Better measurements of high temperatures

The international temperature scale ITS-90 will continue to be used for a long time to calibrate thermometers. The scale is based on several established fixed points where phase transitions for different materials are used to calibrate thermometers with very little measurement uncertainty. However, the realisation of ITS-90 suffers from relatively large measurement uncertainties at high temperatures.

The new definition of kelvin from 2019 has opened new possibilities and methods to realize the unit of temperature, kelvin, and to establish traceability of high temperature measurements. The method involves using several known melting or freezing temperatures as fix points and using them to calibrate a radiation thermometer which is then used as a reference for further calibrations.

Establish the new methods

The new methods are already used at the major national metrology institutes in Europe, such as LNE in France. In this project, RISE and other smaller European national metrology institutes will be supported in establishing their own primary reference scales for high temperatures, by increasing competence and obtaining the knowledge of manufacturing and using the new fixed points. The new methods can significantly reduce measurement uncertainty at high temperatures, which meets the industry's need for better measurements and enables the National Laboratory for Temperature to participate in European research projects and continue to develop thermometry at high temperatures.