Checking The Repeatability (Standard Deviation); Checking And Adjusting The Off-Center Loading; Checking The Off-Center Loading Tolerances - Sartorius CP64 Service Manual

Repeatability / Off-Center Loading
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Checking the Repeatability (Standard deviation)

- Select the test weight from the „Calibration/Adjustment Data Sheet" (see pages
42-43).
- Unload the weighing pan and zero the balance/scale using the t key.
- Center the test weight on the weighing pan.
- Write down the weight displayed.
- Repeat the procedure five times.
- The repeatability is calculated from the 6 weighing operations as follows:
(Max. value displayed - Min. value displayed) / 3
- Compare the calculated value with the given tolerance.
- If the calculated value is not within the given tolerance, it may be due to one
of the following reasons:
- The weighing system needs to be cleaned
- Mechanical parts are in the weighing system
- Bent / defective bending elements
Checking and Adjusting the Off-Center Loading Error
Larger errors in the off-center loading error affect the repeatability of the
weighing system!
The OIML Guideline R76-1 describes the tests for off-center loading tolerances for
square, round and even triangular weighing pans. Therefore, the test weight should
be placed on every 1/4 of the weighing pan surface.
The positions for placing test weights in triangular weighing pans are indicated in
the fi gures to the left.
Please refer to the sketches to the left to establish the testing points for checking
the off-center loading tolerances.
The markings should help you place the test weights in their proper positions.

Checking the Off-Center Loading Tolerances

Note: Select the test weights from the „Calibration/Adjustment Data Sheet (see
pages 42-43).
CP Balances/Scales with Rectangular Weighing Pans
Models: CP622
- Place the test weight on position 1 on the weighing pan and zero the balance/
scale by pressing the t key.
- In the order given, place the test weight in the position 2, 3, 4 and 5 as indicated
and write down the readout at stability, including the plus/minus signs.
- If the off-center loading error is too large, adjust the balance so that the off-
center loading error is within the tolerances specified.
CP Balances/Scales with Square Weighing Pans
Models: CP8201, CP6201, CP4201, CP2201, GP8201
- Compare the test weights with the tolerances listed in the „Calibration/
Adjustment Data Sheet (see pages 42-43).
- If the off-center loading error is too large, adjust the balance so that the off-
center loading error is within the tolerances specified.