Overview

The second of the major hazards is explosion. Explosion in the process industries causes fewer serious accidents than fire but more than toxic release. When it does occur, however, it often inflicts greater loss of life and damage than fire. Explosion is usually regarded as having a disaster potential greater than that of fire but less than that of toxic release.

The First Report of the Advisory Committee on Major Hazards (ACMH) (Harvey, 1976) states

In the case of flammable materials, the greatest threat arises from the sudden massive escape of those volatile liquids, or gases, which could produce a large cloud of flammable, possibly explosive, vapour. If the cloud were ignited, the effects of combustion would depend on many factors including wind speeds and the extent to which the cloud is diluted with air. The worst consequence could be large numbers of casualties and wholesale damage on site and beyond its boundaries. Nevertheless where combustion has taken place it has generally been on or in the immediate vicinity of the site. An important feature of this threat is the small time interval between the initial escape and the fire or explosion, which could be less than a minute.

The Flixborough disaster was primarily due to a vapour cloud explosion. It was this explosion which caused most of the casualties.

There is a considerable literature on explosions. Much of the information relates to chemical or nuclear explosions and to military applications. Reference can be made here only to a...