Combustibility and flammability

Common card · No. 208614

A combustible material is a material that can burn (i.e. sustain a flame) in air under certain conditions. A material is flammable or inflammable if it ignites easily at room temperature. In other words, a combustible material takes more effort to ignite and a flammable material ignites almost immediately when exposed to a flame. The degree of flammability in air depends largely on how easy the material vaporizes. This is related to its composition-specific vapor pressure, which is temperature dependent. The quantity of vapor produced can be enhanced by increasing the surface area of the material, forming a mist or dust. Wood is an example. Finely divided wood dust can undergo explosive flames and produce a blast wave. A piece of paper (made from pulp) catches on fire quite easily. A heavy oak desk is much harder to ignite, even though the wood fibers are the same in all three materials. Common sense, and scientific consensus until the mid-1700s, suggests that material disappears when burned...

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