Small Fixed-Point Cells for Use in Dry Well Block Calibrators
Gregory F. Strouse
As part of a research project for the Combined Calibration Group (CCG) of the U.S. Armed Forces, three rugged fixed-point cells were developed for use in dry well block calibrators (DWBCs). The small fixed-point cells of the water triple point (0.01 C), the Ga triple point (29.7666 C), and the In melting point (156.5985 C) are intended to provide either calibration temperature points for industrial platinum resistance thermometers (IPRTs) or single-point calibration checks on IPRTs for the CCG mobile calibration facilities. While the ITS-90 indium fixed point is defined as a freezing point, realization of the three fixed-point cells in the melting mode simplifies the realization process, yet still provides the required expanded uncertainty (k=2) of less than 10 m C. These three fixed-point cells were tested in two DWBCs using standard platinum resistance thermometers (SPRTs) by measuring realization plateaus and by direct comparisons with the PRT Laboratory reference cells. Adequacy of immersion of the thermometers in the cells during realization of the fixed points in the DWBCs was checked and the results were used to quantify the immersion uncertainty. This paper presents the realization methods, behavior of the fixed-point cells in the DWBCs and the uncertainty assigned to each of cells.
International Sympoisum on Temperature and Thermal Measurements in Industry and Science | 8th | | VDE
dry well block calibrator, fixed-point cells, gallium triple point, indium freezing point, indium melting point, ITS-90, TPW, triple point of water
Small Fixed-Point Cells for Use in Dry Well Block Calibrators, International Sympoisum on Temperature and Thermal Measurements in Industry and Science | 8th | | VDE, Berlin, GE, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=830736
(Accessed June 3, 2023)