Combustible Dust found lying on top of pipes in a manufacturing company. The conditions required for, mechanisms of, and impacts of the following types of explosion Unconfined vapour cloud explosion An unconfined vapour cloud arises from the sudden, or significant, release of flammable gas/vapour into the atmosphere. A UVCE occurs when this cloud mixes with air (within the flammable limits) and finds a source of ignition. High overpressures can be generated from this type of explosion. This is possible when the vapour cloud is ignited in the vicinity of plant structures with two key geometrical features - a dense distribution of obstacles in the path of the flame front, and a configuration of parallel planes (such as boundary walls), which provides confinement for the explosion. Such explosions have the potential for considerable widespread destruction (for example: Buncefield, UK 2005, Texas City, USA 2005, Flixborough, UK 1974).
Confined Vapour Cloud Explosion (CVCE) Occurs as a result of the ignition of a flammable vapour (when mixed with air) which is under confinement (such as in a building or a vessel.) Only small amounts of flammable vapour are necessary (for example: flammable material left in a drum). The explosion and pressure generated may be sufficient to rupture the containment and cause considerable localised damage. A simple example would be cutting up an (almost) empty gasoline drum or aerosol can (which contains a small amount of residual vapour with a burning torch.
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