A New Graduation Method for Thermal Resistance Thermometers

Industrial platinum resistance thermometer is a widely used temperature measuring instrument. For a long time, the calculation method of CVD equation has been generally used in relevant standards or technical specifications at home and abroad to calibrate and divide it. However, the industrial platinum resistance thermometer calibrated and divided by CVD equation has low accuracy, low stability and large uncertainty, and cannot be used as a transfer standard.

Most industrial temperature measurement fields or laboratories with low requirements can only use standard platinum resistance thermometers with higher accuracy as traceability transfer standards, but due to various conditions in the actual industrial temperature measurement field, standard platinum resistance thermometers cannot be used, making temperature value transfer and traceability impossible in these places, and actual metrological calibration work cannot be carried out.

The feasibility of calibrating and dividing industrial platinum resistance thermometers using the interpolation formula defined by the ITS-1990 international temperature scale is studied, and the calculation results of the temperature-resistance relationship given by the commonly used CVD equation are compared, and then the differences between the two are given, and the ways and methods of establishing precision industrial platinum resistance thermometers as transfer standards are explored. Through the research and analysis of different models and different manufacturers of industrial platinum thermal resistors in different temperature zones, the experimental results, data curves and measurement errors caused by two different methods of division are given for each thermometer.

Experimental proof:

It is feasible to use the interpolation method of ITS-1990 international temperature scale for industrial platinum thermal resistor thermometers. Compared with the calculation method of CVD equation for industrial platinum resistor calibration division, it has better accuracy and consistency.

Previously, the national metrology technical institutions of Italy and Canada conducted research on the industrial platinum resistor division method using the international temperature scale interpolation formula. The traditional means to improve the accuracy and stability of industrial resistor temperature measurement are to work hard on component purity, packaging technology, and production process, which lays the foundation for the improvement of temperature value transfer and traceability system of precision platinum resistors and industrial platinum resistors in my country, and can be widely used in the field of industrial platinum resistor temperature measurement.