Flammability of gas mixtures containing volatile organic compounds and hydrogen

An experimental program was conducted to evaluate the accuracy of some curr ent methods for predicting the flammability of gas mixtures containing hydr ogen and flammable or nonflammable volatile organic compounds (VOCs) in air . The specific VOCs tested were toluene, 1,2-dichloroethane, 2-butanone, an d carbon tetrachloride. The lower flammability limits (LFLs) of gas mixture s containing equal molar quantities of the components were determined in a 19.4-1 laboratory flammability chamber using a strong spark ignition source and a pressure criterion for flammability. All but one of the LFL values f or the individual components were in agreement with earlier Literature valu es. However, the LFL of 1,2-dichloroethane was found to be significantly lo wer than the range of values reported for previous determinations in smalle r chambers. Two methods for calculating the LFL of mixtures were considered . The Group Factor (atomic) Contribution Method was determined to be genera lly more accurate than the LeChatelier Method for estimating the LFL of the gas mixtures reported here, although the LeChatelier Method was usually mo re conservative. The Group Factor Method predicted higher values (nonconser vative) for the LFLs of several mixtures than were experimentally measured. For the case of a mixture of hydrogen and carbon tetrachloride, the Group Method estimation of the LFL was seriously in error. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.