What is the explosion limit of combustible gas?

The mixture of combustible gas (vapor) and air can not explode when meeting fire source at any concentration, but can only explode when meeting fire source within a certain concentration range. The concentration range of combustible gas that can explode in case of fire source is called the explosion limit of combustible gas (including lower explosion limit and upper explosion limit).

The explosion limits of different combustible gases (Vapors) are different. For example, the explosion limit of hydrogen is 4.0% - 75.6% (volume concentration), which means that if the volume concentration of hydrogen in the air is between 4.0% - 75.6%, it will explode in case of fire source. When the concentration of hydrogen is less than 4.0% or greater than 75.6%, it will not explode even in case of fire source. The explosion limit of methane is 5.0% ～ 15%, which means that when the volume concentration of methane in the air is between 5.0% ～ 15%, it will explode in case of fire, otherwise it will not explode.

The concept of explosion limit of combustible dust is consistent with that of combustible gas.

The explosion limit is generally expressed by the volume percentage of combustible gas (dust) in the air (%), and can also be expressed by the weight percentage of combustible gas (dust) (g / m * or mg / L).

Explosion limit is a very important concept, which has great practical significance in fire and explosion protection work

It can be used to evaluate the fire and explosion risk of combustible gas (steam and dust), as the basis for classification of combustible gas and determining its fire risk category. At present, the combustible gas with the lower explosive limit less than 10% is classified as the first class combustible gas, and its fire risk is classified as class A.

It can be used as the basis of design, such as determining the fire resistance grade of the building, designing the ventilation system of the plant, etc., all need to know the explosion limit value of combustible gas (steam and dust) in the site.

It can be used as the basis for the establishment of safe production operation rules. In the place where combustible gas (steam and dust) is produced, used and stored, the concentration of combustible gas (steam and dust) shall be strictly controlled below the lower explosive limit in order to avoid fire and explosion accidents. To ensure this, in the preparation of safe production operation procedures, corresponding preventive measures shall be taken according to the flammability and explosion hazard and other physical and chemical properties of combustible gas (steam and dust), such as ventilation, replacement, inert gas dilution, detection and alarm.

The explosion limit of combustible gas in air is as follows

The explosion range of methane in air is 5% - 15%;

The explosion limit of ethane in air is 3.0% - 16.0% (vol);

The explosion limit of propane in air is 2.1% - 9.5%;

The explosion limit of methanol in air is 6.0-36.5%

The explosion range of ethanol in air is 3.3% ～ 19.0%;

The explosion range of ethylene in air is 2.7% - 36%;

The explosion limit of gasoline in air is 1.4% ~ 7.6%;

The explosion limit of diesel in air is 1.3% ~ 6.0%;

The explosion limit of carbon monoxide in air is 12.5% ～ 74%;

The explosion limit of hydrogen in air is 4.1% ～ 74.8%;

The explosion limit of ethanol methanol mixture in air is 3-30%;

The explosion limit of acrylonitrile in air is 3.05% - 17.0%;

The explosion limit of vinyl chloride in air is 4% - 22%;

The explosion limit of benzene in air is 1.2% ~ 7.8%