This paper presents the effects of short-term and long-term temperature exposure on noble metal thermocouples in the range from 1000 °C to 1720 °C in oxidizing atmosphere (air). As thermocouples voltage output depends on the wire material of which the sensors are constructed, high-temperature and long continuous exposure to limit temperatures can introduce changes to the materials composition and structure. This can result in drift of generated voltage independent of the thermal environment and into reduced lifetime of the sensors. The intensions of conducted measurements were to determine the drift and lifetime of commonly available alumina-sheathed noble metal thermocouples and furthermore to establish traceable techniques to enable lifetime testing and thermoelectric stability evaluation of noble metal thermocouples at high temperatures. Result presented within this paper is not intended to test the capabilities of thermocouple Types B, R and S in general, but to show a possible behavior in the above-specified temperature conditions. This work puts more emphasis on the procedures that can be used for regular checks of intensely used thermocouple. Results obtained by this study show that the long-term temperature drift of Type B thermocouples at 1600 °C, and R-, S-type thermocouples at 1000 °C are much smaller than thermoelectric stability declared by IEC 60584-1:2013 standard (International standard IEC 60584-1:2013, Thermocouples—Part 1: EMF specifications and tolerances, 2013 ) tolerance classes after exposure to thermal stress up to 4 months. More specifically tolerance for class 1 thermocouple Types R, S from 0 °C up to 1100 °C is ± 1 °C and for class 2 tolerance for Type B at 1600 °C is ± 1.5 °C. The short-term thermoelectric stability of R- and S-type thermocouples exposed to 1600 °C for repeated 8 h periods has been within 2 °C when measured by comparison with a reference Pt–Pd thermocouple at 960 °C. The short-term thermoelectric stability of B-type thermocouple when exposed to 1720 °C for repetition of 8 h has been within 1 °C.

This report describes the measurement procedures and participant results for the EURAMET project 658 extension—'project to examine underlying parameters in radiance temperature scale realisation from 156 °C to 1000 °C', with particular emphasis on the results of the variable temperature and fixed point blackbody measurements for the justification of radiation thermometry CMCs. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

More than one decade ago, an InGaAs detector-based transfer standard infrared radiation thermometer working in the temperature range from \(150\,{^{\circ }}\hbox {C}\) to \(1100\,{^{\circ }}\hbox {C}\) was built at TUBITAK UME in the scope of collaboration with IMGC (INRIM since 2006). During this timescale, the radiation thermometer was used for the dissemination of the radiation temperature scale below the silver fixed-point temperature. Recently, a new radiation thermometer with the same design but with different spectral responsivity was constructed and employed in the laboratory. In this work, we present the comparative study of these thermometers. Furthermore, the paper describes the measurement results of the thermometer’s main characteristics such as the size-of-source effect, spectral responsivity, gain ratio, and linearity. Besides, both thermometers were calibrated at the freezing temperatures of indium, tin, zinc, aluminum, and copper reference fixed-point blackbodies. The main study is focused on the impact of the spectral responsivity of thermometers on the interpolation parameters of the Sakuma–Hattori equation. Furthermore, the calibration results and the uncertainty sources are discussed in this paper.

The mise-en-pratique for the definition of the kelvin at high temperatures will formally allow dissemination of thermodynamic temperature either directly or mediated through high-temperature fixed points (HTFPs). In this paper, these two distinct dissemination methods are evaluated, namely source-based and detector-based. This was achieved by performing two distinct dissemination trials: one based on HTFPs, the other based on absolutely calibrated radiation thermometers or filter radiometers. These trials involved six national metrology institutes in Europe in the frame of the European Metrology Research Programme joint project ‘Implementing the new kelvin’ (InK). The results have shown that both dissemination routes are possible, with similar standard uncertainties of 1–2 K, over the range 1273–2773 K, showing that, depending on the facilities available in the laboratory , it will soon be possible to disseminate thermodynamic temperatures above 1273 K to users by either of the two methods with uncertainties comparable to the current temperature scale.

