QA September 2001 Fire Topic

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QA September 2001Fire Topic

• Fire Stream Practices

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Fire Extinguishment Theory

• Temperature Reduction usually by applying water
• Fuel Removal
• stop fuel from being added
• remove fuel from path of fire
• Oxygen Exclusion or Dilution
• introduce inert gas carbon dioxide, nitrogen
• separate or smother steam, foam
• Inhibiting Chemical Reaction
• Dry chemicals, halons, etc. interrupt flame
  production.
• most effective on liquid and gas fuels

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Compatibility

• Determine the extinguishing method or
  extinguishing agent compatible with the material
  involved.

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Characteristics of Water

• Molecule of two parts hydrogen and one part
  oxygen
• Solid (ice) _at_lt 32 degrees (freezing point)
• Liquid (water) _at_ 32 to 212 degrees (boiling
  point)
• Gas (water vapor or steam) _at_ gt 212 degrees
• Practically incompressible
• Weight approximately 62.5 lb/ft3
• Absorbs large amounts of heat by 2 laws of
  physics
• Law of specific heat heat-absorbing capacity of
  a substance (water is given a value of 1.00)
• Latent Heat of Vaporization heat absorbed during
  vaporization

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Advantages of Water as Agent

• Great heat absorption capacity
• Readily available
• Inexpensive
• 1,7001 vaporization expansion ratio

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Disadvantages of Water

• High surface tension
• Reactivity with certain materials
• Can freeze
• Low viscosity
• Electrically conductive
• Heavy

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6 Principles of Pressure

• Fluid pressure is perpendicular to any surface.
• Fluid pressure at a point in a fluid at rest is
  the same intensity in all directions.
• Pressure applied to a confined liquid from
  without is transmitted equally in all directions.
• The pressure of a liquid in an open vessel is
  proportional to its depth.

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6 Principles of Pressure (cont.)

• The pressure of a liquid in an open vessel is
  relative to its density
• The shape of a vessel is irrelevant to the
  pressure of the liquid.

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Types of Pressure

• Atmospheric the pressure applied to the surface
  by the Earths atmosphere (14.7 psi _at_ sea level)
• Head height of a water supply above discharge
• Static pressure in a water system before water
  flows from a hydrant
• Normal Operating pressure in water distribution
  system during normal consumption demands
• Residual pressure remaining after overcoming
  gravity and friction loss when forcing water
  through pipe, fittings, fire hose, and appliances

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Types of Pressure (cont)

• Flow / Velocity forward force pressure at a
  discharge opening while flowing water
• Elevation Loss and Gain
• nozzle above pump pressure loss
• nozzle below pump pressure gain
• 0.434 psi per foot

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Principles of Friction Loss

• Friction Loss portion of total pressure lost
  while forcing water through pipe, fittings, fire
  hose, etc.
• varies with length of hose
• varies with velocity (if flow doubles, FL
  quadruples)
• varies with hose diameter
• FL same, regardless of pressure
• Critical Velocity turbulent agitation created
  when velocity limits are exceeded
• Water Hammer damaging energy surge created when
  water is suddenly stopped

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Fire Stream a stream of water or water-based
extinguishing agent from the time it leaves the
nozzle until it reaches the desired point.

• The condition and effectiveness of the stream is
  influenced by
• design, adjustment, and condition of the nozzle
• operating pressure
• velocity
• gravity
• wind
• friction with the air

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Fire Stream Production4 basic elements

• Water Supply
• Static Supply lakes, rivers, swimming pools,
  portable tanks, etc. (Where are the drafting
  locations in your run districts?)
• Apparatus Water Tanks (What is the capacity of
  your booster tank?)
• Pressurized Distribution System (Do you know the
  hydrant capacity color-coding system?)

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Fire Stream Production4 basic elements (cont.)

• Fire Department Pumper receives water supply and
  increases pressure to required level for an
  effective production of fire streams (What is the
  rated capacity of your engine?)

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Fire Stream Production4 basic elements (cont.)

• Fire Equipment
• Hose (What sizes and lengths are on your engine?)
• Nozzles forms and shapes the stream
• Appliances wyes, siameses, manifolds, double
  couplings, water thieves, etc.
• Hardware spanner wrenches, hose straps, hose
  bridges, etc.

