NONUNIQUENESS OF THE ITS-90 (UNCERTAINTIES IN TEMPERATURE-MEASUREMENTS)

Causes of uncertainties in temperature measurements are analysed. Some uncertainties are intrinsic to the temperature scale itself (built-in uncertainties). The rest are due to an assortment of experimental unc ertainties. A simplified calibration procedure is proposed in the temp erature range 0 degrees C less than or equal to T less than or equal t o 660 degrees C that reduces the time (and thus the cost) of calibrati on by about 30% without a significant change in the accuracy of the sc ale imprinted on the calibrated platinum resistance thermometers.