NFPA 2001 Edition 2012xd

NFPA2001Edition2012Review August 22, 2011

Fir e Supp Supp ression Syst Syst ems Associati Associati on 5024 -R Campbell Campbell Boulevard Balt Ba lt imore, Maryland 21236-5974

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Copyright, 2011, Fire Suppressions Systems Association, All rights reserved.

NFPA2001Edition2012Review I.

Introduction ..........................................................................................................................................

3

II.

Summary of Select Changes and Additions ..........................................................................................

3

III.

NFPA 2001 Chapter 1 Administration ...............................................................................................

5

Safety ........................................................................................................................................................

5

Environmental Impact...............................................................................................................................

5

IV.

NFPA 2001 Chapter 3 Definitions .....................................................................................................

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Final Design Concentration (FDC). ........................................................................................................

8

Adjusted Minimum Design Concentration (AMDC)..............................................................................

8

NFPA 2001 Chapter 4 System Components..........................................................................................

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High Pressure FK‐5‐1‐12 and HFC‐227ea ..................................................................................................

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300 bar IG541............................................................................................................................................

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Manual Control .........................................................................................................................................

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Supervision of Electric Actuators ..............................................................................................................

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Disconnect Switch .....................................................................................................................................

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VI. NFPA 2001 Chapter 5 Design Considerations........................................................................................

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Protection of Rooms having Subfloors ...................................................................................................

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Extent of Protection ............................................................................................................................

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Agents for Protection under Subfloor Only ........................................................................................

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Minimum Design Concentrations ...........................................................................................................

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V.

Class A fuels.........................................................................................................................................

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Class C fuels.........................................................................................................................................

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Deep Seated Class A............................................................................................................................

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Duration of Protection (Hold Time) ........................................................................................................

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Discharge Time (Inert Agents) ................................................................................................................

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VI.

Annex C Enclosure Integrity Procedure ..........................................................................................

August 22, 2011

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Page 2

NFPA2001Edition2012Review I.

Introduction

DuringtheirAugust2011meeting,theNFPAStandardsCouncilreleasedarevisededition ofNFPAStandard2001.Therevisionwillbeknownasthe2012editionofNFPA2001and hasaneffectivedateofAugust31,2011.InthisFSSAdocument,selectchangestoNFPA 2001arereviewed.Thechangeswillbepresentedintheordertheyappearinthestandard andnotinanyorderofimportanceorimpact.Pleasenotethatthereareadditional changesandcorrectionspresentintheNFPA2001StandardEdition2012whicharenot addressedinthisdocument.

II.

Summary of Select Changes and Additions

UnderSafetyinChapter1,exposuretothedischargeofcleanagentduringalocal applicationdischargeisdiscussed. Theinformationonenvironmentalimpactofcleanagentsgiveninthe2008editionis expandeduponinthe2012edition. DefinitionsofFinalDesignConcentration(FDC)andAdjustedMinimumDesign Concentration(AMDC)aregiven. FK‐5‐1‐12andHFC‐227eahighpressuresystemsupto725psiareincludedinthe standard. IG541storedat300barisincludedinthestandard. SupervisionoftheinstallationofelectricactuatingdeviceswillbecomemandatoryJanuary 1,2016. Themandatorydisconnectswitch(“servicedisconnectswitch”)mustbeeitherlocated withinalockablecabinetorrequireakeytooperate.Itisreiteratedthatthismustbea physicalswitchwhichopenstheconnectionbetweenthereleasingcontrolunitandthe actuatingdevice. Whenprotectingaroomwhichhasasubfloor,cleanagentsystemswhichprotectthespace abovetheraisedfloormustsimultaneouslyprotectthespacebelowtheraisedfloor.The spaceundertheraisedfloormustbeequippedwithdetectors,pipeandnozzles. Ifacleanagentsystemisusedtoprotectonlythespacebelowaraisedfloor,NFPA2001 onlypermitstheuseofaninertgascleanagentsystem. MinimumdesignconcentrationforClassAfuelsshallbethegreateroftheClassA minimumextinguishingconcentrationdeterminedbytheClassAapprovaltesttimesa factorof1.2orthecupburnerextinguishingconcentrationfornormalheptane. MinimumdesignconcentrationforClassCfirehazardswithelectricpowersuppliedat480 voltsorlessshallbe1.35timestheminimumextinguishingconcentrationdeterminedby theClassAapprovaltest. Theminimumdesignconcentrationforasmolderingcombustionhazard(deepseatedfire hazard)shallbedeterminedbyanapplicationspecifictest. August 22, 2011

