ATF’s Fire Research Laboratory (FRL) in Maryland is routinely contacted by investigators to perform forensic fire testing and collect scientific data related to local, state and federal cases. The below videos show an experiment for one of those cases involving a fire pit that lead to a death.
The FRL conducted 17 fire tests in the Large Burn Room to test a witness statement that the flames from the fire pit may have entered the gasoline container (which didn’t have a spout installed), creating a momentary flame jet that engulfed the victim as they passed by the fire pit. A sample of the liquid found in the actual fire scene container was analyzed and determined to be a mixture of gasoline and heavy petroleum distillate. A witness said that the diesel mixture within the 2-gallon container was collected during the cleaning of contaminated fuel pump lines as part of a job servicing fuel pumps. The container was said to be less than 1/4 full at the time of the incident.
For safety purposes, an apparatus was constructed to allow the gasoline container to be remotely poured from an enclosure. Since the results could not be assumed in advance, lighting the fire directly with a lighter in hand would have been dangerous.
In these videos, the container is positioned above a natural gas burner and poured 10 ounces of gasoline without a nozzle in place. The gasoline was "weathered" or evaporated to 75% of its original mass.
As the container tilts over the flames, a large flame jet rapidly develops from the mouth of the container and extends in excess of 6.5 feet without warning and without damaging the container. The flames result in sustained head-to-toe burning to a mannequin placed at the same distance the victim was from the fire pit.
Flame jetting was only observed when “weathered” gasoline was utilized. It occurred when the gasoline container was tilted and the vapors were poured from the mouth of the container; when burner flames came in direct contact with the mouth of the gasoline container (piloted ignition) and when burner flames were several inches from the mouth of the gasoline container at the time of ignition (non-piloted ignition).
Testing indicated that flame jetting typically occurred less than five seconds after liquid began to pour from the mouth of the container. 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 damage to the container. The length of the flame jet was dependent the total quantity of liquid, the mixture ratio and the percentage that the gasoline was “weathered.”