applying security seals to the device; and     |
| >                                                                     |
| > \(c\) readily bringing the testing equipment of the weights and     |
| > measures official to the device by customary means and in the       |
| > amount and size deemed necessary by such official for the proper    |
| > conduct of the test.                                                |
| >                                                                     |
| > Otherwise, it shall be the responsibility of the device owner or    |
| > operator to supply such special facilities, including such labor as |
| > may be needed to inspect, test, and seal the device, and to         |
| > transport the testing equipment to and from the device, as required |
| > by the weights and measures official.                               |
| >                                                                     |
| > (Amended 1991)                                                      |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-UR.2.**                 |
+-----------------------------------------------------------------------+

Note that paragraph G‑UR.2.2. is intended to insure that the operator of
the scale who is stationed at the indicating element can have accurate
information about the application of the load to the load-receiving
element, either based on his/her own visual observation, upon a report
from a third party who is a direct observer, or through other means such
as a live camera which allows visual contact. In the case of vehicle and
axle-load scales, for example, it is essential that the operator know
when the vehicle is entirely on the platform, with its axles positioned
correctly and the driver out of the truck and off the platform, before
recording the weight. This does not necessarily require that indicating
and weighing elements be simultaneously visible by the customer (this
stricter requirement is set forth in another paragraph of the General
Code, G‑UR.3.3., applicable to devices used in direct sales only).

Paragraph G-UR.2.3. requires that a device be located or access provided
such that the device can be inspected and tested, security seals can be
applied to the device, and the inspector can bring the necessary test
equipment to the device through normal means. Otherwise, the device
owner must provide assistance or labor to allow the inspector to
accomplish these tasks.

In the environments in which vehicle and axle-load scales are used,
exposure to wind, rain, dust, etc., may be a very real hazard to proper
operation of a scale. Therefore, Paragraph UR.2.3.of the Scales Code
requires that the indicating elements, lever system, and load-receiving
element on a permanently installed scale must be protected from
environmental factors that could affect their operation, including
protection for electronic elements from the effects of electromagnetic
or radio-frequency interference (RFI/EMI). Tests for the adequacy of
protection from RFI/EMI will be described in Chapter 6.

Because plumb and level conditions are generally necessary for accurate
scale operation, the foundations and supports must be installed in such
a manner as to provide a rigid footing for the scale components. They
must be sufficiently strong, rigid, and permanent for the purpose. There
must be enough clearance between the scale and surrounding walls to
prevent any contact between the two, either during a weighing or when
the deck is empty. Paragraph UR.2.4. requires these conditions.

+-----------------------------------------------------------------------+
| **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.*                                        |
|                                                                       |
| *\[Non­retroactive as of January 1, 1973\]*                            |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraphs UR.2.3. and UR.2.4.**     |
+-----------------------------------------------------------------------+

The scale deck should be made of a material suitable for its use, with a
surface that provides appropriate traction for vehicles. In addition,
the nonretroactive portion of UR.2.4. states that the clearance between
the deck and the coping at the bottom edge of the deck must be greater
than at the top edge of the deck, as illustrated in Figure 3-6.

+-----------------------------------------------------------------------+
| ![](media/image5.png){width="5.316666666666666in" height="3.45in"}    |
+-----------------------------------------------------------------------+
| ##                                                                    |
|                                                                       |
| ## Figure 3-6. Typical Deck Configuration                             |
+-----------------------------------------------------------------------+

This helps to prevent a stone or other material from binding in the
scale. With a wooden deck, this is accomplished by undercutting, sawing
the wood of the deck so that it angles in. On concrete decks, a small
strip of steel --- called a crushing strip --- is usually attached to
the upper edge of the deck where it meets the pit coping.

# [Weighing And Load-Receiving Elements]{.underline}

**Design**

The weighing elements must be designed in a way that minimizes friction
between opposing surfaces. Wherever friction occurs, some of the energy
transmitted through the system is converted to heat and lost. To the
degree that this energy loss due to friction is not controlled, the
repeatability of the scale is likely to suffer. The Scales Code,
therefore, requires adequate provision in the design of weighing
elements for minimizing friction.

  -----------------------------------------------------------------------
  **S.4.1. Antifriction Means.** - Frictional effects shall be reduced to
  a minimum by suitable antifriction elements. Opposing surfaces and
  points shall be properly shaped, finished, and hardened. A platform
  scale having a frame around the platform shall be equipped with means
  to prevent interference between platform and frame.

