The Consultative Committee for Thermometry Key Comparison 2 (CCT-K2) results were published two years ago (2002 Metrologia 39 551–71). NRC served as the pilot laboratory for CCT-K2 and remains able to provide a scale and measurement system suitable for performing bilateral comparisons linked to the original key comparison results. In March 2003, measurements of two VNIIFTRI 100 Ω capsule-style platinum resistance thermometers (CSPRTs), S/N 356 and 476, were undertaken to relate their local calibration to the results from the CCT-K2 exercise. The NRC Leeds and Northrup (L&N) CSPRT S/N 1872174 provides the link to the CCT-K2 results. The three CSPRTs were compared at the eight defining cryogenic temperatures of the International Temperature Scale of 1990 (ITS-90) in the range from 13.8033 K to 273.16 K.

The reader is referred to the full text of the CCT-K2 report for a detailed explanation of the methodology employed for the comparison. Only the details unique to the measurements reported here will be addressed in this article.

The NRC/VNIIFTRI bilateral comparison of capsule-style platinum resistance thermometers over the range 13.8 K to 273.16 K has revealed calibrations at VNIIFTRI to be in agreement with the KCRV of CCT-K2 within the expanded uncertainty for all temperatures of the comparison with the exception of the triple point of hydrogen at 13.8033 K. One of the two CSPRTs supplied by VNIIFTRI was found to be discrepant as revealed by differences at the triple point of water and at the lowest temperatures of the comparison, and was therefore excluded from further analysis. The linkage to the CCT-K2 data supports the evaluation of the VNIIFTRI CMCs in Appendix C of the KCDB.

Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the Mutual Recognition Arrangement (MRA).