The measurement uncertainty in the calibration of a thermometer depends on the calibration method used, the uncertainty contri



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uTrc

Calibration PRT

0 K

10 mK

normal

1

10 mK

uTrd

Drift - reference thermometer

0 K

10 mK

rectangular

1

5.8 mK

uTrcon

Conduction -

reference thermometer



0 Ω

1.2 mK

rectangular

1

1.2 mK

uTca

Standard deviation

0 K

2 mK

normal

1

2 mK

uTch

DUC Hysteresis

0 K

1.2 mK

rectangular

1

1.2 mK

uTccon

DUC Conduction

0 K

1.2 mK

rectangular

1

1.2 mK

uRohm

Calibration multimeter

0 K

10mΩ

normal

2.5

20 mK

uRts

Time stability multimeter

0 K

0.5mΩ

rectangular

2.5

1.25 mK

uRres

Mulrimeter resolution

0 K

0.5mΩ

rectangular

2.5

1.25 mK

uRohmDUC

Calibration multimeter

0 K

10mΩ

normal

2.5

20 mK

uRtsDUC

Time stability multimeter

0 K

0.5mΩ

rectangular

2.5

1.25 mK

uRresDUC

Multimeter resolution

0 K

0.5mΩ

rectangular

2.5

1.25 mK

ubath h

Bath homogenity

0 K

18.4mK

normal

1

18.4mK

ubath s

Bath stability

0 K

3.2mK

normal

1

3.2mK

Expanded measurement uncertainty U (k=2)

72.2mK

The above example relate to the calibration of a thermometer at one temperature only. Usually, a thermometer is calibrated at several temperatures (calibration points) for which, as a rule, different measurement uncertainties result. As the user also employs the thermometer to carry out temperature measurements between the calibration points, it is, how­ever, helpful if the calibration certificate also contains statements on the use of the thermome­ter in the whole temperature range.



At the customer's, the thermometer is possibly used under conditions which are different from those under which the calibration was carried out. So contributions to the measurement uncer­tainty might dominate which could remain unaccounted for in the calibration. The measure­ment uncertainty in use can therefore considerably exceed the measurement uncertainty in calibration.



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