Establishment of the Co-C Eutectic Fixed-Point Cell for Thermocouple Calibrations at NIMT

In 2015, NIMT first established a Co-C eutectic temperature reference (fixed-point) cell measurement capability for thermocouple calibration to support the requirements of Thailand’s heavy industries and secondary laboratories. The Co-C eutectic fixed-point cell is a facility transferred from NPL, where the design was developed through European and UK national measurement system projects. In this paper, we describe the establishment of a Co-C eutectic fixed-point cell for thermocouple calibration at NIMT. This paper demonstrates achievement of the required furnace uniformity, the Co-C plateau realization and the comparison data between NIMT and NPL Co-C cells by using the same standard Pt/Pd thermocouple, demonstrating traceability. The NIMT measurement capability for noble metal type thermocouples at the new Co-C eutectic fixed point (\(1324.06\,{^{\circ }}\hbox {C}\)) is estimated to be within \(\pm 0.60\,\hbox {K}\) (\(k=2\)). This meets the needs of Thailand’s high-temperature thermocouple users—for which previously there has been no traceable calibration facility.