Hazard and Risk 06
Hazard and Risk 06 : Explosions: (1) Description of Effects: The term Explosion is not a scientific one and it is used frequently in common parlance to describe incidents where there is just a loud noise. The Working Party recommends, however, that its use be confined to describing incidents where there is a rapid release of energy, which causes a significant Blast Wave capable of causing damage. In a chemical explosion, the gases, which form as a result of chemical reactions, expand rapidly due to a sudden increase in temperature, thereby increasing the pressure relative to the surrounding atmosphere (medium). A similar expansion can occur in a physical explosion when a gas under pressure is released suddenly into the atmosphere. These expansions initiate a blast wave, which travels outwards, at first with a velocity comparable with that of the expanding gases. A blast wave consists of an initial positive pressure phase followed by a negative pressure phase. Where the pressure pulse formed by a blast wave creates a sharp discontinuity then this is usually termed a Shockwave. The damage, which arises from an explosion, may be caused either by the effect of the blast wave or by damage caused by MISSILES. Part of the energy liberated in an explosion may be imparted to fragments or whole systems in the form of kinetic energy. These fragments, or missiles, may be projected outwards some considerable distance from the centre of an explosion. (2) Explosion: A release of energy, which causes a pressure discontinuity or blast wave. (3) Blast Wave: A pressure pulse formed by an explosion. (4) Shock Wave: A pressure pulse formed by an explosion in which a sharp discontinuity in pressure is created as the wave travels through a fluid medium at greater than sonic velocity. (5) Missiles: Fragments or whole systems, which are projected by a release of energy.
No records Found