Laboratory manual for the evaluation of non-automatic weighing devices

Part 2, section 23—Devices used for direct sale to the public

Table of contents


Sections 30 to 33, 46, 47, 50, 59 and 60 of the Specifications Relating to Non Automatic Weighing Devices (1998)

23.0 Devices used for direct sale to the public—Generalities

Several requirements apply to devices intended to be used for direct sale to the public. These requirements are to ensure that transactions are accurate and that customers normally present during the weighing operations are provided with sufficient information so that they can observe and understand the weighing process.

23.1 Customer's display

23.1.1 The device must be provided with a display (customer display) that duplicates all significant metrological information displayed for the operator (Weight, unit price, total price, tare weight, annunciators for "net" weight or "tare entered", centre-of-zero light, etc.); or, as a minimum, the scale must have a connection for a separate duplicate display (Customer display must be submitted to the Laboratory for evaluation).

23.1.2 Customers' scoreboard: Scoreboards on vehicle scales, livestock scales, etc. do not require approval. However they must have the following features:

23.2 (Reminder) See item 7.3, section 7.0 in this manual

23.2.1 The devices must display the unit price if the total price is displayed.

23.2.2 If the device displays in kilograms, the unit price that can be entered and displayed is limited to Price/100 g and Price/kg; if the device displays in Canadian units, the unit price that can be entered and displayed is limited to Price/lb.

23.3 (Reminder) See item 17.4, section 17.0 in this manual

23.3.1 Except for pre-programmed tare, proportional tares and POS systems, when keyboard or platter tare values are entered, the scale must comply with one of the following requirement: the tare value is permanently indicated on a separate display; or the tare value is indicated as a negative value when there is no load on the load receptor.

23.3.2 A platter or keyboard tare value may not be entered, modified or cancelled unless the device is at gross load zero or the device indicates a negative weight value. This does not apply when the tare is continuously indicated on a separate display and to pre-programmed tare.

23.3.3 Platter or keyboard tares may retained between transactions.

Example A platter or keyboard tare value is entered in a computing scale; a negative value is indicated. If the wrong tare value was entered, it may be cancelled and replaced by a new tare value when the platter is empty. This new tare value will be indicated as a negative weight value. However, the correction must not be possible with the commodity resting on the platter (positive weight indication). The operator must remove the commodity from the receptor and then cancel or change the tare value.

Clarification The zero indication/no load condition does not apply to a preprogrammed tare value. The idea is that the operator should not be capable of altering a tare value without providing the consumer with an indication that a new tare value was entered. In the case of a pre-programmed tare associated with a PLU code, the tare value is rarely displayed. However, it is unlikely that the operator will select the wrong PLU code or product name, or change the PLU code during the weighing operation to reduce the tare value. It would affect the unit price which would be detectable by the consumer.

23.3.4 Auto-tares are prohibited in direct sale to the public applications.

Note: Devices that are not intended for direct sale to the public but resemble those approved for direct sale to the public, must be marked as follows: <<Not for use indirect sale to the public>> or words that convey the same meaning. The marking must be permanent and located near the weight display so that it is readily observable by the user.


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