Investigating the Inconsistency of ITS-90 for SPRTs in the Subrange 0 A°C to 419.527 A°C

The subrange inconsistency is a significant factor to uncertainty in the standard platinum resistance thermometer (SPRT) subranges of the International Temperature Scale of 1990 (ITS-90). This paper investigated the subrange inconsistency between the water-zinc and water-aluminum subranges. The calibration data for 60 SPRTs from four manufacturers were analyzed, and the result confirms that the coefficient c in the interpolation of ITS-90 is available to determine the subrange inconsistency in this temperature range again. The inconsistency, Delta t, can be simply equal to 59.83c.