Procedure for calibration of balance XS 204 DR.

 

• To lay down a procedure for calibration of Weighing Balance XS – 204 DR

• SCOPE
• This Standard Calibration Procedure (SOP) is applicable in quality control area.
• RESPONSIBILITY
• Quality Control Officer/ Executive
• ACCOUNTABILITY
• Head –Quality Assurance

• PROCEDURE
• 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.

• PRECAUTIONS

• 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
• .Repeatability:
• 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 5.4.5.2 to 5.4.5.3 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:
• Linearity:
  
• 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.

• Eccentricity:
• 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
• Distribution
• Master copy –  Quality Assurance
• Controlled copies- Quality Assurance, Production, Quality Control.engineering
• History
  

  Date	Revision Number	Reason for Revision
  –	00	New SOP

Annexure-1

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 1.0000 g 100.000g	+ 0.1 % of certified mass value of standard weight	Daily
5.	External Calibration (Linearity Test)	50.000 g 100.000 g 200.000 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 1.0000 g 2.0000 g 5.0000 g 10.0000 g 20.0000 g 50.0000 g 100.000g 200.000g	Ratio of three times standard deviation (of 10 replicate weighing) to certified mass value of standard weight should be less than 0.001	Monthly

  Annexure-2

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

Certified Mass value

1

2

3

4

5

6

7

8

9

10

Average

SD

3 X SD

3 X SD/Certified mass value

Remarks

Calibrated By Sign/ Date

Checked By Sign/ Date

Annexure-3

Calibration plan

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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