  **NIST Handbook 44, Scales Code, Paragraph S.4.1.**
  -----------------------------------------------------------------------

In a mechanical vehicle or axle-load scale, friction normally occurs
primarily at the lever pivots. Pivots --- sharpened to a knife edge ---
receive and transmit the force, support levers, and serve as axes for
levers. Pivots should be of hardened steel and each should be opposed by
a bearing of suitable shape. Friction should [not]{.underline} occur
between the deck and the surrounding surface. The requirement that
clearance be maintained between the load-receiving element and the
adjacent coping was also stated in UR.2.4 described above.

You will recall from an earlier discussion that the only adjustable
element on mechanical weighing elements, except for the zero-balance
elements, are nose-irons, which may be used to vary slightly the power
arm of one or more levers in the system when major adjustment is
necessary. The Scales Code requires that such elements must be capable
of holding their setting.

+-----------------------------------------------------------------------+
| **S.4.2. Adjustable Components.** - An adjustable component such as a |
| nose-iron or potentiometer shall be held securely in adjustment. The  |
| position of a nose-iron on a scale of more than 1000-kg (2000-lb)     |
| capacity, as determined by the factory adjustment, shall be           |
| accurately, clearly, and permanently defined.                         |
|                                                                       |
| (Amended 1986)                                                        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph S.4.2.**                   |
+-----------------------------------------------------------------------+

In addition, the position of a nose-iron on vehicle and axle-load
scales, and other large-capacity scales, as set by the manufacturer
prior to installation, must be clearly marked. This is usually
accomplished by filing a mark on the fixed surface upon which the
nose-iron slides. This mark should be clearly visible.

Multiple-scale systems generally have indicating and recording elements
that sum the weights of the individual weighing elements, although each
scale may also have its own indicating and recording elements as well.
Depending upon the length of a given vehicle and the configuration of
the scales, in some cases, a vehicle may not be resting on all
load-receiving elements in the system. This is acceptable as long as all
parts of the vehicle are resting on one or more of the load receiving
elements in the system. However, a shared indicating or recording
element must be designed to prohibit the activation of scale elements
that are not in use, and to indicate those which are in use at any given
time.

  -----------------------------------------------------------------------
  **S.4.3. Multiple Load-Receiving Elements.** - Except for mechan­ical
  bench and counter scales, a scale with a single indicating or recording
  element, or a combination indicating-recording element, that is coupled
  to two or more load-receiving elements with independent weighing
  systems, shall be provided with means to prohibit the activation of any
  load-receiving element (or elements) not in use, and shall be provided
  with automatic means to indicate clearly and definitely which
  load-receiving element (or elements) is in use.

  NIST Handbook 44, Scales Code, Paragraph S.4.3.
  -----------------------------------------------------------------------

This requirement is intended to prevent fraudulent or accidental
addition of loads that are not part of the current transaction. The
shared indicator may use indicating lights or other means to show which
scales are active. The correct operation of this indication, and of the
mechanism that locks out non-active scales, should be checked during the
test of the system.

Some mechanical systems are equipped with a scissor type hoist beneath
the load-receiving deck, which can be used to lift the deck and
weighbridge off the weighing elements while the vehicle is being loaded
or unloaded, making it possible to determine tare without driving the
vehicle off the scale. If a scale is so equipped, there must be means
for the operator to determine when the load-receiving element is in the
weighing position, that is, resting fully on the load bearing points.

  -----------------------------------------------------------------------
  **UR.2.8. Hoists.** ‑ On vehicle scales equipped with means for raising
  the load‑­receiving element from the weighing element for vehicle
  unloading, means shall be provided so that it is readily apparent to
  the scale operator when the load receiving element is in its designed
  weighing position.

  NIST Handbook 44, Scales Code, Paragraph UR.2.8.
  -----------------------------------------------------------------------

Again, during the test of the system, you should observe the operation
of this indicator while the scale is in operation.

**Access**

Most vehicle and axle-load scales are designed to have a pit underneath
the weighing deck that allows access to the weighing elements.
Maintenance personnel and weights and measures officials must have ready
access to the pit in order to inspect, adjust, and repair the scale, and
the Scales Code requires provision for such access.

A clearance height of at least 48 inches is recommended as the minimum
for ready access, but pit requirements vary from one jurisdiction to
another. Your instructor will explain guidelines adopted by your
jurisdiction. Note that both above- and below-ground vehicle scales must
also be designed to provide access to scale elements beneath the deck.

