The principle of thermocouple and what is main species _ instrument

Commonly used in low temperature zone thermocouple is a kind of temperature detector. Thermocouple temperature measurement is based on the metal conductor resistance value increases with the increase of the temperature of the properties for temperature measurement. Thermocouple installation method 1, first of all should be good measuring thermocouple the size of the teeth, the car a good teeth. 2, according to the diameter of the screw tooth holder, the need to measure the hole in the pipeline. 3, the teeth of welding, the screw tooth seat insert has open hole, the screw teeth with measured pipe welding. 4, the thermocouple precession is welded teeth. 5, according to the wiring diagram to connect the thermocouple junction box good line, and connected to the corresponding display instrument dial photogenic, pay attention to the junction box cannot be measured medium and pipeline wall contact, to ensure that the terminal box temperature less than 0 Range of 100 ℃, terminal box shall be installed under the outlet hole, to prevent bad sealing, water vapor dust deposition such as shorting terminal. 6, the location of the thermocouples installed, should consider to repair and maintenance is convenient. The main characteristic of thermocouple thermocouple is high accuracy, stable performance. The platinum thermocouple measuring accuracy is high, it is not only widely used in industrial temperature measurement, and is made into standard benchmark instrument. Thermocouple are mostly made of pure metal materials, the application is more platinum and copper, in addition, now have begun to use the materials such as nickel, manganese and rhodium thermocouple. Metal thermocouple commonly used thermal material sort is more, the commonly used is a platinum wire. Industrial measurement with metal material in addition to the platinum wire, thermocouple as well as copper, nickel, iron, iron - Nickel, etc. Working principle of thermocouple temperature measurement principle is based on a conductor or semi-conductor resistance changes over temperature of thermocouple this feature to measure temperature and parameters related to the temperature. Thermocouple is usually need to get the resistance signal through wire transfer to the computer control device or other secondary instrument. Main kinds of ordinary thermocouples 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. Thermocouple thermocouple is by thermal components ( The resistor body) , wire, insulation materials, stainless steel casing combination solid body, its diameter is commonly phi - 2 Phi is 8 mm, achieve more xiaoke phi is 0. 25mm。 Compared with conventional type thermocouple, it has the following advantages: 1, small volume, no internal air gap, thermal inertia, the measured value after small; 2, good mechanical properties and resistance to vibration and impact resistant; 3, can bend, easy to install 4, long service life. Capillary thermocouple ends thermocouple temperature sensing element resistance wire winding by special processing, close to the face in the thermometer. Compared with general axial thermocouple, it can reflect more correctly and quickly end face of the actual temperature being measured, is suitable for measuring temperature bearing and other parts of the face. Explosion-proof explosion-proof thermocouple explosion-proof explosion-proof thermocouple through the special structure of the junction box, its shell internal explosive mixed gas by affected by sparks or electric arc explosion limit within the junction box, that wouldn't make production field explosion. Explosion-proof explosion-proof thermocouple can be used in the bla B3c level zone with explosion danger place temperature measurement.