Positive pressure

Overpressure is physically not quite correct term for pressure measured relative to atmospheric pressure, or air pressure. The term is used in current standards again and can also be negative according to their definition. This then corresponds to the designation under pressure is no longer used.

Pressure was measured earlier at ( technical atmosphere ) or atm ( physical atmosphere ) pressure in atm ( atmospheric pressure ), the numerical value of the overpressure by exactly 1 was lower than the absolute pressure. This unit is no longer used today, in its place the unit Pascal or bar is depressed.

Applications

Cleanroom

In a clean room, the intrusion of dust is prevented in that in said space there is a permanent pressure.

Tunneling

In the early days of tunneling, the penetration of water through the pressure prevailing in the tunnel pressure was particularly at river crossings Under prevented. The physical properties of an artificially constructed overpressure is made, inter alia, in modern tunneling as a security measure advantage. By a sub-studs to build already in the design of a tunnel system in which excess pressure. Now, if a fire breaks out, rescue teams can reach the accident site, without having to use the smoke-filled tunnel.

Building Security

Modern buildings, especially skyscrapers, often possess one or more staircases that are equipped with a pressure relief system. Comparable to the application in tunnel, they serve here as well to keep out toxic smoke from escape routes.

Bridge building

Establishing of bridge piers below the water surface ( caissons ) are common downwardly open caissons, is introduced into the external compressed air to displace the water and to allow a dry work.

Important military installations, such as bunkers, but also vehicles and tanks are equipped with a pressure relief system to the ingress of warfare ( NBC) protection to prevent.

Storage and transport of gases

Gases, in particular compressed gases are transported or stored under often high pressure up to liquefaction. This happens both in pipes (ie transport of natural gas ) as well as in pressure containers (eg natural gas and hydrogen tanks in vehicles) and gas cylinders (especially chemical and medical applications).

Other applications

• Tire
• Blimps
• Pressure cooker
• Scuba diving
• Decompression chamber

Generation

Over pressure in a space formed by the fact that at the same time a greater volume flow into this space as introduced is discharged.