CALIBRATION OF WEIGHING BALANCES

• Calibration of Weighing Balance (MAKE: METTLER TOLEDO, Model: PB3002-S/FACT):
• Operate the instrument as per SOP.
• Daily Calibration Model: PB3002-S/FACT
• Environmental conditions:
• Check the cleanliness of balance and surroundings, if not clean.
• Check for condition of silica gel, if not, replace or regenerate. Check for spirit level, if not adjust.
• Internal Calibration:
• Press and hold a few seconds Cal/menu Key from key pad of the balance.
• The display indicates ——- Cal During the internal calibration.
• The balance adjusts itself automatically.
• The adjusting is finished when the message “CAL done” appears briefly in the display, followed by 0.00000g.
• The balance is again in weighing mode and ready for internal calibration.
• Once the internal calibration is completed, calibration shall be done with external calibrated weights.
• Instrument shall calibrate using 200g, 100g, 20g and 500mg external weights.After completion of external calibration record the results in Format.
• Perform the calibration for Repeatability measurement as given below.
• The weights selected for Repeatability measurement are 1.0 g. Weigh 1.0 g of standard weight, for 10 times and take the print out of all the weighings and record the results in Format-II.
• Calculate mean and standard deviation (S.D.) for the weights taken above or press “STAT” key of printer to obtain mean and standard deviation (S.D.).
• Calculate the Repeatability for all the selected weights by using following formula
• Monthly Calibration:
• Environmental conditions:
• Complete the internal Calibration as per test points mentioned above
• Linearity check:
• Calibration shall perform using external weights in the range of 200g, 100g, 50g, 20g, 10g, 5g, 2g, 1g and 500mg and record the results in Format.
• Repeatability:

• Perform the calibration for Repeatability measurement as given below.
• The weights selected for Repeatability measurement are 1.0 g. Weigh 1.0 g of standard weight, for 10 times and take the print out of all the weighings and record the results in Format-II.
• Calculate mean and standard deviation (S.D.) for the weights taken above or press “STAT” key of printer to obtain mean and standard deviation (S.D.).
• Calculate the Repeatability for all the selected weights by using following formula

• Record the observations in Balance monthly calibration record as per Format-II.
• Acceptance criteria: Repeatability should not be more than 0.10%
• Drift: Calibration shall perform using 20g.
• Measure 20g for 10 times.
• Acceptance criteria: Individual reading should not differ by more than 0.2mg from mean weight.
• When the standard weights are sent for external calibration, the Format can be changed as per the new mass values with change control.
• In case any failures observed during calibration due to instrument problem raise the break Down Memo and inform to the Service Engineer.
• In Case, any failure is observed during calibration, “Under Maintenance” label shall be affixed and inform to Head-Quality control.

• Tolerance of weight used does not exceed 0.05 % of the certified mass value (Ref. USP-41)

• ANNEXURES: 

Annexure-I
BALANCE DAILY CALIBRATION RECORD

Annexure-II