This article indicates the status of platinum resistance thermometry in temperature definition and measurement and outlines some potential sources of error.
Perhaps the most important factor requiring consideration is the influence of thermometer structural materials on conformity with the IPTS-68. An analysis of calibration measurements, including data reported in earlier work, strengthens the hypothesis that stem heat transmission can contribute discrepancies greater than those that would arise as a result of applying the IPTS-68 to thermometers having low temperature coefficients of resistance (e g, 3.850 x 10-3 per K). Indeed, with the available data it is impossible to discern any systematic effect of temperature coefficient on deviation from the IPTS-68.
Quantitative illustration of the various features discussed is included where appropriate.
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