Final report on VMI–NMISA bilateral comparison APMP.T-K3.1: Realizations of the ITS-90 over the range −38.8344 °C to 419.527 °C

Abstract

The Comité Consulatif de Thermométrie (CCT) has organized several key comparisons to compare realizations of the ITS-90 in different National Metrology Institutes. To keep the organization, time scale and data processing of such a comparison manageable, the number of participants in a CCT key comparison (CCT KC) is limited to a few laboratories in each major economic region. Subsequent regional key comparisons are linked to the applicable CCT KC by two or more linking laboratories.For the temperature range from 83.8058 K (triple point of Ar) to 933.473 K (freezing point of Al), a key comparison, CCT-K3, was carried out from 1997 to 2001 among representative laboratories in North America, Europe and Asia. Following CCT-K3, the Asia-Pacific Metrology Program Key Comparison 3 (APMP.T-K3) was organized for National Metrology Institutes in the Asia/Pacific region. NMIA (Australia) and KRISS (South Korea) provided the link between CCT-K3 and APMP.T-K3. APMP.T-K3, which took place from February 2000 to June 2003, covered the temperature range from −38.8344 °C (triple point of Hg) to 419.527 °C (freezing point of Zn), using a standard platinum resistance thermometer (SPRT) as the artefact.In June 2007 the Vietnam Metrology Institute (VMI) requested a bilateral comparison to link their SPRT calibration capabilities to APMP.T-K3, and in October 2007 the National Metrology Institute of South Africa (NMISA) agreed to provide the link to APMP.T-K3. Like APMP.T-K3, the comparison was restricted to the Hg to Zn temperature range to reduce the chance of drift in the SPRT artefact. The comparison was carried out in a participant–pilot–participant topology (with NMISA as the pilot and VMI as the participant). VMI's results in the comparison were linked to the Average Reference Values of CCT-K3 via NMISA's results in APMP.T-K3.The resistance ratios measured by VMI and NMISA at Zn, Sn, Ga and Hg fixed points agree within their combined uncertainties, and VMI's results also agree with the CCT-K3 reference values at these fixed points.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 CIPM Mutual Recognition Arrangement (MRA).