Key Selection Considerations for Compound Gas Detectors
① Confirm target gas types and concentration‑measuring ranges Different production departments face different gas compositions. All potential scenarios shall be taken into consideration when selecting a gas detector. When methane and other low‑toxicity alkanes predominate, an LEL detector is a suitable choice. It features simple principle, wide application scope, and convenient maintenance and calibration.
If toxic gases such as carbon monoxide and hydrogen sulfide are present, dedicated gas detectors shall be prioritized to guarantee workers' safety. For organic toxic‑hazardous gases that cause poisoning at low concentrations, such as aromatic hydrocarbons, halogenated hydrocarbons, amines, ethers, alcohols and esters, a photoionization detector (PID) shall be adopted. LEL detectors must never be used as a makeshift substitute, as this may lead to personal injury or death.
② Define application scenarios According to different industrial operating environments, gas detectors are divided into three types: fixed‑type gas detectors, portable gas detectors and compound multi‑gas detectors.
Fixed‑type gas detector It is installed at designated monitoring points to detect specific gas leakage. Most units adopt a two‑part structure. The sensing probe assembled with sensor and transmitter is mounted on‑site. The secondary instrument composed of circuit, power supply and display‑alarm unit is installed in a safe area for easy monitoring.
Portable gas detector It boasts easy operation and compact size and can be carried to various production locations. For open‑site environments such as open workshops, wearable diffusion‑type gas detectors are suitable for safety alarming, which can continuously, real‑time and accurately display the concentration of toxic‑hazardous gases.
For confined‑space entry into reaction tanks, storage vessels, sewers, underground pipelines, underground facilities, sealed agricultural grain silos, railway tank cars, ship cargo holds, tunnels and other locations, detection must be performed outside the confined space before personnel go inside.
Compound multi‑gas detector Multiple required gas‑detection sensors can be integrated into one single instrument. It has the advantages of small size, light weight, fast response and simultaneous multi‑gas concentration display, offering higher convenience compared with ordinary gas detectors.
