Fault Causes and Solutions for Flammable 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 the most suitable. 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.
However, if there are gases such as hydrogen sulfide present on site that can cause poisoning of catalytic components, especially in cases where there may be oxygen deficiency or the concentration of combustible gases may exceed LEL, choosing an infrared sensor is undoubtedly a safer approach.
In situations where various toxic and harmful gases may exist, such as enclosed spaces, in addition to combustible gases such as methane, there may also be toxic gases such as carbon monoxide and hydrogen sulfide. In addition, it is necessary to constantly detect the state of oxygen deficiency, and a standard four gas detector must be used 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 lead to casualties.
2. Determine the usage scenario
The selection of gas detectors varies depending on the industrial environment.
(1) 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 composed of sensors and transmitters installed as a whole on the detection site, and a secondary instrument composed of circuits, power supplies, and display alarm devices installed as a whole in a safe place 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 the most likely leak location of specific gases, such as selecting the most effective height for sensor installation based on the specific gravity of the gas, and so on.
(2) Portable gas detector
Due to its convenient operation and compact size, the portable instrument can be carried to different production sites. The electrochemical detector is powered by alkaline batteries and can be used continuously for 1000 hours; The new LEL detectors, PID and composite instruments use rechargeable batteries (some have already adopted memory free nickel hydrogen or lithium-ion batteries, allowing them to work continuously for more than 12 hours), so their application in various factories and health departments is becoming increasingly widespread.
