Laboratory manual for the evaluation of non-automatic weighing devices
Part 2, section 13—Damping means and up-dating of weight/price data
Table of contents
Sections 30 to 33 of the Specifications Relating to Non Automatic Weighing Devices (1998)
13.0 Damping means and up-dating of weight/price data–generalities
The weight indications must stabilize shortly after a load is applied to the scale. Weight indications must not oscillate significantly or update so slowly that intermediate weight values are misinterpreted as the final stable weight value. Weight indications, unit and total computed sale prices, after the weight indication is stable and after introduction of unit price, must remain visible while the load is on the platter to allow proper reading of the values.
- On a mechanical device, damping should achieve a stable indication after three to five half periods of oscillation.
- (OIML criteria) For digital electronic devices, after a change in load sufficient to overcome the sensitivity threshold of the device, the previous indication should not persist for longer than 1 second.
- (OIML criteria) On a price computing scale, indication of weight, unit price and total price should remain visible for at least 1 second after the weight indication is stable and after introduction of a unit price while the load is on the platter.
- (OIML criteria) After the removal of the load, the indications may remain visible for no more than 3 seconds provided that the indication has been stable before and the indication should otherwise be zero. As long as there is a weight indication after removal of the load, it must not be possible to enter or change a unit price. Computed prices may remain visible while the platter is empty provided that this does not lead to confusion, measurement errors or fraud.
13.1 The mechanical device is equipped with an effective means for damping oscillations.
13.2 The electronic device up-dates the displayed weight information at a sufficient rate to prevent misinterpretation of the final weight value.
13.3 Indications of weight, and if applicable unit and total prices, are visible and stable when the load is on the platter.
13.4 A digital computing scale may continue to display computed price information following removal of the load provided that:
13.4.1 it does not display computed price information for more than 15 seconds (hold period);
13.4.2 it returns immediately to its zero weight reference;
13.4.3 it must automatically return to a "non-hold" or active mode at any time a new unit price is entered or the next load is placed on the platter;
13.4.4 it must return to an active mode and print the correct weight and price information for the current load conditions if it initiates label printing or a "print command" is given during the "hold" period.
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