What is a flameproof thermocouple?

Mar 18, 2025

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Explosion-proof thermocouple is a temperature sensor. It is widely used in the automatic control system of the chemical industry. Through the temperature sensor, the temperature parameters of the controlled object can be turned into electrical signals, which are transmitted to the display, recording and conditioning instruments to detect, regulate and control the system. In chemical plants, the production site is often accompanied by various flammable and explosive chemical gases and steam. If ordinary thermocouples are used, it is very unsafe and can easily cause environmental gas explosions. Therefore, explosion-proof thermocouples must be used as temperature sensors in these places. The explosion-proof thermocouple products produced by our company are suitable for places with explosive gas hazards within the dⅡCT6 temperature group range.

Working principle:

If a closed circuit is formed by two homogeneous conductors (hot electrodes) of different components, when there is a temperature gradient at both ends, current will flow in the circuit, and then there will be a thermoelectric potential between the two ends.

Explosion-proof principle:

Using the gap explosion-proof principle, the design has sufficient strength of the junction box and other components, and all the parts that will generate sparks, arcs and damage temperature are sealed in the junction box. When an explosion occurs in the cavity, it can be extinguished and cooled through the gap of the joint surface, so that the flame and temperature after the explosion will not be transmitted to the outside of the cavity.

Features:

Designed according to the explosion-proof regulations GB3836 in accordance with IEC standards; adopts a two-chamber explosion-proof structure, easy to replace the temperature measuring element, and uses the safe and reliable explosion-proof mark dⅡCT6, which is suitable for temperature measurement in places below ⅡC level, above ignition temperature T6, and containing explosive gas.

Notes:

Please turn off the power during maintenance and repair.

Important technical parameters:

When the temperature of the thermocouple is 20±15°C, the humidity is not more than 80%, and the test voltage is 500±50V (DC), the insulation resistance between the electrode and the outer tube is>1000Ω.m.

Model Graduation Tolerance Grade

I II

Tolerance Temperature Range °C Tolerance Temperature Range °C

WRN K ±1.5°C -40～+375 ±2.4 °C -40～+333

±0.004ltl 375～1000 ±0.0075 ltl 333~1200

WRM N ±1.5°C -40～+375 ±2.4°C -40～+333

±0.004 ltl 375～1000 ±0.0075 ltl 333～1200

WRE E ±1.5°C -40～+375 ±1.5°C -40～+333

±0.004 ltl 375～800 ±0.004 ltl 333～900

WRF J ±1.5°C -40～+375 ±1.5°C -40～+333

±0.004 ltl 375～750 ±0.004 ltl 333～750

WRC T ±1.5°C -40～+125 ±1°C -40～+133