Fire Investigation Definition Series – BLEVE

Posted: September 1, 2015 in Fire Investigation, Fire Science
Tags: , , , ,

by: Jason A. Sutula

 

According to the 2014 Edition of NFPA 921 – Guide for Fire and Explosion Investigations, “The boiling liquid expanding vapor explosion (BLEVE) is the type of mechanical explosion that will be encountered most frequently by the fire investigator.” NPFA 921 provides a good basic description of how a BLEVE occurs. In general, a BLEVE event will begin when a container that is filled with a liquid undergoes an insult that results in the rupture of the container. The rupture can be caused either thermally or mechanically. In the thermal case, the heating of the container is responsible for the mode of failure. In the mechanical case, the container rupture is due to an impact or other event that causes a portion of the container to be breached. When the container is breached, the vapor of the liquid expands while the liquid becomes superheated. The superheating of the liquid results in the boiling of the liquid. Additionally, a pressure wave will be generated at the time of rupture and release, which can lead to the fragmentation of the container and the production of missiles. If the liquid in the container is flammable, a premixed system of fuel and air will develop and result in a fireball [Abbasi and Abbasi, 2007]. The Youtube video shown above is one that I show to my students to demonstrate the awesome power of the BLEVE.

One of the most famous BLEVE events took place in Crescent City, Illinois on Father’s Day, June 21, 1970. A freight train with 109 cars derailed. Ten of the rail cars were tank storage cars each carrying 34,000 gallons of liquefied propane gas. At the start of the derailment, one of the liquefied propane gas cars collided with another, tearing a large rupture into one of the other tanks. The result was a large initial fireball and subsequent sustained fire. Five of the liquefied propane gas cars achieved a BLEVE in the first four hours.

According to an excellent article by Robert Burke that was published by Firehouse in 2010 (http://www.firehouse.com/article/10467137/crescent-city-train-derailment-40-years-later), twenty-five homes and sixteen businesses were destroyed by fire. Three homes were destroyed by “flying” tank cars and numerous other homes received damage. More than $2 million in property damage occurred as a result of the derailment, fires and explosions along with six fire trucks [Burke, 2010].

It can be hard to put into perspective this amount of damage and how massive the fire and fireballs from the explosion were. After digging around on Youtube, I found the following video that shows actual footage of the Crescent City event. This particular video is narrated in Russian, but still clearly shows the magnitude of the event and the dangers of a BLEVE to both citizens and fire service personnel.

 

References

Abbasi and S. Abbasi, “The boiling liquid expanding vapour explosion (BLEVE): Mechanism, consequence assessment, management,” Journal of Hazardous Materials, no. 141, pp. 489-519, 2007.

Burke, 2010, http://www.firehouse.com/article/10467137/crescent-city-train-derailment-40-years-later

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