FOAM APPLICATION TECHNIQUES HOSTED BY THE Jefferson County Fire and Rescue Training Academy
TACTICS • DO NOT START A FOAM OPERATION IF YOU DO NOT HAVE ENOUGH FOAM. (The fire will not go out and you will just waist foam) • *INSTEAD, ATTEMPT TO PROTECT EXPOSURES OR EVACUATE • IF YOU HAVE AN ETHANOL FIRE, USE AR-FOAM • IF AT A FIXED FACILITY, ASK THE PEOPLE THAT WORK THERE FOR HELP. (They are the experts with the product on fire.)
OBJECTIVES • TERMS • HOW FOAM WORKS • FOAM GENERATION • TYPES OF FOAM • APPLICATION RATES • FOAM EQUIPMENT • PRACTICAL EVOLUTION
What is Foam? • NFPA- 11 describes Foam as an aggregate of air filled bubbles and is lower in density than flammable liquids. • Must be able to- • Flow Freely • Have a high resistance to heat • Fuel tolerance • Form a tough, cohesive blanket • Must hold water
Smothering: prevents release of vapors Foam’s Extinguishing Characteristics Separating: creates a barrier between the fuel and fire Cooling: lowers temperature of the fuel
Limitations of Foam • Foam solution is 94%-97% water • Cannot be used on: • Electrical fires • Three Dimensional Fires • Pressurized Gases • Combustible Metals
Kinds of Foam • Protein • Fluroprotein • Film Forming Protein (FFFP) • Aqueous Film Forming Foam (AFFF) • Alcohol Resistant AFFF (ARFFF)
Aqueous Film Forming Foam (AFFF) • Good penetrating characteristics • Can be used with non-aerating nozzles • Spreads a vapor-sealing film over fuels • Can be pre-mixed • Can be mixed with antifreeze • Good low temperature viscosity May be applied directly on fuel surface, applied indirectly, or used with subsurface injection
Foam Delivery Systems • In-Line Eductors • Around the Pump Eductor • Compressed Air Foam System • By-Pass Line Eductor
In-line Foam Eductors Most commonly usedAttached to pump or at some point in the hose lay The foam concentrate inlet to the inductor must be no more than six feet above the surface of the liquid foam concentrate
Venturi Principle in Eductors As water at a high pressure passes over a reduced opening, it creates a low pressure near the outlet side of the eductor The low pressure creates a suction which draws the foam concentrate into the water stream.
REMEMBER • MATCH NOZZLE TO EDUCTOR • MAINTAIN 200 PSI INLET PRESSURE
HYDRAULICS Back Pressure should not exceed 70% of inlet pressure • Back Pressure=NP+FLH+FLE 250’ of 1.75” and 0’ elevation • FLH= 100 + 30psi + 0= 130 psi • FLE= 70 psi • 130psi + 70 psi= 200 psi
Foam Production • Foam must be proportioned with water and aerated with air to be used effectively • Most fire fighting foams are designed to be mixed at 3% to 6% concentrate in water
Foam & Foam Streams To be effective, foam concentrates must be matched to the fuel to which they are applied
DETERMINE TYPE OF LIQUID • POLAR SOLVENTS- .16 GPM SQ. FT. • HYDROCARBONS - .10 GPM SQ. FT.
HOW MUCH FOAM - NFPA 11 • DETERMINE SQUARE FOOTAGE 10 FT. X 1OO FT.= 1000 SQ. FT. 2. DETERMINE TYPE OF LIQUID POLAR SOLVENT- .16 GPM/SQ. FT. HYDROCARBONS- .10 GPM/SQ.FT.
APPLICATION RATEShydrocarbon fuels 3. DETERMINE AMOUNT OF FOAM CONCENTRATE. 100 GPM X .O3 = 3 Gal. Foam/Min. 4. AMOUNT REQUIRED FOR 15 MIN. 3 GPM X 15 MIN. = 45. Gal of Foam will be required.
APPLICATION RATEShydrocarbon fuels • Determine amount of water needed 100 GPM X .97 = 97 GPM 97 X 15 = 1455 Gallons of Water
Foam Application Methods • Roll – On Method • Bank Down Technique • Rain – Down Method
FOAM APPLICATION • SCBA • SWEEPING MOTION • DO NOT PLUNGE FOAM • DO NOT WALK IN LIQUID • DO NOT TURN YOUR BACK TO FLAMMABLE • DO PRESERVE THE FOAM BLANKET
Causes of Poor Foam Generation • Eductor and Nozzle Mismatch • Too Much Hose between Eductor & Nozzle • Nozzle Elevation • Partially closed Nozzle Shut Off • Kinked Discharge Line
Fuel Mixture comprised of 85% ethanol and 15 % gasoline • Fires should be treated differently than traditional gasoline fires- • These mixtures are polar/water-miscible flammable liquids ( ie- they mix readily with water) • Degrade effectiveness of fire-fighting foam which is not alcohol- resistant • Refer to Guide 127 ( Flammable Liquids Polar/Water Miscible) of 2004 ERG
PRACTICAL FOAM • HOOK-UP EDUCTOR • MAKE SURE NOZZLE MATCHES EDUCTOR • SET METERING DEVICE • SET FLOWING PRESSURE • INSERT PICK-UP TUBE INTO FOAM
DETERMINE AMOUNT OF FOAM CONCENTRATE 600 GPM X .03 = 18 GAL. FOAM MIN.
Fluoroprotein Foam • Good water-retention capabilities W Excellent heat resistance W Not affected by freezing & thawing W Can be mixed with antifreeze W Good fluidity on fuel surface
Protein Foam W Excellent water-retention capabilitiesW High heat resistance and re-ignition resistanceW Performance can be affected by freezing and thawingW Can be mixed with antifreeze W Can be made resistant to alcohol Do not allow foam to plunge into burning liquids.