1.0 PURPOSE
1.1 To lay down the procedure for Calibration of Analytical balance.
2.0 SCOPE
2.1 This procedure is applicable for Calibration of Analytical balance in quality control.
3.0 RESPONSIBILITY
3.1 Executive-QC
4.0 ACCOUNTABILITY
4.1 Asst. Manager-QC
5.0 PROCEDURE
5.1 Operate the instrument as per respective SOP and calibrate as follows by taking the following additional precautions.
5.1.1 The calibrated and certified weights shall be carefully handled with the stainless steel forceps and the hand-glove provided with the weight box.
5.1.2 Ensure that the balance is clean and the spirit level is adjusted to the center before putting any of the calibrated weights on the weighing pan.
5.2 The balance calibration shall have two modules; one consisting accuracy test performed on a daily basis, the second consisting Accuracy and Uncertainty on a monthly basis.
5.3 ACCURACY:
5.3.1 Accuracy test shall be performed on a daily basis with the nominal weights 50 mg, 1.0 g and 200 g (Record the results as per Format No.: xxxxx where as accuracy on a monthly basis shall be performed with the 50 mg, 100 mg, 500 mg 1.0 g and 200.0 g nominal weights. Record the calibration details as per Format No.: xxxxx
ACCEPTANCE CRITERION: Error in weighing NMT ± 0.10 %
5.3.2 The linearity plot of the weights measured in monthly accuracy test shall be taken. Correlation coefficient should be not less than 0.999
5.4 UNCERTAINTY
5.4.1 Uncertainty (systematic +random) in weighing shall be tested using the standard weights 0.05000g, and 200.0000g.
5.4.2 From the above weights take one at a time and proceed as follows.
5.4.3 Tare the balance, put the weight in the center of the pan and note down the reading as per Format No.: xxxxx
5.4.4 Remove the weight and close the sliding door.
5.4.5 Repeat the steps 5.4.3 and 5.4.4 to get a total of ten reading by placing the weight at randomly selected points on the weighing pan (to cover the off-center accuracy) for each of the weights as mentioned in 5.4.1.
5.4.6 Calculate uncertainty as per the formula below.
Analytical balance, uncertainty, accuracy,
