Citation

Nettleton MA. J. Occup. Accid. 1977; 1(2): 149-158.

Copyright

(Copyright © 1977, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Since the recent explosion at Flixborough, people have become more aware of the hazards associated with the explosion of large clouds of vapour. This paper reviews pertinent features of such explosions. These include the dispersal of the cloud, subsequent ignition, flammability and detonatability limits and the likely effect of non-uniformities in the cloud. The method of characterising explosions in terms of T.N.T. equivalent is discussed and attention drawn to the limitations inherent in using it to define risks of damage from explosions of vapour clouds. Of particular import is the fact that the T.N.T. model implies a pressure/time history different from that to be expected from a vapour cloud. Attention is also called to the directional effects of blast in recent explosions at Flixborough and Port Hudson (1970). Such effects are not predictable from a T.N.T. equivalent model yet they can account for a factor of at least 5 in the T.N.T. equivalent and depending on the distance from such a charge, in the distance from the source to a given level of pressure. The further errors in the use of a T.N.T. equivalent model are difficult to quantify for reasons discussed at length in the text but are probably in the region of a further factor of 2 to 5.