Blast Wave

Definition - What does Blast Wave mean?

A blast wave is an area of pressure that expands outward from a central explosive point. It is comprised of a highly concentrated high-pressure front (the blast front) and travels at supersonic speeds. The area behind the blast front, called the blast wind, has lower than atmospheric pressure, which creates a suction effect toward the explosion’s origin.

The front of a blast wave and the front of a shock wave are physically the same. Blast waves are primarily differentiated from generic shock waves by the negative-pressure blast wind that trails them. Furthermore, a shock wave may be created by a number of different sources (such as any object reaching supersonic speeds), whereas blast waves are created exclusively by the detonation of explosive material.

Safeopedia explains Blast Wave

Blast waves are a relevant phenomena in every industry in which explosions are used as a normal part of work, as well as in industries in which explosions are a potential workplace hazard. The high pressure created by the blast wave is referred to as “overpressure.” Within industries in which explosions are deliberately used as a part of regular operating procedures, such as mining, workers rely on blast refuges and personal protective equipment (PPE) to avoid harm from the overpressure created by detonations.

In most industries, such as the process industries, blast waves will only occur as a consequence of accidental explosions. Industrial explosions may occur for a variety of reasons. However, the type of explosion most commonly associated with blast waves are dust explosions, which can occur when a sufficient concentration of dust is suspended in the atmosphere. Dust explosions only cause blast waves when they result in detonations (supersonic explosions), as opposed to deflagrations (subsonic combustions).

The blast wave from an explosion may cause direct injuries to individuals exposed to it or cause injuries via the movement of harmful debris. The high pressure may also cause further safety incidents to occur if it damages safety-critical equipment or other explosive material. The blast wave from an initial (primary) dust explosion may also disturb additional dust in amounts greater than that which caused the primary explosion, resulting in an even larger secondary explosion.

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