Laboratory manual for the evaluation of non-automatic weighing devices
LG-3.04 Tilting (off level position)
Table of contents
- Procedure for portable or movable scales
- Interpretation of results
- On-board weighing systems such as systems for forklift trucks or similar vehicles
Sections 9, 10, 11 and 22 of the Specifications Relating to Non Automatic Weighing Devices
This test is performed on any complete portable or movable devices or weighing elements tested separately, that are of a type other than suspended, and that are not equipped with a suitable level indicating means. Devices aimed are: bench and counter scales, floor scales, weighing systems mounted on a vehicle (On-board weighing systems for NH3, on-board waste weighing systems, scales mounted on lift trucks). "Portable" vehicle scales do not fall into this category. The purpose of this test is to ensure that the performance is not affected when the device is off level.
- The AZT may be activated. It must be set so that the weight value that can be tracked at once does not exceed 0.6e.
- If the IZSM range does not exceed 20% of Max, the test will be performed with the IZSM set at the maximum of the range.
- If the IZSM range exceeds 20%, the test will be performed twice: the first test with the IZSM set to the lowest possible value; the second test with the IZSM set to the to the maximum of its range.
Note: In the case of a multi-range device, it is 20% of Max of the lowest range; in the case of a multi-interval device, it is 20% of max of the first range.
- If the device has an "enhance" resolution feature, perform the test with that feature activated; or use the small weight method to determine errors before rounding.
- This test is performed at ambient temperature only.
Measure the distance "x" between the two support points of the scale. Multiply the "x" value by 5⁄100 (0.05 or approx Tan 3°). The result is the elevation "y" at the support point.
Procedure for portable or movable scales
Note: The device is tested for accuracy when leveled, first; then off-level tests are performed.
- The procedure consists of inclining the device in the four directions (+x, -x, +y, -y) using a suitable support. The tests is performed when the device is off level by the lesser of:
- 3 degrees; or
- maximum angle at which the device still provides an indication or registration.
- For each of the four inclinations, set the device to zero and perform an increasing and decreasing load test.
Note: It is not necessary to proceed further if at the first inclination the device does not perform within the prescribed limits of error.
Interpretation of results
The device meets the requirements if it performs within prescribed limits of error when off level.
Note: If the device can not perform within the prescribed limits of error, it must be equipped with a suitable level indicating means permanently installed.
On-board weighing systems such as systems for forklift trucks or similar vehicles
On board weighing system means weighing device designed to be an integral part of, or attached or secured to, the frame, chassis, lifting mechanism or bed of mobile equipment such as a truck, tractor, trailer or forklift
- With the vehicle resting on a level surface, visually inspect, checking for possible binding and additional items secured to the device that may have an effect on accuracy (e.g. mudflaps and fenders must be secured to the frame of the vehicle, not the device).
- Perform load discrimination tests near zero and at capacity; increasing and decreasing load tests; section/corner tests; repeatability; blanking at capacity and motion detection; return to zero; etc.. The device must perform within the prescribed limits of error.
Off level test
- Visually inspect the device while performing the following tests to ensure that the inclination does not cause a shift that may affect the device accuracy.
- Elevate the front or rear wheels to 3 degrees or the maximum inclination at which a weight indication is still provided, whichever is greater. Perform the tests described under "level testing" above, except the section and repeatability test.
- Elevate either the driver side or passenger side to 3 degrees or the maximum inclination at which a weight indication is still provided, whichever is greater. Perform the tests described under "level testing" above, except the section and repeatability test.
- Elevate a single rear wheel combination until the side to side inclination is 3 degrees or the point at which a weight indication is still provided, whichever is greater. This test causes the frame to twist and will reveal defects in poorly constructed devices. Perform the tests described under "level testing" above, except the section and repeatability test.
- Scales mounted on lift trucks (or similar vehicles) must blank their indications when the lift truck is moving, unless the scale can provide an accurate weight indication. Perform an accuracy (in-motion) test using different loads within the capacity range of the device. The test must simulate actual conditions of use.
Interpretation of the results
The device meets the requirements if:
- it provides a weight indication when off level up to at least 3 degrees;
- it performs within the prescribed limits of error when off level by the larger of 3 degrees or the maximum angle at which it still provides a weight indication;
- it blanks its indications and prevent the recording of weight values when it ceases to perform within tolerances;
- in the case of a scale mounted on a lift truck, it provides weight indications within the permissible limits of error while the lift truck is moving, or blanks its indications.
- Rev. 1 (March 2010)
- AZSM renamed to AZT
- Formatting changes
- Date modified: