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Overpressure (or blast overpressure) is the pressure caused by a
shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...
over and above normal
atmospheric pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...
. The shock wave may be caused by sonic boom or by
explosion An explosion is a rapid expansion in volume of a given amount of matter associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Explosions may also be generated ...
, and the resulting overpressure receives particular attention when measuring the effects of nuclear weapons or thermobaric bombs.


Effects

According to an article in the journal '' Toxicological Sciences'',
Blast overpressure (BOP), also known as high energy impulse noise, is a damaging outcome of explosive detonations and firing of weapons. Exposure to BOP shock waves alone results in injury predominantly to the hollow organ systems such as auditory, respiratory, and gastrointestinal systems.
An EOD suit worn by bomb disposal experts can protect against the effects of BOP. The above table details the effects of overpressure on the human body in a building affected by a blast of overpressure waves, as clarified later in the journal. According to documents released by the United States Military Defense Technical Information Center (DTIC),


Calculation for an enclosed space

Overpressure in an enclosed space is determined using "Weibull's formula": \Delta p = 22.5 \left( \right)^ \text where: *22.5 is a constant based on experimentation *m\, = (kilograms) net explosive mass calculated using all explosive materials and their relative effectiveness *V\, = (cubic meters) volume of given area (primarily used to determine volume within an enclosed space)


See also

* Bomb disposal


References

{{Reflist Pressure Explosives Shock waves