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One of a set of metal–carbon eutectic cells (a Pd–C cell, 1765 K) manufactured by NPL and used for a previous comparison of temperature scales with NIST has been investigated at INRIM. There it was implemented in two different furnaces, namely a single- and a three-zone, and measured with a standard radiation thermometer operating at 900 nm and 950 nm. Both ITS-90 and thermodynamic melting temperatures of the cell were determined by means of an extrapolation approach. The thermodynamic temperature differs by only −0.31 K from the NIST value whereas the ITS-90 temperature differs by only −0.46 K from the NPL value. The agreements, within the combined expanded uncertainties, are particularly significant, because of the different approach followed at INRIM, namely the extrapolation of multi-fixed-point scales (n = 3 and n = 4), as compared with a direct radiometric method at NIST and an ITS-90 realization traceable to the gold point at NPL.

An indirect determination of the thermodynamic temperature of the fixed point of copper was made at INRIM by measuring four cells with a Si-based and an InGaAs-based precision radiation thermometer carrying approximated thermodynamic scales realized up to the Ag point. An average value TCu = 1357.840 K was found with a standard uncertainty of 0.047 K. A consequent (T − T90)Cu value of 70 mK can be derived which is 18 mK higher than, but consistent with, the presently available (T − T90)Cu as elaborated by the CCT-WG4.

Four independent radiation temperature scales approximating the ITS-90 at 900 nm, 950 nm and 1.6 µm have been realized from the indium point (429.7485 K) to the copper point (1357.77 K) which were used to derive by extrapolation the transition temperature T90(Co–C) of the cobalt–carbon eutectic fixed point. An INRIM cell was investigated and an average value T90(Co–C) = 1597.20 K was found with the four values lying within 0.25 K. Alternatively, thermodynamic approximated scales were realized by assigning to the fixed points the best presently available thermodynamic values and deriving T(Co–C). An average value of 1597.27 K was found (four values lying within 0.25 K). The standard uncertainties associated with T90(Co–C) and T(Co–C) were 0.16 K and 0.17 K, respectively. INRIM determinations are compatible with recent thermodynamic determinations on three different cells (values lying between 1597.11 K and 1597.25 K) and with the result of a comparison on the same cell by an absolute radiation thermometer and an irradiance measurement with filter radiometers which give values of 1597.11 K and 1597.43 K, respectively (Anhalt et al 2006 Metrologia 43 S78–83). The INRIM approach allows the determination of both ITS-90 and thermodynamic temperature of a fixed point in a simple way and can provide valuable support to absolute radiometric methods in defining the transition temperature of new high-temperature fixed points.

Five Pt/Pd thermocouples, constructed and calibrated at IMGC at fixed points in the temperature range from 0 °C to the Ag point, were calibrated by comparison with the local primary standard radiation thermometer with the aim of replacing the presently used Pt/Pt–Rh alloy thermocouples as secondary reference standards up to 1500 °C. To fully exploit accuracy of Pt/Pd thermocouples, high-level calibration techniques need to be adopted. For this purpose, a new high-temperature three-zone furnace was arranged and characterized in order to obtain the best axial uniformity and a specially designed blackbody cavity was used as a transfer source for calibrating the thermocouples in the temperature range from 962 °C up to 1500 °C. At the end of the comparison measurements, additional calibrations at the Ag fixed point were made, in order to check the stability of the thermocouples' signals. A comparison between experimental results and the reference function is presented and an extrapolation of the fixed-point calibration data is analysed.

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).

We present an emf-temperature reference function for platinum versus palladium (Pt/Pd) thermocouples in air for the range 0 °C to 1500 °C. The reference function is based on the International Temperature Scale of 1990 (ITS-90) and has an expanded uncertainty (coverage factor of two) of less than the equivalent of 11 mK for temperatures up to 1050 °C and rising smoothly to approximately 0.3 K at 1500 °C. The reference function is based on a set of Pt/Pd thermocouples of exceptional stability and homogeneity constructed from Pt and Pd wire of very high purity (99.999% mass fraction and 99.997% mass fraction, respectively). Experimental results are presented on the thermoelectric stability of Pt/Pd thermocouples at high temperatures and on the calibration of Pt/Pd thermocouples based on this reference function.

