Ask an Official: MFD explains use of foam in fire fighting
This week’s featured question was submitted for Merrill Fire Chief Dave Savone.
“In the paper you talked about your new truck having a foam system plus the water system. I have never heard of foam before being used for fire fighting! How is foam useful and how do firemen know when a fire calls for foam compared to water? Nice truck btw!”
Answer as given by Chief Savone:
“Firefighting foam is nothing new to the Merrill Fire Department. Engine 61, Engine 62, Truck 63 and Old Brush Truck 66 have pre-piped foam systems.
Tender 65 has portable equipment to add foam to the fire attack hose lines. As you mentioned the new brush truck along with the new aerial truck that is on order, both have foam systems incorporated on the apparatuses.
“Firefighting foam consists of a mixture of water, foam concentrate and air. The composition of the foam depends on the proportion of the three components. The most common method for producing firefighting foam is nozzle-aspirated foam system, or through our standard hose line nozzles.
“The use of foam to fight class-A fires, or ordinary combustible materials; was first evaluated by the fire service in the 1930’s. Early studies showed that firefighting foams applied to ordinary combustible fuels could suppress fires more efficiently than plain water in most cases.
“However, the available foam concentrates were expensive and could only be mixed at high concentrations. Back in the day, foam was not a cost-effective means of extinguishing fires.
“In the 1980’s, synthetic foam concentrates were developed for use on ordinary combustible fires that could be applied at low concentrations. These new concentrates made the use of foam a cost-effective means of combating fires because smaller amounts of foam concentrate could be used to make effective foam blanket.
“The State of Texas began using foaming additives for brush and wildland firefighting in the 1970’s. The use of firefighting foams for wildland firefighting expanded in the 1980’s and 1990’s. Nozzle-aspirated foams have been developed that can deploy foam from brush trucks and fire engines. Gradually, as fires in wildland/urban interface areas have increased in severity and cost, the urban fire service has been exposed to the use of firefighting foams. Wildland urban interface is roughly defined as the zone where natural areas and development meet.”
“Some of the benefits of firefighting foam include:
•Firefighting foam allows faster fire suppression and extinguishment than with plain water.
•Firefighting foam increases efficiency and conservation of water supply.
•Firefighting foam can be produced at a relatively low cost.
•Firefighting foam forms a protective blanket
•Firefighting foam is visible during and after application.
•Firefighting foam clings to most surfaces and protects exposures much longer than plain water.
•Firefighting foam use may help to preserve evidence of fire cause.
•Firefighting foam can be used on flammable liquid fires.
•Firefighting foam aids wildland/urban interface attack.
•Firefighting foam may provide long-term cost savings and reduced property damage.
•Firefighter stress and fatigue may be reduced.
“Annually the Merrill Fire Department supplements our firefighting foam supply through the Wisconsin DNR Forest Fire Protection Grant Program. Which reduces the cost of the foam by half.”
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