With fine platinum resistance of thermocouple is burned on the platinum rhodium thermocouple ceramic or glass which is made on a support, lead to ordinary steel wire or silver wire. Thermocouple has the following characteristics ( 1) Thermal inertia small, response rapidly, such as the maintenance of tube fu 2 mm diameter common platinum resistance, the time constant of 25 s; The metal casing diameter twist. 0 mm kai thermocouple, the time often effect is only five. The left and right sides. ( 2) With flexible performance, kai thermocouple in addition to the head, can make the direction of bending, so it is suitable for the structure is relatively complex, lateral DE small equipment temperature Ao ( 3) Has good resistance to vibration and shock resistance. ( 4) Long using life, thermocouple in resistance due to iron power twist of insulation materials cover and metal casing maintenance, thermocouple wire is not easy to jung corrosion by harmful medium, thus it thermocouple live longer than ordinary thermocouple. Thermocouple should pay attention to when using the following item ( 1) Object, according to the measured temperature range and measurement of choosing the right of the thermocouple type, specification and maintenance of pipe materials. ( 2) Thermocouple temperature and working pressure shall not use beyond the numerical rating of the thermocouple. ( 3) If the thermocouple to be used in the corrosive medium, maintenance should be made of stainless steel pipe. ( 4) Most of the thermocouple sensor is about 120 mm in length, select the thermocouple inserted depth, should consider to the thermocouple sensor can only measurement of full range of the measured medium uniformity degree. ( 5) Thermocouple wiring, junction box opened the first, and then wiring. Connection way of general there are two wire and three-wire system two kinds. Three wire system has the advantage of cohesion, can prevent the bimetallic thermometer provoked by connecting wire resistance value of the instrument error value for show. ( 6) Thermocouple appeared with the connecting wires should be insulated copper wire, shall not use the thermocouple compensating lead wires. Shows copper wire resistance should be according to the rules of data matching instrument technique conditions, the average of 2 a 50, dc balanced bridge wire resistance value can be used to adjust ( 7) Can't take a thermocouple with two instrument used in parallel, as long as the double branch thermocouple with appeared two instrument can only be used to apply. ( 8) Thermocouple and its attachments without using, the required storage in tungsten-rhenium thermocouples are not affected by vibration and impact. Appropriate storage location condition is: 10 to ambient temperature 35 gc; Relative humidity is not more than 80%; Should not contain may form in the air around the thermocouple parts corrosion substance.