Firefighting Foam - Technical

1 LIBRARY.{~..~!.,.,':'-$t~~,,,,,,.,,,;, ,<..'FIRt8Ef(\} , ~chnicalVolume1 FireServiceTechnology,EquipmentandMediaH MFireServiceInspectoratePublicationsSect ionLondon:TheStationeryOfficeFireService ManualIssuedundertheauthorityoftheHomeOf fice(FireandEmergencyPlanningDirectorate )TheFireServiceCollege*0 0 0 7 2 o'tFIRESERVICECOLLEGELIBRARY&INFORMAnONR ESOURCECENTRERETURNORRENEWON,ORBEFORE,TH ELASTDATESTAMPEDBELOW(2 RENEWALSMAX.)FINESAREPAYABLEONANYITEMSRE TURNEDLATE CrownCopyright2000 PublishedwiththepermissionoftheHomeOffic eonbehalfoftheControllerofHerMajesty'sSt ationeryOfficeApplicationsforreproductio nshouldbemadeinwritingtoTheCopyrightUnit ,HerMajesty'sStationeryOffice, ,2-16 Colegate,NorwiCh,NR3 IBQF irefightingTechnicalPrefaceoam-ISBNO1134 1188 XCoverphotograph:TheFireExperimentationU nitHalf-titlepagephotograph:WestMidlands FireBrigadePrintedintheUnitedKingdomforT heStationeryOfficeTJ7634/00C505673 Thismanual,Volume1,FireServiceTechnology ,EquipmentandMedia-FirefightingFoam,deal swith technicalaspectsoffoamconcentrates, -FireServiceOperations- :TheManualofFiremanshipBook3,Part3 DearChiefFireOfficerLetter2 ,inparticular:MrBryanJohnsonBSc.)

2 ;HomeOfficeFireExperimentalUnit;MidandWe stWalesFireBrigade;AngusFireArmourLtd;Wi lliamsFireandHazardControlInc.;CivilAvia tionAuthority;BritishFireProtectionAssoc iationLtd;CheshireFireBrigade;LondonFire Brigade;FireServiceCollege;DrTonyCash; ,April2000 FirejighfingFoam-Technical111[------~ ,MediumandHighExpansionFinishedFoams6 Chapter2 FoamConcentrate' (a)Protein(P)8(b)Fluoroprotein(FP)9(c)Fi lm-formingFluoroprotein(FFFP) (a)SyntheticDetergent(SYNDET)9(b)Aqueous Film-formingFoam(AFFF) (AFFF-ARandFFFP-AR) [ (RelativeDensity) (acidity/alkalinity) (Sludge) theFuel? (a)SpecificGravity(RelativeDensity)(b)pH (Acidity/Alkalinity)(c)Sediment(Sludge)( d) (a)HowTheyWork(b) 'Snap-on' (a)General(b)DistributionManifold(c)Mete ringDevices(d)InlineFoamInjection(Pelton Wheel)(e)Pre-inductionUnits(f) (a)General(b)Premix(c)Round-the-pump(d)I njectionintoPumpInlet(e)In-lineInductors (f)SuggestionsforanOperationalRequiremen tfora (CAFS) (Base) (a)P(b)FP(c)FFFP(d)Synthetic(SYNDET)(e)A FFF(f)AlcoholResistantFoamConcentrates(A FFF-ARandFFFP-AR) Fires(a)General(b)HighFlashPointWater-im miscibleClassBLiquids(c)LowFlashPointWat er-immiscibleClassBLiquids(d)]]

3 Water-miscibleClassB FirefightingFoams69696970707171727272e72 727273737374747S757575757577777778798081 VU1 FireServiceManualI------------Firefighti ngFoam-TechnicalChapterChapter1 ,specialfirefightingfoams,generallyknown as'alcoholresistant'foamcon-centrates, :Somefirefightingfoamshavealsobeendevelo pedspecificallyforuseagainstclassA fires. Knockdownandextinction:theabilityofthefi nishedfoamtocontrolandextinguishfires. Expansion:theamountoffinishedfoamproduce dfroma :theabilityofthefin-ishedfoam,onceformed onthefuel,tostayintactwhensubjectedtohea tand/orflame. Stability:theabilityofthefinishedfoamtor etainitsliquidcontentandtomaintainthenum ber, ,itsabilitytoremainintact. Sealingandresealing:theabilityofthefoamb lankettoresealshouldbreaksoccuranditsabi Iitytosealagainsthotandirregu-larshapedo bjects. Fluidity:theabilityofthefinishedfoamtobe projectedonto,andtoflowacross,theliquidt obeextinguishedand/orprotected.

