Poisonous and harmful gas is the main dangerous source in tunnel.what are the harmful gases in the tunnel?They mainly include methane, carbon monoxide, carbon dioxide, hydrogen sulfide, nitrogen and some different heavy hydrocarbon and trace amount of rare gases.
According to the chemical properties, these poisonous and harmful gases in tunnels can be divided into two categories: combustible gas and poisonous gas.
According to their different mechanism to the human body,the poisonous gas in tunnel is divided into excitant gas (chlorine, phosgene, diphosgene ozone, sulfur dioxide, nitrogen oxides, formaldehyde, ammonia,), asphyxiation (carbon monoxide, carbon dioxide, hydrogen sulfide, hydrogen cyanide acid) and acute intoxication of organic gas (VOC) three categories.It is worth mentioning that most organic gases (VOC) are both toxic and flammable, such as n-hexane and dichloromethane.The detection of these organic compounds has been mostly to detect their explosive properties, but usually the concentrations below the lower explosive limit (LEL) of the gas,it's toxicity already caused harm to human body. Therefore, for the detection of organic compounds (VOC), we should firstly measure the toxicity and then measure the explosion.
The inflammable gas in tunnel is mainly composed of methane (CH4) and some volatile organic compounds (VOC), which are easy to burn and even cause explosion when encountering fire, thus causing damage to life and property.
After knowing about the possible gas in tunnels, we can choose to buy gas detector accordingly.
First we need to determine the type and concentration range of the gases.Methane as the main component of combustible gas in tunnel, so be sure to have a detector with combustible gas sensor;Secondly, there might be toxic gases such as carbon monoxide (CO) and hydrogen sulfide (H2S) in tunnel, so the detector should be with carbon monoxide (CO) and hydrogen sulfide (H2S) sensors.Considering that there may be organic toxic and harmful gas (VOC), which may cause low concentration of poisoning, such as aromatic hydrocarbon, halogenated hydrocarbon, ammonia (amine), ether, alcohol, ester, etc., it is recommended to choose the light ionization (PID) sensor.
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