Application of thermochemical energy hazard criteria to the prediction of lower flammability limits of hydrocarbons in air

The energy hazard criteria of ASTM program CHETAH have been tested. as crit eria of flammability of gaseous mixtures containing an hydrocarbon vapour a nd air as oxidiser, at lean concentrations. A method for calculating the lo wer flammability limits in air, at atmospheric pressure and ambient tempera ture, is proposed as a result of a statistical study, which involved 67 com bustible compounds. CHETAH's fourth energy hazard criterion was found to be the most reliable flammability criterion. The method is predictive since a ll the input data may be obtained with very good accuracy using a group con tribution method. It is reliable, predicted limits being more frequently un derevaluated, by 0.11 mol% on average, than overevaluated. The method is al so precise, with a standard deviation of the estimates of 0.14 mol%. It is easily applicable to fuel mixtures and gives the same results as Le Chateli er's law.