A STUDY OF F-N CURVES FOR ACCIDENTS INVOLVING HIGHLY FLAMMABLE-GASES AND SOME TOXIC GASES

The f-N curves for highly flammable gases, defined here as LPG (liquef ied petroleum gases), propane, butane, propene (also known as propylen e), butene (also known as butylene) and isobutane, were studied for ac cidents in the following activity sectors: fixed installations; road, rail and pipeline transport; and loading/unloading. The f-N curves for the sectors were very similar, except for loading/unloading accidents which may have different accident escalation patterns. A comparison w ith regard to evolution in time was made and no significant difference s were found. The study is based on 159 accidents. A comparison betwee n f-N curves for ammonia (45 accidents) and for chlorine (39 accidents ) was made and the resulting f-N curves were very similar. The data wa s therefore pooled to give an f-N curve for these gases. An f-N curve was also produced for accidents with highly flammable gases resulting in a boiling liquid expanding vapour explosion (BLEVE). A comparison b etween the f-N curves for highly flammable gases divided into BLEVE an d no-BLEVE accidents and the f-N curve for toxic gases was made. The B LEVE curve seemed significantly different from the two others. The f-N curve for toxic gases is somewhat curved as opposed to the f-N curve for accidents involving highly flammable gases without BLEVE, which ca n be approximated by a straight line.