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NFPA2001Edition2012Review The“holdtime”ordurationofprotectionrequirementisclarifiedtobe85%oftheadjusted minimumdesignconcentration(notthefinaldesignconcentration)tobeheldatthe highestlevelofcombustiblesforaminimumperiodofl0minutesorforatimeperiodto allowforresponsebytrainedpersonnel. ForinertgasagentsystemsprotectingClassAsurfacefireorClassChazards,thedischarge timerequiredtoachieve95percentoftheminimumdesignconcentrationforflame extinguishmentshallnotexceed120seconds. AnnexCEnclosureIntegrityProcedurehasbeenre‐writtenforclarityandanumberof errorsintheformulacontainedinthe2008EditionofNFPA2001havebeencorrected.

IMPORTANT  NOTE  In this FSSA document  portions of the soon to be published NFPA 2001 Standard  2012 edition are quoted based on the published ROP and ROC documents. Neither these quotations nor this document  should be relied upon for  purposes of system specification, design, analysis, commissioning or approval.The official NFPA 2001 Standard  published by the National Fire Protection Association must be obtained and consulted  for all  purposes, including system specification, design, analysis, commissioning or approval. The commentary on NFPA 2001 contained  in this document is not to be considered an official  interpretation of NFPA 2001.To obtain an official interpretation of a NFPA standard, consult  the NFPA.

August 22, 2011

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NFPA2001Edition2012Review III.

NFPA 2001 Chapter 1 Administration

Safety Paragraph1.5.1.1hasaclarificationwhichnotesSNAPevaluationofagentsbytheUSEPA addressestotalfloodingagents.AlsoincludedisanAnnexsectiondiscussingexposureto agentdischargefromlocalapplicationsystems.Theaffectedparagraphsareshownbelow. Newtextisitalicized . 1.5.1.1*Anyagentthatistoberecognizedbythisstandardorproposedfor inclusioninthisstandardshallfirstbeevaluatedinamannerequivalenttothe processusedbytheU.S.EnvironmentalProtectionAgency’s(EPA)SNAPProgram  for total  flooding agents.  A.6.1.3 Local concentrations of agent in the vicinity of the

discharge often will exceed  the maximum permitted exposure limits described in Section 1.5.

Consideration for exposure to agent discharge from local application systems vary   greatly and may be more complicated than that  for total  flooding systems depending on:

‐the amount of agent released, ‐the time needed to extinguish a fire, ‐the size of the room or enclosure in which a fire occurs, ‐the size of the fire, ‐the proximity of the person to the point of discharge of the agent, ‐the rate at which fresh air infiltrates the space, and  ‐the air exchange rate near the fire. Environmental Impact  Paragraph1.6wasmodifiedasfollows: 1.6*EnvironmentalFactors.Whenanagentisbeingselectedtoprotectahazard area,theeffectsoftheagentontheenvironmentshallbeconsidered.Selectionof theappropriatefiresuppressionagentshallincludeconsiderationofthefollowing items: (1)Potentialenvironmentaleffectofafireintheprotectedarea (2)Potentialenvironmentalimpacts,including but not limited to Ozone Depletion Potential (ODP) and Global Warming Potential (GWP), of the clean agents that could be used. TheAnnexmaterialforParagraph1.6wasgreatlyexpandedtoincludeatableofODPand GWPvaluesforthevariouscleanagentsaswellastablescomparingtherelativeGlobal Warmingimpactsofvariouscommontypesofgaseswhichareemittedtotheatmosphere. AdiscussionofthesetablesandtheconceptofGlobalWarmingPotentialisaddedtothe Annex. August 22, 2011

