Title: Operation, Cleaning and Calibration of Precision 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 Quality Control Department.
- Responsibility :
- Quality Control Department: To prepare and review the SOP. To follow the procedures for the Operation, Cleaning and Calibration of Electronic Weighing Balance.
- Engineering Department: To carry out preventive maintenance as per schedule and procedure defined.
- Quality Assurance Department: To review and approve the SOP and Annexure.
- Accountability:
Head Quality Control Department, Head Quality Assurance Department.
- Procedure:
| 5.1 | Safety Precaution: | |
| 5.1.1 | Inspect electrical cables and connectors for any sign of damage or wear prior to use. | |
| 5.1.2 | Do not disconnect electrical connection during weighing operation. | |
| 5.1.3 | Never overload Electronic Weighing Balance (EWB) beyond its capacity to avoid potential damages to load cells. | |
| 5.2 | Checks before switching “ON” the Electronic Weighing Balance | |
| 5.2.1 | Do not keep the EWB near source of vibration /strong air drift. | |
| 5.2.2 | Ensure that the EWB is clean and if not, clean the balance using a non-static brush. | |
| 5.2.3 | Always start the weighing balance 30 minutes prior to use. | |
| 5.2.4 | Do not keep weight on balance during “OFF” condition. | |
| 5.3 | Weighing Operation: | |
| 5.3.1 | Connect the power supply cord to the switch board and switch on the balance and allow the balance to warm up for about 30 minutes. | |
| 5.3.2 | The balance shall perform a self-test in which all display segments light up. | |
| 5.3.3 | Ensure that, the balance is calibrated by checking the calibration status label on the balance. | |
| 5.3.4 | Ensure balance is in clean condition. | |
| 5.3.5 | Place appropriate container on the centre of the pan of the Electronic Weighing Balance. | |
| 5.3.6 | Tare the weight of the container by pressing the ‘ZERO’ key. | |
| 5.3.7 | Check that the display shows zeros. | |
| 5.3.8 | If the display is not showing zero reading then press ‘ZERO’ key to zero the display. | |
| 5.3.9 | To take tare weight, remove the tarred container from the balance, display shows the tare weight of the container. | |
| 5.3.10 | Transfer the required quantity of the material to be weighed onto the container by means of a clean dry spatula and allow the display to stabilize. | |
| 5.3.11 | The display shows the net weight of the material/product. | |
| 5.3.12 | To check the gross weight, remove the container including the material and press the “ZERO” key for auto zero. Check that the display shows zeros and keep the container with material, display will show the sum of weights of the both container and material. | |
| 5.3.13 | After completion and before weighing of every container, balance should be display Zero. (applicable during gross weight checking) If shows zero error, make it zero by pressing “ZERO” key of the balance. | |
| 5.3.14 | After completion of weighing, remove the weighed material/ container from the balance. At end of the shift, switch “OFF” the balance and then switch ‘OFF’ the main supply. | |
| 5.4 | Calibration: | |
| 5.4.1 | Generate the A. R. No. as per SOP and give requisition to QA Department for quarterly calibration formats of instrument on the due date of calibration. | |
| 5.4.2 | Get the calibration record format issued from QA. | |
| 5.4.3 | Daily calibration: Calibration to be performed every day before the starting the weighing in the morning or start of shift. | |
| 5.4.4 | Calibration is performed using standard calibrated weight box. | |
| 5.4.5 | Place 2 gram of calibrated weight on the pan of the balance using forceps and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | |
| 5.4.6 | Place 20 gram of calibrated weight on the pan of the balance using forceps and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | |
| 5.4.7 | Place 50 gram of calibrated weight on the pan of the balance using forceps and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | |
