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 med ...

over and above normal

atmospheric pressure Atmospheric pressure, also known as 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 1013.25 millibars, 7 ...

. The shock wave may be caused by

sonic boom A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to t ...

or by

explosion An explosion is a rapid expansion in volume associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Supersonic explosions created by high explosives are known ...

, and the resulting overpressure receives particular attention when measuring the

effects of nuclear weapon The effects of a nuclear explosion on its immediate vicinity are typically much more destructive and multifaceted than those caused by conventional explosives. In most cases, the energy released from a nuclear weapon detonated within the lower ...

s or

thermobaric bomb A thermobaric weapon, also called an aerosol bomb, a vacuum bomb or a fuel air explosive (FAE), is a type of explosive that uses oxygen from the surrounding air to generate a high-temperature explosion. The fuel–air explosive is one of the be ...

Effects

According to an article in the journal ''

Toxicological Sciences ''Toxicological Sciences'' is a monthly peer-reviewed scientific journal which covers all aspects of research on toxicology. It is published by Oxford University Press on behalf of the Society of Toxicology. It was established in 1981 as ''Fundame ...

'',

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 Bomb disposal is an explosives engineering profession using the process by which hazardous Explosive device, explosive devices are rendered safe. ''Bomb disposal'' is an all-encompassing term to describe the separate, but interrelated functi ...

experts can protect against the effects of BOP.

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 The net explosive quantity (NEQ), also known as net explosive content (NEC) or net explosive weight (NEW), of a shipment of munitions, fireworks or similar products is the total mass of the contained explosive substances, without the packaging, ...

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)

References

{{Reflist Pressure Explosives Shock waves

Effects

Calculation for an enclosed space

See also

References