Misconceptions in Gas Detector Selection and Working Principles
Every gas‑detection procedure concerns personnel health & safety, as well as national and personal property safety. Due to historical and cognitive factors, quite a few problems still exist in the selection of various gas detectors in China, which are reflected in the following aspects:
① More emphasis is placed on combustible‑gas detection than toxic‑gas detection.
② Greater attention is paid to gases that cause acute poisoning than those leading to chronic poisoning. At present, sufficient importance is attached to gases triggering acute poisoning, such as hydrogen sulfide and hydrocyanic acid. However, insufficient attention is given to gases causing chronic poisoning, e.g., aromatic hydrocarbons and alcohols. In fact, the hazards posed by the latter to workers' health and safety are no less severe than those of acutely toxic gases.
Bloody lessons from explosion accidents caused by numerous combustible‑gas leaks have raised people's awareness of combustible‑gas monitoring. In petrochemical and chemical plants, the vast majority of hazardous‑gas detectors are LEL detectors. Nevertheless, merely deploying LEL detectors is far from enough to guarantee personnel safety and health.
Admittedly, most volatile hazardous gases are flammable. Still, catalytic‑combustion LEL detectors are not suitable for all combustible gases. The lower‑explosion‑limit concentrations of some gases are far higher than their permissible safety concentrations. Depending on target gas species, selecting dedicated toxic‑gas detectors is much safer and more reliable than simply adopting LEL detectors.
