Laboratory manual for the evaluation of non-automatic weighing devices

Part 2, section 21—Multiple deck weighing systems

Table of contents


Reference

Sections 30 to 33 of the Specifications Relating to Non Automatic Weighing Devices (1998)

21.0 Multiple deck weighing systems—Generalities

An indicator and/or printer may be connected to more than one weighing element provided that the weighing system is designed to ensure accuracy of the transactions, and to prevent erroneous measurements or fraud.

Two basic Multiple Deck Weighing Systems are used in trade:

21.1 Systems where only one weighing element can be selected and use at a time (multiplex).

Each separate weighing element and the indicating element is considered a separate scale and must be tested accordingly.

21.1.1 The system or scale must prohibit the use of any weighing element that is not in use (only one weighing element at a time).

21.1.2 The indicating element must automatically provide a clear and continuous indication of which load-receiving element is in use (i.e. Scale A, Scale B, Scale C, etc.). The indication must be visible from the operator's normal position.

21.1.3 Weighing elements must be clearly and permanently identified with the corresponding identification.

21.1.4 The printer must provide on the ticket, for each weighing, a clear registration indicating which weighing element was used (Scale A, Scale B, etc.).

21.1.5 When an operator-activated function (Setting zero, entering a tare value, selecting or clearing a function, etc.) is performed on one particular weighing element, functions or parameters of other weighing elements must not be affected or altered. Perform the test described in LG‑21.01

21.1.6 Unless the indicator has independent AZSMs, one for each individual weighing element, individual Centre-of-Zero indicators (annunciators), one for each weighing element, must be provided. Centre-of-Zero indicators must provide a continuous signal (remain active) regardless of which weighing element is selected.

Note: It is preferable to identify scale weighing elements as scale A, scale B, etc. rather than scale 1, scale 2. Numbers that could be confused with weight indications is not acceptable.

21.2 Systems where all the weighing elements can operate simultaneously (Vehicle scales, vehicle axle weighing scales); each weighing element has its own dedicated display that are interfaced to a summing display.

21.2.1 Each weight indicator must be clearly and permanently identified with the corresponding identification (i.e. Scale A, Scale B, Total weight, etc.). Each weight display and its associated weighing element is considered a separate scale and must meet all applicable requirements.

21.2.2 When an operator-activated function (Setting zero, entering a tare value, selecting or clearing a function, etc.) is performed on one particular weighing element, functions or parameters of other weighing elements must not be affected. Perform the test described in LG‑21.01

21.2.3 Unless the indicator has independent AZSMs, one for each individual weighing element, individual Centre-of-Zero indicators (annunciator), one for each weighing element, must be provided. Centre-of-Zero indicators must provide a continuous signal (remain active) regardless of which weighing element is selected.

21.2.4 Each weighing element must be clearly and permanently identified with the corresponding identification (i.e. Scale A, Scale B, etc.).

21.1.5 The printer must automatically register the printed weight associated with the weighing element identification that was used (i.e. Scale A, scale B, etc)

21.2.6 The value of verification scale interval must be the same for all displays including the summing display.

21.2.7 The summing weight display must perform within tolerances; must not indicate nor record nor print any weight values when one individual weighing element exceeds its capacity; must sum any tare entries in the individual indicators; must have a free floating weight signal for summing individual indicators; and must be in mathematical agreement with the sum of all the individual indicators.

Clarification: The device may still display values for individual weighing elements that are not over-capacity (Policy for blanking of displays of multiple LRE hooked together.wpd)

LG-21.01 Alteration of settings or data entries

Purpose

The purpose of this test is to ensure that when a setting is performed or a function is activated on one particular weighing element, functions or settings of the other weighing elements are not changed or altered.

Application

Applicable to any Multiple Deck Weighing Systems or indicator intended for Multiple Deck Weighing Systems

Test procedure
Interpretation of results

The device complies with the requirements if functions performed on individual weighing element do not affect the settings or entries of other weighing elements; if the indicated and printed weights are accurate and identified as required; and if the summing weight display meets the requirements (last bullet above).

Revision

Original document

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