T R U – F i L Document Number

TF/UM/27.1/01

Uncertainty calculations For Electronic Weigh Balance

Date – 11.01.2015 Certificate No. –TF/UM/27.1/01

Uncertainty Calculation for Electronic Weigh Balance

Sources of uncertainties –(A) Repeatability Data (B) Other Uncertainties

Equipment Used

Name of the equipment - Electronic Weigh Balance

Equipment No - TF/EQP/27.1

Make - Presica Serial No. - 2804104

Calibrator Used

Name of the equipment - Standard Weight Box

Equipment no - TF/ACR/1.1

Make - Sakova Serial No. - 1615

Laboratory Condition

Temperature - 26°C Humidity – 36 %

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T R U – F i L Document Number

TF/UM/27.1/01

Uncertainty calculations For Electronic Weigh Balance

Type A

Measurement Data in grams.(Measurement of 10 gms of standard Weight)

Serial No. Test Data (X) (in gms)

( x - X) (x - X)²

1 10.0016 -0.00022 4.84 x 10⁻⁸

2 10.0010 0.000381.44 x 10⁻⁷

3 10.0012 0.00018 3.24 x 10⁻⁸

4 10.0015 -0.00012 1.44 x 10⁻⁸

5 10.0016 -0.00022 4.84 x 10⁻⁸

Mean Reading - x = (∑X)/5. = 10.00138 Gms.

Standard Deviation - √ {∑ (x-X) ² / 4} = 2.68 x 10ˉ⁴

Standard Uncertainty (Ua) - [√ {∑ (x-X) 2 /4}]/√5 = 1.19 x 10ˉ⁴

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T R U – F i L Document Number

TF/UM/27.1/01

Uncertainty calculations For Electronic Weigh Balance

Type B

Include all uncertainties which are related to other factors including calibration uncertainties and another factor.

Calibration Uncertainty At Value (B) Ub (Ub)2

Calibration Uncertainty of 10 gm weight at 95% Confidence Level at Normal Distribution i.e.(Ub = B*2)

0.00004 0.00002 4 x 10ˉ¹⁰

c) Least count of Electronic Weigh Balance is 0.0001 gms then For Rectangular Distribution – B/1.732

0.0001 5.77 x 10-5 3.32 x 10-9

3.72 x 10-9

Combine Uncertainty (Uc) - √ {(Ua)² + (Ub)²} = 1.33 x 10ˉ⁴

Expanded Uncertainty At 95% CL – (Uc x 1.96) = 2.60 x 10ˉ⁴

Result = 10.00138 Gms = ± 2.60 x 10ˉ⁴ gms.

Tested By - Approved By - Calibration-In-Charge Technical Manager

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