METROLOGICAL SUPPORT FOR THE VERIFICATION OF MERCURY THERMOMETERS

Abstract

Modern liquid thermostats used for checking mercury thermometers reproduce a temperature of no more than 300 °C, while the upper limit of measurements of some types of mercury thermometers reaches 600 °C. The paper theoretically substantiates and experimentally confirms the possibility of checking mercury thermometers in temperature calibrators. The measurement equation has been compiled. The components of the transmission error of the unit of magnitude are estimated. Conditions are formulated that allow a priori to assess the possibility of checking a particular type of thermometer in a particular calibrator. All calculations are made taking into account the changes in the state verification scheme. The design of a special thermometer for studying the heterogeneity of the temperature distribution outside the working area of the calibrator channel is proposed. The dependence of the readings of a special thermometer on the depth of immersion is theoretically estimated. The disadvantages of the currently used method for determining the temperature of the protruding mercury column are noted. It is proposed to measure the temperature of the protruding column with a thermal imager, an accuracy analysis is performed. The results of experimental studies of the inhomogeneity of the temperature distribution outside the working area of the channel of the calibrator KT-2M are presented. The reproducibility of measurement results when checking thermometers in a calibrator and a liquid thermostat is estimated.