Water, alone, can be an inefficient firefighting
tool depending on fuel type, fuel loads and fire
conditions. Water as it is converted to steam, has
the ability to absorb and carry away heat. This
happens at an expansion rate of 1700 to 1.
Unfortunately, water's strong surface tension causes
it to form small beads and roll off the fuel it is
being applied to faster than it can absorb its full
heat capacity. This makes water only five percent to
fifteen percent efficient, thus requiring huge
amount of it to extinguish some fires, not to
mention long periods of time
Most Class A foam concentrates are specifically
formulated to make water more efficient. A
combination of surfactants reduces the water surface
tension. As a result the water can spread out over
the surface area of the fire and penetrate deeper
into Class A fuels. The deeper the water can
penetrate into the fuel source, the quicker it can
put out the fire. It can also help to protect
exposure areas from radiant heat and airborne
embers.
Fire Fighters In action!
The benefits of a Class A foam concentrate to the
rural fire service is enormous. Foam's all-white
blanket coats and envelops the fuels source with a
thick layer of water, where water alone would beaded
up and rolled off. With the use of a foam, more
water is now available, allowing the operator of the
apparatus more time to establish a steady water
supply. It also allows water more time to absorb its
full heat capacity. A blanket of foam can also
reduce the time taken to "mop up", overhaul and
improve exposure protection.
Foam's white blanket reflects radiant heat away from
the fuel source, insulates fuel by dispersing the
heat away. It can also help smother the fuel and
creates a fuel vapor barrier between the fuel and
the fire. The foam blanket allows fuels such as
wood, hay, carpets, cloth and insulation more time
to absorb more water for greater heat resistance.
With foam, firefighters can see where water has been
applied, which is valuable in mop-up and overhaul
operations. It is also helpful in combating attic or
interior fires of large structures.
Two sets of experimental burns conducted in
identical rooms showed that foam knocked down the
fire thirty-five to sixty percent faster than water
alone and took fifty to eighty percent less water to
extinguish the fire. Faster knockdowns means less
firefighter fatigue and stress, improved fire scene
safety and reduced water damage.
With myself being from a small, rural Fire
Department, I know the importance of conserving
water until an established water supply can be
achieved. With most rural departments carrying their
water supply with them, will benefits greatly from
the use of a Class A foam system. It is suggested
that a foam concentrate of 0.1% to 1.0% is often
more effective than plain water. Sometimes as much
as three to five times as effective. Therefore
reducing the number of shuttle runs back and forth
to the local farmer's pond. Foam can help greatly in
extinguishing difficult fires in hay, barns,
stables, tire dumps, vehicles and mobile homes. With
several mobile home parks and tire dumps in our
area, foams would greatly reduce the time and
manpower needed to extinguish such blazes. Use of
foam on vehicle fire would also greatly reduce the
amount of smoke and toxic vapors emitted, thus
protecting the public and firefighters at hand.
