How to Correctly Select Various Types of Toxic and Harmful Gas Detectors
The key component of a gas detector is the gas sensor. Gas sensors can be classified into three main categories based on their principles:
A) Gas detector sensors utilizing physical and chemical properties, such as semiconductor based (surface controlled, volume controlled, surface potential based), catalytic combustion based, solid thermal conductivity based, etc.
B) Gas detector sensors utilizing physical properties, such as thermal conductivity, optical interference, infrared absorption, etc.
C) Gas detector sensors utilizing electrochemical properties, such as constant potential electrolysis, galvanic cell, diaphragm ion electrode, fixed electrolyte, etc.
According to the hazards, we classify toxic and harmful gases into two categories: combustible gases and toxic gases. Due to their different properties and hazards, their detection methods also vary. Combustible gases are hazardous gases commonly encountered in industrial settings such as petrochemicals, mainly consisting of organic gases such as alkanes and certain inorganic gases such as carbon monoxide.
The explosion of combustible gases must meet certain conditions, which are: a certain concentration of combustible gas, a certain amount of oxygen, and a source of fire with sufficient heat to ignite them. These are the three elements of explosion (as shown in the explosion triangle in the left figure above), all of which are indispensable. In other words, the absence of any of these conditions will not cause a fire or explosion.
The thermal conductivity VOL toxic and harmful gas detector that directly measures the volume concentration of combustible gases can also be obtained on the market, and there are already LEL/VOL combined detectors available. The VOL combustible detector is particularly suitable for measuring the volume (VOL) concentration of combustible gases in oxygen deficient environments.
Toxic gases can exist in both production raw materials, such as most organic chemicals (VOCs), and by-products in various stages of the production process, such as ammonia, carbon monoxide, hydrogen sulfide, and so on. They are the most hazardous factors to workers. This kind of harm not only includes immediate harm, such as physical discomfort, illness, death, etc., but also includes long-term harm to the human body, such as disability, cancer, etc. For the detection of these toxic and harmful gases, it is necessary to use toxic and harmful gas detectors, which is an issue that developing countries should start to pay full attention to.
The TWA (8-hour statistical weighted average), STEL (15 minute short-term exposure level), IDLH (immediate lethal dose) (ppm), and MAC (maximum allowable concentration in the workshop) mg/m3 of common toxic and harmful gases.
