Digital PRT : A Case Study for Uncertainty Estimation

Industrial Platinum Resistance Thermometers are widely being used for the measurement of temperature in Industry and as working standards in Calibration Laboratories, in the range -200 oC to 650 oC. The IPRTs are calibrated in Liquid Baths or Block Calibrators by comparison method against Standard Platinum Resistance Thermometers. In this paper, the evaluation of uncertainty of measurement in the calibration of Digital Thermometer with IPRT probe has been discussed. A detailed analysis of contributions from various factors to the uncertainty in measurement associated with the calibration results has been given. The expanded uncertainty of digital thermometer with IPRT probe at a temperature of 300 oC has been estimated as ±106 moC (±0.106 oC) at approximately 95% confidence level with coverage factor ‘k’ = 2 for normal distribution.