How to determine if a thermocouple is qualified

The method of thermocouple temperature measurement is to form a closed loop with two different raw material conductors. When there are different temperatures at both ends, there will be current flowing through the loop, and at this moment, there will be an electromotive force between the two ends, which is called the Seebeck effect. Two homogeneous conductors with different compositions are thermoelectric electrodes, with the higher temperature end being the working end and the lower temperature end being the free end, which is usually at a constant temperature.

After a period of use, thermocouples will definitely experience wear and tear, and may even be damaged. The quality of a thermocouple is closely related to the thermocouple wires inside it. To determine the quality of a thermocouple, there are some procedures to check:

Firstly, observe that there is no significant wear on the surface of the thermocouple, and then determine its quality by inspecting the internal structure..

Insert the thermocouple that needs to be inspected into a dedicated porcelain sleeve and place it together with a qualified platinum rhodium thermocouple into a tubular electric furnace. Insert the hot end into a cylindrical body made of porous nickel metal for uniform heating in the tubular electric furnace.

Place the tube furnace at the highest temperature of the thermocouple and stabilize this position. Then, use a qualified potential difference meter to measure and record the thermoelectric potential difference between the qualified platinum rhodium thermocouple and the inspected thermocouple. Based on the recorded thermoelectric potential difference, check the corresponding temperature of each thermocouple, so as to determine whether the thermocouple is qualified.