ABSTRACT
The instantaneous release of energy from a relatively small volume of material can be viewed as an explosive event. This is achieved by changes in the chemical composition of the solid, liquid or gas, and the release of chemical energy. Depending on initiation conditions, charge geometry and chemical composition, this reaction can accelerate until a steady value (detonation) has been achieved, or decelerate (deflagration) and eventually die out. The distinction between true detonation and deflagration is not crucial at this stage, as both processes can lead to release of very large amounts of energy in a small fraction of a second. Most incidents involving dust or vapour cloud explosions (flour, sawdust, gasoline vapours, natural gas, etc.) involve only rapid combustion and not detonation. Most commercial explosives such as ammonium nitrate (AN)-fuel oil mixtures exhibit non-ideal behaviour, in that their sensitivity and severity of explosion falls off rapidly with decreasing diameter and lack of confinement. In this discussion, confined to condensed phase explosions, the words ‘detonation’ and ‘explosion’ are used synonymously and no distinction is made between commercial and military explosives.
