A Detailed Look at the Necked Vessel Flame Thrower Effect
R. Meier, P. Kennedy, K. Smith, G. Gorbett & P. Powell, 2014
Fire Investigation, Flammable Liquids, Fire Behavior, Necked Vessel Fiame Thrower Effect,
In 2013 and 2014 extensive study and laboratory tests were conducted outside the scope of any specific incident or litigation. This data was combined with data collected during case specific research conducted during the previous 36 years. The study viewed and evaluated the variables in producing the “Necked Vessel Flame Thrower Effect”, including: Vessel Shape, Total Vessel Volume, Opening Diameter, Percent Filled, Pouring Rate (fast or slow), Fuel Temperature and Flashpoint, whether the opening is occluded or not, and the nature (character) of the expulsion of ignited contents.
Abstract
Fire and explosion incidents involving ignitable liquids carried in and poured from containers have likely occurred for as long as mankind has been carrying ignitable liquids in containers. These incidents have taken many forms from simple pool fires to massive explosions. The outcome of each incident is dependent on many variables. Each variable has an effect, and the combination of the different variables can end in a result not always obvious or intuitively expected.
Of the many possibilities involving ignitable liquids in containers, one has lately become a “cause célèbre” and the frequent subject of litigation. This particular phenomenon is the overpressure and expulsion of flaming vapor and liquid from a container the when the contents are being poured near or onto a source of ignition. Lately touted as a “newly realized phenomenon,” the forcible ejection of an ignitable liquid is, or at least should be, the recognized result of a container becoming pressurized during the incident and its contents being forced through a narrow opening.
While frequently described as an “explosion”, the phenomenon is in fact a poorly understood type of flash fire which can take several different iterations. The outcome of the event – and in fact whether or not the event will even occur – is the result of several variables and their interactions. It is these variables and the results of their combinations affect which this paper will address.
The first litigation – involving an incident in which burning ignitable liquid was propelled out of a container – was filed in Louisville, Kentucky in 1978. Original investigative research discovered that this was a repeatable phenomenon, and the result of the ignitable liquid being poured out of the container into an open bowl already containing an open flame. Recently, some in the field of fire investigation have “rediscovered” the phenomenon and given it new names even though this phenomenon has been known and documented for almost four decades.
In 2013 and 2014 extensive study and laboratory tests were conducted outside the scope of any specific incident or litigation. This data was combined with data collected during case specific research conducted during the previous 36 years. The study viewed and evaluated the variables in producing the “Necked Vessel Flame Thrower Effect”, including: Vessel Shape, Total Vessel Volume, Opening Diameter, Percent Filled, Pouring Rate (fast or slow), Fuel Temperature and Flashpoint, whether the opening is occluded or not, and the nature (character) of the expulsion of ignited contents. This work, combined with some of the previous research conducted for litigation purposes, will be presented in this paper.