A Bilateral Comparison between UME and PTB

A standard platinum resistance thermometer (SPRT) has been calibrated at the ITS‐90 fixed points of UME and PTB in the range between the triple point of argon (83.8058 K) and the freezing point of zinc (692.677 K). This bilateral comparison was mostly carried out according to the protocol of EUROMET Project 552 based on the protocol of CCT‐K3. It was observed that in all fixed‐point measurements, the agreement between UME and PTB is better than 0.50 mK. All differences found are significantly smaller than their expanded combined uncertainties (coverage factor k = 2). The detailed analysis of the results and the uncertainty budget related to the measurements are presented.