What is the difference between industrial thermal resistance and armored thermal resistance temperature instruments?

Although armored thermal resistors are widely used in industry, their application is limited by their temperature measurement range. The temperature measurement principle of thermal resistors is based on the characteristic that the resistance value of conductors or semiconductors changes with temperature. It has many advantages. It can also transmit electrical signals remotely, has high sensitivity, strong stability, good interchangeability and accuracy, but requires power excitation and cannot measure temperature changes instantaneously. Industrial thermal resistors generally use Pt100, Pt10, Cu50, Cu100. The temperature measurement range of platinum thermal resistors is generally minus 200-800℃, and that of copper thermal resistors is minus 40 to 140℃. Thermal resistors are classified into the same types as thermocouples, but they do not require compensation wires and are cheaper than thermocouples.

As temperature measurement sensors, industrial thermal resistors are usually used in conjunction with temperature transmitters, regulators, and display instruments to form process control systems to directly measure or control the temperature of liquids, steam and gas media and solid surfaces in the range of -200℃-500℃ in various production processes.

Thermal resistors measure temperature by using the property that the resistance of a substance changes when the temperature changes. When there is a temperature gradient in the measured medium, the measured temperature is the average temperature in the medium within the range of the temperature sensing element. What is the difference between industrial thermal resistors and armored thermal resistors?

Although the appearances of various thermal resistors vary greatly, their basic structures are roughly similar. They are generally composed of temperature sensing elements, insulating sleeves, protective tubes, and junction boxes.

From the temperature measurement principle of thermal resistors, it can be seen that the change in the measured temperature is directly measured by the change in the resistance value of the thermal resistor. Therefore, the change in the resistance of various wires such as the lead wire of the thermal resistor will affect the temperature measurement.

The armored thermal resistor is a solid body composed of a temperature sensing element (resistor), lead wire, insulating material, and stainless steel sleeve. Its outer diameter is generally φ2-φ8mm, and can currently reach φ0.25mm. Compared with ordinary thermal resistors, it has the following advantages:

① Small size, no air gap inside, small measurement value due to thermal inertia;

② Good mechanical properties, vibration resistance, and impact resistance;

③ Can be bent and easy to install;

④ Long service life.

Armored thermal resistors are commonly used temperature measuring elements in temperature measuring instruments. When the two ends of two conductors of different components are connected into a loop, when the temperatures of the two junction thermocouples are different, a thermal current will be generated in the loop. If there is a temperature difference between the working end and the reference end of the thermocouple, the display instrument will indicate the temperature value corresponding to the thermoelectric potential generated by the thermocouple.

Armored thermal resistor couple is a temperature sensor. It has a smaller diameter than assembled thermocouples, is easy to bend, and has good shock resistance. It is suitable for installation in places where assembled thermocouples cannot be installed. The armored thermocouples produced by the company use imported thermal resistor temperature measuring elements. Therefore, it has the advantages of accuracy, sensitivity, fast thermal response time, stable quality, and long service life.