Round-robin measurements with a transfer standard radiation thermometer were organized by the NRLM in the framework of a three-year joint research agreement with the NIST, the IMGC and the PTB: the NPL also took part in this exercise. The aim of the study was to assess the mutual traceability of the ITS-90 temperature scales established by the different laboratories in the high-temperature range (above 1000 °C). The thermometer was a monochromatic (0,65 µm) silicon-detector thermometer belonging to the NRLM. It was circulated in the period from May to July 1993 and was calibrated by all the participants against their local reference thermometers. The temperature interval from 1000 °C to 2000 °C was covered by all the participants, but some extended the range down to 800 °C or up to 2700 °C. The results indicate that all the calibrations agree to within 0,5 °C at 1000 °C and to within 2 °C at 2000 °C.

The primary purpose of the comparison was to establish the equivalence of the calibration of infrared radiation thermometers within Europe in the temperature range 800 °C to 2000 °C. Seven EU national metrological institutes (NMIs) participated. The equivalence of calibrations was determined by circulating a transfer standard infrared radiation thermometer between the participating laboratories. The calibrations obtained were compared with the reference calibration performed by the co-ordinating laboratory (National Physical Laboratory). It was found that, after correction for the size-of-source effect, the calibrations of the participating laboratories nearly all agree to better than 0,1 % of temperature.

The National Measurement Institutes (NMIs) of the United States, Germany, France, Italy and Japan, have joined in an inter-laboratory comparison of their infrared spectral emittance scales. This action is part of a series of supplementary inter-laboratory comparisons (including thermal conductivity and thermal diffusivity) sponsored by the Consultative Committee on Thermometry (CCT) Task Group on Thermophysical Quantities (TG-ThQ). The objective of this collaborative work is to strengthen the major operative National Measurement Institutes' infrared spectral emittance scales and consequently the consistency of radiative properties measurements carried out worldwide. The comparison has been performed over a spectral range of 2 μm to 14 μm, and a temperature range from 23 °C to 800 °C. Artefacts included in the comparison are potential standards: oxidized Inconel, boron nitride, and silicon carbide. The measurement instrumentation and techniques used for emittance scales are unique for each NMI, including the temperature ranges covered as well as the artefact sizes required. For example, all three common types of spectral instruments are represented: dispersive grating monochromator, Fourier transform and filter-based spectrometers. More than 2000 data points (combinations of material, wavelength and temperature) were compared. Ninety-eight percent (98%) of the data points were in agreement, with differences to weighted mean values less than the expanded uncertainties calculated from the individual NMI uncertainties and uncertainties related to the comparison process. 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).

A fixed-point technique for calibrating infrared thermometers between the Zn (420°C) and Cu (1085°C) points was analyzed. To do this, a precision silicon detector thermometer working at 900 nm and 950 nm (band-widths of 70 nm and 40 nm, respectively) and a set of four fixed-point black-body cavities (Zn, Al, Ag and Cu) were used. The best results showed that the ITS-90 can be approximated to within ±0.05°C throughout the Zn-Cu interval when the thermometer in its 900 nm configuration is calibrated at the Zn, Al and Cu points.

Two small cells for the realization of the fixed point of copper were constructed and investigated at INRIM. They are of the same hybrid design generally adopted for the eutectic high-temperature fixed-point cells, namely a structure with a sacrificial graphite sleeve and a layer of flexible carbon–carbon composite sheet (C/C sheet). Because of the largely different design with respect to the cells normally adopted for the construction of pure metal fixed points, they were compared and characterized with respect to the normal cells used at INRIM for the ITS-90 realization. Two different furnaces were used to compare hybrid and normal cells. One of the hybrid cells was also used in different configurations, i.e. without the C/C sheet and with two layers of sheet. The cells were compared with different operative conditions, i.e. temperature settings of the furnaces for inducing the freeze, and repeatability and reproducibility were investigated. Freezing temperature and shape of the plateaux obtained under the different conditions were analysed. As expected the duration of the plateaux obtained with the hybrid cells is considerably shorter than with the normal cell, but this does not affect the results in terms of freezing temperature. Measurements with the modified cell showed that the use of a double C/C sheet may improve both repeatability and reproducibility of the plateaux.

A black-body reflectometer has been realised to characterise reference standards for normal spectral emissivity in the spectral range from 1 to 15 mu m. As compared with previous reflectometers of the same type, this apparatus takes advantage of a heat-pipe device which greatly improves the temperature uniformity in the black-body cavity. The description of the apparatus is followed by an accurate analysis of the measuring process from which uncertainty estimates are derived.