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A comparison of the ITS-90 among NPL, NIM and CEM above the silver point using high temperature fixed points.

Machin, G; Dong, W*; Martin, M J*; Lowe, D; Yuan, Z*; Wang, T*; Lu, X* (2010) A comparison of the ITS-90 among NPL, NIM and CEM above the silver point using high temperature fixed points. Int. J. Thermophysics, 31 (8-9). pp. 1466-1476.

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Abstract

A prototype comparison of the ITS-90, as realised by NPL, NIM and CEM, using high temperature fixed points (HTFPs) of Co-C (1324 °C), Pt-C (1738 °C), and Re-C (2474°C), is reported. The local realisations of ITS-90 temperatures were assigned by NPL, NIM and CEM to their own set of HTFPs. NIM and CEM then transported their cells to NPL and the ITS-90 temperatures of all three sets of cells were measured using a linear pyrometer. The ITS-90 temperature differences NPL - NIM, were -0.01°C, -0.12°C, -0.48°C and NPL - CEM +0.06°C, 0.00°C, +0.36°C, with k = 2 uncertainties of approximately ±0.5°C, ±0.8°C, ±1.6°C at the Co-C, Pt-C and Re-C points respectively. These differences are less than the scale realisation uncertainties ascribed by the individual institutes. In addition thermodynamic temperatures were determined for these HTFPs using the current best estimate of the thermodynamic temperature for the copper point, namely 1357.82 K. The good agreement of the scales indicates that: a) the uncertainties in scale realisation ascribed by the individual institutes are possibly conservative and could be revised; b) given their inherent performance, HTFPs should be seriously considered as the scale comparison artefacts of choice when comparing primary realisations either of ITS-90 or thermodynamic temperature.

Item Type: Article
Keywords: Comparison, eutectics, high temperature fixed points
Subjects: Engineering Measurements
Engineering Measurements > Thermal
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4819

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