High-temperature eutectic fixed points have proved to be convenient tools for temperature scale dissemination and thermometer calibrations/checks at temperatures above \(1100\,^{\circ }\text {C}\). In order to investigate the feasibility of metal-carbon eutectic cells in industrial applications as a means for assessing the traceability of non-contact thermometers, a batch of cells was constructed at LNE-Cnam, NPL, and TUBITAK UME. Compared to the usual dimensions of high-temperature fixed point cells (45 mm in length \(\times \) 24 mm in diameter), a new cell design was created to fit with industrial applications. TUBITAK UME constructed and characterized five ruthenium–carbon (Ru–C) eutectic cells of dimensions 24 mm in length \(\times \) 24 mm in diameter. One of these cells has been selected and characterized at CEA premises. Ru–C eutectic cells have been evaluated in terms of short-term repeatability, reproducibility, furnace effect, sharp temperature ramps, and the effect of cell location. Measurements at TÜBİTAK UME have been performed with a transfer standard pyrometer calibrated at the copper point and a BB3500pg high-temperature blackbody furnace was used for construction and measurement. For the measurements at CEA, a Land Standard—HIMERT S1 radiation thermometer and a VITI induction furnace were used. In this article results of the measurements at TÜBİTAK UME and CEA will be presented. The possible use of these mini-eutectic cells as industrial temperature standards will be discussed.

High temperature measurement in industry is subject to large uncertainties due to the non-ideal measurement conditions; for example unknown emissivity and window transmission for radiation thermometry, sensor contamination and ageing causing unpredictable drift in contact thermometry. This paper gives an overview of a European Metrology Research Programme (EMRP) project “High Temperature Metrology for Industrial Applications” (HiTeMS) whose objective was to address, on a broad front, a number of unsolved measurement challenges in the domain of high temperatures (above 1000°C) both in non-contact and contact thermometry. It brought together a total of 15 partner organisations; National Metrology Institutes (NMIs) (10), industrial companies (4) and a Fraunhofer Institute. The project started in September 2011 and was completed August 2014. Significant progress has been made in all the temperature measurement challenges tackled.

In the frame of the European Metrology Research Programme (EMRP)-funded joint research project “Implementing the new kelvin” one work package is devoted to the assessment of two different methods of dissemination of the thermodynamic temperature. These two methods are the dissemination via high temperature fixed points (HTFP) with assigned thermodynamic temperatures and the dissemination by radiometers or radiation thermometers calibrated in terms of thermodynamic temperature. To achieve a thorough assessment of these two distinct dissemination methods two dissemination exercises were organised in the form of comparisons. In one case the circulating artefacts were off-the-shelf high-temperature fixed point cells with transition temperatures ranging from 1324 °C to 2474 °C, in the other case absolutely calibrated pyrometers and filter radiometers were compared in the temperature range 1000 °C to 2500 °C. This work showed that both schemes were achievable with competing advantages and drawbacks and would most probably help disseminating thermodynamic temperature in the future at the level of 1 K to 2 K uncertainty over the whole temperature range.

Due to problems that have occurred during the conversion of the article into PDF format, and the resulting loss of many special characters, a new correct version of the article is published below.

Over the medium temperature range (from 156 ^∘C to 1000 ^∘C ), radiation thermometry is usually established within a national metrology institute (NMI) by means of variable temperature blackbody radiation sources, whose temperature is determined using a platinum resistance thermometer or thermocouple, calibrated in terms of the International Temperature Scale of 1990 (ITS-90), positioned in close proximity to the back radiating surface of the blackbody. It is also reasonably common to establish a scale using a suitable radiation thermometer, such as an indium gallium arsenide (InGaAs) detector-based narrow band radiation thermometer, calibrated using a number of fixed-point blackbody sources from the indium (In) to silver (Ag) (or copper (Cu)) points, with the calibration results fitted using a parameterized Planckian interpolation function. During 2007 and 2008, two InGaAs-based radiation thermometers were circulated around seven NMIs within the European Association of National Metrology Institutes (EURAMET) region in order to undertake a comparison of parameters necessary for radiation thermometry over the medium temperature range. Measurements were made of the size-of-source effect and gain (range) ratios of the two thermometers along with an assessment of the effect of changes in the ambient temperature and humidity on the thermometer output. The thermometers were also calibrated using fixed-point and/or variable temperature blackbody sources at each institute. A brief overview of the results obtained by this project is presented in this paper.

