ANALYTICAL BALANCE CALIBRATION

CALIBRATION OF TOP PAN BALANCE

Calibration procedure:

Internal Calibration

It shall be performed as per the manufacturer’s instructions.

Drift Check

For the calculation of the drift 10 mg weight shall be used.

Note down the 10 measurements of the 10 mg weight in the performance check log. (Attachment No. 01)

Variation in the observed weight from the mean value does not exceeds ± 0.2 mg.

The 10mg weight shall meet the performance check critical of the mass value i.e. 0.1% of actual mass value.

E.g. For all the 10 measurements of 10 mg weight, variation in the weighings cannot exceed 0.01 mg.

Performance Check

After the Auto Calibration Put 1 mg, 2 mg, 5 mg, 10 mg and 20 mg weights individually. The measurement shall within the 0.1% of actual mass value of the individual weight as given in the performance check log. (Attachment 02)

Measurement uncertainty check

The measurement of uncertainty shall be carried out by using 10 mg weight.

Put the external weight of 10 mg on the pan and note the 10 measurements. (Attachment no.03)

Calculate the measurement of uncertainty as follows.

Measurement uncertainty = Standard Deviation X 3

                                             Actual mass value

Measurement of uncertainty shall be Not More Than 0.001.

Calibration frequency: It shall be performed daily, after any maintenance, after the relocation and after the power failure of the balance.

Each manufacturer supplies the maximum loading condition of the balance. The calibration of the balance shall be designed in such a way that the performance check weights cover the entire loading range of the balance. Lower higher load limits shall be checked for the performance check. Before Calibration make sure that the level bubble is in the center of the indicator and if internal calibration facility is available in the balance then it shall also be performed daily before performance check of the balance.

Always use a check weight appropriate for the particular balance. E.g. a 100 – mg check weight might be selected for a balance has a load limit of 150 mg. Thus the operator must know the maximum capacity of the balance to select the correct check weight.

Attachment-1: Performance Check Log of Microbalance

Instrument:________________                                             Code No:________________

Make       :________________                                                           Model    :________________

Date	Level Indicator check	1 mg	2 mg	5 mg	10 mg	20 mg	Weight box no. and valid upto	Done by	Checked by	Remark
Std.Wt.Cal No. Þ
Limit Þ	Bubble should be in Center	±0.1% of Std. Weight (      to       )	±0.1% of Std. Weight (      to       )	±0.1% of Std. Weight (      to       )	±0.1% of Std. Weight (      to       )	±0.1% of Std. Weight (      to       )

Attachment – 2: Auto Performance Check log of Microbalance

Instrument:________________                                             Code No:________________

Make       :________________                                                           Model    :________________

Check level Indicator (Bubble should be in center) : __________________________________

                                                                                    (Paste Performance Check Chart Here)

Calibrated By :_________________                                       Date :_________________

Checked By    :_________________                                      Date :_________________

Attachment – 3: Measurement Uncertainty Check of Microbalance

Instrument:________________                                             Code No:________________

Make       :________________                                              Model    :________________

Date

Std.Wt

Std. Wt. Cal.No.

Observation

Observation of Uncertainty Less than or equal to 0.001

Weight box no. and valid upto

Done by

Checked by

Remark

10 mg

Calculation

Measurement uncertainty = Standard Deviation X 3

          Actual Mass Value