+-----------------------------------------------------------------------+
| **UR.2.5. Access to Weighing Elements.** ‑ Adequate provision shall   |
| be made for ready access to the pit of a vehicle, livestock, animal,  |
| axle-­load, or railway track scale for the purpose of inspection and   |
| main­tenance. Any of these scales without a pit shall be installed     |
| with adequate means for inspection and maintenance of the weighing    |
| elements.                                                             |
|                                                                       |
| (Amended 1985)                                                        |
+-----------------------------------------------------------------------+
| NIST Handbook 44, Scales Code, Paragraph UR.2.5.                      |
+-----------------------------------------------------------------------+

# [Approaches]{.underline}

As explained in Chapter 1, correct design and construction of the
entrance and exit ends of a vehicle or axle-load scale are essential to
accurate weighing of vehicles. If correctly designed and constructed,
they help reduce wear on the weighing element, insure that the vehicle
will be positioned properly over the load-receiving element, that any
load inside the truck is stable and is not likely to shift during
weighing, and, in the case of axle-load scales, that the entire vehicle,
including the part not bearing directly on the deck, is level. The
Scales Code specifies relative dimensions for approaches, which you
should check in the course of your inspection.

+-----------------------------------------------------------------------+
| **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, and 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.                                         |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph UR.2.6.**                  |
+-----------------------------------------------------------------------+

These requirements are illustrated in Figure 3-7.

+-----------------------------------------------------------------------+
| ![](media/image6.wmf)                                                 |
+-----------------------------------------------------------------------+
| ##                                                                    |
|                                                                       |
| ## Figure 3-7. Requirements for Approaches                            |
+-----------------------------------------------------------------------+

# [Maintenance, Use, And Environmental Factors]{.underline}

All weighing and measuring devices must be maintained in proper
operating condition and operated only in the manner for which they are
designed. A number of general requirements relating to maintenance are
set forth in the General Code.

The second part of G‑UR.4.1. establishes an important point regarding
adjusting of devices, which is also addressed in G‑UR.4.3. Adjustments
should always be made with the objective of bringing the device as close
as possible to zero-error accuracy. The fact that tolerances allow a
small degree of inaccuracy must not be construed by device operators or
repair personnel as a license to adjust devices in a way that, while
nominally meeting performance requirements, favors the device owner or
operator.

If in the course of an examination you observe a consistent pattern in
performance on a number of scales which could indicate this type of
abuse, you should question the operator and, if necessary, repair
service personnel, about their practices in adjusting scales. Since it
is unlikely that they will admit to an improper practice and since the
evidence for abuse or possible fraud will, in that case, be entirely
circumstantial, you should also consider the following in making your
determination:

-   number of devices at the same location,

-   results of recent tests of these devices, and

-   complaints that have been received from the public.

If you have strong suspicions, but the evidence is inconclusive, you
should inform the operator of the seriousness of this violation, require
that the scales be readjusted properly, and make careful notes for
comparison at the next examination. If the observed pattern is strongly
supported by historical evidence or complaints, you may consider
compliance action, especially if there is evidence (such as a prior
warning) of willful intent to defraud the public. Your instructor will
explain your jurisdiction's policies and procedures regarding this type
of violation.

+-----------------------------------------------------------------------+
| **G-UR.4. Maintenance Requirements.**                                 |
|                                                                       |
| > **G-UR.4.1. Maintenance of Equipment.** - All equipment in service  |
| > and all mechani­sms and devices attached thereto or used in          |
| > connection therewith shall be continuously maintained in proper     |
| > operating condition throughout the period of such service.          |
| > Equipment in service at a single place of business found to be in   |
| > error predominantly in a direction favorable to the device user     |
| > shall not be considered \"maintained in a proper operating          |
| > condi­tion.\"                                                        |
| >                                                                     |
| > (Amended 1973 and 1991)                                             |
| >                                                                     |
| > **G-UR.4.2. Abnormal Performance.** - Unstable indications or other |
| > abnormal equip­ment performance observed during operation shall be   |
| > corrected and, if neces­sary, brought to the attention of competent  |
| > service personnel.                                                  |
| >                                                                     |
| > (Added 1976)                                                        |
| >                                                                     |
| > **G-UR.4.3. Use of Adjustments. -** Weighing elements and measuring |
| > elements that are adjus­table shall be adjusted only to correct      |
| > those condi­tions that such elements are designed to control, and    |
| > shall not be adjusted to compensate for defective or abnormal       |
| > installation or accessories or for badly worn or otherwise          |
| > defective parts of the assembly. Any faulty instal­lation conditions |
| > shall be cor­rected, and any defective parts shall be renew­ed or     |
| > suitably repaired, before adjustments are undertaken. Whenever      |
| > equip­ment is adjusted, the adjust­ments shall be so made as to bring |
| > performance errors as close as practicable to zero value.­           |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-UR.4.**                 |
+-----------------------------------------------------------------------+

