SOP Title: Operation and Calibration of Weighing Balance
- Objective: To lay down the procedure for Operation, Cleaning and Calibration of Electronic Weighing Balance.
- Scope: This SOP is applicable for Operation, Cleaning and Calibration of Electronic Weighing Balance in the Production Department.
- Responsibility :
- Production Department: To prepare and review the SOP. To follow the procedures for the Operation, Cleaning and Calibration of Electronic Weighing Balance.
- Quality Assurance Department: To review and approve the SOP and Annexure.
- Accountability:
Head, Production Department / Head, Quality Assurance Department.
- Procedure:
- Definitions:
5.1.1 Breakdown: Any activity leading to operation of machine other than the set parameters and / or unusual readings displayed on balance.
5.1.2 Calibration: Tests performed to ensure that the instrument is functioning as per set parameters. These tests are performed daily, quarterly and also after repair or replacement of parts.
5.2. Procedure:
| Safety Precaution | |||
| 5.2.1 | Inspect electrical cables and connectors for any sign of damage or wear prior to use. | ||
| 5.2.2 | Do not disengage electrical connection unit during weighing operation. | ||
| 5.2.3 | Never overload balance beyond its capacity to avoid potential damages to load cells. | ||
| Checks before switching “ON” the Electronic Weighing Balance (EWB) | |||
| 5.2.4 | Do not keep the EWB near source of vibration /strong air drift. | ||
| 5.2.5 | Ensure that the EWB is clean and if not, clean the balance using a non-static brush. | ||
| 5.2.6 | Always start the weighing balance 30 minutes prior to use. | ||
| 5.2.7 | Do not keep weight on balance during “OFF” condition. | ||
| Weighing Operation | |||
| 5.2.8 | Connect the power supply cord to the switch board. | ||
| 5.2.9 | Switch “ON” the main power supply of the Electronic Weighing Balance. Then switch “ON” the balance by pressing ON/OFF switch provided at the bottom of the balance. | ||
| 5.2.10 | The balance starts with displaying.
1234567890 Then stabilises zero with beep sound. |
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| 5.2.11 | Allow the Electronic Weighing Balance to stabilize for 30 minutes before carrying out the any operation. | ||
| 5.2.12 | Ensure that, the balance is calibrated by checking the calibration status label on the balance. | ||
| 5.2.13 | Check the zero error, if there is error adjusts it by levelling the adjustment screw of the balance provided bottom the platform. | ||
| 5.2.14 | Introduction To Keys:
TARE = Zero-Setting Key MODE = Gross Weight. |
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| 5.2.15 | Place appropriate Container/Shipper/Box in the centre of the pan of the Electronic Weighing Balance. | ||
| 5.2.16 | Tare the weight of the Container/Shipper/Box by pressing the ‘TARE’ key. | ||
| 5.2.17 | Check that the display shows zeros. | ||
| 5.2.18 | If the display is not showing zero reading then press ‘TARE’ key to zero the display. | ||
| 5.2.19 | To take tare weight, remove the tarred Container/Shipper/Box from the EWB, display shows the tare weight of the Container/Shipper/Box. | ||
| 5.2.20 | Transfer the required quantity of the material to be weighed into the tarred Container/Shipper/Box and allow the display to stabilize. | ||
| 5.2.21 | The display shows the net weight of the material/product. | ||
| 5.2.22 | To check the gross weight, remove the weighed Container/Shipper/Box including the material and press the ‘TARE’ key for auto zero. Check that the display shows zero and keep the previously weighed Container /Shipper /Box with material, display will show the sum of weights of the both Container/Shipper/Box and material. | ||
| 5.2.23 | To check gross weight of the Container/Shipper/Box press the mode key, display will show the gross weight of the material for a few second then displays the net weight. | ||
| 5.2.24 | After completion and before weighing of every Container/Shipper / Box, balance should be display Zero. (applicable during gross weight checking) If shows zero error, make it zero by pressing “TARE” key of the balance. | ||
| 5.2.25 | After completion of weighing remove the weighed material/ container from the balance. If the balance not to be used for full day, then switch “OFF” the balance and switch ‘OFF’ the main supply. | ||
| Calibration | |||
| Daily Calibration: | |||
| 5.2.26 | Calibration to be performed every day before the start of the work. | ||
| 5.2.27 | Calibration is performed using standard calibrated weight box. | ||
| 5.2.28 | Place 0.100 kg of calibrated weight on the pan of the balance using hand gloves and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | ||
| 5.2.29 | Place 1.000 Kg of calibrated weight on the pan of the balance using hand gloves and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | ||
| 5.2.30 | Place 10.000 Kg of calibrated weight on the pan of the balance using hand gloves and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | ||
| 5.2.31 | Place 20.000 Kg of calibrated weight on the pan of the balance using hand gloves and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | ||
