Appraisal of Interpolation Instruments for the International Practical Temperature Scale from 630.74 to 1064.43°C

A better interpolating instrument has long been needed to replace the standard platinum-10% rhodium/platinum thermocouple for the International Practical Temperature Scale. In this paper we compare the characteristics of the high temperature platinum resistance thermometer and the photoelectric spectral pyrometer with those of the standard thermocouple and conclude that the resistance thermometer is the better replacement, in terms of both accuracy and convenience.