Traceability in infrared radiation thermometry from -50 °C to 800 °C (TRIRAT)

Final Report, 18 March 2003

The overall objective of the four-year TRIRAT project was to provide within Europe improved, sub-Kelvin accuracy in infrared radiation thermometry at industrial levels in the range from -50°C to 800°C. The effectiveness of the traceability system in which accuracy is transferred from the highest metrological level down to industry was crucial in achieving this goal. This would include international intercomparisons for radiation thermometry in this range, with an inherent accuracy, approaching 0.2 K. A restriction was made to the class of single-spot, single-channel radiation thermometers.

Work program
Two possible traceability schemes II and I were established in phase one, "Research and Development", of the project. Subsequently they were evaluated in phase two "Comparison of regional medium-temperature MT scales (150°C to 800°C) and low-temperature LT scales (-50°C to 300°C)". Each phase took two years for completion.

Results and achievements
In phase one more than 50 reference blackbody radiators (BBRs), either continuously variable in temperature (scheme II) or operating at a fixed-point (scheme I), have been developed, further improved and characterized. In addition to the BBRs 4 MT- and 6 LT- radiation thermometers (RTs) were developed, tested and extensively characterized. Two sets of RTs were selected to serve as transfer instruments in phase two. In the MT range two local scales consisting of fixed-points were compared showing differences within 50 mK, much less than the transfer standards uncertainty of 0.3 K. However when comparing thirteen local temperature scales (scheme II), differences larger than 2 K were observed. Further analysis showed that the differences could be traced back and explained qualitatively to specific features of the participant BBR configuration in combination with characteristics of the RT used. Similarly, in the LT range, more than 75 % of the local temperature scales were found equivalent within 1 K using scheme II while the RTs demonstrated their use to a level of 450 mK. The final output of TRIRAT is a series of recommendations for the standardization and testing of infrared RTs for use as transfer devices. The wealth of experience gained during the project has facilitated improved realization of non-contact thermometry scales throughout Europe. An important adjunct to the comparisons is that the results will be used to underpin traceability of local scales in Europe by submission into the international mutual recognition arrangement database providing the technical basis for wider agreements negotiated for international trade, commerce and regulatory affairs.

Project Description

The overall objective is to provide improved, sub-Kelvin accuracy at industrial levels in the range from -50 °C to 800 °C. The effectiveness of the traceability system in which accuracy is transferred from the highest metrological levels down to the industrial levels is crucial in achieving this goal.

The project is funded within the SM&T, FW-IV program. Its duration is four years. Two temperature ranges - 50 °C to 800 °C (LT), 150 C to 800 °C (MT), and 11 workpackages are involved. Phase I (year 1 and 2) is devoted to the development of an operational traceability system. In phase II (year 3 and 4) local scales will be compared by the circulation of two transfer radiation thermometers in each of the ranges MT and LT.

In total 17 partners are involved which include specialized institutions: IKE (DE), LNE (FR) and RISOE(DK), as well as manufacturers; Cimel (FR), Heitronics (DE), Raytek (DE) and Sensor Partners (NL).

Thermometry (T)
Eric W. M. van der Ham, VSL (The Netherlands)
Coordinating Institute
VSL (Netherlands)
Further Partners