Thermocouple has to bend, heat resistance to high pressure, fast response time and the advantages of strong and durable, thermocouple, thermocouple and fabricated as measure temperature sensor, thermocouple and usually display instrument, recorder and electronic regulator, at the same time, hot I also can be used as a prefabricated thermocouple temperature sensing element. Thermocouple can be directly measured from 0 ℃ ~ 1100 ℃ in the process of various production within the scope of the liquid, steam and gas medium, as well as the temperature of the solid surface. Thermocouple can bend, high pressure resistance, heat fast response time and strong and durable many advantages, such as it and industrial prefabricated thermocouple, as measure temperature transmitter, through the compensating conductor and display meter, recording meter and electronic regulator, at the same time can also be as prefabricated thermocouple temperature sensing element. It can be directly measured in the production of chian from 0 ~ 800 ℃ in the scope of liquid, steam and gas medium, as well as the temperature of the solid surface. Thermocouple are two different ingredients of conductor on both ends of the welding, forming circuit, direct measurement WenDuan call work side, the terminal end is called the cold end, also known as the reference. When work end and reference end there is temperature difference, will produce thermal current in the circuit, connected to display instrument, the instrument will indicate the thermocouple thermoelectric emf generated by the corresponding temperature value. The working principle of thermocouple thermoelectric emf will grows with the temperature measuring end, only the size of the thermoelectric emfs and thermocouple temperature difference on both ends of the conductor material and, had nothing to do with hot electrode length and diameter. The structure principle of thermocouple is consists of a conductor, high insulation magnesium oxide, coat 1 cr18ni9ti stainless steel protecting tube, after many integrated control. Thermocouple products are mainly composed of terminal block, terminal and thermocouple basic structure, and with various mounting device. Thermocouple insulation type and hull type two kinds.