Thermocouple With Good Pressure Resistance

Thermocouple is composed of two different components of the conductor at both ends into the loop, when the two junction temperature is different, it will generate heat in the loop. If there is a temperature difference between the working end of the thermocouple and the reference end, Thermocouple the display instrument will indicate the temperature value corresponding to the thermoelectric potential generated by the thermocouple. The thermoelectric heat of the thermocouple will increase with the temperature of the measuring end. Thermocouple Its size is only related to the temperature of the thermocouple material and both ends, independent of the length and diameter of the hot electrode.

Thermocouple characteristics

1, the assembly is simple,

Easy to replace

2, compression spring-type temperature sensor, seismic performance is good;

3, high precision measurement;

4, measuring range (-200 ℃ ~ 1300 ℃, special circumstances -270 ℃ ~ 2800 ℃);

5, fast response time;

6, high mechanical strength, good pressure resistance;

7, high temperature up to 2800 degrees;

8, long service life

Structural requirements

Thermocouple structure In order to ensure reliable and stable thermocouple work, Thermocouple its structure requirements are as follows:

1, the composition of the two thermocouple thermocouple welding must be strong;

2, the two hot electrodes should be well insulated from each other to prevent short circuit;

3, compensation wire and thermocouple free end of the connection to be convenient and reliable;

4, protective casing should be able to ensure that the thermal electrode and harmful media fully isolated.

Thermocouple principle Features When there are two different conductors or semiconductors A and B form a loop, the two ends connected to each other, as long as the two nodes at different temperatures, Thermocouple one end of the temperature T, known as the working or hot side, the other One end of the temperature T0, known as the free end (also known as the reference side) or cold side, the circuit will produce an electromotive force, the direction and size of the electromotive force and the material of the two contacts and the temperature. This phenomenon is called "thermoelectric effect", the circuit composed of two conductors called "thermocouple", Thermocouple the two conductors called "hot electrode", the resulting electromotive force is called "thermoelectromotive force".

The thermoelectromotive force consists of two parts electromotive force, part of which is the contact electromotive force of the two conductors, and the other is the thermoelectromotive force of the single conductor.

The size of the thermoelectromotive force in the thermocouple circuit is only related to the temperature of the conductor material forming the thermocouple and the two junctions, Thermocouple regardless of the shape and size of the thermocouple. When the thermocouple two electrode material is fixed, the thermoelectromotive force is the two junction temperature t and t0. The function is poor.

This relationship has been widely used in practical temperature measurement. Since the cold junction t0 is constant, the thermoelectromotive force generated by the thermocouple changes only with the change of the temperature of the hot end (measuring end), that is, Thermocouple a certain thermoelectromotive force corresponds to a certain temperature. We only need to measure the thermoelectromotive force method can achieve the purpose of temperature measurement.

Thermocouple temperature is the basic principle of two different components of the material conductor composition closed loop,

When there is a temperature gradient at both ends, there will be a current through the circuit, there is between the two ends of the electromotive force - thermoelectromotive force, which is the so-called Seebeck effect (Seebeck effect). Two different components of the homogeneous conductor for the thermal electrode, Thermocouple the higher the temperature of the end of the working end, the lower end of the temperature is free, the free end is usually at a constant temperature. According to the relationship between the thermoelectromotive force and the temperature, the thermocouple indexing table is made. The indexing table is obtained under the condition that the free end temperature is 0 ℃, and the different thermocouples have different indexing tables.

When the third metal material is connected to the thermocouple circuit, the thermoelectric power generated by the thermocouple will remain constant as long as the temperature of the two contacts of the material is the same, that is, not affected by the third metal access circuit. Therefore, Thermocouple the thermocouple temperature measurement, access to measuring instruments, measured thermoelectromotive force, you can know the temperature of the measured medium. Thermocouple temperature measurement requirements of its cold end (the measurement side of the hot end, through the lead and the measurement circuit connected to the end of the cold side) to maintain the same temperature, the thermal potential of the temperature and the measured temperature was a certain proportion. If measured, the cold (ambient) temperature changes will seriously affect the accuracy of the measurement. Thermocouple In the cold side to take some measures to compensate for the cold side of the temperature changes caused by the impact of the cold side of the thermocouple compensation as normal. A special compensation wire for connection to a measuring instrument.