Fire Streams

Fire StreamsIntermediateSFFMA Objectives: 6-02.01 6-02.068Hrs ReceivedMethods to Reduce Heat and Provide Protection Applying water or foam directly onto burning material to reduce its temperatureApplying water or foam over an open fire to reduce the temperature so firefighters can advance handlinesReducing high atmospheric temperature

Firefighter I142(Continued)Methods to Reduce Heat and Provide Protection Dispersing hot smoke and fire gases from a heated areaCreating a water curtain to protect firefighters and property from heatCreating a barrier between a fuel and a fire by covering the fuel with a foam blanket Firefighter I143How Water Extinguishes FirePrimary way is coolingSmothering by diluting or excluding oxygenFirefighter I144Heat AbsorptionWhen heated to boiling point, water absorbs heatVisible form of steam is called condensed steamComponents of heat absorptionSpecific heatFirefighter I145(Continued)Heat AbsorptionLatent heat of vaporizationExpansion capabilityEffective extinguishment with water generally requires steam productionFirefighter I146(Continued)

Heat AbsorptionWater absorbs more heat when converted to steam than when heated to boiling pointFirefighter I147

Characteristics of Water Valuable for Fire ExtinguishmentReadily available, relatively inexpensiveHas greater heat-absorbing capacity than most other common agentsWater changing to steam requires large amount of heatCan be applied in variety of waysFirefighter I148Solid StreamProduced from fixed orifice, solid-bore nozzleHas ability to reach areas others might not; reach affected by several factorsDesign capabilitiesFirefighter I149(Continued)

Solid StreamVelocity of stream a result of nozzle pressureNozzle pressure, size of discharge opening determine flowCharacteristics of effective fire streamsFlow rateFirefighter I1410Advantages of Solid StreamsMay maintain better interior visibility than othersMay have greater reach than othersOperate at reduced nozzle pressures per gallon (liter) than othersMay be easier to maneuverFirefighter I1411(Continued)Advantages of Solid StreamsHave greater penetration powerLess likely to disturb normal thermal layering of heat, gases during interior structural attacksLess prone to clogging with debrisFirefighter I1412(Continued)Advantages of Solid StreamsProduce less steam conversion than fog nozzlesCan be used to apply compressed-air foamFirefighter I1413Disadvantages of Solid StreamsDo not allow for different stream pattern selectionsProvide less heat absorption per gallon (liter) delivered than othersHoselines more easily kinked at corners, obstructionsFirefighter I1414DISCUSSION QUESTIONWhat type of fire situation would be ideal for a solid-stream nozzle?

Firefighter I1415

Fog StreamFine spray composed of tiny water dropletsDesign of most fog nozzles permits adjustment of tip to produce different stream patternsFirefighter I1416(Continued)

Fog StreamWater droplets formed to expose maximum water surface for heat absorptionDesired performance of fog stream nozzles judged by amount of heat that fog stream absorbs and rate by which the water is converted into steam/vaporFirefighter I1417(Continued)Fog StreamNozzles permit settings of straight stream, narrow-angle fog, and wide-angle fogNozzles should be operated at designed nozzle pressure

Firefighter I1418(Continued)Fog StreamSeveral factors affect reach of fog streamInteraction of these factors on fog stream results in fire stream with less reach than that of straight or solid streamFirefighter I1419(Continued)Fog StreamShorter reach makes fog streams less useful for outside, defensive fire fighting operationsWell suited for fighting interior firesFirefighter I1420Fog Stream: Waterflow AdjustmentTwo types of nozzles control rate of water flow through fog nozzleManually adjustable nozzlesAutomatic nozzlesFirefighter I1421

DISCUSSION QUESTIONHow should adjustments to the rate of flow be made?

