New Reference Functions for Platinum-10% Rhodium versus Platinum (Type S) Thermocouples Based on the ITS-90. Part II. Results and Discussion

摘要

The Comite Consultatif de Thermometrie requested its Working Group 2 to collaborate with national laboratories in the production of new reference tables and functions for thermocouples based on the International Temperature Scale of 1990 (ITS-90). Pursuant to this recommendation, eight national laboratories have obtained new data on type S thermocouples obtained from several sources. The thermoelectric voltages of those thermocouples have been measured as a function of t90 in the range -50 degrees C to 1070 degrees C, with temperatures obtained from standard platinum resistance thermometers that were calibrated in accordance with the ITS-90 to 962 degrees C, and extrapolated to 1070 degrees C. Also in the range from 710 degrees C to 1065 degrees C, temperatures were measured with a radiation thermometer. In addition, the thermoelectric voltages of the thermocouples have been determined at various thermometric fixed points. From the results of these measurements, polynomials giving the thermoelectric voltage as a function of t90 have been developed, and new estimates for the temperature differences between the ITS-90 and the IPTS-68 in the range 630 degrees C to 1064 degrees C have been derived.