an unplanned drop in the pressure of a sealed systemUncontrolled decompression is an unplanned drop in the pressure of a sealed system, such as an aircraft cabin or hyperbaric chamber, and typically results from human error, material fatigue, engineering failure, or impact, causing a pressure vessel to vent into its lower-pressure surroundings or fail to pressurize at all.
Such decompression may be classed as Explosive, Rapid, or Slow:
- Explosive decompression (ED) is violent, the decompression being too fast for air to safely escape from the lungs.
- Rapid decompression, while still fast, is slow enough to allow the lungs to vent.
- Slow or gradual decompression occurs so slowly that it may not be sensed before hypoxia sets in.
The term uncontrolled decompression here refers to the unplanned depressurisation of vessels that are occupied by people; for example, a pressurised aircraft cabin at high altitude, a spacecraft, or a hyperbaric chamber. For the catastrophic failure of other pressure vessels used to contain gas, liquids, or reactants under pressure, the term explosion is more commonly used, or other specialised terms such as BLEVE may apply to particular situations.
Decompression can occur due to structural failure of the pressure vessel, or failure of the compression system itself. The speed and violence of the decompression is affected by the size of the pressure vessel, the differential pressure between the inside and outside of the vessel, and the size of the leak hole.
The US Federal Aviation Administration recognizes three distinct types of decompression events in aircraft:
- Explosive decompression
- Rapid decompression
- Gradual decompression
Explosive decompression occurs at a rate swifter than that at which air can escape from the lungs, typically in less than 0.1 to 0.5 seconds. The risk of lung trauma is very high, as is the danger from any unsecured objects that can become projectiles because of the explosive force, which may be likened to a bomb detonation.
After an explosive decompression within an aircraft, a heavy fog may immediately fill the interior as the relative humidity of cabin air rapidly changes as the air cools and condenses. Military pilots with oxygen masks have to pressure-breathe, whereby the lungs fill with air when relaxed, and effort has to be exerted to expel the air again.
Rapid decompression typically takes more than 0.1 to 0.5 seconds, allowing the lungs to decompress more quickly than the cabin. The risk of lung damage is still present, but significantly reduced compared with explosive decompression.
Slow, or gradual, decompression occurs slowly enough to go unnoticed and might only be detected by instruments. This type of decompression may also come about from a failure to pressurize as an aircraft climbs to altitude. An example of this is the 2005 Helios Airways Flight 522 crash, in which the pilots failed to check the aircraft was pressurising automatically and then to react to the warnings that the aircraft was depressurising, eventually losing consciousness (along with most of the passengers and crew) from hypoxia.
Pressure vessel seals and testing
Seals in high-pressure vessels are also susceptible to explosive decompression; the O-rings or rubbergaskets used to seal pressurised pipelines tend to become saturated with high-pressure gases. If the pressure inside the vessel is suddenly released, then the gases within the rubber gasket may expand violently, causing blistering or explosion of the material. For this reason, it is common for military and industrial equipment to be subjected to an explosive decompression test before it is certified as safe for use.
Exposure to a vacuum causes the body to explode
This persistent myth is based on a failure to distinguish between two types of decompression: the first, from normal atmospheric pressure (one atmosphere) to a vacuum (zero atmospheres); the second, from an exceptionally high pressure (many atmospheres) to normal atmospheric pressure.
The first type, a pressure reduction from normal atmospheric pressure to a vacuum, is the more common. Research and experience in space exploration and high-altitude aviation have shown that while exposure to vacuum causes swelling, human skin is tough enough to withstand the drop of one atmosphere, although the resulting hypoxia will cause unconsciousness after a few seconds. At the extreme low pressures encountered at altitudes above about 62,000 feet (19,000 m), only 0.0618 of an atmosphere short of a complete vacuum, the boiling point of water becomes less than normal body temperature; this is known as the Armstrong limit, which is the practical limit to survivable altitude without pressurization.
However, in the case of an explosive or rapid decompression from one atmosphere to zero, pulmonary barotrauma (a rupture of the lung) may occur if the air in the lungs expands faster than the person is able to exhale; if the breath is forcibly held, this can happen even with a gradual decompression.
The second type is rare since it involves a pressure drop over several atmospheres, which would require the person to have been placed in a pressure vessel. The only likely situation in which this might occur is during decompression after deep-sea diving. There is only a single, well-documented occurrence of this: the 1983 Byford Dolphin incident in the North Sea in which a violent, explosive decompression of eight atmospheres, from nine to one atmospheres, caused massive and lethal barotrauma. A similar but fictional death was shown in the James Bond film Licence to Kill, when a character's head explodes after his hyperbaric chamber is rapidly depressurized. Neither of these incidents would have been possible if the pressure drop had been only from normal atmospheric to a vacuum.
Bullets cause explosive decompression
Aircraft fuselages are designed with ribs to prevent tearing; the size of the hole is one of the factors that determine the speed of decompression, and a bullet hole is too small to cause rapid or explosive decompression.
