Presentation on theme: "QA September 2001 Fire Topic Fire Stream Practices."— Presentation transcript:
QA September 2001 Fire Topic Fire Stream Practices
Home Fire Extinguishment Theory n Temperature Reduction: usually by applying water n Fuel Removal: – stop fuel from being added – remove fuel from path of fire n Oxygen Exclusion or Dilution – introduce inert gas: carbon dioxide, nitrogen – separate or smother: steam, foam n Inhibiting Chemical Reaction – Dry chemicals, halons, etc. interrupt flame production. – most effective on liquid and gas fuels
Home Compatibility n Determine the extinguishing method or extinguishing agent compatible with the material involved.
Home Characteristics of Water n Molecule of two parts hydrogen and one part oxygen n Solid 32 degrees (freezing point) n Liquid 32 to 212 degrees (boiling point) n Gas (water vapor or > 212 degrees n Practically incompressible n Weight: approximately 62.5 lb/ft3 n 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
Home Advantages of Water as Agent n Great heat absorption capacity n Readily available n Inexpensive n 1,700:1 vaporization expansion ratio
Home Disadvantages of Water n High surface tension n Reactivity with certain materials n Can freeze n Low viscosity n Electrically conductive n Heavy
Home 6 Principles of Pressure n Fluid pressure is perpendicular to any surface. n Fluid pressure at a point in a fluid at rest is the same intensity in all directions. n Pressure applied to a confined liquid from without is transmitted equally in all directions. n The pressure of a liquid in an open vessel is proportional to its depth.
Home 6 Principles of Pressure (cont.) n The pressure of a liquid in an open vessel is relative to its density n The shape of a vessel is irrelevant to the pressure of the liquid.
Home Types of Pressure n Atmospheric: the pressure applied to the surface by the Earths atmosphere (14.7 sea level) n Head: height of a water supply above discharge n Static: pressure in a water system before water flows from a hydrant n Normal Operating: pressure in water distribution system during normal consumption demands n Residual: pressure remaining after overcoming gravity and friction loss when forcing water through pipe, fittings, fire hose, and appliances
Home Types of Pressure (cont) n Flow / Velocity: forward force pressure at a discharge opening while flowing water n Elevation Loss and Gain: – nozzle above pump = pressure loss – nozzle below pump = pressure gain – psi per foot
Home Principles of Friction Loss n 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 n Critical Velocity: turbulent agitation created when velocity limits are exceeded n Water Hammer: damaging energy surge created when water is suddenly stopped
Home Fire Stream: a stream of water or water-based extinguishing agent from the time it leaves the nozzle until it reaches the desired point. n 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
Home Fire Stream Production 4 basic elements: n 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?)
Home Fire Stream Production 4 basic elements: (cont.) n 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?)
Home Fire Stream Production 4 basic elements: (cont.) n 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.
Home Fire Stream Production 4 basic elements: (cont.) n Trained Personnel: The best supply, apparatus, and equipment will not produce effective fire streams without well trained personnel.
Home Sizes & Types of Fire Streams Fire Streams are identified by size and type. n Size: stream volume in gallons per minute (GPM) – Handline: 40 GPM to 350 GPM – Master Stream: >350 GPM n 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.
Home 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.
Home Types of Fire Streams (cont.) – Broken Streams n produced by special stream nozzles (water curtains, rotary distributor, spoon billed, etc.) or by directing two solid streams together n do not have a specific pattern n composed of large drops n usually not adjustable n for fires in attics, basements, partitions, etc. n increased water damage should be expected
Home Types of Nozzles n Solid Stream Nozzles n Fog Stream Nozzles n Handline Nozzles n Master Stream Nozzles n Special Purpose Nozzles
Home Foam Fire Streams n Foam concentrate is added to a water fire stream using a proportioning device, which creates a foam solution n Air is added to the solution, which creates the finished foam n Effective on flammable liquids, hazardous materials spills, confined space fires, bulk class A fires
Home 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
Home PP = NP + FL + EL n PP: Pump Pressure n NP: Nozzle Pressure – know the manufacturers specifications n FL: Friction Loss – determined by field tests or by calculations – includes hose and appliances n EL: Elevation Loss – approximately 0.5 psi/ft (vertically)
Home 2 FL = CQ L + A n C = Coefficient specific to hose construction n Q = Quantity of water in hundreds of gpm n L = Length of hose in hundreds of feet n A = Appliances: siameses, wyes, master stream devices, etc.
Home Strategic Objectives ( in order of importance) n Rescue: direct streams to protect victims and rescuers n Exposure Protection: nearby combustibles – Interior: areas of the fire building not involved – Exterior: adjacent buildings n Confinement: coordinate streams and ventilation to attack and contain the fire n Extinguish: apply sufficient streams to seat of fire to reduce heat and heat production
Home Types of Attack n 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
Home Types of Attack (cont.) n 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
Home Types of Attack (cont.) n 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