Tips for Using Catalytic Combustion Sensors

The catalytic combustion sensor (Catalytic Combustion Method Sensor) is one of the most widely used gas sensors specifically designed to detect various combustible gases. It operates based on the heat generated when flammable gases combust on an oxidation catalyst. This type of sensor offers high reaction rates and excels in responsiveness, accuracy and reproducibility.

When the sensor is powered on, the precious metal coil inside heats the detection element to temperatures between 300°C and 450°C. Combustible gases burning on the surface of the detection element raise its temperature, which in turn increases the resistance of the precious metal coil. The change in resistance is nearly proportional to the gas concentration. A bridge circuit within the sensor detects this resistance change and converts it into a voltage output, thereby determining the gas concentration.

The sensor responds to all combustible gases, making it unsuitable for identifying the concentration of a specific gas in complex flammable gas environments.

Due to its combustion-based principle, when the concentration of flammable gas is too high, incomplete combustion may occur, leading to carbon deposition on the detection element. This significantly reduces both the detection accuracy and lifespan of the sensor. Therefore, a protective mechanism should be incorporated into the external circuit during use: when the gas concentration reaches 100% LEL, the power supply to the sensor should be cut off to prevent damage.