New Reference Functions for Platinum-10% Rhodium versus Platinum (Type S) Thermocouples Based on the ITS-90. Part I. Experimental Procedures

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. The experimental procedures, apparatuses, and materials used for the measurements are described in this part.