Which principle of sensor is suitable for combustible gas detection2022-08-25
As the main energy in production and life, combustible gas can be seen everywhere in industrial production and daily life. Common flammable gases include hydrogen, carbon monoxide, methane, propane, ethylene and hydrogen sulfide, etc. Moreover, many combustible gases themselves are toxic gases, such as carbon monoxide, hydrogen sulfide and chlorine, etc.
Once these flammable gases exceed a certain concentration, they may explode or cause fire accidents. For their detection, different applications have different requirements. How to choose a suitable combustible gas sensor for our gas detector?
Combustible gas sensors mainly include semiconductor sensor, catalytic combustion sensor, electrochemical sensor and infrared sensor. They are suitable for combustible gas detection in different applications.
In general household field, it is usually required to be able to quickly detect when the concentration of combustible gas leakage is low, and it must be long-term maintenance-free which is convenient for home use.
The semiconductor combustible gas sensor has low detection limit and long life span. There is only gas adsorption and desorption during the detection process and the cooking oil fume is less residual on the surface of sensitive materials. It is the best choice for household alarms.
Catalytic combustion sensor is the most widely used gas alarm sensor in the world. It has fast response speed and the accuracy and repeatability is extremely good. Up to the lower explosion limit concentration (LEL), the output of the sensor is almost proportional to the gas concentration, it is suitable for quantitative detection in coal mine, petroleum, chemical industry, combustible gas and other fields.
However, the catalytic combustion sensor has a high working temperature, and the catalyst is easily deactivated. The silicone and sulfide released by the adhesive and rubber products in the environment can easily poison the catalytic material and cause the sensor to fail. In industrial field, the alarm is usually calibrated regularly by standard gas to prevent the accuracy deteriorated.
For the detection of low concentration carbon monoxide in artificial coal gas and incomplete combustion process, due to the high toxicity of carbon monoxide, the alarm point generally does not exceed 200ppm. In order to prevent false alarm or not alarm, it is best to choose electrochemical sensor with high sensitivity and precision.
The infrared combustible gas sensor uses the principle of non-dispersive infrared (NDIR) to detect hydrocarbon combustible gases in the air. It has the advantages of good selectivity, strong anti-interference ability, hard to be poisoned and frequent recalibration is not required. It has played an important role in industrial safety and gas detection in recent decades.