Among the activities of the European Metrology Research Programme (EMRP) project HiTeMS one work package is devoted to the development and testing of industrial solutions for long-standing temperature measurement problems at the highest temperatures. LNE-Cnam, NPL, TUBITAK-UME have worked on the design of high temperature fixed points (HTFP) suitable for in-situ temperature monitoring to be implemented in the facilities of CEA (Commissariat à l’énergie atomique et aux énergies alternatives). Several high temperature fixed point cells were constructed in these three national metrology institutes (NMIs) using a rugged version of cells based on the hybrid design of the laboratory HTFP developed and continuously improved at LNE-Cnam during the last years. The fixed points of interest were Co-C, Ru-C and Re-C corresponding to melting temperatures of 1324 °C, 1953 °C and 2474 °C respectively. The cells were characterised at the NMIs after their construction. Having proved robust enough, they were transported to CEA and tested in an induction furnace and cycled from room temperature to temperatures much above the melting temperatures (> +400 °C) with extremely high heating and cooling rates (up to 10 000 K/h). All the cells withstood the tests and the melting plateaus could be observed in all cases.

Over the medium temperature range (from \(156\,^{\circ }\mathrm{C}\) to \(1000\,^{\circ }\mathrm{C}\)), radiation thermometry is usually established within a national metrology institute (NMI) by means of variable temperature blackbody radiation sources, whose temperature is determined using a platinum resistance thermometer or thermocouple, calibrated in terms of the International Temperature Scale of 1990 (ITS-90), positioned in close proximity to the back radiating surface of the blackbody. It is also reasonably common to establish a scale using a suitable radiation thermometer, such as an indium gallium arsenide (InGaAs) detector-based narrow band radiation thermometer, calibrated using a number of fixed-point blackbody sources from the indium (In) to silver (Ag) (or copper (Cu)) points, with the calibration results fitted using a parameterized Planckian interpolation function. During 2007 and 2008, two InGaAs-based radiation thermometers were circulated around seven NMIs within the European Association of National Metrology Institutes (EURAMET) region in order to undertake a comparison of parameters necessary for radiation thermometry over the medium temperature range. Measurements were made of the size-of-source effect and gain (range) ratios of the two thermometers along with an assessment of the effect of changes in the ambient temperature and humidity on the thermometer output. The thermometers were also calibrated using fixed-point and/or variable temperature blackbody sources at each institute. A brief overview of the results obtained by this project is presented in this paper.

The article presents the results of the EURAMET Project No. 927 "Comparison of blackbodies for calibration of infrared ear thermometers (IRETs)". The objective of the comparison was to determine the agreement of blackbodies used for the calibration of IRETs among European national laboratories. To verify the accuracy of an IRET, a suitable blackbody (BB) is needed. Such a blackbody related to the EN standard, designed for the calibration of ear thermometers and immersed in a stirred water bath, was provided for the comparison by the pilot laboratory. The pilot provided also the transfer IRET and organized the comparison.

Eutectic phase transitions are commonly considered for use as fixed points in future 20XX temperature scales. Despite their potential as possible interpolation points in a high-temperature radiation thermometry scale (1000 °C and above), more studies on the reproducibility of the plateau temperature values are required. Various ongoing research projects on the long-term stability and reproducibility of the eutectic fixed points will likely improve the uncertainties enough to allow for their use as reference (or secondary) temperature points. In this article, the long-term reproducibility results of Co–C eutectic plateau realizations performed in the UME Radiation Thermometry Laboratory over four years, along with studies of the dependence on furnace heating/cooling rate and the short-term (1 day) repeatability, are presented. These measurements were performed with a monochromatic radiation thermometer calibrated according to ITS-90.

