The relationship between the service life of the thermocouple and its deterioration
What is the relationship between the service life of the thermocouple and its deterioration? In the case of
Our standards only require stability of the thermocouple. That is specified at a certain temperature by 200h, before and after the use of thermoelectromotive force changes. However, the service life has not been found. Japan's thermocouple service life requirements, is based on the Japanese JIS (C-1602-1995) standard thermocouple in the continuous use of time. For B ﹑ R ﹑ S thermocouple in terms of 2000h, K ﹑ E ﹑ J ﹑ T thermocouple for 10000h. In the case of
In actual use, the assembled thermocouple usually has a protective tube, only in special circumstances only used bare wire. Therefore, in most cases, the life of the protective tube determines the thermocouple life. The actual life of the thermocouple to judge, must be through long-term collection, accumulation of actual use of the data, it is possible to give more accurate results. Thermocouple is scientific research and production of the most commonly used temperature sensor, although the structure is simple, but the use of attention will still produce a large measurement error. In this paper, the main reason for the error of thermocouple insertion, the depth of the thermocouple, the response time, the heat radiation and the thermal impedance are discussed in detail, and the thermocouple is not uniform and the atmosphere is used. Insulation resistance, K-type thermocouple selective oxidation, K state and armored thermocouple shunt error in the use of the note. In the case of
Thermocouple degradation and life
The so-called thermocouple degradation, that is, after the use of thermocouples, aging deterioration phenomenon. Thermocouples made of metal or alloy, in its high temperature of the internal grain to gradually grow up. At the same time the alloy contains a small amount of impurities, its location or shape will also change, but also on the surrounding environment of the reduction or oxidation of the gas should also react. With the above changes, thermocouple thermoelectromotive force will also be extremely sensitive to change. So the thermocouple degradation phenomenon is inevitable. In the case of
Thermocouple degradation is a quantitative process, it is very difficult to quantify, with the type of thermocouple diameter, the use of temperature, atmosphere, time varies. Thermocouple service life refers to the development of thermocouple to exceed the allowable error, or even disconnected can not use the time.
