ORLANDO – There’s more to specifying foam systems for apparatus than simply checking off the option box on the specifications, according to experts who lectured at the 27th annual Fire Department Safety Officers Association apparatus symposium on Monday.
David Durstine who was recently appointed as the vice president of Weldon, a division of Akron Brass, and Michael Dupay, sales manager of FoamPro, a division of Fire Research, offered tips and advice to several dozen attendees interested in learning more about foam systems.
“You need to identify the size of the hazard and then size and select the proportioning system,” Durstine said. “Do it in this order. Not the other way around. You can end up with a completely inappropriate system for the hazards you face.”
In identifying the department’s hazards, Durstine said firefighters should review things like highways, rail yards, commercial enterprises, manufacturing and even dairy farms that can have thousands of gallons of diesel fuel on site at any given time.
Dupay said fire departments should also look to the future when deciding foam needs.
“It’s not just what you see now, it’s what you might have down the road,” Dupay said.
Dupay and Durstine offered a lot of formulas for deciding flow rates for foam and the kind of foam that should be used.
Boiling it down, they said the foam system should match the size of the hazard. For instance, a portable handheld eductor system, primarily used for wildland firefighting is not going to handle an 8,000-gallon gasoline spill when the tanker overturns on the highway.
“You’ll have to run it for a very long time,” Durstine said, noting that even then it won’t handle the hazard.
A tank fire at a petroleum plant will need industrial size foam systems as will airports and industrial complexes.
On a basic level, all foam systems “get the juice in the water” Dupay said, describing the different kinds of systems. He also described Class A foam as a surfactant that makes plain water more effective by breaking down surface tension and providing faster cool down and knockdown times.
Class B foams are for hydrocarbon and polar solvents, Dupay said and they come in several different formulations, but its basic mission is to seal the surface of the liquids.
The different agents have different viscosity too, with some of the Class A foams, used for typical house fires having the consistency of water and some of the heaviest Class B weighing in like “snot,” Durstine said, noting that the equipment is different in getting it into the water and the volume are also different.
Rates of injection can range from .09 percent up to 10 gallons a minute, depending on the need and application, Durstine said, noting that is important firefighters, especially those who work on specifications, understand critical application rates for different types and size incidents.
Common, a critical to all foam systems, is the need to flush systems because foam is corrosive, the experts said.
No matter what the applications and needs are, Durstine and Dupay said working with the manufacturer and accurately describing the needs will ensure the departments get what they need.
Dupay said it’s important that manufacturers need to know the number of discharges needed, the type of foam to be used and how accurate the metering needs to be.
“There’s a wide range of performance, costs and features,” Durstine said. “It’s not just the initial cost purchase cost, but the ongoing costs. How important is accuracy? At low flow rates, accuracy is not as important, but at high rates, and the cost of foam at $30 to $40 per gallon, what is the cost of wasted foam?”
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