| 5.4.8 | Place 100 gram of calibrated weight on the pan of the balance using forceps and record the weight as per Annexure. Ensure that the value meets with the acceptance limits. | |
| 5.4.9 | Permissible tolerance for verification should be as per define in Annexure. | |
| 5.4.10 | If daily calibration complies with permissible tolerance, affix / update ‘Calibration Status Label’ as per SOP. | |
| 5.5 | Quarterly or after carrying out any major maintenance work: | |
| 5.5.1 | Perform the complete calibration once in three months., Refer Annexure | |
| 5.5.2 | Following parameters shall be checked:
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| 5.6 | Weighing performance / Accuracy Across the Operating Range: | |
| 5.6.1 | Set the balance to Zero before the start of the weighing performance, do not set zero in between two consecutive weighing operations. | |
| 5.6.2 | The standard weights should be distributed evenly on the balance pan. | |
| 5.6.3 | Calibration shall be carried out by using calibrated standard weights as per Annexure. | |
| 5.7 | Repeatability / Precision: | |
| 5.7.1 | Load standard calibrated weight [500 gram] on weighing pan and record the reading displayed after stabilization. | |
| 5.7.2 | Remove the weight and ensure that reading returns back to Zero. | |
| 5.7.3 | Again place the same weight and repeat the above steps 5 more times. | |
| 5.7.4 | Record the reading displayed in Annexure. | |
| 5.7.5 | Permissible tolerance for verification should be as per Annexure. | |
| 5.8 | Eccentricity / Corner : | |
| 5.8.1 | Load standard calibrated weight [500 gram] in the centre of weighing pan and record the stabilized reading displayed. | |
| 5.8.2 | Repeat the procedure by placing the standard weight at different corners [as displayed below] of weighing pan. | |
| 5.8.3 |
Weighing Pan C – Centre, 1, 2, 3, 4 – Corners. |
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| 5.8.4 | Record the readings displayed in each location of weight placement. | |
| 5.8.5 | Update the “Instrument/Equipment Usage Log Book”, as per SOP. | |
| 5.8.6 | Affix the “Calibration Status Label” on the Instrument as per SOP. | |
| 5.8.7 | If calibration activity is outsourced, the values are to be transcribed in the Annexure, and external party certificate to be attached. | |
| 5.8.8 | Switch “OFF” the balance after completion of weighing at the end of the shift. | |
| 5.9 | Cleaning: | |
| 5.9.1 | Switch “OFF” the balance during cleaning. | |
| 5.9.2 | Cleaning of the balance should be done daily before calibration, after each weighing activity or whenever necessary. | |
| 5.9.3 | First remove the dust and powder with the help of soft nylon brush. | |
| 5.9.4 | Clean the balance with soft cloth soaked and squeezed in IPA to remove any oily substances or spots from the balance and clean with lint free cloth. | |
| 5.10 | Action Plan During Break Down of Balance: | |
| 5.10.1 | If any breakdown occurs, follow procedure as per SOP “Calibration of Instruments and Equipments”. | |
| 5.10.2 | After rectification calibrate the balance with all suitable weights before use. | |
- Definitions / Abbreviations:
- Definitions:
- Breakdown: Any activity leading to operation of instrument/equipment other than the set parameters or unusual sound or vibration observed in the instrument/equipment.
- Calibration: Tests performed to ensure that the instrument/equipment is functioning as per set parameters. These tests are performed as per predefined frequency and also after any major repair or replacement of parts.
- Preventive Maintenance: Maintenance activity performed to ensure that the instrument/equipment will function smoothly and to avoid breakdowns. These activities are performed as per predefined frequency.
- Abbreviations:
| Abbreviation | Expansion |
| SOP | Standard Operating Procedure |
| QC | Quality Control |
| IPA | Isopropyl alcohol |
*Note – Ready to use SOP available in “DOWNLOAD” Section.
Daily Performance check
Acceptance Criteria: +0.1% Standard weight box ID no. _____________
|
Date |
Standard Weights |
Remark |
Done by | Checked by | |||
| 2.000 g | 20.000 g | 50.000g | 100.000g | ||||