procedure for Operation and Calibration of Analytical balance (AUX220)

1.0	Objective	:  To lay down a procedure for Operation and Calibration of Analytical balance (AUX220)
2.0	Responsibility	:  Microbiologist/ QC Executive
3.0	Accountability	:  Head /QC Executive
4.0	Procedure	:
4.1	Operating Procedure :
4.1.1	Clean the pan thoroughly prior to operation with a clean, dry lint free cloth.
4.1.2	Ensure that the weighing balance is not disturbed by direct air current.
4.1.3	Leveling of the balance shall be done by adjusting the leveling screws till the spirit bubble is at the center.
4.1.4	The weighing balance shall be used within the minimum and maximum weight range of the balance. The minimum weight shall be Least count x 100 and maximum weight shall be 90 % of the maximum capacity.
4.1.5	Switch ‘ON’ the balance and allow it to stabilize for 15 minutes.
4.1.6	Weigh the sample as per requirement.
4.1.7	Read the displayed weight after the display is stable.
4.1.8	After completion of the any weighing operation, make the entry in the usage logbook.
4.1.9	Material shall be brought to the room temperature, to avoid condensation of moisture, refrigerated materials must be allowed to come to room temperature.

4.2	Calibration Procedure :
	Internal calibration shall be done before each calibration.
	Daily calibration shall be performed at the start of the day’s work as per format as metioned in DC/23/F/01-01.
	Monthly calibration shall be formed as per format as mentioned in DC/23/F/02-01 and DC/23/F/03-01.
4.2.1	External  Calibration :
4.2.1.1	Ensure that the balance pan is not loaded and the door of the weighing chamber is closed properly.
4.2.1.2	From the mass display press the CAL/MENU key several times when the Func.SEL is displayed ,press the  O/T KEY
4.2.1.3	Press the O/T key when CAL is displayed.
4.2.1.4	Press the CAL/MENU key When E TEST is displayed press the O/T key .Span checks start at this point.
4.2.1.5	Zero appears on the display and blinks.
4.2.1.6	The predetermined mass for the calibration weight is displayed and blinks.
4.2.1.7	Place the correct calibration weight on the pan.
4.2.1.8	Zero appears on the display and blinks.
4.2.1.9	Place calibrated standard weight on the weighing pan.
4.2.1.10 4.2.1.11	Use weights as per DM/24/F/01-01andDM/24/F/02-01 for daily and monthly calibration. The observed weight shall not deviate 0.1 % from the calibrated weight. Do not drop the weight on the balance pan because balance may get damaged.
4.2.2	Measurement Uncertainty :
4.2.2.1	Place certified weights of 50 mg; allow stabilizing the display of mass, removing the weight from the pan. Close the doors and ensure that display comes 0.0000, place the weight on the pan again and note the displayed value after stabilization, repeat the weighing and note down the displayed value after stabilization for total 10 replicate weighing.
4.2.2.2	Carry out the 10 replicates weighing for 500 mg also.
4.2.2.3	Calculate the measurement uncertainty as given below Measurement Uncertainty = Random Error + Systematic Error x 100 Calibrated weight Random Error = 3 x standard deviation (n = 10) Systematic Error = Observed weight (average) – Calibrated weight The measurement uncertainty should not be more than 0.1%. Note : Measurement uncertainty is applicable for 5 digit analytical balances and above only
4.3	Frequency of Calibration :
4.3.1	The frequency of calibration shall be mentioned as below :
4.3.2	Daily (as mentioned in DQM/24/F/01-01.
4.3.3	Monthly (as mentioned in DQM/24/F/02-01 and DQM/24/F/03-01).
4.3.4       Action : If calibration results not meeting the acceptance criteria, repeat the procedure and confirm the result. 4.3.5       Affix the “Under Maintenance” Label on the balance and inform to Head–QC for necessary action.