The working principle of thermocouple thermometer _ instrument

Commonly used in low temperature zone thermocouple is a kind of temperature detector. Its main characteristic is high accuracy, stable performance. Among them is platinum thermal resistance measurement accuracy is high, it is not only widely used in industrial temperature measurement, and is made into standard benchmark instrument. 1, thermocouple temperature measurement principle and material of 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 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. 2, thermocouple type 1) 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. 2) 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 of (1) small volume, no internal air gap, thermal inertia, the measured value after small (2) good mechanical properties, resistance to vibration, shock; (3) can bend, easy to install (4) long service life. 3) 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. 4) Flameproof thermocouple junction box flameproof thermocouple with special structure, 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. Flameproof thermocouple can be used in the Bla B3c level zone with explosion danger place temperature measurement.