- To lay down a procedure for calibration of Weighing Balance XS – 204 DR
- This Standard Calibration Procedure (SOP) is applicable in quality control area.
- Quality Control Officer/ Executive
- Head –Quality Assurance
- PRE STARTUP
- Check the cleaning of the weighing balance especially pan & display terminal.
- Check the power supply of balance.
- Check the level of balance using built in level indicator.
- Clean up balance base / pan using soft brush.
- Allow balance to stabilize for at least 30 min before starting the calibration.
- Avoid direct hand contact with weights; Always use clean gloves or special lifting tools like forceps.
- Avoid sliding weights across any surface, especially across the stainless steel weighing pan of the balance under test.
- Do not drop the weights on the balance pan. Gently place the weights by placing/ lifting using forceps.
- Check the balance performance as per calibration plan in normal weighing mode.
- Daily calibration:
- Auto calibration:
- Operate the balance as per sop BA(II)QA208-00. Press “Adj.Int ” for internal adjustment.
- After completion of internal adjustment, note down the display value in calibration record for balance.Acceptance criteria: display value shall return to 0.0000 g.
- After completion of Internal adjustment verify the performance of balance with external standard weights
- Place the check weight (1,2,3) in center of balance pan with the help of forceps. Check weights are (1.) 0.1000 g
(2.) 1.0000 g (3.) 100.000 g.
- Note down reading/ print the stabilized displayed values and remove the weight with the help of forceps.
- Allow display to come to zero (do not tare the balance to zero).
- Again place the same weight and repeat the steps 184.108.40.206 to 220.127.116.11 for 4 more times.
- Select the next check weight (2,3) and repeat the steps 1 to 4. Enter results in calibration record for balance.
- Tolerance limit is ± 0.1 % of each standard weight.
- Weekly calibration:
- Before starting the weighing rezero the balance by pressing ’⇒0⇐’
- Place standard weight of 50.0000 g using forceps at the center of the pan.
- Note down the reading of stabilized display value and tare the weight (step –1)
- Remove the standard weight and place 100.0000 g weight using forceps at the center of the pan
- Note down the reading of stabilized display value and tare the weight (step – 2).
- Do not remove the 100.0000 g weight and introduce 50.0000 g weight on balance pan.
- Note down the reading of stabilized display value and tare the weight (step –3).
- Remove the both 50.0000 and 100.0000 g weights and place standard weight 200.0000 g.
- Note down the reading of stabilized display value in calibration record for balance.
- Tolerance value is 50.0000±0.002 g for all steps.
- Place the check weight of 100.0 g in center of the pan & tare the weight. Record the displayed weight in annex – III
- Remove the weight from balance & reintroduce on pan in defined segments, as shown in diagram – 1 and note down the value in calibration record for balance.
- Repeat the step 5.6.2 for other three segments and record the readings Compare the segment 1-4 values with the center weight displayed.
- Monthly calibration: Measurement of uncertainty
- Place 100 mg weight in center of balance record the weight and note down in annex – II
- Remove the weight from balance pan and reintroduce the same weight again & record the weight
- Take 10 readings of check weight 100 mg following 5.7.1 to 5.7.2 steps.
- Repeat the steps 5.7.1 to 5.7.3 using 1g, 5g, 10g, 20g, 50g, 100g, 200g weights.
- Calculate standard deviation for 10 consecutive readings.
- Calculate measurement of uncertainty for each weight using the formula [3 x s / std weight.] s= standard deviation.
- Tolerance limit for Measurement of Uncertainty is 0.001 for individual check weights.
- Fill the details of calibration status on the label pasted on the instrument.
- Enter the details of calibration in balance log book.
- Report any discrepancy observed during calibration to Head – Quality Assurance and notify the defect to engineering department or service Engineer of the instrument. Affix an Under Maintenance label on the instrument.
- Forms and Records (Annexures)
- Calibration plan – Annexure-1
- Format for monthly calibration – Annexure-2
- Calibration plan- Annexure-3
- Master copy – Quality Assurance
- Controlled copies- Quality Assurance, Production, Quality Control.engineering
Date Revision Number Reason for Revision – 00 New SOP
|Sr. No.||PARAMETER||STANDARD WEIGHT||ACCEPTANCE CRITERIA||FREQUENCY|
|1.||Load cell||—||Bubble shall be present in the center of the load cell.||Daily, before auto calibration.|
|2.||Zero setting||—||Balance display shall be 0.0000 g||Daily, before auto calibration.|
|3.||Auto calibration (Internal Calibration)||Auto||The calibration is completed when the message “internal adjustment done” appears briefly in the display, followed by “0.0000 g”.||Daily|
|4.||External Calibration (Repeatability Test)||0.1000 g
|+ 0.1 % of certified mass value of standard weight||Daily|
|5.||External Calibration (Linearity Test)||50.000 g
|50.0000 g ± 0.002 g||Weekly|
|6.||External Calibration (Eccentricity Test)||100.000g
|+ 0.0002 g of center reading displayed.||Weekly|
|7.||External Calibration (Uncertainty Test)|| 0.1000 g
|Ratio of three times standard deviation (of 10 replicate weighing) to certified mass value of standard weight should be less than 0.001||Monthly|
Format for monthly calibration
|Make||METLER TOLEDO||Model||XS 204 DR|
|Instrument No.||2QA038||Ref. No. of Certified Weight Box|
|Test Methods||Uncertainty Test||Frequency of Calibration||Monthly|
|Date of Calibration||Due Date for Calibration|
|Tolerance Limit: : NMT 0.001 (3 X SD/Certified mass value)|
|Std. Wt.||0.1000 g||1.0000 g||2.0000 g||5.0000 g||10.0000 g||20.0000 g||50.0000 g||100.000g||200.000 g|
|3 X SD|
|3 X SD/Certified mass value|
STD WEIGHT BOX REF . NO : STD WEIGHT BOX VALID UPTO:
|S. NO.||DATE||TEST PARAMETER / FREQUENCY||CHECK WEIGHT||STANDARD MASS VALUE||DISPLAY VALUE||TOLERANCE||DONE BY||NEXT CALIBRATION DUE ON||CHECKED BY||REMARKS|
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