Note also, that because a device is capable of performing within
tolerances on an official test does not mean that it is being correctly
maintained. A badly worn or malfunctioning device can often be hastily
and improperly adjusted to pass a test, but will soon be inaccurate
again and is likely to perform more and more erratically. You should
point out to the operator of worn or improperly maintained equipment
that the ultimate cost of replacing equipment, including the cost of
taking it out of service for some period of time, generally outweighs
the cost of regular and thorough preventative and corrective
maintenance.

During a scale examination, you should be on the lookout for elements of
design, application, or installation that could facilitate fraud, since
this is specifically prohibited by the General Code.

  -----------------------------------------------------------------------
  **G-S.2. Facilitation of Fraud.** - All equipment and all mechanisms
  and devices attached thereto or used in connection therewith shall be
  so constructed, assembled, and installed for use such that they do not
  facilitate the perpetration of fraud.

  NIST Handbook 44, General Code, Paragraph G-S.2.
  -----------------------------------------------------------------------

Note that facilitation of fraud does not require evidence of intent to
defraud or fraudulent acts; in fact, in some cases, the device owner may
be innocent of any deceitful intent. Often facilitation of fraud arises
from installing equipment that is not suitable for its application in an
effort to save money on the equipment purchase and/or installation,
rather than from an attempt to cheat customers. You should be especially
aware of features that have no apparent purpose in a particular
application --- the example of tare on a livestock scale is a good
example --- and for modifications which are not described in the
manufacturer's instructions or plans.

In this regard, also remember that a device may only be
[operated]{.underline} in the manner for which it was designed and
constructed. For example, a zero-balance adjustment must not be used to
take tare. The proper method of operation is also required by the
General Code.

  -----------------------------------------------------------------------
  **G-UR.3.1. Method of Operation.** - Equipment shall be operated only
  in the manner that is obviously indicated by its construction or that
  is indicated by instructions on the equip­ment.

  **NIST Handbook 44, General Code, Paragraph G-UR.3.1.**
  -----------------------------------------------------------------------

Another requirement relating to suitability of a scale applies to
money-operated devices. If the user must deposit money in an automatic
payment-taking device in order to make the scale operate, information
must be displayed at or near the device regarding how to contact the
person or agency responsible for the device for refunds if the scale
does not work correctly. Note that this information is not required at
locations where employees are present and responsible for resolving any
discrepancies.

+-----------------------------------------------------------------------+
| **G-UR.3.4. Responsibility, Money-Operated Devices.** -               |
| Money-­operated devices other than parking meters shall have clearly   |
| and conspicuously displayed thereon, or immediately adjacent thereto, |
| adequate information detailing the method for the return of monies    |
| paid when the product or service cannot be obtained. This information |
| shall include the name, address, and phone number of the local        |
| responsible party for the device. This requirement does not apply to  |
| devices at locations where employees are present and responsible for  |
| resolving any monetary discrepancies for the customer.                |
|                                                                       |
| (Amended 1977 and 1993)                                               |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-UR.3.4.**               |
+-----------------------------------------------------------------------+

As stated earlier, the suitability of a device includes its capability
to perform correctly and accurately under the environmental conditions
of its normal service. Since vehicle and axle-load scales are often
installed outdoors, and are thus exposed to wind, sun, moisture,
pollution, and temperature variations, they must be adequately
protected. Electronic devices must also be adequately shielded against
the effects of RFI and EMI, which can be generated either by electrical
equipment used on the site, radio transmitting equipment, or other
environmental sources. The General Code includes suitability for service
under normal environmental factors as a user requirement.

