- The demonstration that an instrument or a device produces results within specified limits when compared to those produced by a reference standard (or) the standard, which is traceable to a national or International standard, over an appropriate range Of measurements.
- difference types of balance calibration.
- Daily calibration.
- Monthly calibration
- Quarterly calibration.
1. Daily calibration:
Spirit Level Check:
- Should be in center position.
- Check balance position.
- If it is leveled,
- Air bubble exactly in the middle position.
- If not in center position adjust it and proceed for calibration.
- Press CAL (old modal C).
- Display shows a zero read out, to active internal calibration function.
- During Calibration : “C” will be displayed
- After completion : display shows “CC”
- After calibration of the internal calibration the Display shows the zero reading.
3. Daily verification:
- verify the required amount of standards.
Nominal Weight
|
Actual value
(g) *
|
Observed Reading (g)
|
Minimum Limit
|
Maximum Limit
|
Tolerance
Limit
(±0.05%)
|
Remarks
|
400 g
|
200.0002 +
200.0002
|
399.999
|
399.800
|
400.20
|
0.00%
|
Nil
|
100 g
|
100.00028
|
99.999
|
99.950
|
100.050
|
0.00%
|
Nil
|
10 g
|
10.00007
|
9.999
|
9.995
|
10.005
|
0.00%
|
Nil
|
1 g
|
1.000037
|
0.999
|
0.999
|
1.000
|
0.00%
|
Nil
|
*Based on standard weight calibration
certificate.
Tolerance limit = Actual weight- Observed weight
/ actual weight X 100
Monthly Calibration :
- Spirit level Check
- Auto calibration
- Monthly Verification
Nominal Weight
|
Actual value
(g) *
|
Observed Reading (g)
|
Minimum Limit
|
Maximum Limit
|
Tolerance
Limit
(±0.05%)
|
Remarks
|
400 g
|
200.0002 +
200.0002
|
399.999
|
399.800
|
400.20
|
0.00%
|
Nil
|
200 g
|
200.0002
|
200.000
|
199.900
|
200.100
|
0.00%
|
Nil
|
100 g
|
100.00028
|
99.999
|
99.950
|
100.050
|
0.00%
|
Nil
|
20 g
|
20.00013
|
20.000
|
19.990
|
20.010
|
0.00%
|
Nil
|
10 g
|
10.00007
|
9.999
|
9.995
|
10.005
|
0.00%
|
Nil
|
5 g
|
5.00009
|
5.000
|
4.997
|
5.002
|
0.00%
|
Nil
|
1 g
|
1.000037
|
0.999
|
0.999
|
1.000
|
0.00%
|
Nil
|
*Based on standard weight calibration
certificate.
Tolerance limit = Actual weight- Observed weight
/ actual weight X 100
4. Drift Check:
Actual Standard weight : _20.00015g___________
Time
|
Observed Weight
|
Intial
|
20.000
|
After 5 minutes
|
20.000
|
After 10 minutes
|
20.000
|
After 15 minutes
|
20.000
|
After 20 minutes
|
20.000
|
After 25 minutes
|
20.000
|
After 30 minutes
|
20.000
|
Average
|
20.000
|
% RSD
|
0.00%
|
Acceptance Criteria: % RSD NMT 0.05.
Observation : passes / fails.
5. Uncertainty:
Actual Standard weight : 10.00007g___________
Sr
No
|
Observation
X1
|
1
|
10.000g
|
2
|
10.000g
|
3
|
10.000g
|
4
|
10.000g
|
5
|
10.000g
|
6
|
10.000g
|
7
|
10.000g
|
8
|
10.000g
|
9
|
10.000g
|
10
|
10.000g
|
Mean X
|
10.000g
|
SD
|
0.00
|
Uncertainty = 2 X SD / Actual weight as per certificate
= 2 X 0.00 /10.00007
= 0.000
Acceptance Criteria: Uncertainty should not exceed 0.001.
Observation: passes / fails.
