The use of liquid-in-glass thermometers is described in many documentary standards in the fields of environmental testing, material testing, and material transfer. Many national metrology institutes, including the National Institute of Standards and Technology (NIST) and the National Research Council of Canada (NRC), list their calibration services for these thermometers among the Calibration Measurement Capabilities of Appendix C of the BIPM Key Comparison Database. NIST and NRC arranged a bilateral comparison of a set of total-immersion ASTM-type liquid-in-glass thermometers to validate their uncertainty claims. Two each of ASTM thermometer types 62C through 69C were calibrated at NIST and at NRC at four temperatures distributed over the range appropriate to each thermometer, in addition to the ice point. Collectively, the thermometers span a temperature range of 38 °C to 305 °C. In total, 160 measurements (80 pairs) comprise the comparison data set. We have formed the pair-wise differences (TNIST TNRC) for each thermometer at each temperature. For 5 of the 80 pairs (6%), the differences exceed the k=2 combined uncertainties. We consider the results evidence of a generally satisfactory state of affairs.
Citation: 10th International Symposium on Temperature and Thermal Measurements in Industry and Science
Pub Type: Others
Calibration, Calibration and Measurement Capability, CMC, Comparison, Liquid-in-Glass thermometer, Supplemental comparison, Temperature.