+-----------------------------------------------------------------------+
| **G-UR.1.2. Environment.** - Equipment shall be suitable for the      |
| environ­ment in which it is used including, but not limited to, the    |
| effects of wind, weather, and RFI.                                    |
|                                                                       |
| (Added 1976)                                                          |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, General Code, Paragraph G-UR.1.2.**               |
+-----------------------------------------------------------------------+

Among the requirements listed on the EPOs under this heading are two
which are also listed under **Appropriateness**, and were discussed
earlier. These paragraphs in the Scales Code, UR.3.2., and UR.3.3.,
stated, respectively, that a scale may not be used to weigh loads that
exceed its nominal capacity, and that single-draft weighing is required
for all commercial weighing of vehicles. Related to these requirements
are two paragraphs which specify minimum net loads for vehicle and
livestock scales.

+-----------------------------------------------------------------------+
| **UR.3.7. Minimum Load on a Vehicle Scale.** - A vehicle scale shall  |
| not be used to weigh net loads smaller than:                          |
|                                                                       |
| \(a\) 10 d when weighing scrap material for recycling;                |
|                                                                       |
| \(b\) 50 d for all other weighing.                                    |
|                                                                       |
| As used in this paragraph, scrap materials for recycling shall be     |
| limited to ferrous metals, paper (including cardboard), textiles,     |
| plastic, and glass.                                                   |
|                                                                       |
| (Amended 1988 and 1992)                                               |
|                                                                       |
| **UR.3.8. Minimum Load for Weighing Livestock.** - A scale with scale |
| divisions greater than 2 kg (5 lb) shall not be used for weighing net |
| loads smaller than 500 d.                                             |
|                                                                       |
| (Amended 1989)                                                        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraphs UR.3.7. and UR.3.8.**     |
+-----------------------------------------------------------------------+

Paragraph UR.3.7. specifies that the smallest net load that is permitted
to be weighed on a vehicle scale (other than those use to weigh scrap
metal) is 50d (1,000 lb for a scale with a division value of 20d). The
basis for this requirement is that the magnitude of potential round-off
errors increases as the size of the load decreases. For example, the
following table shows, for various loads from 100d to 10d, the potential
error that could exist because devices are permitted a round-off error
of up to plus or minus one-half the value of the scale division (0.5d).
Column 1 of the table shows potential round-off error for gross loads
weighed on an "accurate" scale.

+-------------------+-------------------------+------------------------+
| **Test Load in    | **Column 1 --- Gross    | **Column 2 --- Net     |
| d**               | Loads**                 | Loads**                |
|                   |                         |                        |
|                   | Potential error (±0.5d) | **Potential error      |
|                   |                         | (±1.0d)**              |
+-------------------+-------------------------+------------------------+

  ------------------- ------------------------- -------------------------
  100                 0.5%                      1.0%

  50                  1.0%                      2.0%

  20                  2.5%                      5.0%

  10                  5.0%                      10.0%
  ------------------- ------------------------- -------------------------

As you can see, the same amount of error (±0.5d) becomes more
significant as the test load decreases (0.5d is an error of 0.5% at 100d
but it represents a 5% error at 10d).

Note that, for vehicle scales used to weigh scrap material for
recycling, the minimum is 10d. This application is permitted a smaller
minimum load because of the special conditions under which these
weighments are made.

Column 2 shows the potential round-off error for net loads that may have
±0.5d round-off error with both the gross and tare weight. Because
vehicle scales are frequently used to determine both gross and net
loads, the potential error at small loads may be as much as double that
for a scale used to record only gross loads.

For example, a 100,000 lb × 20 lb scale is used to weigh an empty
vehicle; the actual weight of the vehicle is 20,010 lb, but the scale
indicates 20,000 lb because of the round-off error of 0.5d. Then, the
truck is loaded with product and reweighed to get a gross weight; the
actual weight is 21,990 lb, but the scale rounds off and indicates
22,000 lb. If the indicated weight of the empty truck is then subtracted
from the indicated weight of the loaded truck, the resulting net weight
is 2,000 lb; however, the actual net weight for this example is 1,980
lb. The difference between 2,000 lb and 1,980 lb is 20 lb or the value
of 1 scale division.

As mentioned before, the potential errors shown are those for an
"accurate" scale --- one that meets the performance requirements of
Handbook 44. If the scale is inaccurate, additional error will be
introduced. In order to keep net loads within acceptable limits of
inaccuracy, Handbook 44 specifies the minimum loads that can be weighed
on vehicle scales. As indicated above, this limits the potential error
from rounding off to no more than 2 percent of the value of the net load
for vehicle weighing applications other than the weighing of scrap metal
for recycling.

