An Introduction to the Classification and Operating Principles of Toxic Gas Detectors
When facing toxic gases, we can classify them into two categories based on their hazards: combustible gases and toxic gases. Due to their different properties and hazards, their detection methods also vary. Toxic gas detector is a professional detection tool. 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 requires certain conditions, and combustible gases are hazardous gases commonly encountered in industrial sites such as petrochemicals. That is a certain concentration of combustible gas, a certain amount of oxygen, and enough heat to ignite its ignition source. These are the three essential elements of an explosion, and none of them are indispensable. In other words, the absence of any of these conditions will not cause a fire or explosion.
When combustible gas vapor, dust, and oxygen are mixed and reach a certain concentration, they will explode when exposed to a fire source with a certain temperature. The concentration at which combustible gases can explode when exposed to a source of fire is called the explosive concentration limit, abbreviated as the explosive limit, and is generally expressed in%. In fact, this mixture does not explode at any mixing ratio and requires a concentration range.
When the concentration of combustible gas is below the LEL minimum explosive limit, a lack of combustible gas concentration, and when its concentration is above the UEL maximum explosive limit, a lack of oxygen will not cause an explosion.
The LEL and UEL of different combustible gases are different. Please refer to the introduction in the eighth issue for this point, which should be taken into account when calibrating instruments. For safety reasons, I should generally issue an alarm when the concentration of combustible gas is at LEL 10% and 20%, here referred to as 10% LEL.
Make a warning alert, while 20% LEL is called a danger alert. This is why the combustible gas detector is also known as the LEL detector. Classification and working principle of toxic gas detectors:
A) Gas sensors that utilize physical and chemical properties, such as semiconductor type (surface control type, volume control type, surface potential type), catalytic combustion type, solid thermal conductivity type, etc.
B) Gas sensors utilizing physical properties such as thermal conductivity, optical interference, infrared absorption, etc. C) Gas sensors utilizing electrochemical properties, such as constant potential electrolysis, galvanic cell, diaphragm ion electrode, fixed electrolyte, etc.
