Flame jetting happens when a container of flammable liquid meets an ignition source, causing flames to shoot out 15 feet, or even more. Extremely dangerous, this unexpected, blowtorch-like effect can engulf bystanders in flames, leading to serious injury or death.
Flame jetting has been known to happen in classrooms, teenage hangouts, and work receptions. In other words, this isn't something that just happens in laboratories.
What Causes Flame Jetting?
The Fire Research Laboratory at the Bureau of Alcohol, Tobacco, Firearms and Explosives has conducted extensive research on flame jetting to figure out how it happens. This research has uncovered the following common denominators behind flame jetting:
1. Almost any necked, portable, flammable liquid container with a flammable liquid can potentially jet.
Common flammable liquids include gasoline, methanol, ethanol, acetone, and liquor above 150 proof. Containers with large openings, such as buckets, cannot jet.
2. Typically, the container is tilted and vapors are pouring from its mouth.
This allows air to enter the container's headspace, which dilutes the flammable liquid vapors within their flammable limits.
3. If the container has a nozzle installed when combustion occurs, flames can travel back into the container.
The nozzle restricts expanding gases from venting, resulting in rupture along the container seam. Flames are expelled where the container fails, injuring the person holding the container.
4. If no nozzle is installed, typically the person pouring the container is uninjured and injuries will occur to victims located opposite the container.
5. The longest flame jets occur when a container is about one-third full of liquid.
This allows for sufficient vapors to accumulate in the headspace of the container and for sufficient flammable liquid to be expelled when jetting occurs.
6. In cases involving gasoline jetting, older (weathered) gasoline that has undergone evaporation is more prone to jetting.
Older gasoline releases vapors more slowly than fresh gasoline. This means it can support flame propagation inside the portable flammable liquid container.
7. Flame arrestors are highly effective in preventing flame jetting.
In ATF testing, no flame jetting was observed in portable flammable liquid containers equipped with flame arrestors, which typically cost about 50 cents.