Firefighter I1422

Fog Stream: Nozzle PressureCombination nozzles designed to operate at different pressuresDesignated operating pressure for most combination nozzles is 100 psi (700 kPa)

Firefighter I1423(Continued)Fog Stream: Nozzle PressureNozzles with other designated operating pressures availableSetbacks of nozzles with lower operating pressuresFirefighter I1424

Courtesy of Elkhart Brass Manufacturing Company.Advantages of Fog StreamsDischarge pattern can be adjusted for situationCan aid ventilationReduce heat by exposing maximum water surface for heat absorptionWide fog pattern provides protection to firefightersFirefighter I1425Disadvantages of Fog StreamsDo not have as much reach/penetrating power as solid streamsMore affected by wind than solid streamsMay disturb thermal layering May push air into fire area, intensifying the fireFirefighter I1426Ways Fire Fighting Foam Extinguishes/Prevents FireSeparatingCoolingSmotheringPenetratingFirefighter II1427

Terms Associated With FoamFoam concentrateFoam proportionerFoam solutionFoam (finished foam)Firefighter II1428How Foam is GeneratedFoams used today are of mechanical type and before use must beProportionedAeratedFirefighter II1429(Continued)How Foam is GeneratedElements needed to produce fire fighting foamFoam concentrateWaterAirMechanical agitation

Firefighter II1430(Continued)

How Foam is GeneratedAll elements must be present and blended in correct ratiosAeration produces foam bubbles to form effective foam blanketFirefighter II1431Foam ExpansionThe increase in volume of foam when aeratedMethod of aerating results in varying degrees of expansionTypes of foam

Firefighter II1432Foam Concentrates General ConsiderationsFoam concentrates must match fuel to which appliedClass A foams not designed to extinguish Class B firesClass B foams designed solely for hydrocarbon fires will not extinguish polar solvent firesFirefighter II1433Class A FoamIncreasingly used in both wildland and structural fire fighting

Firefighter II1434(Continued)

Class A FoamSpecial formulation of hydrocarbon surfactants Aerated Class A foam coats, insulates fuels, preventing pyrolysis and ignitionMay be used with variety of nozzlesFirefighter II1435Class B FoamUsed to prevent ignition of or extinguish fires involving flammable and combustible liquidsFirefighter II1436(Continued)

Courtesy of Williams Fire & Hazard Control, Inc.Class B FoamFirefighter II1437Used to suppress vapors from unignited spills of these liquidsSeveral types of Class B foam concentrates available

(Continued)

Class B FoamManufactured from synthetic or protein baseMay be proportioned into the fire stream through fixed system, apparatus-mounted system, or by portable foam proportioning equipment

Firefighter II1438(Continued)Class B FoamFoams such as AFFF and FFFP foam may be applied with standard fog nozzles or air-aspirating foam nozzles

Firefighter II1439(Continued)

Courtesy of Harvey Eisner.Class B FoamRate of application depends on several factors Unignited spills do not require same application rates as ignited spillsTo be most effective, blanket of foam 4 inches (100 mm) thick should be applied to fuel surfaceFirefighter II1440Specific Application FoamsNumerous types of foam available for specific applicationsProperties of foams varyFirefighter II1441ProportioningMixing of water with foam concentrate to form foam solutionMost concentrates can be mixed with fresh/salt waterFirefighter II1442(Continued)

ProportioningFor maximum effectiveness, foam concentrates must be proportioned at designated percentageMost fire fighting foams intended to be mixed with 94 to 99.9 percent waterFirefighter II1443

(Continued)ProportioningFirefighter II1444

Proportioning MethodsInduction

InjectionFirefighter II1445

(Continued)Proportioning MethodsBatch-mixing

Premixing

Firefighter II1446

Courtesy of Ansul.Firefighter II1447DISCUSSION QUESTIONWhat proportion methods does your department use?

Foam Proportioners General ConsiderationsMay be portable or apparatus-mountedOperate by one of two basic principlesFirefighter II1448Courtesy of Conoco/Phillips.

Portable Foam ProportionersSimplest, most common form of proportioning devicesIn-line foam eductorsFoam nozzle eductorsFirefighter II1449

Apparatus-Mounted ProportionersMounted on structural, industrial, wildland, and aircraft rescue and fire fighting apparatus, as well as on fire boatsThree typesFirefighter II1450

Firefighter II1451DISCUSSION QUESTIONWhat is the advantage of an apparatus-mounted proportioner?

