explosive decompression

Explosive decompression (ED) refers to a sudden marked drop in the pressure of a system that occurs in less than 0.1 seconds, associated with explosive violence. Generally it results from some sort of material fatigue or engineering failure, causing a contained system to suddenly vent into the external atmosphere.

Explanation

Seals in high pressure vessels are also susceptible to explosive decompression; the rubber gaskets 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.

The pressure drop in other situations often takes longer than 0.1 second, and is then more accurately described as rapid decompression. Well known examples of explosive decompression are the Byford Dolphin diving bell accident, the Turkish Airlines Flight 981 disaster, and a balloon popping.

Fallacies

Misunderstandings of the meaning of the words are quite likely to be a fuelling factor for a persistent myth that humans would explode if exposed to the non-pressure of space. Accidents in space exploration research and high-altitude aviation have shown that while vacuum exposure causes swelling, human skin is tough enough to handle a drop of one atm. A sudden drop of eight atm in the Byford Dolphin accident had intensely fatal results.

Explosive decompression accidents on aircraft

• BOAC Flight 781
• South African Airways Flight 201 (suspected)
• American Airlines Flight 96
• Turkish Airlines Flight 981
• Japan Airlines Flight 123
• Pan Am Flight 125
• Aloha Airlines Flight 243
• United Airlines Flight 811
• British Airways Flight 5390
• 18 September, 2001 TAM Fokker F-100 incident

See also

• Cabin pressurization

References

National and international standards for explosive decompression testing include:

• MIL-STD-810, 202
• RTCA/D0-160
• NORSOK M710
• API 17K and 17J
• NACE TM0192 and TM0297
• TOTALELFFINA SP TCS 142 Appendix H

External links

• Human Exposure to Vacuum

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