As the main energy source in production and life, combustible gas can be found everywhere in industrial production and daily life. Common combustible gases include hydrogen, carbon monoxide, methane, propane, ethylene, hydrogen sulfide, etc.... Moreover, many combustible gases themselves are toxic and harmful gases, such as carbon monoxide, hydrogen sulfide, chlorine, etc.

    Once these combustible gases exceed a certain concentration, they may explode and cause fire accidents. For their detection, specific analysis should be made according to the specific situation.

Different application scenarios have different requirements for gas detectors, and also have different requirements for their core components-gas sensors. How to choose a suitable combustible gas sensor for our detector?

    How to select combustible gas sensors?

    Combustible gas sensors mainly include semiconductor type, catalytic combustion type, electrochemical type and infrared type, which are suitable for combustible gas detection in different scenarios.

1 Semiconductor gas sensors

    In general household places, it is usually required to quickly detect the combustible gas leakage when the concentration is low, and to achieve a single-point alarm, and it must be able to meet the requirements of long-term maintenance-free and convenient for home use.

    The semiconductor combustible gas sensor has a low detection limit and a long service life. In addition, there is only gas adsorption and desorption process during the detection process. The serious oil smoke in the kitchen is less likely to remain on the surface of sensitive materials. It is the best choice for home alarms.

MQ-D4B Flat semiconductor sensor

2 Catalytic combustion gas sensors

    Catalytic combustion gas sensor is the most widely used sensor in the world. It has a fast response speed. Up to the lower explosion limit concentration (LEL), the output of the sensor is almost proportional to the gas concentration, so the accuracy and repeatability are very high. It is suitable for quantitative detection in coal mines, petroleum, chemical industry, gas and other fields.

    However, the operating temperature of catalytic combustion sensors is high, and the catalyst is easily deactivated. At the same time, the silicone and sulfide released by adhesives and rubber products in the surrounding environment can easily poison the catalyst and cause the sensor to fail. In industrial sites, the alarm is generally calibrated regularly with standard gas to adjust the amplification factor to prevent the sensitivity of the catalytic sensor from attenuating and causing a significant deterioration in accuracy.

ZC25 /ZC25C Catalytic Combustion Gas Sensor

3 Electrochemical gas sensors

    For the detection of low-concentration carbon monoxide in artificial gas and incomplete combustion, due to the high toxicity of carbon monoxide, the alarm point generally does not exceed 200ppm. In order to prevent false alarms or missed alarms, it is best to use an electrochemical gas sensor with high sensitivity and accuracy.

MQ-E3-CO Electrochemical CO Sensor

4 Infrared type

    Infrared combustible gas sensors use the non-dispersive infrared (NDIR) principle to detect hydrocarbon combustible gases in the air. They have the advantages of good selectivity, strong anti-interference ability, and low risk of poisoning. They do not require frequent recalibration. In recent decades, they have played an important role in industrial safety and gas detection.

TX721-A1B Low Power Infrared Gas Sensor

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