Metal-carbon eutectic fixed-point construction and characterization are subjects of ongoing investigation within the field of radiation thermometry. National metrology institutes are in constant search of stable eutectic points with minimal uncertainty for the purposes of either increasing the working temperature range of radiation thermometry or obtaining intermediate check points for both contact and non-contact thermometries. The Co–C eutectic point (~1,324°C) would be very effective in reducing certain calibration uncertainties at this temperature, once long-term stable and reproducible cells are constructed. For these purposes, one Co–C eutectic cell was fabricated at UME, in collaboration with LNE-INM, while a second Co–C cell was constructed for UME. At UME, the cell was filled (in the Vega-BB3500PG blackbody) using methods developed by LNE-INM. Eutectic plateaux, eutectic temperatures, and their uncertainties have been assessed using the UME Transfer Standard Pyrometer TSP-2, calibrated at UME, and an IKE LP3, calibrated at INM. The two Co–C eutectic cells (one constructed at INM and the other at UME) were compared at UME. The short-term stability and reproducibility of the cells have been assessed for various thermal conditions. A provisional uncertainty budget for the thermodynamic temperature of the Co–C cell as determined by LNE-INM has been established.

Facilities at UME for the calibration of radiation thermometers are described for temperatures generally below 961.78 °C, the lower limit of temperature defined by radiation thermometry on the International Temperature Scale of 1990 (ITS‐90). Traceability in the range 200 °C to 1100 °C is obtained using fixed‐point blackbody radiators, while traceability from −30 °C to 200 °C is obtained through a homemade variable‐temperature blackbody with calibrated 100 Ω Pt (Pt100) temperature sensors. The best overall uncertainty for the first range is 0.6 °C, and 0.3 °C for the second range (k=2).

In the course of the EC-funded project TRIRAT ("TRaceability in Infrared Radiation Thermometry") an international comparison of local radiation temperature scales took place among fourteen laboratories in the temperature range from 150 degreesC to 962 degreesC. This paper describes the equipment and the transfer standards used for the comparison. The results and the procedures adopted for deriving a "comparison reference value" (CRV) and the degree of equivalence of each laboratory with respect to the CRV are then discussed. The different arrangements adopted for the calibration of the thermometers and additional experimental investigations allowed an analysis on the effect of some influencing parameters, e.g., the size of source effect (SSE), to be performed and indications on the most convenient experimental arrangements to be derived.

UME radiance temperature scale is derived from the UME Silver fixed point black body and is maintained and disseminated by the UME standard radiation thermometer. According to ITS-90, temperature scale is derived from the Planckian ratio equation by comparing the thermometer signal at an arbitrary temperature with the thermometer reference signal at the fixed point. Therefore, the uncertainty associated with the reference signal is transferred to radiance temperatures calculated. Using the Wien's approximation, the temperature uncertainty of the reference signal must be lower than 30 mK in order to keep the uncertainty component due to reference signal within 100 mK at 2000 degreesC. Uncertainty in the reference signal obtained at the silver point originates from two sources. These are the uncertainties associated to the fixed point itself and, the uncertainties associated to the radiance thermometer. For the first part of the uncertainty, metal impurity, emissivity, cavity uniformity, aperture uniformity of the fixed point are considered. For the second part, spectral responsivity function, size of source effect, residual response out of spectral responsivity function, time drift of the standard radiation thermometer are considered. Finally, to assess the total uncertainty associated with the reference signal, we have also considered the standard uncertainty of the freezing plateaus obtained during the melting and freezing cycles.

Radiation temperature scales were realized with a precision infrared thermometer at IMGC, NPL and UME using fixed-point blackbodies at the freezing points of indium, tin, zinc, aluminium and silver. From the fixed-point calibration in each laboratory, continuous scales were obtained with a four-coefficient interpolation equation. The differences between the three scales were well within 0.1°C at all temperatures between the indium and silver points. Calibrations of the same thermometer performed at NPL and UME using a more traditional calibration scheme based on the comparison with contact thermometers showed differences of up to more than 0.4°C. This suggested that the fixed-point scheme, that has been used for the first time in an international comparison, should be more reliable for accurate calibrations of precision infrared thermometers.