Hybrid comparison of measurements from -100 °C to -0 °C

Project Description

There are no running comparisons in this temperature range and there is an urgent need for NSAI to obtain CMCs down to -100 °C. Therefore, a hybrid comparison will be run between LMK (the issuing NMI) and NSAI (the applicant NMI). The range of temperatures to be covered is from -100 °C to 0 °C in a comparison calibration, using an industrial 25 Ohm PRT, which has been blinded for the applicant NMI. The protocol for the above comparison has been drafted and forwarded to the TC-T chair.

The technical protocol can be downloaded here>>

Final Report 2019-11-27

The project has been completed and the report can be downloaded here>>

Measurements were performed as per the protocol in both NSAI (IE) and MIRS/UL-FE/LMK (SI) at -98 °C, -85 °C, -75 °C, -50 °C and 0.01 °C, using a resistance thermometer as a travelling artefact. The resulting comparison of resistance versus temperature measurements in both laboratories were found to agree to within ±1 mK, with expanded (k=2) uncertainty estimates of ±2.7 mK and ±3.8 mK respectively for MIRS/UL-FE/LMK (SI) and NSAI (IE). The analysis of the equivalence between the laboratories showed that the uncertainty estimations were realistic, and a valid reflection of the NMI capabilities. The report of the hybrid comparison has been submitted to the EURAMET CMC committee for review.