Flammability, of gases and vapors

Before a fire or explosion can occur, three conditions must be met simultaneously. A fuel (i.e., combustible gas), a comburant (e.g., oxygen, air, chlorine) must exist in certain proportions, along with a source of ignition (e.g., chemical, thermal, electrical, or mechanical), such as a spark or flame. The most important factors to consider when assessing the flammability of gas mixtures are the following  

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Based on Coward and Jones, Limits of Flammability of Gases and Vapors, U.S. Bureau of Mines Bulletin 503 (USNTIS AD-701575), 1952,... 

Table 3. Limits of flammability of gases and vapors, percent in air ...

Coward HE, Jones GW (1952) Limits of flammabilities of gases and vapors. Bulletin 503, Bureau of Mines, U.S. Government Printing Office, Washington... 

The flammability of gases and vapors of flammable liquids is a great concern in the chemical process industries. The result of an ignition can be a fire, heat, or an explosion, or the sum of all, with varying magnitude. The flammability of liquids depends on the lower flammability limit of the material and its vapor pressure at that temperature. One needs to consider ambient and reaction temperatures. The boiling point may be taken as an indication of the volatility of a material. 

Note The theoretical minimum extinguishing concentrations in air for the above materials were obtained from a compilation of Bureau of Mines limits of flammability of gases and vapors (Bulletins 503 and 627). 

Coward, H. F., and G. W. Jones, Timits of Flammability of Gases and Vapors," Bulletin 503, Bureau of Mines, 1952. 

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