Investigating the Behaviour of Industrial Platinum Resistance Thermometers from 13.8 K to 273.16 K

摘要

Platinum resistance thermometers (PRTs) are the defined interpolating instruments for the ITS-90 from 13.8033 K to 1234.93 K. However, it is understood that the PRTs must satisfy certain characteristics if they are to be considered suitable for the task, e.g. made from high-purity platinum wire supported in a strain-free manner. On the other hand, the majority of PRTs for industrial use (IPRTs) must have fast response and ruggedness, as well as accuracy. Nonetheless, we undertook comparison calibrations from 13.8 K to 273 K of five IPRTs and the data were used to compute the coefficients of the ITS-90 deviation function appropriate to the temperature range. The residuals were mostly within +-2 mK, suggesting that the ITS-90 interpolation equations provide a useful means to describe the behaviour of such IPRTs, even at temperatures as low as 13.8 K.