How to choose gas alarm

According to the characteristics of gas sensors, the sensors used on various types of gas alarms are very sophisticated. Because of the inability to measure quantitatively, semiconductor sensors are mostly used in home alarms and spot-type alcohol detectors, which is more in line with the situation where such alarms require only qualitative measurements and have lower price requirements.

Due to the need for quantitative measurement of industrial alarms, catalytic combustion sensors and electrochemical sensors are often used. However, the use of semiconductor sensors was also adopted in the early days, but due to the higher requirements, almost no manufacturers have used semiconductor sensors. Industrial gas alarms can be classified into point-type gas detectors and portable gas detectors. Taking into account price factors, electrochemical sensors are generally used only for quantitative measurement of toxic gases. For the occasions where the explosion is measured, catalytic combustion sensors are generally used because the requirements are not high.

1. Selection principle of detector type for explosion protection 1) Flameproof type should be used for catalytic combustion type maintenance.

2) For electrochemical detectors and semiconductor detectors, flameproof or intrinsically safe explosion proof types are available;

3) Select the explosion-proof rating and group of the detector according to the type, level, and group of flammable gas being detected;

4) The explosion-proof structure should be selected for the electric suction sampler.

5) Select the explosion-proof type of the detector according to the division of explosion hazard area in the use place;

2. The selection of combustible gas detectors should meet the following requirements:

1) Catalytic combustion sensors should be used for gases that are inherently combustible.

2) When using a place where the atmosphere contains a small amount of sulfur, phosphorus, arsenic, halogen compounds and other media that can poison the catalytic combustion type detection element, an anti-toxic catalytic combustion type detector or a semiconductor type detector should be selected;

3) The detection of hydrogen gas should use electrochemical sensors or conductor type detectors.

3. The selection of toxic gas detectors can be determined based on the detailed characteristics of the toxic gases detected:

1) Hydrogen sulphide and carbon monoxide gas can be fixed electrolysis type or semiconductor type;

2) Chlorine can be used as diaphragm electrode type, fixed potential electrolysis type or semi-conductor type 3) Ethylene oxide, acrylonitrile gas can be used as semi-conductor type or fixed potential electrolysis type 4) Hydrogen cyanide gas can be used for gel electrolysis (cell type ) type, diaphragm electrode type or fixed potential electrolysis type;

5) Chloroethylene gas should use semiconductor type or photoionization type 4, the selection of toxic gas detectors, should consider the cross-effects of extremely toxic gases and other gases may exist in the installation environment 5, the detector sampling method to determine 1) should be adopted Diffusion detectors 2) The following conditions should be used single or multi-point suction detector a, due to a small amount of leakage may cause severe consequences of the place;

b. Because of the installation prerequisites and environmental preconditions, it is difficult to use diffusion detectors.

c, I (extremely hazardous) toxic gas release source;

d. Locations with more concentrated release of toxic gases.

3) When inhaled toxic gas detectors are used to detect flammable toxic gases, pneumatic suction sampling systems should be used.