An overpressure protection system is one designed to protect an individual or group of individuals in a chemical, biological, radiological and nuclear (
CBRN
Chemical, biological, radiological and nuclear defence (CBRN defence) are protective measures taken in situations in which chemical, biological, radiological or nuclear warfare (including terrorism) hazards may be present. CBRN defence consist ...
) environment. The two parts of the system are a safe area which as far as possible is
sealed from possible contaminated air and an
air filtration system which will filter out all possible toxins. Air pumps force clean air through the filters into the safe area such that the air pressure within the safe area will always be higher than that outside of the safe area. This pressure differential means that any flows of air will always be from the safe area to the outside, preventing the ingress of toxins.
The safe area may be as small as a protective hood for an individual, to a full body
hazmat suit
A hazmat suit (hazardous materials suit) is a piece of personal protective equipment that consists of an impermeable whole-body garment worn as protection against hazardous materials. Such suits are often combined with self-contained breathing a ...
, to a
fallout shelter
A fallout shelter is an enclosed space specially designated to protect occupants from radioactive debris or fallout resulting from a nuclear explosion. Many such shelters were constructed as civil defense measures during the Cold War.
Durin ...
or warship. Most modern
armoured fighting vehicles
An armoured fighting vehicle (AFV) is an armed combat vehicle protected by armour, generally combining operational mobility with offensive and defensive capabilities. AFVs can be wheeled or tracked. Examples of AFVs are tanks, armoured car ...
will have such a system with the safe area being the crew and passenger compartments, these systems being first adopted to protect against
poison gas
Many gases have toxic properties, which are often assessed using the LC50 (median lethal dose) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or perm ...
attack. On a larger scale an overpressure system may be designed into the structure of a building or mobile prefabricated military structures to provide
collective protection.
In a civilian context the same principles of filtration and
positive pressure is used in
positive pressure personnel suits.
See also
*
Cleanroom
A cleanroom or clean room is an engineered space, which maintains a very low concentration of airborne particulates. It is well isolated, well-controlled from contamination, and actively cleansed. Such rooms are commonly needed for scientif ...
References
Chemical, biological, radiological and nuclear defense
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