As per USP 41 do I need to perform the accuracy test covering the operation range. How many test weights need to be used for the accuracy test? if I select 3 test weights 5%, 50% and 90% capacity of the balance, is this ok?
Yes. But be aware that the weighing error increases nearer to the upper end of the operation range. You might want to add another test weight in that region
Someone was asking to cover the operation range during performing the accuracy test. Do you think its rational?
Do you want to perform calibration or Daily check ?
Based on USP 41 It does not make sense to conduct Accuracy test below 5% of balance capacity , at this lower range Repeatability test is to be conducted
Different auditors differ in their visions
I advise you to really consider consulting:
1- USP chapter 1251 because it provides detailed scientific beneficial information
2- Mettler Toledo GWP: The standard science based weighing
3- Euramet Calibration guide No. 18: Guidelines on the calibration of Non-automatic weighing instruments
The following statement is from USP Chapter 41:
The following is the link of Mettler Toledo GWP: The standard science based weighing:
The following is the link of Euramet Calibration guide No. 18: Guidelines on the calibration of Non-automatic weighing instruments
If your objective is to comply with USP 41
It is also important to consult the following 2 links:
https://www.mt.com/dam/MT-NA/pdf/USP_NA0025-009-051117-USPM_B535371765_XPE204_Mettler%20Toledo.pdf