Laboratory manual for the evaluation of non-automatic weighing devices

LG-3.14 Creep and creep-return-to-zero

Table of contents


Reference

Sections 17 and 18 of the Specifications Relating to Non Automatic Weighing Devices (1998)

Application

This test is performed on any complete mechanical or electronic weighing device and on any mechanical or electronic weighing element tested separately.

Settings

Procedure

Single range or multi-interval device

Creep test
  1. Following the increasing and decreasing load test, allow the device to "recover" for a period of time equal to the increasing and decreasing test time. Exercise the scale 3 times up to at least 90% Max.
  2. Place on the weighing element a load equal to at least 90% of Max, and take a reading 20 seconds after the indication has stabilized. Observe the indication for 30 minutes, taking a reading at 15 minutes and 30 minutes. Do not remove the load
Creep—Return to zero test
  1. Remove the load and take a reading as soon as the indication has stabilized (wait no more than 20 seconds). If the AZT could not be disabled leave a small weight on the platter to keep the indication above the AZT range.

Multiple range devices

Creep test
  1. Complete the creep test described for Single Range or Multi-Interval Devices for each range, using 90% of the Max of the range being tested.
Creep—Return to zero test
  1. After the creep test for the lowest range has been completed remove the load and take a reading as soon as the indication has stabilized (wait no more than 20 seconds). If the AZT could not be disabled leave a small weight on the platter to keep the indication above the AZT range.
  2. After the creep test for the highest range (using 90% of the capacity of the device) Remove the load and take a reading as soon as the indication has stabilized (Wait no more than 20 seconds). If the AZT could not be disabled leave a small weight on the platter to keep the indication above the AZT range.
  3. Immediately, switch the device to the lowest range, take a reading of the weight indication. Observe the weight indication for 5 minutes. Record any changes in the weight indication.

Interpretation of results (creep test)

The device meets the requirements if the difference between the indication obtained 20 seconds after placing the load on the device and the indication observed during the following 2 an hour does not exceed the absolute value of the applicable limit of error for that load.

Interpretation of results (creep—return-to-zero)

Revision

Rev. 1 (September 2009)
  • Removed requirement for testing at temperatures other than nominal
Rev. 2 (March 2010)
  • AZSM renamed to AZT
  • Formatting changes
  • Procedures adjusted for 30 minute creep test length
Date modified: