3 replies to this topic

[gvdlans]

http://www.gexcon.co.../GEXHBchap4.htm

This is the Gas Explosion Handbook. Look for Le Chatelier's Law. This law can be used both to estimate LFL and UFL.

[mbeychok]

George Morten:

As a supplement to the response you got from Gvdlans:

For a mixture of combustible gases, you can use Le Chatelier's relationship:

Lm = 1 / SUM ( Xi / Li )

Where:
Lm = LFL of mixture
Xi = mol fraction (or volume fraction) of each component gas in the
combustible gas mixture
Li = LFL of each component gas in the combustible gas mixture

Please note:

(1) The same relationship can be used to calculate the UFL of a mixture of
combustible gases.

(2) Lower and Upper Flammability Limits (also known as Lower and Upper
Explosive Limits) apply only to gases or vapors.

(3) You will find it very useful to read web.umr.edu/~dludlow/classes/che258/Flammability.ppt

[gvdlans]

I just want to add that the temperature corrections shown in web.umr.edu/~dludlow/classes/che258/Flammability.ppt are not correct. They should be:

LFLT=LFL25-0.75(T-25)/Hc
UFLT=UFL25+0.75(T-25)/Hc

Reference is made to Zabetakis M.G.; Flammability Characteristics of Combustible Gases and Vapors Bulletin 627, Bureau of Mines, Washington (1965). Equations (33) and (36) on pages 22 and 23.