Comparison of the Realizations of ITS-90 Over the Range of $-38.8344\,{}^{\circ }\hbox {C}$ to $419.527\,{}^{\circ }\hbox {C}$

Abstract

In this paper, an interlaboratory comparison in the field of the measurement of temperature is presented. The purpose of the interlaboratory comparison described here is to compare the capabilities for the calibration of a standard platinum resistance thermometer (SPRT) at fixed points in the range from the triple point of mercury $(-38.8344\,{}^{\circ }\hbox {C})$ to the freezing point of zinc $(419.527\,{}^{\circ }\hbox {C})$. Results are used to support the process of accepting calibration and measurement capabilities. The interlaboratory comparison was organized by the University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Metrology and Quality (MIRS/UL-FE/LMK). The circulated artifact was a $25 \,\Omega$ metal-sheathed SPRT. The interlaboratory comparison included three fixed points of the International Temperature Scale of 1990 (mercury, tin, and zinc) in the range between $-38\,{}^{\circ }\hbox {C}$ and $420\,{}^{\circ }\hbox {C}$. Prior to the start of measurements, annealing was performed in accordance with protocol. MIRS/UL-FE/LMK performed measurements at the beginning of the interlaboratory comparison and at the end. Prior to the calibration at fixed points in each laboratory, a test measurement at the triple point of water was done in order to assess the stability of the traveling SPRT. It was recommended that the participants use their standard procedure for the calibration of the SPRT at each fixed point and follow instructions from the protocol during the temperature calibration. The results of $W$ at each fixed point for both laboratories are summarized, and they agree within their expanded uncertainties.