The Platinum Resistance Thermometer Range of the International Temperature Scale of 1990

Abstract

Within the International Temperature Scale of 1990 (ITS-90) the platinum resistance thermometer (PRT) is used to realize the scale from approximately 13,8 K to 1 235 K. Such a temperature range is wider than the corresponding range in the International Practical Temperature Scale of 1968 (IPTS-68) because the PRT is used up to the freezing point of silver (1 234,93 K). In this way, the ITS-90 can be realized with much more precision than the IPTS-68, particularly between 901 K and 1 235 K where the standard Pt-10% Rh vs Pt thermocouple was previously used.