Thermocouple with small size, high precision, good mechanical properties, resistance to vibration, shock, can bend, easy installation, long life and other characteristics, commonly used in low temperature zone thermocouple is a kind of temperature detector, and is widely used in industrial temperature measurement. In use, we found that the thermocouple type many, is a lot of platinum thermocouple and copper thermocouple used in it. In order to further understand the relevant contents of thermocouple, there are four common types of thermocouple: industrial thermocouple, thermocouple, end thermocouple, explosion-proof explosion-proof platinum resistance 1, industrial thermocouple: industrial commonly used thermocouple temperature sensing element ( The resistor body) The structure and characteristics. From the thermocouple temperature measurement principle, the measured the change in temperature is directly measured by thermocouple resistance change, therefore, the wires of a thermocouple body such as a variety of wire resistance change will affect temperature measurement. As to eliminate the influence of the lead resistance with the three wire or four wire; 2, thermocouple, thermocouple is by thermal components ( The resistor body) , wire, insulation materials, stainless steel casing combination solid body, its diameter is generally from 2 to 8 mm, 3, end thermocouple: end thermocouple temperature sensing element resistance wire winding by special processing, close to the face in the thermometer, it is compared with general axial thermocouple, can more accurately and quickly to reflect the actual temperature of end face, is suitable for measuring temperature bearing and other parts of the face. 4, explosion-proof explosion-proof platinum thermocouple: flameproof thermocouple by explosion-proof junction box, the influence of such as a spark or arc explosion limits within the junction box, that wouldn't make production field explosion.