A pan-European investigation of the Pt-40%Rh/Pt-20%Rh (Land–Jewell) thermocouple reference function

Accurate high temperature measurement has always been problematic for industry. The vast majority of industrial temperature measurements are performed with thermocouples. The development of any new thermocouple types requires the characterization of the relationship between thermocouple output and temperature, i.e. the reference function. An important thermocouple for measuring temperatures above about 1500 °C is the so-called Land–Jewell (Pt-40%Rh/Pt-20%Rh) thermocouple. This was used as a test thermocouple for a new European distributed facility for characterizing thermocouple reference function. The facility is described, and used to generate a demonstrator reference function for the thermocouple. It is found that the demonstrator reference function differs from the de-facto standard reference function of ASTM E1750-09 by several degrees above 1500 °C; a suggested explanation for this is given. (paper)