Many stockyards use the same Class III L vehicle scale to weigh both
trucks loaded with livestock and animals on the hoof. Paragraph UR.3.8.
permits this established practice when the scale division is 5 lb,
without any minimum load requirement (a scale division of 5 lb is
considered to be adequate resolution for weighing individual animals). A
50,000 × 5 lb vehicle scale could thus be used both for weighing
livestock loaded on trucks or on the hoof. However, if a scale with
larger scale divisions is used, the minimum net load is 500d. This means
that the minimum net load of livestock (excluding the truck) that can be
weighed on a vehicle scale with 20-lb divisions is 10,000 lb when the
livestock is on a truck.

Obviously, you will not be able to determine compliance with UR.3.7. or
UR.3.8. by observing the scale. However, you can ask to review records
of transactions to see whether any net loads have been less than the
required minimums.

Finally, the Scales Code includes a requirement that prohibits specific
modifications that:

• increase the length or width of the scale deck beyond the dimensions
specified by the manufacturer, or

• increase the system capacity by installing an indicator with a higher
capacity, unless the modification is approved by a competent engineering
authority [and]{.underline} the weights and measures jurisdiction.

+-----------------------------------------------------------------------+
| **UR.4.3. Scale Modification. -** The dimensions (e.g., length,       |
| width, thickness, etc.) of the load receiving element of a scale      |
| shall not be changed beyond the manufacturer's specifications, nor    |
| shall the capacity of a scale be increased beyond its design capacity |
| by replacing or modifying the original primary indicating or          |
| recording element with one of a higher capacity, except when the      |
| modification has been approved by a competent engineering authority,  |
| preferably that of the engineering department of the manufacturer of  |
| the scale, and by the weights and measures authority having           |
| jurisdiction over the scale.                                          |
|                                                                       |
| (Amended 1996)                                                        |
+-----------------------------------------------------------------------+
| **NIST Handbook 44, Scales Code, Paragraph UR.4.3.**                  |
+-----------------------------------------------------------------------+

This requirement is intended to prevent modifications that could affect
the measurement accuracy of the scale from being made simply for the
purpose of increasing the capacity or platform size of the scale. You
may need to review the manufacturer's specifications for the equipment
to determine whether modifications described in this requirement have
been made.

# [Assistance]{.underline}

Owners of weighing and measuring devices are required to provide
assistance to weights and measures officials in conducting tests if
special equipment or an extraordinary amount of labor is required
because of the design, construction, or location of that device.

  -----------------------------------------------------------------------
  **G-UR.4.4. Assistance in Testing Operations.** - If the design,
  con­struction, or location of any device is such as to require a testing
  procedure involving special equipment or acces­sories or an abnormal
  amount of labor, such equipment, accesso­ries, and labor shall be
  supplied by the owner or operator of the device as required by the
  weights and measures official.

  NIST Handbook 44, General Code, Paragraph G-UR.4.4.
  -----------------------------------------------------------------------

You will recall that G‑UR.2.3. requires that devices be installed in
such a manner as to provide access for testing purposes. However, some
installations may still require assistance as is recognized by both
paragraph G-UR.4.4. and paragraph G‑UR.2.3.

The most common problem of this sort arises when the scale is located
under hoppers, or where the weights and weight movers cannot be
maneuvered. You may require the use of a forklift, or whatever devices
and labor are needed, to position and remove the test weights.

# [Summary]{.underline}

A field examination of vehicle and axle-load scales begins with the
inspection of the device to determine if the equipment complies with all
applicable specifications of NIST Handbook 44 concerning scale design,
installation, and use.

The EPOs for vehicle and axle-load scales list the following major items
that must be checked.

-   zero-load balance as found

-   marking

-   suitability of system components

-   indicating and recording elements

-   installation

-   weighing elements and load-receiving elements

-   approaches

-   maintenance, use, and environmental factors

-   assistance

Items to be checked on indicating and recording elements include the
following:

-   scale division: value (d) and number (n)

-   rounding

-   tare division value

-   tare mechanism

-   weighbeams

-   poises

-   dials and balance indicators

-   damping means

-   appropriateness

-   customer readability, if applicable

-   marking

-   adjustable elements

-   provision for sealing

-   audit trail information, if applicable

Marking requirements may also apply to weighing elements (including load
cells) and load-receiving elements.

The EPOs also list specific General Code and Scales Code references in
NIST Handbook 44 for each item to be inspected. You must know how to
interpret these code references to determine the "correctness" of the
equipment being examined.