International comparison of radiation temperature scales among five national metrological laboratories using a transfer radiation thermometer

Round-robin measurements with a transfer standard radiation thermometer were organized by the NRLM in the framework of a three-year joint research agreement with the NIST, the IMGC and the PTB: the NPL also took part in this exercise. The aim of the study was to assess the mutual traceability of the ITS-90 temperature scales established by the different laboratories in the high-temperature range (above 1000 °C). The thermometer was a monochromatic (0,65 µm) silicon-detector thermometer belonging to the NRLM. It was circulated in the period from May to July 1993 and was calibrated by all the participants against their local reference thermometers. The temperature interval from 1000 °C to 2000 °C was covered by all the participants, but some extended the range down to 800 °C or up to 2700 °C. The results indicate that all the calibrations agree to within 0,5 °C at 1000 °C and to within 2 °C at 2000 °C.