BLEVE
From Wikipedia, the free encyclopedia
BLEVE (pronounced /ˈblɛvi/ BLEV-ee), is an acronym for boiling liquid expanding vapor explosion. This is a type of explosion that can occur when a vessel containing a pressurized liquid is ruptured. Such explosions can be extremely hazardous.
A BLEVE results from the rupture of a vessel containing a liquid substantially above its atmospheric boiling point. The substance is stored partly in liquid form, with a gaseous vapour above the liquid filling the remainder of the container.
If the vessel is ruptured — for example, due to corrosion, or failure under pressure — the vapour portion may rapidly leak, lowering the pressure inside the container. This sudden drop in pressure inside the container causes violent boiling of the liquid, which rapidly liberates large amounts of vapour in the process. The pressure of this vapour can be extremely high, causing a significant wave of overpressure (an explosion) which may completely destroy the storage vessel and project fragments over the surrounding area. BLEVEs can also be caused by an external fire near the storage vessel causing heating of the contents and pressure build-up. While tanks are often designed to withstand great pressure, constant heating can cause the metal to soften and eventually fail. If the tank is being heated where there is no liquid, it may rupture faster since the liquid would not absorb the heat from the metal. Gas containers are usually equipped with relief valves that vent off excess pressure, but the tank can still fail if the pressure is not released quickly enough.
A BLEVE can occur even with a non-flammable substance, sometimes one that's known for being extremely cold, like liquid nitrogen or liquid helium or other refrigerants or cryogens, and therefore is not usually considered a type of chemical explosion. However, if the substance involved is flammable, it is likely that the resulting cloud of the substance will ignite after the BLEVE has occurred, forming a fireball and possibly a fuel-air explosion, also termed a vapor cloud explosion (VCE). If the materials are toxic, a large area will be contaminated.[1] BLEVEs are not limited to pressurized containers; they can happen in water heaters.[2]
Significant industrial BLEVEs include accidents at Feyzin in France in 1966, Kingman, Arizona in 1973, Texas City, Texas in 1978, Murdock, Illinois in 1983 and San Juan Ixhuatepec in Mexico City in 1984[3]. In 1978, a BLEVE occurred after a road accident with an LPG truck in the Los Alfaques Disaster in Spain.
Some fire mitigation measures are listed under liquefied petroleum gas.
In the firefighting community, BLEVE is sometimes used as a humorous backronym for "big loud explosion very exciting" or "blast leveling everything very effectively."
[edit] References
- ^ http://chemelab.ucsd.edu/processdesign/safety/safety-notes.pdf accessed 2009-01-06
- ^ http://www.inspect-ny.com/plumbing/Water_Heater_Relief_Valves.htm
- ^ www.hse.gov.uk
[edit] See also
 |
Look up bleve in Wiktionary, the free dictionary. |
- Boiler explosion
- Expansion ratio
- Passive fire protection
- Fireproofing
- Phreatic eruption
- Dry ice bomb
- Chlorine bomb
[edit] External links
- History of Kingman Regional Medical Center — An account of the July 5, 1973 explosion in Kingman, with photographs.
- Huge Explosions - Video of propane and isobutane BLEVEs from a train derailment at Murdock, Illinois (September 3, 1983).
- Propane BLEVE - Video of BLEVE from the Toronto propane depot fire (see also 2008 Toronto explosions)
- Propane Tank Explosions - Description of circumstances required to cause a propane tank BLEVE.
- Article on BLEVE facts and mitigation
