Legendary industrial firefighter Dwight Williams is proposing a compromise. If he pulls it off, it could be a major step forward in resolving the irreconcilable controversy over the continued use of fluorinated chemicals in firefighting foam.
Dwight P. Williams and US Fire Pump used the 42-foot diameter storage tank project at the newly reopened International Rescue Training Field in Beaumont, TX to test his fluorinated 1 x 3 AR-AFFF Signature series foam using the US Fire Pump Defender fixed appliance.
With nearly a minute of pre-burn before application of the foam the fire was totally extinguished in two minutes and 43 seconds using the single Defender appliance. Foam was metered with a 1½-inch line educator moving 125 gmp set at one percent.
“Although this was impressive, our application rate was only .07,” Williams said “If our application rate was up to about .10 it puts the fire out a lot quicker.”
The large-tank test was conducted using 3.8 gallons of Signature Series 1x3 AR-AFFF foam concentrate, he said.
US Fire Pump’s Defender system is an air aspirating foam appliance designed to provide effective full surface as well as rim seal fire suppression for storage tanks. The semi or fixed system appliance provides quicker response time and less manpower than a portable, large-volume delivery approach. The Defender requires less flow rate and lower application densities because100 percent of the foam is directed inside the tank and exposes fewer personnel to a hazardous situation.
Fluorinated foam makes the aqueous film forming aspect of AFFF possible. The low surface tension of fluorinated surfactants allows the film to form over hydrocarbon fuels. Oleophobic, the fuel shedding quality of the AFFF, makes it possible for the foam to survive its plunge beneath the fuel surface.
By comparison, non-fluorinated foam depends solely on “bubble technology,” Williams said.
Fluorinated firefighting foam is under environmental attack worldwide over concern about a category of man-made chemicals known as per- and polyfluoroalkyl substancews (PFAS) essential in making the fluorinated surfactants used in firefighting foam.
However, live-tests using proposed non-fluorine foam alternatives have yielded disappointing results, Williams said.
“It’s like telling an infantry soldier that you can’t have your semi-automatic weapon anymore,” he said. “We’re going to go back and use .45-70 single shot rifles instead.”
Williams’ compromise is to restrict fluorinated foam to extinguishment only. For continuing vapor suppression after extinguishment, firefighters would switch to non-fluorine foam specially designed to keep the flammable vapor apart from the oxygen needed for ignition.
This new product, called VSP (Vapor Suppression Product) will be available in 2019 through US Fire Pump, master distributors for Dwight P. Williams’ foam concentrates.
“I don’t see how anybody in a decision making situation would not be thrilled to have 80 percent of the foam being shot be non-fluorine,” Williams said. “That’s got to please people.”
In conjunction with the live-fire testing conducted in December at IRTF was a live-fire plunge test in which a Type 3 over-the-top application of VSP was delivered to the unignited surface of non-ethanol based 93 octane pump gasoline contained in a 42-inch diameter pan.
“One hour after the application of VSP a propane torch was passed over the pan without igniting the gasoline fumes. The test was repeated twice more at one-hour intervals without refreshing the foam blanket. The results were the same as the initial test.
“This is about the time that a good AFFF would have given up,” Williams said one hour after application.
Passing the test again at the two hour mark was counted as “a big accomplishment,” Williams said.
“If we can get three hours, that is huge,” Williams said. “Every hour you gain will count as two applications of AFFF. If you look at a 300-foot-diameter tank, just in dollars, you’re saving over a million dollars in three days of application with VSP.”
The water needed during that three days would be cut in half, he said.