Compressed-Air Foam Systems (CAFS)Newer structural engines are equipped with CAFSFirefighter II1452(Continued)

Compressed-Air Foam Systems (CAFS)Standard centrifugal pump supplies water, direct-injection foam-proportioning system mixes foam solution with water on discharge side of pump, onboard air compressor adds air to mix before discharging from engineFirefighter II1453(Continued)Compressed-Air Foam Systems (CAFS)Unlike other systems, hoseline contains finished foamAdvantagesDisadvantagesFirefighter II1454Handline NozzlesSolid-bore nozzlesFog nozzlesAir-aspirating foam nozzlesFirefighter II1455

Medium- and High-Expansion Foam Generating DevicesProduce foam that is semistable with high air contentMedium-expansion foamHigh-expansion foamWater-aspirating type nozzleMechanical blower generatorFirefighter II1456

Reasons for Poor-Quality Foam/Failure to Generate FoamEductor, nozzle flow ratings do not match so foam concentrate cannot induct into fire streamAir leaks at fittings cause loss of suction

Firefighter II1457(Continued)Reasons for Poor-Quality Foam/Failure to Generate FoamImproper cleaning of proportioning equipment causes clogged foam passagesNozzle not fully open, restricting water flow

Firefighter II1458(Continued)

Reasons for Poor-Quality Foam/Failure to Generate FoamHose lay on discharge side of eductor is too longHose is kinked and stops flow Nozzle is too far above eductorFirefighter II1459(Continued)Reasons for Poor-Quality Foam/Failure to Generate FoamMixing different types of foam concentrate in same tank results in mixture too viscous to pass through eductor

Firefighter II1460Roll-On Foam Application MethodDirects foam stream on ground near front edge of burning liquid spillFoam rolls across surface of fuelFirefighter II1461(Continued)

Roll-On Foam Application MethodFirefighters continue to apply foam until spreads across entire surface of fuel and fire extinguishedUsed only on pool of liquid fuel on open groundFirefighter II1462Bank-Down Foam Application MethodMay be employed when elevated object is near/within area of burning pool of liquid or unignited liquid spillObject may be wall, tank shell, similar vertical structure

Firefighter II1463(Continued)

Bank-Down Foam Application MethodFoam stream directed onto object, allowing foam to run down onto surface of fuelUsed primarily in dike fires, fires involving spills around damaged/overturned transport vehiclesFirefighter II1464Rain-Down Foam Application MethodUsed when other two methods not feasible because of size of spill area or lack of object from which to bank foamFirefighter II1465(Continued)

Rain-Down Foam Application MethodPrimary manual application technique on aboveground storage tank firesDirects stream into air above fire/spill, allows foam to float gently down onto surface of fuelFirefighter II1466Firefighter II1467DISCUSSION QUESTIONWhat are some examples of when each of these techniques should be used?

Foam Hazards to HumansFoam concentrates pose minimal health risks to humansMay be mildly irritating to skin, eyes

Firefighter II1468(Continued)Foam Hazards to HumansAffected areas should be flushed with waterSome concentrates, vapors may be harmful if ingested/inhaledConsult MSDS for specific informationFirefighter II1469Foam Hazards to EquipmentMost Class A, Class B foam concentrates are mildly corrosiveFollow proper flushing procedures to prevent damageFirefighter II1470Foam Hazards to EnvironmentPrimary impact is effect of finished foam after application to fire/liquid spillBiodegradability of foam determined by rate at which environmental bacteria cause decompositionFirefighter II1471(Continued)Foam Hazards to EnvironmentEnvironmental impact of foam concentrates variesIn the U.S., Class A foams should be approved by USDA Forest ServiceFirefighter II1472(Continued)Foam Hazards to EnvironmentChemical properties of Class B foams and environmental impact vary on type and manufacturerProtein-based foams safer for environmentFirefighter II1473(Continued)