6. Accuracy :
Actual Standard weight : 50.00023g___________
No.of
Reflicates
|
Observed
weight
|
1
|
50.000g
|
2
|
50.000g
|
3
|
50.000g
|
4
|
50.000g
|
5
|
50.000g
|
Average
|
50.000g
|
Standard Deviation
|
0.0000g
|
Deviation = Actual weight- Observed weight / actual weight X 100
= 50.00023 - 50.000 / 50.00023 X 100
=0.000%
Acceptance Criteria: The difference between measured average value and actual mass value should be NMT 0.10%.
Measured Uncertainty : 2 X SD / Actual weight as per certificates
=2 X 0.0000/ 50.00023
=0.0000
Calculation: 1/3 X (mass value x 0.10 / 100)
= 1/3 X (50.00023 x 0.10 / 100)
=0.0167
Acceptance Criteria: Measure uncertainty of the weight should be NMT 1/3 of 0.10% (mass value).
Observation: passes / fails.
7. Sensitivity :
Standard
Weight
|
Actual
Standard Weight
|
Observed Weight
|
400 g
|
200.0002 +
200.0002
|
400.000g
|
1 g
|
1.000037
|
1.000g
|
Calculation: Actual weight- Observed weight / actual weight X 100
= 200.0002 + 200.0002 - 400.000 / 200.0002 + 200.0002 X 100= 0.00%
=1.000037- 1.000 / 1.000037 X 100 =0.00%
Acceptance Criteria: % deviation NMT 0.05%
Observation: passes / fails.
Quarterly Calibration:
1. Spirit Level Check
2. Quarterly verification
Nominal weight
|
Actual value (g)
|
Observed reading (g)
|
400 g
|
200.0002 + 200.0002
|
399.999
|
200 g
|
200.0002
|
199.999
|
100 g
|
100.00028
|
100.000
|
20 g
|
20.00013
|
20.000
|
5 g
|
5.00009
|
5.000
|
1 g
|
1.000037
|
0.999
|
Correlation Coefficient (K)
|
1
|
|
Acceptance Criteria : Correlation coefficient (K) : 1 ± 0.0001
Observation : Passes / Fails
3. Eccentricity :
Repetitions
|
Observed
Weight (g)
|
Center
|
199.999
|
Upper left (UL)
|
200.000
|
Upper Right (UR)
|
200.000
|
Lower Left (LL)
|
200.000
|
Lower Right (LR)
|
200.000
|
Average
|
200.000
|
% RSD
|
0.000204
|
Acceptance Criteria : % RSD NMT 0.05
4. Repeatability:
Repetitions
|
Observed
weight
|
||||
1
g
|
10
g
|
100
g
|
200
g
|
400
g
|
|
1
|
1.000
|
10.000
|
100.000
|
200.000
|
400.000
|
2
|
1.000
|
10.000
|
100.000
|
200.000
|
400.000
|
3
|
1.000
|
10.000
|
100.000
|
200.000
|
400.000
|
4
|
1.000
|
10.000
|
100.000
|
199.999
|
400.000
|
5
|
1.000
|
10.000
|
100.000
|
200.000
|
400.000
|
6
|
1.000
|
9.999
|
100.000
|
200.000
|
400.000
|
7
|
1.000
|
10.000
|
99.999
|
200.000
|
399.999
|
8
|
1.000
|
10.000
|
100.000
|
200.000
|
400.000
|
9
|
0.999
|
10.000
|
100.000
|
200.000
|
400.000
|
10
|
1.000
|
10.000
|
100.000
|
200.000
|
400.000
|
Average
|
1.000
|
10.000
|
100.000
|
200.000
|
400.000
|
SD
|
0.000302
|
0.000302
|
0.000302
|
0.000302
|
0.000302
|
Calculation : 2 X SD
/ Actual weight of Measurement X 100
Example:
Repeatability at 1 g = 2 X 0.000302 / 1.000037 X 100 = 0.06 %
Acceptance Criteria :
Deviation NMT 0.10%
Observation : Passes
/ Fails