A small hole will blow people out of a fuselage
The television program MythBusters examined this belief informally using a pressurised aircraft and several scale tests. The MythBusters approximations suggested that fuselage design does not allow this to happen.
The following physical injuries may be associated with decompression incidents:
Implications for aircraft design
Modern aircraft are specifically designed with longitudinal and circumferential reinforcing ribs in order to prevent localised damage from tearing the whole fuselage open during a decompression incident. However, decompression events have nevertheless proved fatal for aircraft in other ways. In 1974, explosive decompression onboard Turkish Airlines Flight 981 caused the floor to collapse, severing vital flight control cables in the process. The FAA issued an Airworthiness Directive the following year requiring manufacturers of wide-body aircraft to strengthen floors so that they could withstand the effects of in-flight decompression caused by an opening of up to 20 square feet (1.9 m2) in the lower deck cargo compartment. Manufacturers were able to comply with the Directive either by strengthening the floors and/or installing relief vents called "dado panels" between the passenger cabin and the cargo compartment.
Cabin doors are designed to make it nearly impossible to lose pressurization through opening a cabin door in flight, either accidentally or intentionally. The plug door design ensures that when the pressure inside the cabin exceeds the pressure outside the doors are forced shut and will not open until the pressure is equalised. Cabin doors, including the emergency exits, but not all cargo doors, open inwards, or must first be pulled inwards and then rotated before they can be pushed out through the door frame because at least one dimension of the door is larger than the door frame. Pressurization apparently prevented the doors of Saudia Flight 163 from being opened on the ground after the aircraft made a successful emergency landing, resulting in the deaths of all 287 passengers and 14 crew members from fire and smoke.
Prior to 1996, approximately 6,000 large commercial transport airplanes were type certified to fly up to 45,000 feet (14,000 m), without being required to meet special conditions related to flight at high altitude. In 1996, the FAA adopted Amendment 25-87, which imposed additional high-altitude cabin-pressure specifications, for new designs of aircraft types. For aircraft certified to operate above 25,000 feet (FL 250; 7,600 m), it "must be designed so that occupants will not be exposed to cabin pressure altitudes in excess of 15,000 feet (4,600 m) after any probable failure condition in the pressurization system." In the event of a decompression which results from "any failure condition not shown to be extremely improbable," the aircraft must be designed so that occupants will not be exposed to a cabin altitude exceeding 25,000 feet (7,600 m) for more than 2 minutes, nor exceeding an altitude of 40,000 feet (12,000 m) at any time. In practice, that new FAR amendment imposes an operational ceiling of 40,000 feet on the majority of newly designed commercial aircraft.[Note 1]
In 2004, Airbus successfully petitioned the FAA to allow cabin pressure of the A380 to reach 43,000 feet (13,000 m) in the event of a decompression incident and to exceed 40,000 feet (12,000 m) for one minute. This special exemption allows the A380 to operate at a higher altitude than other newly designed civilian aircraft, which have not yet been granted a similar exemption.
The Depressurization Exposure Integral (DEI) is a quantitativemodel that is used by the FAA to enforce compliance with decompression-related design directives. The model relies on the fact that the pressure that the subject is exposed to and the duration of that exposure are the two most important variables at play in a decompression event.
Other national and international standards for explosive decompression testing include:
Notable decompression accidents and incidents
Decompression incidents are not uncommon on military and civilian aircraft, with approximately 40–50 rapid decompression events occurring worldwide annually. In the majority of cases the problem is relatively manageable for aircrew. Consequently, where passengers and the aircraft do not suffer any ill effects, the incidents tend not to be considered notable. Injuries resulting from decompression incidents are rare.
Decompression incidents do not occur solely in aircraft—the Byford Dolphin incident is an example of violent explosive decompression on an oil rig. A decompression event is an effect of a failure caused by another problem (such as an explosion or mid-air collision), but the decompression event may worsen the initial issue.
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- ^ abDehart, R. L.; J. R. Davis (2002). Fundamentals Of Aerospace Medicine: Translating Research Into Clinical Applications, 3rd Rev Ed. United States: Lippincott Williams And Wilkins. p. 720. ISBN 978-0-7817-2898-0.
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- ^"Advisory Circular 61-107"(PDF). FAA. pp. table 1.1.
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- ^ abcdefMartin B. Hocking; Diana Hocking (2005). Air Quality in Airplane Cabins and Similar Enclosed Spaces. Springer Science & Business. ISBN 3-540-25019-0. Retrieved 2008-09-01.
- ^ abBason R, Yacavone DW (May 1992). "Loss of cabin pressurization in U.S. Naval aircraft: 1969-90". Aviat Space Environ Med. 63 (5): 341–5. PMID 1599378.
- ^Brooks CJ (March 1987). "Loss of cabin pressure in Canadian Forces transport aircraft, 1963-1984". Aviat Space Environ Med. 58 (3): 268–75. PMID 3579812.
