4 commonly used thermocouples

Thermocouple is a commonly used temperature measuring instrument that has certain applications in many fields. There are also various classifications of thermocouples, among which the most commonly used are four types: coarse pass type thermistor, armored thermistor, end face thermistor, and explosion-proof thermistor. Below, we will introduce in detail the four commonly used thermocouples.

1) Coarse type thermistor: The structure and characteristics of commonly used thermistor temperature sensing elements (resistors) in the industry. From the principle of temperature measurement using thermal resistors, it can be seen that changes in the measured temperature are directly measured through changes in the resistance value of the thermal resistor. Therefore, changes in the resistance of various wires such as the lead wires of the thermal resistor body can have an impact on temperature measurement. To eliminate the influence of lead resistance, a three wire or four wire system is generally adopted.

(2) Armored Thermistor: Armored Thermistor is a sturdy body composed of temperature sensing elements (resistors), leads, insulation materials, and stainless steel sleeves. Its outer diameter is occasionally between 2~8mm, and the smallest can reach up to 8mm. Compared to conventional thermistors, it has the following advantages:

① Small size, no external air gap, low measurement lag in terms of thermal inertia;

② Good machine function, vibration resistance, and impact resistance;

③ Capable of twists and turns, easy to install

④ Long application lifespan.

(3) End face thermistor: The temperature sensing element of the end face thermistor is wound with specially treated resistance wire and tightly attached to the end face of the thermometer. Compared with individual axial thermistors, it can accurately and quickly reflect the actual temperature of the measured end face, and is practical for measuring the end face temperature of bearing shells and other components.

(4) Explosion proof thermal resistor: The explosion-proof thermal resistor uses a specially constructed junction box to contain the explosive mixture of gases outside the shell that may be affected by sparks or arcs within the junction box, and will not cause an explosion at the production site. Explosion proof thermal resistance can be used for temperature measurement in Bla~B3c level areas where there is explosion damage.