Thermocouple sensor is a kind of spontaneous electric sensor, measurement does not need additional power supply, will be directly converted into voltage output measurement. Use is very convenient, and is often used as measurement of gas stove, the pipe surface temperature or the temperature of the liquid and solid. Its temperature range is very wide: - 270℃~2500℃。 It has simple structure, easy fabrication, wide measuring range, high precision, small inertia, and output signal remote transmission and many other advantages. Standard thermocouple a total of 13 kinds of thermocouple, it has good compatibility, unified indexing table, digital display table. Electrotechnical commission recommended in 1975 the seven standard thermocouple, table 3 - 1 is their basic features. One of the top six kinds of are produced in our country. Commonly used thermocouple and basic features of thermocouple names used degree, temperature measuring range characteristics of platinum rhodium - 30 Platinum rhodium b0 6 ~ 1700 ℃ high temperature limit, stable performance. In (high temperature fields such as metallurgy, 1200℃~1600℃) Can be used as a standard thermometer is used. Platinum rhodium - 10 Platinum s0 ~ 1600 ℃ performance stability, oxidation resistance, high accuracy, small thermoelectric potential output is suitable for oxidation, the inert gas in the work, in the ( 419. 58℃~1084. 88℃) Used as a standard standard thermometer is used. Nickel chrome - K - nickel and silicon Wide range of 200 ~ 1200 ℃ temperature measurement, thermoelectric potential large and approximate to linear, cheap, poor stability, the cathode has a magnetic conductivity, wide application of nickel and chromium - Constantan e - 200 ~ 900 ℃ thermoelectric potential very suitable for oxidizing, iron - inert gas in the work Constantan j - 200 ~ 750 ℃ cheap, thermoelectric potential is bigger, easy to cupric oxide - Constantan t - High precision of 200 ~ 400 ℃, in 0 ~ - 200 ℃ range, can be made into standard thermocouples are used for making low temperature measurements in the laboratory and research platinum rhodium - 30 Platinum r with department of non standard thermocouple platinum rhodium - Stable performance, suitable for all kinds of high temperature measurement of iridium rhodium - Thermoelectric emfs good linear relationship with temperature, the long-term use of temperature below 2000 ℃ tungsten rhenium - Can use up to 2800 ℃.