Transfer Radiation Thermometer Covering the Temperature Range from −50 °C to 1000 °C

Abstract

The EC‐project TRIRAT (TRaceability in Infrared RAdiation Thermometry) was launched to improve the accuracy in infrared radiation thermometry, on an international basis, at industrial level, in the range from −50 °C to 800 °C. The temperature range has been divided in the Low Temperature Range (LT) from −50 °C to 300 °C and the Medium Temperature Range (MT) from 150 °C to 800 °C. Within this project a Transfer Radiation Thermometer has been developed which covers both, the Low Temperature Range and the Medium Temperature Range from −50 °C to 800 °C. Within the project the MT‐range has been extended from 300 °C to 980 °C to meet the silver point. It can be used for the transfer of radiation temperatures in scheme II. The Transfer Radiation Thermometer will be calibrated against fixed‐point black body radiators and it is capable to transfer radiation temperatures between black body radiators (BBR). The instrument has two built‐in spectral bands, which are related to the temperature ranges. The construction of the thermometer and the tests characterizing performances are described. General specifications, spectral responses, temperature resolution, influence of ambient temperature and atmospheric effects causes by humidity as well as size of source effects are investigated and presented in this paper. The described instrument is a further development of the instrument developed in the TRIRAT project.