Information problems when choosing harmful gas detectors
The use of oxygen in industrial environments, especially in closed environments, requires great attention. Generally, we refer to oxygen content exceeding 23.5% as excess oxygen (oxygen enrichment), in which case the danger of explosion is likely to occur; while oxygen content below 19.5% is oxygen deficiency (hypoxia), in which case workers are prone to suffocation and coma. to the risk of death. Normal oxygen content should be around 20.9%. Oxygen detector is also a type of electrochemical sensor.
Current problems when choosing a harmful gas detector:
In our country, due to historical and cognitive reasons, we still have many problems when selecting various types of detectors, which are specifically reflected in:
1) The detection of combustible gases is more important than the detection of toxic gases.
2) The detection of gases that may cause acute poisoning is more important than the detection of gases that may cause chronic poisoning.
Due to the bloody lessons of explosion accidents caused by numerous combustible gas leaks, people attach great importance to combustible gas detection. It can be said that in any petrochemical and chemical plant, the vast majority of dangerous gas detectors are LEL detectors. However, only equipping with LEL detectors is far from enough to truly protect the health and safety of workers.
It is undeniable that most volatile dangerous gases are combustible gases. However, catalytic combustion flammable gas detectors (LEL) are not the best choice for all combustible gas detection. It is specifically designed to detect methane and has poor performance in detecting other substances. Therefore, the lower concentration limit of combustible gases other than methane that they can detect is much higher than their allowable concentration. For example: for dangerous and toxic gases such as benzene and ammonia, simply using a flammable gas detector is a very dangerous approach. For example, the lower explosion limit of benzene is 1.2%, and its correction coefficient on the LEL detector is 2.51. In other words, the concentration of benzene displayed on an LEL detector calibrated with methane is only 40% of its actual concentration!! This way , the lowest alarm concentration of benzene that can be detected with LEL is 10%LEL=10%*1.2%*2.51=3.0*10-3. This concentration is nearly 600 higher than the allowable concentration of benzene 5*10-6. times!!. Similarly, the alarm concentration 1.5*10-2 of ammonia obtained on the LEL detector is about 600 times higher than its allowable concentration 2.5*10-5. Therefore, depending on the gas being detected, choosing a specific toxic gas detector is much safer and more reliable than simply choosing an LEL detector.
In addition, we currently pay more attention to the detection of gases that can cause acute poisoning, such as hydrogen sulfide and hydrocyanic acid, but not enough attention to the detection of gases that can cause chronic poisoning, such as aromatic hydrocarbons and alcohols. In fact, the latter is The hazards to workers' health and safety are no less harmful than gases that can cause acute poisoning! They may cause cancer and other invisible diseases, affecting workers' lifespan and health. In addition to the cognitive reasons for the emergence of this phenomenon, the lack of suitable organic gas detectors that can detect lower concentrations on the market is also an important reason.
