1. OBJECTIVE
To lay down the procedure for operation, Cleaning and calibration of Weighing Balance
2. SCOPE
This procedure is applicable to Quality Control Department
3. RESPONSIBILITY
• Officer QC
• Manager QC
4. SAFETY INSTRUCTIONS
• Proper handling the instrument.
• Care to be taken for proper drying during use of IPA
5. PROCEDURE
5.1 OPERATING PROCEDURE
5.1.1 To switch the balance on to touch the ON/OFF key after the main power supply of balance has been
switched on.
5.1.2 Check the level of weighing balance; center the position of air bubble.
5.1.3 To switch the balance off by touch the “ON/OFF” Key.
5.1.4 Weighing:
5.1.4.1 Open the sliding glass door by hands.
5.1.4.2 Place a container or butter paper on the weighing pan.
5.1.4.3 Press the O/T key, the display changes to zero. Close the glass door.
5.1.4.4 Place the sample to be weighted up to the desired target
5.2 CLEANING
Frequency: once in a week/ whenever necessary
5.2.1 Switch “OFF” the instrument.
5.2.2 Switch “OFF” the mains.
5.2.3 Open the shuttle of the instrument and remove the pan which is inside the balance.
5.2.4 Remove dust and powder with the help of tissue paper.
5.2.5 Sock the tissue paper in the isopropyl alcohol and squeeze out the isopropyl alcohol and clean the
balances to remove oily substances or any spot inside the balance.
5.2.6 Finally clean it with tissue paper. Care to be taken for proper drying during use of IPA.
5.2.7 Clean the outside of balance with tissue paper wetted with IPA and then with dry tissue paper.
5.2.8 Also clean the shuttle of balance with tissue paper wetted with IPA and then with dry tissue paper.
5.2.9 After cleaning close the shuttle.
5.3 CALIBERATION PROCEDURE
5.3.1 Switch “ON” the mains.
5.3.2 Switch “OFF” the instrument.
5.3.3 The display is blink with 8.8.8.8
5.3.4 After few seconds the display will show 0.00g
5.3.5 Perform internal calibration
5.3.6 For internal calibration use the pre-calibrated set of dead weights
For Accuracy
5.3.7 Place 5gm on the weighing pan.
5.3.8 Note the weight
5.3.9 Calculate the difference between the weight in certificate and the observed weight.
5.3.10 Repeat the above step by using 50gm and 100gm
5.3.11 Record the reading
5.3.12 Tolerance should be ± 5mg
For Precision
5.3.13 Place 5gm in the weight pan.
5.3.14 Note the weight
5.3.15 Repeat the above two steps 9 times.
5.3.16 Record the weight.
5.3.17 Calculate the standard deviation
5.3.18 Calculate the measurement uncertainty using following equation
Measurement Uncertainty = 2 X SD/ Actual weight from certificate
5.3.19 Tolerance should not be more then 0.10.
Frequency
5.3.20 Internal calibration and accuracy: Daily
5.3.21 Precision: Once in a month
6. RELATED DOCUMENTS
Operational Log Book Format – Annex. I
Cleaning Log Book Format – Annex. II
Calibration Report Format – Annex. III
7. DISTRIBUTION INDEX
Original Copy will be retained by Quality Assurance Department.
DISTRIBUTION INDEX
Distributed To Copy No. Received By/Date
Quality Control Department 01
8. ABBRIVIATIONS
Q.C Quality Control Department
SD Standard Deviation
IPA Isopropyl alcohol
9. REVISION HISTORY
Revision No Issue Date Supersedes
Reason of Change/ Description
Revision No. Dated
00 25-12-2015 NA NA First Version
01 01-11-2020 00 25-12-2015 Due to revision date is over. And change in format