A simplified method for calibration of PRTs used in heat meters

Many thousands of industrial platinum resistance thermometers are used in heat meters that are devices for measurement of the heat being spent in heat-exchange water systems. That is why it is important to develop an inexpensive, quick and simple method for calibration of the IPRTs. There are standard documents on verification of the heat meters, such as EN 1434 and OIML R75, adopted in several countries. It seems that the method of calibration of the temperature sensors suggested in these documents is not the optimum one. When developing the method of calibration of the IPRTs, several important characteristics should be considered, such as the IPRT's instability, hysteresis, and the small temperature range ( 0 to 170 degreesC) in which the IPRTs work. A method for calibration of the IPRTs was suggested that made it possible to use only two calibration points: 0 degreesC and 100 degreesC. The technique was applied to more than a hundred IPRTs of different designs, which were developed, manufactured and calibrated at Industrial Company "TESEY" (Russia). The main advantages of the two-point calibration of the IPRTs for heat meters over the method of the EN and OIML standards are its simplicity, quickness and a lower cost, as well as a satisfactory accuracy.