SIM Thermocouple Type S Supplementary Comparison

Abstract

Main textA collapsed star type S thermocouple intercomparison was performed over the International Temperature Scale of 1990 (ITS-90) temperature range from 0 °C to 1100 °C. This was an Inter-American Metrology System (SIM) regional intercomparison piloted by the National Institute of Standards and Technology (NIST). Eleven laboratories (including NIST) participated in the intercomparison. Twenty-one type S thermocouples were constructed and calibrated at NIST, of which ten served as transfer standards. The thermocouples were identified as Cut 1 through Cut 21. Each thermocouple was calibrated by the metal fixed-point method at the freezing points of Zn, Al, Ag, and Au. The 21 calibrations were ultimately used to determine the reference values (RV) for the intercomparison. Subsequently the artifacts were calibrated at a participating laboratory by comparison with a local standard and/or by fixed-point method. Subsequently they were returned to the pilot laboratory where they were remeasured at the freezing point of silver (for purposes of determining a transfer uncertainty). Although thermocouples are not a standard interpolating instrument on the ITS-90, they are proposed as an approximation technique and are a widely used thermometer; so, it is useful to look at the measurement capabilities involved in their calibration.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 https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).