Presentation on theme: "QA September 2001 Fire Topic"— Presentation transcript:
1QA September 2001 Fire Topic Fire Stream Practices
2Fire Extinguishment Theory Temperature Reduction: usually by applying waterFuel Removal:stop fuel from being addedremove fuel from path of fireOxygen Exclusion or Dilutionintroduce inert gas: carbon dioxide, nitrogenseparate or smother: steam, foamInhibiting Chemical ReactionDry chemicals, halons, etc. interrupt flame production.most effective on liquid and gas fuels
3CompatibilityDetermine the extinguishing method or extinguishing agent compatible with the material involved.
4Characteristics of Water Molecule of two parts hydrogen and one part oxygenSolid 32 degrees (freezing point)Liquid 32 to 212 degrees (boiling point)Gas (water vapor or > 212 degreesPractically incompressibleWeight: approximately 62.5 lb/ft3Absorbs 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
5Advantages of Water as Agent Great heat absorption capacityReadily availableInexpensive1,700:1 vaporization expansion ratio
6Disadvantages of Water High surface tensionReactivity with certain materialsCan freezeLow viscosityElectrically conductiveHeavy
76 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.
86 Principles of Pressure (cont.) The pressure of a liquid in an open vessel is relative to its densityThe shape of a vessel is irrelevant to the pressure of the liquid.
9Types of PressureAtmospheric: the pressure applied to the surface by the Earth’s atmosphere (14.7 sea level)Head: height of a water supply above dischargeStatic: pressure in a water system before water flows from a hydrantNormal Operating: pressure in water distribution system during normal consumption demandsResidual: pressure remaining after overcoming gravity and friction loss when forcing water through pipe, fittings, fire hose, and appliances
10Types of Pressure (cont) Flow / Velocity: forward force pressure at a discharge opening while flowing waterElevation Loss and Gain:nozzle above pump = pressure lossnozzle below pump = pressure gain0.434 psi per foot
11Principles of Friction Loss Friction Loss: portion of total pressure lost while forcing water through pipe, fittings, fire hose, etc.varies with length of hosevaries with velocity (if flow doubles, FL quadruples)varies with hose diameterFL same, regardless of pressureCritical Velocity: turbulent agitation created when velocity limits are exceededWater Hammer: damaging energy surge created when water is suddenly stopped
12Fire 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 nozzleoperating pressurevelocitygravitywindfriction with the air
13Fire Stream Production 4 basic elements: Water SupplyStatic 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?)
14Fire Stream Production 4 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?)
15Fire Stream Production 4 basic elements: (cont.) Fire EquipmentHose (What sizes and lengths are on your engine?)Nozzles: forms and shapes the streamAppliances: wyes, siameses, manifolds, double couplings, water thieves, etc.Hardware: spanner wrenches, hose straps, hose bridges, etc.
16Fire Stream Production 4 basic elements: (cont.) Trained Personnel: The best supply, apparatus, and equipment will not produce effective fire streams without well trained personnel.
17Sizes & Types of Fire Streams Fire Streams are identified by size and type. Size: stream volume in gallons per minute (GPM)Handline: 40 GPM to 350 GPMMaster Stream: >350 GPMType: stream shape or patternSolid: 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.
18Types 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.
19Types of Fire Streams (cont.) Broken Streamsproduced by special stream nozzles (water curtains, rotary distributor, spoon billed, etc.) or by directing two solid streams togetherdo not have a specific patterncomposed of large dropsusually not adjustablefor fires in attics, basements, partitions, etc.increased water damage should be expected
20Types of Nozzles Solid Stream Nozzles Fog Stream Nozzles Handline NozzlesMaster Stream NozzlesSpecial Purpose Nozzles
21Foam Fire StreamsFoam concentrate is added to a water fire stream using a proportioning device, which creates a foam solutionAir is added to the solution, which creates the finished foamEffective on flammable liquids, hazardous materials spills, confined space fires, bulk class A fires
22Foam Fire Stream Production 1. Choose appropriate foam concentrate2. Use hydraulically compatible eductor and nozzle3. Set eductor to proper concentration percentage4. Attach eductor, attack hose, and nozzle to pump5. Assemble sufficient foam concentrate at eductor6. Place eductor suction hose in concentrate7. Increase water pressure to eductor specifications8. Apply finished foam
23PP = NP + FL + EL PP: Pump Pressure NP: Nozzle Pressure know the manufacturer’s specificationsFL: Friction Lossdetermined by field tests or by calculationsincludes hose and appliancesEL: Elevation Lossapproximately 0.5 psi/ft (vertically)
24C = Coefficient specific to hose construction 2 FL = CQ L + AC = Coefficient specific to hose constructionQ = Quantity of water in hundreds of gpmL = Length of hose in hundreds of feetA = Appliances: siameses, wyes, master stream devices, etc.
25Strategic Objectives ( in order of importance) Rescue: direct streams to protect victims and rescuersExposure Protection: nearby combustiblesInterior: areas of the fire building not involvedExterior: adjacent buildingsConfinement: coordinate streams and ventilation to attack and contain the fireExtinguish: apply sufficient streams to seat of fire to reduce heat and heat production
26Types of Attack Offensive: direct interior attack greatest risk to firefightersIC must weigh fire and building conditions, life hazards, and building construction typemust be coordinated with ventilation effortsattack crews must understand the principles of fire spreadstreams must be of adequate size and appropriate type to achieve the tactical objectives
27Types 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, orrepeated interior attacks have failed, orstructural stability is compromised, orinterior crews’ safety is questionableDirect streams to protect last-minute rescue and interior attack crews’ egress
28Types of Attack (cont.) Defensive (cont.): concentrate on protecting exposuresremove apparatus, crews, appliances, and hose lines from collapse zoneattack fire from outside with monitors and elevated master streams