How to extend the service life of thermocouples

In practice, assembled thermocouples usually have protective tubes, and in special cases only bare wires are used. Therefore, in most cases, the lifespan of the protective tube can determine the lifespan of the thermocouple. To determine the actual lifespan of a thermocouple, it is necessary to collect and accumulate data for a long time under actual application conditions in order to provide relatively accurate results.

Thermocouples are important and commonly used temperature control sensors in scientific research, production, and daily life. Although the structure is simple, if not careful, there can still be significant measurement errors. Here, in response to simple issues in applications, a detailed analysis and discussion were conducted on the selection of temperature measurement points, penetration depth of thermocouples, response working time, thermal radiation, and thermal impedance. The non-uniformity of thermocouples, application environment, and insulation resistance were mainly pointed out through error data sources.

The so-called thermocouple degradation refers to the aging and degradation of thermocouples after use. Thermocouples made of metal or alloy grow at high temperatures. Alloy materials contain a small amount of impurities together, which can cause changes in orientation or shape, and can also have adverse reactions with recycled or oxidizing gases in our surrounding living environment.

With these changes, the thermoelectric potential of the thermocouple will also become sensitive. Therefore, the degradation of thermocouples is unavoidable. The degradation of thermocouples is a difficult to quantify quantitative process. It will affect the variety, diameter, usage environment temperature, atmosphere, and time of the artificial thermocouple. The service life of a thermocouple is defined as the time during which the loss of the thermocouple exceeds the allowable error or the thermocouple cannot be used due to disconnection.