Guidelines for Choosing Toxic & Hazardous Gas Detectors
(1) Confirm the type and concentration range of the gas to be detected
The types of gases encountered by each production department are different. When choosing a gas detector, all possible scenarios should be considered. If methane and other less toxic hydrocarbons are predominant, choosing an LEL detector is undoubtedly appropriate. This is not only because the principle of LEL detector is simple and widely used, but also because it has the characteristics of easy maintenance and calibration. If there are toxic gases such as carbon monoxide and hydrogen sulfide, it is necessary to prioritize the use of a specific gas detector to ensure the safety of workers. If there are more organic toxic and harmful gases, considering their low concentration that may cause poisoning to personnel, such as aromatic hydrocarbons, halogenated hydrocarbons, ammonia (amines), ethers, alcohols, lipids, etc., the photoionization detector introduced in the previous chapter should be chosen instead of using LEL detectors, as this may result in casualties.
If the gas types cover the above categories, choosing a composite gas detector may achieve twice the result with half the effort.
(2) Determine the usage scenario
The selection of gas detectors varies depending on the industrial environment.
A - Fixed gas detector
This is a commonly used detector in industrial equipment and production processes. It can be installed at specific detection points to detect specific gas leaks. Fixed detectors are generally two-piece, with a detection head (probe) consisting of sensors and transmitters installed as one unit at the detection site, and a secondary instrument (controller) consisting of circuits, power supplies, and display alarm devices installed as one unit at location for easy monitoring. Its detection principle is as described in the previous section, but it is more suitable for the continuous and long-term stability required for fixed detection in terms of process and technology. They also need to be selected based on the type and concentration of the gas on site, and attention should be paid to installing them in specific areas where the gas may leak, such as selecting the effective height of the sensor installation based on the specific gravity of the gas, and so on.