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Fire Stream Production4 basic elements (cont.)

• Trained Personnel The best supply, apparatus,
  and equipment will not produce effective fire
  streams without well trained personnel.

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Sizes Types of Fire StreamsFire Streams are
identified by size and type.

• Size stream volume in gallons per minute (GPM)
• Handline 40 GPM to 350 GPM
• Master Stream gt350 GPM
• Type stream shape or pattern
• Solid Produced by a smoothbore, fixed-orifice
  nozzle (long range/ high volume). The stream must
  maintain continuity, must shoot 9/10ths through a
  15 circle and 3/4ths through a 10 circle, must
  attain height in moderate wind.

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Types of Fire Streams (cont.)

• Solid (cont.) The flow rate and the reach depend
  upon the velocity (discharge pressure) and the
  diameter of the nozzle orifice. At equal
  pressure, doubling the nozzle size will quadruple
  the GPM. The maximum horizontal reach is achieved
  at 32 degrees. The optimum vertical reach is at
  70 to 75 degrees.
• Fog Stream varied pattern stream, composed of
  water droplets/ from wide (45-80 degrees), to
  narrow (15-45 degrees), to straight.

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Types of Fire Streams (cont.)

• Broken Streams
• produced by special stream nozzles (water
  curtains, rotary distributor, spoon billed, etc.)
  or by directing two solid streams together
• do not have a specific pattern
• composed of large drops
• usually not adjustable
• for fires in attics, basements, partitions, etc.
• increased water damage should be expected

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Types of Nozzles

• Solid Stream Nozzles
• Fog Stream Nozzles
• Handline Nozzles
• Master Stream Nozzles
• Special Purpose Nozzles

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Foam Fire Streams

• Foam concentrate is added to a water fire stream
  using a proportioning device, which creates a
  foam solution
• Air is added to the solution, which creates the
  finished foam
• Effective on flammable liquids, hazardous
  materials spills, confined space fires, bulk
  class A fires

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Foam Fire Stream Production

• 1. Choose appropriate foam concentrate
• 2. Use hydraulically compatible eductor and
  nozzle
• 3. Set eductor to proper concentration percentage
• 4. Attach eductor, attack hose, and nozzle to
  pump
• 5. Assemble sufficient foam concentrate at
  eductor
• 6. Place eductor suction hose in concentrate
• 7. Increase water pressure to eductor
  specifications
• 8. Apply finished foam

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PP NP FL EL

• PP Pump Pressure
• NP Nozzle Pressure
• know the manufacturers specifications
• FL Friction Loss
• determined by field tests or by calculations
• includes hose and appliances
• EL Elevation Loss
• approximately 0.5 psi/ft (vertically)

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2FL CQ L A

• C Coefficient specific to hose construction
• Q Quantity of water in hundreds of gpm
• L Length of hose in hundreds of feet
• A Appliances siameses, wyes, master stream
  devices, etc.

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Strategic Objectives( in order of importance)

• Rescue direct streams to protect victims and
  rescuers
• Exposure Protection nearby combustibles
• Interior areas of the fire building not involved
• Exterior adjacent buildings
• Confinement coordinate streams and ventilation
  to attack and contain the fire
• Extinguish apply sufficient streams to seat of
  fire to reduce heat and heat production

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Types of Attack

• Offensive direct interior attack
• greatest risk to firefighters
• IC must weigh fire and building conditions, life
  hazards, and building construction type
• must be coordinated with ventilation efforts
• attack crews must understand the principles of
  fire spread
• streams must be of adequate size and appropriate
  type to achieve the tactical objectives

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Types of Attack (cont.)

• Defensive goal is to contain fire to building
  involved (written off)
• used when available fire flow is insufficient or,
• structure is obviously lost, regardless of flow,
  or
• repeated interior attacks have failed, or
• structural stability is compromised, or
• interior crews safety is questionable
• Direct streams to protect last-minute rescue and
  interior attack crews egress

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Types of Attack (cont.)

• Defensive (cont.)
• concentrate on protecting exposures
• remove apparatus, crews, appliances, and hose
  lines from collapse zone
• attack fire from outside with monitors and
  elevated master streams