标准铂电阻温度计校准实验室

The SPRTCL provides an extensive list of calibration services that cover the whole temperature range for which long-stem SPRTs, including high-temperature SPRTs, are the ITS-90 interpolation artifacts. This range spans from the triple point of argon (-189.3442 °C) to the freezing point of silver (961.78 °C). The laboratory also provides calibrations of capsule-type SPRTs in a limited temperature range, from the triple point of argon up to the freezing point of tin (231.928 °C). The SPRTs are calibrated by employing fixed-point cells, artifacts that realize the ITS-90 by enclosing high-purity materials (99.9999% or more) for which the phase transition temperatures (melting, freezing or triple points) are known with extreme accuracy. Such temperatures are the defining ITS-90 fixed points, and SPRTs are calibrated at combinations of these fixed points that correspond to the desired ITS-90 subrange. The fixed points realized by the SPRTCL are:

Fixed point	T, K	T, °C	Uncertainty, mK (k=2)
Triple point of argon	83.8058	-189.3442	0.14
Triple point of mercury	234.3156	-38.8344	0.15
Triple point of water	273.16	0.01	0.09
Melting point of gallium	302.9146	29.7646	0.13
Freezing point of indium	429.7485	156.5985	0.25
Freezing point of tin	505.078	231.928	0.27
Freezing point of zinc	692.677	419.527	0.55
Freezing point of aluminum	933.473	660.323	TBD
Freezing point of silver	1234.93	961.78	TBD