MONTHLY CALIBRATION OF BALANCES
For monthly Calibration of Balances check following parameters-
1. Accuracy - verify the balance with minimum weight (least count × 100), 5%, 20%, 50%, 90% capacity of respective balance capacity.
Tolerance - the variation if any should be ± least count of the balance or ± 0.2% of certified standard weight used whichever is higher
2. Reproducibility -
Check the reproducibility by using minimum standard weight of balance capacity. Place the weight in the middle of the weighing pan observe the displayed value
Then calculate the %RSD by following formula
RSD= SD×100 / X
Where,
X= mean of the individual value
Acceptance = %RSD should not be more than 2.0%
3. Eccentricity
Eccentricity is the difference between the weight placed in centre and at peripheral points of the weighing pan