NIST Calibration Uncertainties of Liquid‐in‐Glass Thermometers over the Range from −20 °C to 400 °C

The National Institute of Standards and Technology (NIST) Industrial Thermometer Calibration Laboratory (ITCL) is responsible for calibrating several different types of industrial thermometers. One of those types is the liquid‐in‐glass (LiG) thermometer, which includes both mercury (partial and total immersion) and organic (total immersion) filled models. Over the past two years, improvements in both calibration equipment and software used in the ITCL has led to a new assessment of the uncertainties assigned to the calibration of LiG thermometers covering the temperature range from −20 °C to 400 °C. In total, eighteen thermometers from three different manufacturers, six of which are mercury‐filled partial immersion, twelve of which are mercury‐filled total immersion, and two of which are organic‐filled total immersion models, were used for the determination of LiG thermometer calibration uncertainties over the range from −20 °C to 400 °C in the NIST ITCL.