I would like to help you out, but I'm not sure if I can.  For HEL and LEL, I just use the tabulated numbers our safety people give us.  

Do the tables have calculations of explosive limits in oxygen deficient atmospheres?  Or are you working on sustaining a flame with a poor fuel gas?  Or maybe you have another application entirely?

dwedel
Hotrod Big Engines!
For site policies and guidelines
see FAQ731-376

Hello dwedel,

I am working with fire in under-ventilated situation. To explain that, imagine that fire room full of unburn and not-unburn gases and at this time not oxygen available.

If now, we open a window, a new supply of fresh air enters the compartment. So the mixture will be pass across the UFL and then across the LFL.

Doing that when non-flammable gases are present is easy but I dont know how to do with non-flammable gases.

Thanks a lot!!

I have no experience in this situation.  Good Luck,

dwedel
Hotrod Big Engines!
For site policies and guidelines
see FAQ731-376

I'm not sure how much assistance we will be to you at this forum.  We “try” to get a completely new charge of air in the combustion chamber each time, so we don’t have to calculate the effects of unburned gasses.

Just a friendly warning, be sure to state your complete situation in your question, as people are getting more picky about poorly written questions.  Reading the FAQ in my signature is not a bad idea either, but you have probably seen that already.

dwedel
Hotrod Big Engines!
For site policies and guidelines
see FAQ731-376

To moquiton,

you say

Quote:

..so the mixture will be pass across the UFL and then across the LFL.

How do you know that you'll be out of the fire envelope.

Then you say

Quote:

Doing that when non-flammable gases are present is easy but I don't know how to do with non-flammable gases

This is a self-contradictory expression. Please be more clear.

Hi-  there is some info on this in a book called "Technical Data on Fuel"  published by The British National Committee, Wold Power Conference, 1962.  See p. 262 in the section called Inflammability Limits.  The info is based on old Bureau of Mines bulletins.  You can buy the bulletins on the web.  The upper & lower flammability limits are listed for some different fuels.

See also my, and other answers to this question on Thread798-33615