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VG-BT05 Awakening of Twin Blades
January 14th, 2012 (JP)
February 22nd, 2013 (EN)
Awakening of Twin Blades is the 5th Booster Set released in the Japanese/Korean format, and the 7th released in the English format.
- There are a total of 80 different cards (RRR x8, RR x12, R x20, C x40) + SP cards x12 (Parallel).
- Includes further support for the Royal Paladin, Shadow Paladin, Kagero, Oracle Think Tank, Nova Grappler, Dimension Police, Dark Irregulars, and Pale Moonclans.
- Introduces the "Neo Nectar" and "Murakumo" clans.
- The Japanese version introduces the Cross Ride units.
- The English version introduces the "Sentinel" keyword.
- The package illustration features Aichi Sendou, Toshiki Kai and Ren Suzugamori, with Majesty Lord Blaster behind them.
- The booster's slogan is "Fight and believe in your own strength".
伊藤彰／Azusa／Daisuke Izuka／Eel／funbolt／Hirokorin／koji／Kou Takano／Morechand／NINNIN／Ryo-ta.H／toi8／ToMo／touge666／uni／ZB／安達洋介／雨宮慶太／伊咲ウタ／石田バル／イトウヨウイチ／叶之明／木下勇樹／米谷尚展／茶壱／齋藤タヶオ／齋藤直葵／沙村 広明／山宗／スズキゴロウ／タイキ／高田明美／タカヤマトシアキ／竹浪秀行／田所哲平／たにめそ／千葉サドル／てるみぃ／萩谷薫／パトリシア／前河悠一／前田ヒロユキ／雅／増田幹生／松島一夫／碧風羽／三好載克／村枝賢一／村瀬倫太郎／村山竜大／瞑丸イヌチヨ／山崎太郎／山﨑奈苗／結城遼也／由利真珠郎／余湖裕輝／竜徹／鷲尾直広
カードファイト!! ヴァンガード ブースター第5弾 CM
CARDFIGHT!! VANGUARD TVC BT05
Add a photo to this gallery
|BT05/001||Covert Demonic Dragon, Mandala Lord||3||Murakumo||RRR+SP|
|BT05/002||Majesty Lord Blaster||3||Royal Paladin||RRR+SP|
|BT05/003||Star Call Trumpeter||2||Royal Paladin||RRR+SP|
|BT05/004||Phantom Blaster Overlord||3||Shadow Paladin||RRR+SP|
|BT05/005||Dragonic Overlord the End||3||Kagero||RRR+SP|
|BT05/006||Miracle Beauty||3||Dimension Police||RRR+SP|
|BT05/007||King of Diptera, Beelzebub||3||Dark Irregulars||RRR+SP|
|BT05/008||Mistress Hurricane||3||Pale Moon||RRR+SP|
|BT05/009||Maiden of Trailing Rose||3||Neo Nectar||RR+SP|
|BT05/010||Glass Beads Dragon||2||Neo Nectar||RR|
|BT05/011||Maiden of Blossom Rain||1||Neo Nectar||RR|
|BT05/012||Stealth Fiend, Midnight Crow||2||Murakumo||RR+SP|
|BT05/013||Stealth Beast, Leaves Mirage||1||Murakumo||RR|
|BT05/014||Knight of Loyalty, Bedivere||2||Royal Paladin||RR|
|BT05/015||Knight of Friendship, Kay||1||Royal Paladin||RR|
|BT05/016||Wingal Brave||0||Royal Paladin||RR+SP|
|BT05/017||Moonlight Witch, Vaha||2||Shadow Paladin||RR|
|BT05/018||Knight of Nullity, Masquerade||2||Shadow Paladin||RR+SP|
|BT05/019||Evil-eye Princess, Euryale||3||Oracle Think Tank||RR|
|BT05/020||Street Bouncer||2||Nova Grappler||RR|
|BT05/021||Frontline Valkyrie, Laurel||3||Neo Nectar||R|
|BT05/022||Knight of Harvest, Gene||3||Neo Nectar||R|
|BT05/023||Avatar of the Plains, Behemoth||3||Neo Nectar||R|
|BT05/024||Iris Knight||2||Neo Nectar||R|
|BT05/025||Hey Yo Pineapple||2||Neo Nectar||R|
|BT05/026||Shield Seed Squire||0||Neo Nectar||R|
|BT05/027||Stealth Fiend, Kurama Lord||3||Murakumo||R|
|BT05/028||Stealth Dragon, Voidgelga||3||Murakumo||R|
|BT05/029||Stealth Beast, Bloody Mist||2||Murakumo||R|
|BT05/030||Caped Stealth Rogue, Shanaou||2||Murakumo||R|
|BT05/031||Stealth Dragon, Cursed Breath||2||Murakumo||R|
|BT05/032||Stealth Dragon, Turbulent Edge||1||Murakumo||R|
|BT05/033||Stealth Beast, Million Rat||1||Murakumo||R|
|BT05/034||Stealth Beast, Evil Ferret||0||Murakumo||R|
|BT05/035||Knight of Purgatory, Skull Face||3||Shadow Paladin|