Problems that arise when choosing toxic and harmful gas detectors
Due to historical and cognitive reasons, we still have many problems when selecting various 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 the leakage of many combustible gases, people attach great importance to the detection of combustible gases. It can be said that in any petrochemical and chemical plant, most of the dangerous gas detectors are LEL detectors. But only equipped with LEL detectors is far from enough to truly protect the safety and health of workers. It is undeniable that most of the volatile hazardous gases are combustible gases, but the catalytic combustion combustible gas detector (LEL) is not the best choice for all combustible gas detection. It is designed specifically for the detection of methane, and its detection performance for other substances is relatively poor. Therefore, the lower limit concentration 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, it is a very dangerous practice to simply use a combustible gas detector. For example, the lower explosion limit of benzene is 1.2%, and its correction coefficient on the LEL detector is 2.51, that is to say, the concentration of benzene displayed on a LEL detector calibrated with methane is only 40% of its actual concentration! ! In this way, the lowest alarm concentration of benzene that can be detected by LEL is 10%LEL=10%*1.2%*2.51=3.0*10-3, which is nearly 600% higher than the allowable concentration of benzene 5*10-6 times!!. Similarly, the alarm concentration of 1.5*10-2 obtained by ammonia on the LEL detector is about 600 times higher than the allowable concentration of 2.5*10-5. Therefore, depending on the detected gas, it is much safer and more reliable to choose a specific toxic gas detector than to simply choose an LEL detector.
In addition, at present, we pay more attention to the detection of gases that can cause acute poisoning, such as hydrogen sulfide and hydrogen cyanide, but not enough attention to the detection of gases that can cause chronic poisoning, such as aromatic hydrocarbons and alcohols. The hazard to the health and safety of workers is no less than that of gases that can cause acute poisoning! They can cause cancer and other invisible diseases, affecting the lifespan and health of workers. The appearance of this phenomenon, in addition to the cognitive reasons, is also an important reason for the lack of suitable organic gas detectors that can detect lower concentrations in the market.
