Using thermocouple protection tube in order to avoid the thermocouple to suffer from the erosion of measured medium and ease of installation, it is necessary to use protection tube. According to the temperature requirement, can choose quartz, corundum, refractory clay for protecting tube. Below 600 ℃ available hard glass tube. Cold end to compensate shows the relationship between the thermocouple thermoelectric potential and temperature of the indexing table, in the cold end humidity remain at 0 ℃, so keep this kind of condition, when use good namely the thermocouple cold end directly, or use the cold end compensating conductor extending derivation, in ice water. Temperature measurements to make the temperature of hot end, exactly the same as that of measured medium, first requires good thermal contact, make the two quickly establish a heat balance; Hot end of the second does not transfer heat to the media outside, in order to avoid the hot end never reach equilibrium with the media and there is a certain error. Thermocouple over a period of time after use may have a bad phenomenon, so every one thermocouple before actual use, should be calibrated, comparative verification method are available, and melting point of material known can also be used for calibration, to make the working curve.