Type WRQ-130 Platinum Rhodium Thermocouple

1、 Introduction

RType thermocouple (platinum rhodium 13 platinum thermocouple)

Platinum rhodium 13 platinum thermocouple (R-type platinum rhodium thermocouple) is a precious metal thermocouple. The diameter of the wire is specified as 0.5mm, with an allowable deviation of -0.015mm. The nominal chemical composition of its positive electrode (RP) is platinum rhodium alloy, with rhodium content of 13% and platinum content of 87%. The negative electrode (RN) is pure platinum, with a long-term maximum usage temperature of 1300 ℃ and a short-term maximum usage temperature of 1600 ℃.

RThe platinum rhodium thermocouple has the advantages of high accuracy, good stability, wide temperature measurement range, and long service life in the thermocouple series. It has good physical and chemical properties, stable thermoelectric potential, and excellent oxidation resistance at high temperatures, making it suitable for both oxidizing and inert atmospheres. Due to the comparable comprehensive performance of R-type platinum rhodium thermocouples to S-type thermocouples, it has been difficult to promote in China. Apart from being used for temperature measurement in imported equipment, it is rarely used for temperature measurement in China.

RThe shortcomings of platinum rhodium thermocouples are thermoelectric potential, low thermoelectric potential, low sensitivity reading, decreased mechanical strength at high temperatures, high sensitivity to pollution, expensive precious metal materials, and therefore a large one-time investment.

2、 Working principle of thermocouple

Two conductors with different compositions are welded at both ends to form a circuit. The direct temperature measuring end is called the measuring end, and the wiring terminal end is called the reference end. When there is a temperature difference between the measuring end and the reference end, a thermal current will be generated in the circuit. When connected to a display instrument, the instrument will indicate the corresponding temperature value of the thermoelectric potential generated by the thermocouple. The thermoelectric potential of a thermocouple will increase as the temperature at the measuring end rises. The magnitude of the thermoelectric potential is only related to the material of the thermocouple conductor and the temperature difference between the two ends, and is independent of the length and diameter of the thermoelectric electrode.