Investigation of Pd–C cells to improve thermocouple calibration

Abstract

An intercomparison of the melting temperatures of four Pd–C eutectic fixed-point cells was performed using four Pt/Pd thermocouples. The cells are designed for the calibration of thermocouples and were constructed in the participating laboratories of NPL, LNE, NMIJ and PTB. The measurements were performed in four different high-temperature furnaces but by applying the same measurement procedure. In spite of slightly different cell designs and different material sources, the melting temperatures of three of the four Pd–C cells (NPL, LNE and NMIJ) agreed very well within their expanded uncertainties of k = 2.