National Physical Laboratory

Calibration of gold-platinum thermocouples (0 °C to 1000 °C)

Thermocouple calibration

NPL offers a UKAS-accredited thermocouple calibration service (laboratory number 0478) for gold-platinum (Au/Pt) thermocouples using freezing points of zinc, aluminium and silver (up to 1000 °C).

Thermocouples are widely used in industry to provide temperature measurement and control for numerous applications. They are popular because they are small and rugged, suitable for use to very high temperatures and are relatively low-cost. They also provide a convenient electrical output for data logging and control. Gold-platinum thermocouples are often chosen above platinum-rhodium (Type R, S and B) thermocouples where stability and homogeneity are critical. They are also used in place of standard platinum resistance thermometers (SPRTs) in some instances where the lower cost and insensitivity to mechanical knocks are of importance.

Ranges and uncertainties

Calibration uncertainties (coverage probability of approximately 95 %) for Au/Pt thermocouples:

Calibration Range Calibration uncertainty (k = 2) Calibration points
0 °C to 1000 °C ± 0.05 °C Zn, Ag
420 °C ± 0.05 °C Zn
660 °C ± 0.05 °C Al
962 °C ± 0.05 °C Ag

† Calibration points used are freezing fixed-point cells


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Last Updated: 27 Aug 2015
Created: 19 Mar 2015


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