Posted By David Scott Paul, not sure if you are after a definitive listing, but normally, LEL and UEL should be part of the Material Safety Data Sheets for the product under question as part of the Physical Properties section. Another source could be Croners Substances Hazardous to Health or similar publications. My Chemists say that this cannot be calculated but is determined by test. Whether this is true or not who knows! Sorry, can't be of anymore help.

Posted By Robert K Lewis Both the MDHS and EH40 can provide the info and the Chemist friend is absolutly correct as it has to be measured individually for any single chemical or mixture of several. It is all to do with vapour pressures and partial vapour pressures. It is theoretically possible to mix a highly flammable substance in water and for the resultant to be non flammable as insufficient vapour is given off to reach the Lower flammable limit. With gas mixtures one will need to look at the individual concentrations to assess which one's have entered their LEL/UEL zone. So ultimately the answer is the same. A test is the only means of assessment. Bob ps It is 20+ years since I pracrised as a chemist

Posted By Robert K Lewis Apologies - EH40 I seem to remember had such information but no longer. The Rubber Handbook is the ultimate resource but it is as scarce as rocking horse manure outside the Chemical industry and the like. Like all good chemists I was trained as a Chem E. and am still reasonably good with the "buckets". (Gu)estimates are possible but it is one of our black arts not a definitive calculation. I would press the supplier/manufacturer route. Unless of course you are the manufacturer then the answer is to test it. Bob

Posted By Roger K. Bentley This question has reminded me of something in a book entitled Chemical Risk Analysis by Bernard Martel, which I reviewed for JIOSH. Whilst I agree with other respondents that explosive limits are usually determined experimentally, and can often be found on safety sata sheets, Prof. Martel does give two methods to calculate them for pure substances. The formulae are somewhat complex to quote here. He goes on to say that it is only in a few cases that the flammability limits of vapour mixtures can be calculated.

Posted By Paul Leadbetter Thank you to everyone who has responded so far. Jay's link took me, eventually, to the information I was looking for about calculating the LEL of a mixture but I am still seeking a comprehensive listing of LELs for future reference. Paul