Flammable limits

From GAWDAwiki

Flammable limits, also called explosive limits, refer to the conditions under which a mixture of a flammable material and air will catch fire or explode. If the percentage of flammable material in the air is between the minimum and maximum limits, the presence of a flame or a source of ignition will likely lead to rapid combustion or explosion.^[1]

Simply put, the lower flammable limit (LEL) is the concentration below which a flame will not propagate; the upper flammable limit (UEL) is the concentration above which a flame will not propagate. A change in temperature or pressure may vary the flammable limits.^[2]

See also: Flammable range.

References

1. http://msds.chem.ox.ac.uk/glossary/flammable_limit.html
2. http://www.airproducts.com/Products/fastfacts/charts_n_tables/definitions.asp