Most temperature indicators that use thermocouples as sensors include an internal thermometer for compensating room temperature variations. This thermometer measures ambient temperature, which is then converted to a thermoelectric voltage. This voltage is added to the electromotive force measured in the thermocouple sensor and then converted back to temperature. Although precise calibration of the indicator can be conducted in a controlled room-temperature environment, additional uncertainty arises due to room temperature compensation during actual measurements. To address this issue, we calibrated temperature indicator at the ice point. In this experiment, the indicator was placed in an environment where the temperature varied between 8 and 38oC, demonstrating its dependency on ambient temperature. In a second set of experiments, we shorted the thermocouple input terminal to verify whether the indicator correctly indicated the ambient temperature. This study proposed a method to assess additional uncertainty that must be considered when using a thermocouple connected to an indicator calibrated with an external ice point in a laboratory. It also highlights additional steps and factors to consider during the calibration of temperature indicators that employ internal temperature compensation.

The unit of the thermodynamic temperatures, kelvin, will be redefined after May of 2019, by the new process of fixing the numerical value of the Boltzmann constant. In this respect, the Boltzmann constant, which is a conversion factor between the thermal energy and the thermodynamic temperature, will be assigned as 1.380 649 × 10^-23 J K^-1 after the redefinition procedure. This paper reviews the three experiments which have contributed to the determination of the Boltzmann constant, which are namely: the acoustic gas thermometry, dielectric constant gas thermometry and the noise thermometry. By and large, the physical principles of these experiments are important even after the redefinition takes place, because they are methods used as primary thermometers for the determination of the thermodynamic temperatures. The status of the redefinition and the relation between the thermodynamic temperature and temperature scale is reviewed in this paper.

We present experimental data on the time response behavior of industrial platinum resistance thermometers (IPRT) to help with the selection of proper sensors in industry and research laboratories. Time constants of IPRTs were measured using a method specified in ASTM standards. Two different sensors of different protecting sheath diameters were tested in air, water and silicon oil at temperatures from 0 °C to 200 °C. The time constant was the smallest in water and the highest in air. As the test temperature increased, time constants tended to decrease at all heat conducting media. For different diameters of sheath of IPRT at the same temperature, it was found that the IPRT of larger diameter showed higher time constant in air, but the opposite dependence was observed in water and oil. From the measured results, it was suggested that the sensor diameter and heat conducting medium should be considered if one wants to select proper thermometer to measure the dynamic temperature change in industry and research area.