4 Contaminationresistance:theabilityofthef inishedfoamtoresistcontaminationbytheliq uidtowhichitisapplied. , densitythatisgreaterthanmostflammableliq uidsso,whenapplied,itquicklysinksbelowth eirsUIfaces, ,whensomeburningliquids,suchasheavyfuelo ilsandcrudeoils,becomeextremelyhot, thiseventisknownasa ,thewaterthatsinksbelowthefuelwillcollec tinthecontainerand,shouldthecontainerbec omefull, ,ontheotherhand,consistofbubblesthatarep roducedfroma com-binationofa , ,suchassomepolarsol-vents, : Thetypeoffoam-makingequipmentusedandthew ayitisoperatedandmaIn-tained. Thetypeoffoamconcentrateused. Thetypeoffireandthefuelinvolved. Thetacticsoffoamapplication. Therateatwhichthefoamisapplied. Thequalityofthewaterused. ,finishedfoamsandfoamequipment;applicati onrates;andtheclassesof,andtypesof, ;practicalscenarioconsiderations; , , ,firstpatentedbya Proteinfoamconcentratefirstproducedalong withequipmentdesignedfortheproductionand deliveryofthisfirst'mechanical' ,mediumandhighexpansionfoamscouldnowbepr oducedfroma (AqueousFilm-formingFoam) Furtherdevelopmentofalcoholresistantfoam concentratestoproducemUlti-purposefoamsf oruseat3%onhydrocarbonsand6%onwater-misc ibleliquids.

5 "Hazmat" (alcoholresis-tantAFFF).Developmentofflu oroproteinfoamstoproduceFFFP(Film-formin gFluoroprotein)andmulti-purposeFFFP-AR(A lcoholResistantFFFP) (lessdense) : Byexcludingair(oxygen)fromthefuelsurface . Byseparatingtheflamesfromthefuelsurface. Byrestrictingthereleaseofflammablevapour fromthesurfaceofthefuel. Byforminga radiantheatbarrierwhichcanhelptoreducehe atfeedbackfromflamestothefuelandhencered ucetheproductionofflammablevapour. Bycoolingthefuelsurfaceand anymetalsuli' ;foamconcentrate, (usuallyexpressedasapercentage) (orproportioners) 'premix' , ,premixsolutionsareproducedbymixingtheco r-rectproportionsofwaterandfoamconcentra teinacontainer,suchasanappliancetank, ,sometypesoffoam-makingequipmentarefitte dwithameansofpickingupfoamconcen-trateat theequipment;theseareknownas'self-induci ng' (aspiration) ,theseproducefinishedfoamwithlowexpansio n(LX)ratios,thatistosay,theratioofthevol umeofthefinishedfoamproducedbythenozzle, tothevolumeofthefoamsolutionusedtoproduc eit,is20 (MX)withexpansionratiosofmorethan20:I butlessthan200:1,andhighexpansionfoam(HX )withexpansionratiosofmorethan200:I andpossiblyinexcessof1000 ,toformafoamsolution, ,3%orI % : 6%concentrates6 partsfoamconcentratein94partswater, 3%concentrates3 partsfoamconcentratein97partswater, 1 % ,andjustasimportantly, hoseline,therearea ,foamapplicationisreferredtoasbeingeithe r'aspirated'or'non-aspirated':1%concentr ateisbasicallysixtimesasstrongas6%concen trate,and3%concentrateistwiceasstrongas6 % ,thefirefightingcharacteristicsoffinishe dfoamproducedfrom1%.

6 3%and6%concentratesofa particulartypeofmanufacturer' , , , ,effectivesec-ondaryaspiratedfoamcanonly beproducedusinga foamsolutioncanbeaspiratednotonlydepends ontheequipment, ,syn-theticdetergent(SYNDET)foamconcentr atesaretheonlytypethatcanbeusedtoproduce low,mediumandhighexpansionfoams;proteinf oamconcentratescanonlybeusedtoproducelow expansionfoamandtheremainingcommonlyused foamconcentrates( ,AFFF-AR,FP, ) ,3 and4 , (seeVolume2).Secondaryaspiratedfoamsgene rallyhaveanexpansionratiooflessthan4:I. Lowexpansionlessthanorequalto20:I Mediumexpansiongreaterthan20:Ibutlesstha norequalto200:I Highexpansiongreaterthan200: ,finishedfoamisusuallyclassifiedasbeinge itherlow, ,ormorestrictlytheexpansionratio,ofa if100litresoffoamsolutionwerepassedthrou ghafoam-makingbranchand800litresoffoamwe reproduced,thentheexpansionratioofthefoa mwouldbecalculatedasfollows:volumeoffoam volumeoffoamsolution8800litres100litresI tishighlyunlikelythata foamsolutioncanbeappliedoperationallytoa ,shouldsuchcircum-stancesoccur, ,suchaswettingagents,maybeformulatedsoth attheydonotfoam;useofthesetypesofadditiv ewouldresultinnon-aspiratedapplication, rapidfilm-formationonafuelisrequired(see Chapter4, ).

