Catalytic Combustion Type Gas Sensor
The sensor is fabricated by coating a high-temperature resistant catalyst layer on the surface of a platinum resistor. At a preset temperature, flammable gases undergo catalytic combustion on the catalyst surface. The combustion reaction raises the temperature of the platinum resistor, causing a change in its resistance. The magnitude of this resistance variation is a function of the concentration of the flammable gas.
Catalytic combustion gas sensors selectively respond to combustible substances: they can detect any gas capable of burning and produce no signal for non-combustible gases. Admittedly, there are numerous exceptions to the rule that "all combustible gases can be measured", yet the above selectivity generally holds true.
Catalytic combustion gas sensors feature accurate measurement, fast response and long service life. Their output directly correlates with the explosion hazard level of the surrounding environment, making them a dominant sensor type in safety detection applications.
Disadvantages
No gas selectivity within the scope of flammable gases;
Operates with a hidden hot surface, posing a risk of igniting gas mixtures and triggering explosions;
Most elemental organic vapors can poison and deactivate the sensor.
Major suppliers of this type of sensor are located in China, Japan and the United Kingdom (the country of original invention). China is currently the largest end user, mainly for coal mine applications, and also possesses leading domestic manufacturing technologies for these sensors. Despite misleading promotional information from various distributors distorting public understanding of the product, the mainstream manufacturers of catalytic combustion gas sensors are based in China.
