How to choose toxic and harmful gas detectors in tunnel construction?
In recent years, the state has attached great importance to the safe production of tunnel construction, in order to ensure that the situation of safe production in tunnel construction is basically stable. The State Administration of Work Safety, the Ministry of Transport, the State-owned Assets Supervision and Administration Commission of the State Council, and the National Railway Administration jointly issued the "Nine Regulations on Tunnel Construction Safety". It clearly stipulates that "toxic and harmful gases must be monitored and monitored, ventilation management should be strengthened, and construction operations with concentrations exceeding the standard are strictly prohibited." This requires the construction unit to be equipped with a suitable toxic gas detector.
1. Analysis of Toxic and Harmful Gases in Tunnel Construction
Toxic and harmful gases in tunnels have always been the main source of danger during construction, and major safety accidents are likely to occur if construction is improper. Harmful gases in the tunnel mainly include methane, carbon monoxide, carbon dioxide, hydrogen sulfide, nitrogen and varying amounts of heavy hydrocarbons and trace amounts of rare gases.
The toxic gases in the tunnel are divided into three categories according to their different mechanisms of action on the human body: irritating gases, asphyxiating gases, and acute poisoning organic gases (VOC). Irritant gases include chlorine, phosgene, diphosgene, sulfur dioxide, nitrogen oxides, formaldehyde, ammonia, ozone and other gases. The characteristic of the action of irritating gas on the body is that it has a strong stimulating effect on the skin and mucous membranes, and some of them have a strong corrosive effect at the same time. Asphyxiating gases include carbon monoxide, hydrogen sulfide, hydrogen cyanide, carbon dioxide and other gases. These compounds lead to hypoxia of tissue cells after entering the body. In other words, it is necessary and necessary to detect the toxicity of organic compounds.
2. Selection of Toxic and Harmful Gas Detectors
At present, when we choose various gas detectors, there are still many problems, which are specifically manifested in:
A) The detection of combustible gases is more important than the detection of toxic gases.
B) The detection of gases that may cause acute poisoning is more important than the detection of gases that may cause chronic poisoning.
For various production occasions and testing requirements, choosing the right gas detector is a must for every person engaged in safety and production work.
1. Determine the type and concentration range of the gas to be detected
If there are mostly methane and other less toxic alkanes, choosing a flammable gas detector (LEL) is undoubtedly the best choice. This is not only because the principle of the flammable gas detector (LEL) is simple and widely used, it also has the characteristics of convenient maintenance and calibration. If there are toxic gases such as carbon monoxide (CO) and hydrogen sulfide (H2S), a specific gas detector should be selected first to ensure the safety of the staff. If there are more organic toxic and harmful gases, considering the low concentration that may cause personnel poisoning, such as aromatic hydrocarbons, halogenated hydrocarbons, ammonia (amines), ethers, alcohols, esters, etc., you should choose a photoionization detector (PID) and never use a flammable gas detector (LEL) as this could result in personal injury or death. If the gas types cover the above types of gases, choosing a composite gas detector may achieve twice the result with half the effort.
2. Determine the occasion of use
Different use environments require different types of gas detectors to be selected.
A. Fixed gas detector
This is a detector that is widely used in industrial installations and production processes. It can be installed on a specific detection point to detect specific gas leaks.
B. Portable gas detector
The portable gas detector adopts pumping method to detect gas, and the sensitive element adopts excellent gas sensor, which has excellent sensitivity and excellent repeatability; the instrument adopts embedded microcomputer control, which is easy to operate, complete in function, high in reliability, and has a variety of self-adaptive capabilities ;Using dot-matrix LCD display, intuitive and clear; small and beautiful portable design not only makes you fondle admiringly but also facilitates mobile use. The casing of the portable gas detector is made of high-strength engineering plastics and composite non-slip rubber. It has high strength, good hand feeling, and is waterproof, dustproof and explosion-proof.
