High-Temperature Fixed-Point Facilities for Improved Thermocouple Calibration—Euromet Project 857

Abstract

LNE, NPL, and PTB decided in 2005 to join their research efforts in the framework of Euromet Project 857 with the aim of reducing the calibration uncertainty of noble metal and other high-temperature thermocouples by at least a factor of two. This ambitious target will be met through the development and implementation of robust high-temperature fixed points based on metal-carbon eutectic technology. The Euromet project is structured around five work packages and ensures good and efficient cooperation between the partners to meet the objectives within the project timeframe of four years. Furthermore, a formal cooperative research agreement has been established with the National Metrology Institute of Japan (NMIJ) to demonstrate, on a worldwide basis, that this new method is a significant improvement over current calibration methods. In summary, the project consists of (a) the development of sets of cells at the cobalt-carbon eutectic point (1,324 • C) and palladium-carbon eutectic point (1,492 • C) and (b) the construction of platinum/palladium (Pt/Pd) thermocouples carefully stabilized for use to these temperatures. Supplementary research to be undertaken as part of this project is the improvement of fixed-point construction and realization capabilities through high-temperature furnaces with low thermal gradients. This paper describes the European project and gives an overview of current progress.

Comparison of Co–C and Pd–C Eutectic-Point Cells for Thermocouple Calibration Between LNE-Cnam and NMIJ

“…To confirm and improve the performance of Co-C and Pd-C eutectic points for thermocouple calibration, comparisons of Co-C and Pd-C eutectic points were planned in the framework of the Euramet 857 project, involving three EU laboratories (LNECnam, PTB, and NPL) and one non-EU laboratory (NMIJ) [9]. At first, the comparison of the Co-C eutectic point was conducted.…”

Amélioration des références et dissémination dans le domaine des hautes températures et de la pyrométrie optique au LNE-Cnam

“…C'est dans cette optique que nous travaillons depuis une dizaine d'années au développement de thermocouples Pt/Pd de très haute stabilité et de points fixes à haute température adaptés à leur étalonnage jusqu'à 1500 °C [26]. Au-delà de cette température, d'autres thermocouples peuvent être utilisés (W/Re, Ir/Ir-Rh, Pt-Rh/Pt-Rh..) mais leur stabilité aux plus hautes températures est insuffisante, rendant encore plus indispensable la disponibilité de références de température qui permettraient leur étalonnage et la correction de leur dérive en cours d'utilisation.…”

Calibration of Thermocouples and Infrared Radiation Thermometers by Comparison to Radiation Thermometry

“…Cu at 1084.62 • C is the highest conventional FP; for this reason, in the last years there has been significant research in thermocouple calibrations in metal-carbon (M-C) fixed points up to 1550 • C [1][2][3][4]. However, the comparison method is an alternative to M-C fixed points that could be used to calibrate thermocouples to 1600 • C [5,6].…”