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The main factors affecting the measurement error of thermocouple

Thermocouple is a very commonly used temperature sensor in scientific research and production. Although the structure is simple, it will still produce large measurement errors if you do not pay attention to it.

In the temperature measurement system, a very common temperature sensor—thermocouple, but the field personnel think that the two wires of the thermocouple are simple in structure. If the thermocouple is not tested or used correctly before use, there will still be various problem. For example: improper installation or use will cause large measurement errors. Even a certified thermocouple will fail in use due to improper operation. In a reducing atmosphere such as carburizing, if you do not pay attention, K-type thermocouple Occasionally, it is too bad due to selective oxidation. In order to improve measurement accuracy, reduce measurement errors, and prolong the service life of thermocouples, users are required not only to have instrumentation skills, but also knowledge of physics, chemistry and materials.

Thermocouple is an indispensable temperature sensor for modern temperature measurement. It is also a very simple and common temperature measuring instrument. The temperature error and product maintenance of thermocouple in the process of use are both serious problems faced by the site. Improper use will cause direct economic losses, or false alarms and misjudgments. Thermocouples play an indispensable role in temperature measurement. In view of current problems, we will discuss in detail the main factors affecting measurement errors:

1. Temperature sensor insertion depth, response time, thermal radiation and thermal resistance, etc., point out the inhomogeneity of thermocouple wire, shunt error of sheathed thermocouple, selective oxidation of type K thermocouple, K state, use atmosphere, insulation resistance and Precautions should be taken in use such as thermocouple deterioration.

　　2. Model selection: Sometimes the actual needs of the site are not fully considered in the selection of the site, but the model is selected with theoretical thinking. The temperature adaptation range is too large or too small.

　　 3. The control of the material is uncertain.

　　 4. The on-site environment has not been fully considered.

　　 5. Skills of on-site operators.