| 5.2.32 | Permissible tolerance for verification should be as per Annexure. | ||
| 5.2.33 | If daily calibration complies with permissible tolerance, affix / update the ‘Calibration Status Label (Daily)’ as per Annexure. | ||
| 5.2.34 | In case of non-compliance in step nos. 5.2.28 to 5.2.32, inform “Head of Department” and “Quality Assurance”. Label the balance as ‘Balance Under Maintenance’. | ||
| Quarterly [03 months ± 3 Days] | |||
| 5.2.35 | Perform the complete calibration once in three months. | ||
| 5.2.36 | Following parameters should be checked:
|
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| Weighing performance / Accuracy across the operating range | |||
| 5.2.37 | Set the balance to Zero before the start of the weighing performance test. | ||
| 5.2.38 | The standard weights should be distributed evenly on the balance pan. | ||
| 5.2.39 | Calibration should be carried out by using calibrated standard weights as per Annexure. | ||
| Repeatability / Precision | |||
| 5.2.40 | Load standard calibrated weight [20.000 Kg] on weighing pan and record the reading displayed after stabilization. | ||
| 5.2.41 | Remove the weight and ensure that reading returns back to Zero. | ||
| 5.2.42 | Re – place the same weight and repeat the above steps 5 more times. | ||
| 5.2.43 | Record the reading displayed as per Annexure. | ||
| 5.2.44 | Permissible tolerance for verification should be as per Annexure. | ||
| Eccentricity / Corner | |||
| 5.2.45 | Load standard calibrated weight [20.000 Kg] in the centre of weighing pan and record the stabilized reading displayed as per Annexure. | ||
| 5.2.46 | Repeat the procedure by placing the standard weight at different corners [as displayed below] of weighing pan. | ||
| 5.2.47 | 1 2
C 3 4 Weighing Pan C – Centre, 1, 2, 3, 4 – Corners. |
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| 5.2.48 | Record the readings displayed in each location of weight placement as per Annexure. | ||
| 5.2.49 | If quarterly calibration complies with permissible tolerance, affix / update the ‘Calibration Status Label (Quarterly)’as per Annexure. | ||
| 5.2.50 | If the test does not comply with permissible tolerance, affix ‘Balance Under Maintenance’ as per Annexure and inform Engineering Department and Service Engineer for rectification. | ||
| 5.2.51 | Switch “OFF” the balance, (if it is not using for full day) and cover with clean poly bag. | ||
| Cleaning | |||
| 5.2.52 | Switch “OFF” the balance during cleaning. | ||
| 5.2.53 | Cleaning of the balance should be done daily before calibration, after each weighing activity or whenever necessary. | ||
| 5.2.54 | First remove the dust and powder with the help of soft nylon brush. | ||
| 5.2.55 | Clean the balance (except display) with soft cloth soaked and squeezed in IPA to remove any oily substances or spots from the balance and clean with dry lint free cloth. | ||
| Action plan during Break down of Balance | |||
| 5.2.56 | If any breakdown occurs, inform to Head of the Department / QAD / Engineering Department. Put the tag “Balance Under Maintenance” as and inform to Service Engineer for rectification. | ||
| 5.2.57 | After rectification calibrate the balance with full scale before use. | ||
- Abbreviation:
| Abbreviation | Expansion |
| IPA | Isopropyl Alcohol |
| Kgs | Kilo Grams |
| EWB | Electronic Weighing Balance |
| QAD | Quality Assurance Department |
Balance Calibration Record (Daily)
| Date | Calibrated
Weights |
Acceptance criteria
(± 0.1% of certified value in Kg) |
Observed
value (Kg) |
Compliance
(Pass/Fail) |
Done By | Checked By | ||||
| From | To | |||||||||
| 0.100 kg | 0.099 | 0.100 | ||||||||
| 1.000 Kg | 0.999 | 1.001 | ||||||||
| 10.000 Kg | 9.990 | 10.010 | ||||||||
| 20.000 Kg | 19.980 | 20.020 | ||||||||
Balance Calibration Record (Quarterly)
- Weighing performance / Accuracy across the operating range
| Date | Calibrated
Weights |
Acceptance criteria
(± 0.1% of certified value in Kg) |
Observed
value (Kg) |
Compliance
(Pass/Fail) |
|
| From | To | ||||
| 0.050 Kg | 0.049 | 0.050 | |||
| 0.100 Kg | 0.099 | 0.100 | |||
| 0.500 Kg | 0.499 | 0.500 | |||
| 1.000 Kg | 0.999 | 1.001 | |||
| 2.000 Kg | 1.998 | 2.002 | |||
| 5.000 Kg | 4.995 | 5.005 | |||
| 10.000 Kg | 9.990 | 10.010 | |||
| 15.000 Kg | 14.985 | 15.015 | |||
| 20.000 Kg | 19.980 | 20.020 | |||
| 25.000 Kg | 24.975 | 25.025 | |||
- Repeatability / Precision
| Date | Calibrated
Weights |
Acceptance criteria
(± 0.1% of certified value) |
Observed
value (Kg) |
Compliance
(Pass/Fail) |
|
| From | To | ||||
|
|
20.000 Kg | 19.980 Kg | 20.020 Kg | ||
III. Eccentricity / Corner
| Date | Calibrated
Weights |
Acceptance criteria
(± 0.1% of certified value) |
Location | Observed value (Kg) | Compliance
(Pass/Fail) |
|
| From | To | |||||
| 20.000 Kg | 19.980 Kg | 20.020 Kg | Centre | |||
| Corner 1 | ||||||
| Corner 2 | ||||||
| Corner 3 | ||||||
| Corner 4 | ||||||
CONCLUSION: The quarterly calibration of balance is found to be SATISFACTORY/ NOT SATISFACTORY.
*Note – Ready to use SOP available in “DOWNLOAD” Section.