Tuesday, March 5, 2013

ATF: Gas Can "Old Gas" Flame Jetting Phenomenon

ATF studying and recreating 'flame jetting phenomenon' which killed one teenager and severely burned another
The test resulted from a fire in which father was accused of purposely pouring fuel on his daughter who was killed. Father claimed he was igniting logs in a fire pit.

In December 2010, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) Fire Research Laboratory (FRL) was asked to determine whether a 2 gallon gasoline container with no nozzle or flame arrester could explode when fuel was poured on an open fire, spraying flames from the mouth of the container.

 The request was made by police in the case of Majd Al- Shara, a Michigan man who had been accused of purposely killing his six-year-old daughter Aliaa by dousing her in gas and lighting her on fire. Police didn't believe Al-Shara's story that his gas can exploded when he tried to accelerate flaming logs in a fire pit, engulfing Aliaa in flames just as she approached.

The ATF conducted 17 tests. An explosion producing jetting flames and fuels was documented 13 out of 17 times, just as Al-Shara had described. The longest flame jet was 13 feet, completely encompassing the body of a mannequin at distances up to 6.16 feet. Liquid from the can was propelled with the flame jet and deposited on the mannequin up to 4.33 feet.






Videos from ATF's laboratory to showing the test.



Here's a quick overview of what the ATF crew thinks is going on: 
 Based on the testing series conducted at the ATF FRL, several observations were made regarding the flame jetting phenomenon. Flame jetting was only observed when the container was being tilted and the vapors were pouring from the mouth of the container.

 It is hypothesized that initially when the container is upright, the head space above the liquid is too fuel rich (above the Upper Flammability Limit) and combustion is not supported within the container. As the container is tilted and vapors begin to pour from the container, air is entrained into the head space and the fuel rich mixture eventually falls within the flammable limits, allowing flame propagation within the container.
 The flame jetting phenomenon was only observed with “weathered” or evaporated gasoline (25% weathered gasoline was evaluated).No flame jetting was documented when “fresh” gasoline was poured from the container.
 It is hypothesized that“fresh” gasoline releases vapors more readily than “weathered” gasoline at the same temperature.Consequently, even when air is entrained into the container headspace while pouring, “fresh”gasoline releases flammable vapors readily enough that the headspace never drops below the upper flammable limit and therefore does not support flame propagation within the container. 
 In separate tests, flame jetting was documented with burner flames in direct contact with the mouth of the container (piloted ignition) as well as with burner flames that were several inches from the mouth of the container at the time of ignition (non-piloted ignition).

  •  The flame jet was observed extending as far as 4 m (13 ft) horizontally.
  •  The flame jet propelled ignited liquid out of the gasoline container.
  •  The propelled liquid ignited cotton clothing on a mannequin located 1.3 m (4.3 ft) away and sustained burning after the momentary flame jet self-extinguished.
  •  The entire jetting event lasted less than one second, with no observable warning signs prior to the phenomenon.
 When jetting did occur, there was no evidence of thermal or pressure damage to the container.The length of the flame jet was dependent on several variables, including the total quantity of liquid, the mixture ratio and the percentage that the gasoline was “weathered.”Flame jets as small as 6 inches were observed in subsequent testing. 
 If the nozzle is in place when the flame travels into the container, the container has been documented to rupture and often injures the person holding the container.


GASOLINE AT HOME

NFPA Safety Tips
Keep gasoline out of children's sight and reach. Children should never handle gasoline. See all safety tips.
Gas canThere has been a steady decline in the average number of gasoline fires in homes each year since 1980 when there were 15,000 fires.
Facts & figures
  • In 2003-2006, municipal fire departments responded to an estimated 2,400 gasoline structure fires in U.S. homes, annually.  These fire resulted in 110 civilian deaths, 313 civilian injuries and $105.9 million in direct property damage.
  • 49% of home gasoline structure fires each year between 2003 and 2006 were categorized as intentional. Almost three-quarters of civilian injuries resulted from unintentional causes.  Fuel spills or releases; using gasoline to kindle fire, and gasoline too close to a heat source; were the leading factors contributing to ignition in home gasoline structure fires.
  • Spark ember or flame from operating equipment was the most common ignition source in home gasoline structure fires, followed by matches and lighters.
RELATED FLAME JETTING ARTICLES AND VIDEOS:

Here's a link to the news segment that tells one  family's story and explains how the flame jetting occurs: http://www.abc2news.com/dpp/news/region/baltimore_county/atf-studies-fire-phenomenon-that-a-burned-baltimore-county-teenager

Here's a link to several HD videos of the flame jetting: 
http://www.abc2news.com/dpp/news/local_news/investigations/atf-studying-and-recreating-flame-jetting-phenomenon-which-severely-burns-essex-teenager
ATF studies fire phenomenon that a burned Baltimore County teenager

The Backstory Read more: http://www.abc2news.com/dpp/news/region/baltimore_county/atf-studies-fire-phenomenon-that-a-burned-baltimore-county-teenager#ixzz2MhXAYE5B


.....ARE YOU aware of any other situations related to FLAME JETTING? If so, please contact: Adam.D.St.John@usdoj.gov 

More info The Secret List:  http://www.firefighterclosecalls.com/news/fullstory/newsid/182882

CFN - California Fire News 2012 

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