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Fire Streams. Geronimo Vol. Fire Dept. Extinguishing Properties of Water. Water extinguishes fires by Cooling Remove heat from the fire Smothering Absorb large quantities of heat Dilute oxygen. Heat Absorption.
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Fire Streams Geronimo Vol. Fire Dept.
Extinguishing Properties of Water • Water extinguishes fires by • Cooling • Remove heat from the fire • Smothering • Absorb large quantities of heat • Dilute oxygen
Heat Absorption • Small particles absorb heat and converts into steam more rapidly than a compact form • Example - same cubes of ice melt faster then large cube of ice • Fog stream verse straight stream
Water’s Expansion Capability • At 212 F water expands approximately 1,700 times its original volume when converted to stream • Example - If a nozzle discharges 150 gallons a minute, 20 cubic feet of water will be created. At 500 F that will convert into 48,000 cubic feet of steam. This will fill a room 50 feet wide by 96 feet long
Water’s Expansion Capability • Steam will displace smoke and gases and mess up the thermal balance. • Insure that adequate ventilation is available • If ventilation is adequate • Fire will be extinguished or reduced in size • Visibility may be maintained • Room temperature is reduced
Important Characteristics of Water • Readily available and inexpensive • Water has a greater heat-absorbing capacity than other common extinguishing agents • Water changing into steam requires a relatively large amount of heat • The greater the surface area of the water exposed, the more rapidly heat is absorbed
Pressure Loss/Gain • Pressure Loss and Gain are effected by • Friction loss • Elevation • Friction loss is caused by • Hoses (length and diameter) • Nozzles • Adapters • Elevation • If nozzle is above the pump pressure is lost • If nozzle is below the pump pressure is gained
Water Hammer • Water hammer is the sudden stoppage of water through fire hose or pipe • This can damage water mains, plumbing, fire hose, hydrants, valves, and hose clamps • Close valves and nozzles slowly to prevent water hammers
Water Fire Stream Patterns and Nozzles • Low-volume streams • Less then 40 gpm (booster hoselines) • Handline streams • 40 to 350 gpm (1 1/2 to 3 in hose) • Master streams • 350 gpm + (multiple 2 1/2 or 3 in hoses)
Water Fire Stream Patterns and Nozzles • Solid Stream • Produced from a fixed orifice, smoothbore nozzle • Long reach • Penetration • 50 psi at the nozzle for handlines • 80 psi at the nozzle for master streams • No foam
Water Fire Stream Patterns and Nozzles • Fog Stream • Composed of very fine water droplets • Settings • Straight streams • Narrow-angle fog (15 to 45) • Wide-angle fog (45 to 80) • Operate at the set nozzle pressure • Used mainly for interior attacks
Factors That Affect Reach • Gravity • Water velocity • Fire stream pattern selection • Water droplet friction with air • Wind
Fog Nozzles • Manually adjustable nozzles • You set the gpm on the nozzle • Automatic nozzles • Pressure from the pump determines the gpm
Fog Nozzle Advantages • Dissipate more heat then solid stream nozzles due to greater water surface area • Aids in ventilation • Adjustable pattern
Maintenance of Nozzles • Check the swivel gasket for damage or wear • Look for external damage • Look for internal damage and debris • Check for ease of operation by physically operating the nozzle parts • Check to make sure that the pistol grip is secure
Foam • Foam extinguishes and/or prevents fire by • Separating • Creates a barrier between the fuel and the fire • Cooling • Lowers the temp. of the fuel and adjacent surfaces • Suppressing • Prevents the release of flammable vapors and therefore reduces the possibility of ignition or reignition
Class A Foam • Used on ordinary combustibles • Wildland and structure fires • May be proportioned as needed • From a dry (thick) foam to a wet (thin) foam
Class B Foam • Used to help extinguish hydrocarbon fuel fires • Oil, fuel oil, gasoline, benzene, naphtha, jet fuel, and kerosene • Floats on top of the fuel • Traps vapors in • Keeps oxygen out • Proportion is per manufacturer’s recommendations • Normally 3 to 6 percent
Proportioning • Four methods • Induction • Injection • Batch-mixing • Premixing
Foam Application Techniques • Roll-On Method • Stray foam at the front edge of the burning fuel • Bank-Down Method • Stray foam on an elevated object in the fuel • Rain-Down Method • Stray foam in the air above the fuel and let it rain down