7 , Asittravelsthroughtheairduetotheturbulen ceproducedbythestream. 'Aspirated'foamismadewhenthefoamsolution ispassedthroughpurposedesignedfoam-makin gequipment,suchasa (aspirate)andthenagitatethemixturesuffic ientlytoproduceuniformlysizedbubbles(fin ishedfoam). 'Non-aspirated' ,theterm'non-aspiratedfoam' ,suchasa ,theuseofthistypeofequipmentwilloftenres ultinsomeaspirationofa :Thereissufficientairentrainedbythesepro cessestoproducea foamofverylowexpansion(oftenwithanexpans ionratiooflessthan4:I). Primaryaspiratedfoam- 'primary'or'secondary'aspiratedareprefer red: Secondaryaspiratedfoam- finishedfoamthatisproducedbyallothermean s, poorqualityfoambeingproduced, ,thefoamwillgenerallyhavea verylowexpansionratioanda veryshortdrainagetime(seebelow). ,thentwicethecorrectamountoffoamconcentr atewillbeusedcreatinga ,butitwillalsoleadtofinishedfoamwithless thanoptimumfirefightingperformance, ,using3%foamconcentratewherethesystemiss etforI%willresultina [----Chapter2 ,MediumandHighExpansionFinishedFoamsThev ariousexpansionratiosaretypicallyusedfor thefollowingapplications.]

8 ,withexpansionsofbetween20and200, ,combinedwithitsabilitytoflowrelativelye asily, ( ,tankbunds)RoadtrafficaccidentsFlammable liquidspillfiresVapoursuppressionHelidec ksJettiesAircraftcrashrescuePortablefire extinguishersMediumexpansionVapoursuppre ssionFlammableliquidstoragetankbundsSmal lcableductsSmallfiresinvolvingflammablel iquids,suchasthosefollowingroad trafficaccidentsTransformerprotectionHig hexpansionKnockdownandextinctionin,andpr otectionof,largevolumessuchaswarehouses, aircrafthangars,cellars,ships'holds,mine shafts, (includingcryogenicliquidssuchasLNG/LPG) SecondaryAspiratedFinishedFoamsLargeflam mableliquidfires( ,tankbunds) (expansionratiosaresometimesinexcessof10 00:I) , ,highexpansionfoamismorelikelythanlowand mediumexpansionfoam,tobreakupinmoderate- lystrongwindconditions(ReferenceI). (seeChapter4, ),hasa verylowexpansionratioandshortdrainagetim e, ,combinedwiththefilm-formingnatureofthef oamconcentratesused,canresultina ,thefoamblankettendstocollapsequickly, :I.

9 ,thatistosay,theyareeitherproteinbasedor syntheticbased,dependingonthechemicalsus edtopro-ducethem. Proteinbasedfoamconcentratesinclude:Prot ein(P)Fluoroprotein(FP)Film-formingf1uor oprotein(FFFP)AlcoholresistantFFFP(FFFP- AR) Syntheticbasedfoamconcentratesinclude:Sy ntheticdetergent(SYNDET)Aqueousfilm-form ingfoam(AFFF)AlcoholresistantAFFF(AFFF-A R)Thecharacteristicsofeachofthesefoamcon cen-trates,andthefinishedfoamsproducedfr omthem, , ,thebasicchemicalconstituentishydrolysed protein, (the'foamingagent') , ,andhenceproducethedifferentfoamconcentr atetypes, (orsurfac-tants) ( )andtoincreasethefluidityofthefinishedfo am( ). ,hydrocar-bonsurfaceactiveagents,orasthe yaremorecom-monlyknown,syntheticdetergen ts, it ,surfaceactiveagentsformanaqueousfilmoff oamsolutionwhich,incertainconditions, ,solvents(toreduceviscosity andtoenhancefoam-ingproperties),preserva tives(topreventthegrowthofbacteriaandmou lds),stabilisers(tohelpmaintainfoambubbl estability) ,otherspecialisedfoamconcentratesandwate radditivesareavailable,inparticular: Hazmatfoamconcentrates- forvapoursuppressionoftoxic,odorousand/o rflammablematerials.

10 Wettingagentsforincreasingthepenetrating abilitiesofwater. ClassAfoamconcentrates-primarilyforuseon classAfires. Fuelemulsifiers- ,FP,FFFP, ' ,thequalityofa particularmanufacturer'sversionofa foamconcentratemayvaryslightlyona ,somemanufacturers producedifferentgradesofthesamefoamconce ntratetypefordifferentmar-ketsand,obviou sly, , , ,inanycase,varydependingontheequipmentan dtacticsused, ,thesestandardsneedtobecloselyscrutinise dtoensurethattheymeetthewiderangeoffires ervicerequirements(seeChapter3). , (a)Protein(P)Proteinfoamconcentratesarel iquidsthatcontainhydrolysedproteinwith,t ypically,theadditionofstabilisingadditiv esandinhibitorstohelppreventcorrosion,re sistbacterialdecomposition, , ,include:soyabeans,corngluten,animalbloo d,hornandhoofmeal, ,proteinfoamconcentrateshavebeenwidelyus edbyindustry,thefireservice, , , ,materialssuchasepoxycoatedcarbonsteel,G RP(GlassReinforcedPlastic)andpolyethylen eshouldbeconsideredforthestorageofprotei nfoamconcentrate.