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NFPA2001Edition2012Review  Annex 1.6: Table A 1.6  Agent  FIC‐13I1 FK‐5‐1‐12 HCFC Blend A HFC Blend B HCFC‐124 HFC‐125 HFC‐227ea HFC‐23 HFC‐236fa IG‐01 IG‐100 IG‐541 IG‐55

GWP (IPCC 2007) 0.4 1 1550 1540 609 3500 3220 14800 9810 0 0 0 0

ODP 0* 0 0.048 0 0.022 0 0 0 0 0 0 0 0

*Agentmayhaveanon‐zeroODPifreleasedataltitudeshighaboveground level Greenhouse‐gaseffect:TheGWPsoftheagents(aslistedinTableA.1.6(A))provide arelativecomparisonofthedirectgreenhousegasemissionsoffireprotection systemsanddonottakeintoaccountanyeffectsfromindirectemissions.Formost applications,theindirecteffectsarenegligiblecomparedwiththedirecteffects.By contrastwithothersectors,theamountofenergyrequiredtooperatefire protectionsystemsistrivialandlargelyunaffectedbytheagentused. Globalwarmingpotential(GWP)isameasureofhowmuchagivenmassof greenhousegasisestimatedtocontributetoglobalwarming.Itisarelativescale whichcomparesthegasinquestiontothatofthesamemassofcarbondioxide (whoseGWPisbyconventionequalto1).AGWPiscalculatedoveraspecifictime intervalandthevalueofthismustbestatedwheneveraGWPisquotedorelsethe valueismeaningless. ThesubstancessubjecttorestrictionsintheKyotoprotocoleitherarerapidly increasingtheirconcentrationsinEarth'satmosphereorhavealargeGWP. TheGWPdependsonthefollowingfactors:

•theabsorptionofinfraredradiationbyagivenspecies •thespectrallocationofitsabsorbingwavelengths •theatmosphericlifetimeofthespecies Thus,ahighGWPcorrelateswithalargeinfraredabsorptionandalong atmosphericlifetime.ThedependenceofGWPonthewavelengthofabsorptionis morecomplicated.Evenifagasabsorbsradiationefficientlyatacertainwavelength, August 22, 2011

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NFPA2001Edition2012Review thismaynotaffectitsGWPmuchiftheatmospherealreadyabsorbsmostradiation atthatwavelength.Agashasthemosteffectifitabsorbsina"window"of wavelengthswheretheatmosphereisfairlytransparent. GlobalWarmingPotential(GWP) Itisimportanttounderstandthattheimpactofagasonclimatechangeisafunction ofboththeGWPofthegasandtheamountofthegasemitted.Forexample,carbon dioxide(CO2)hasoneofthelowestGWPvaluesofallGHGs(GWP=1),yetemissions ofCO2accountforapproximately85%oftheimpactofallGHGemissions.TheUS EPAhasemployeditsVintagingModel[USEPA,InventoryofGreenhouseGas Emissions:1990‐2007,USEPA2009]toestimatetheemissionsofGHGsfrom varioussources,andthemostrecentresultsareshowninTableA.1.6(A)andTable A.1.6(B),whichindicatetherelativeimpactofGHGemissions(TgofCO2 equivalents)forthevariousGHGs(TableA.1.6(A))andforHFCsasafunctionof industry(TableA.1.6(B)). Table A.1.6 (A): Relative Impact of GHG Emissions

GHG CO2 CH4 N2O HFCs PFCs SF6 Total

Emissions, Tg CO2 Equivalents 6103.4 585.3 311.9 125.5 7.5 16.5 7150.1

% of  Total Impact  85.40% 8.20% 4.40% 1.70% 0.10% 0.20% 100%

Source:EPA(4/15/2009) Table A.1.6 (B): Impact of HFC Emissions

Source Semiconductor Industry HCFC‐22 production Refrigeration/AC Aerosol Foams Solvents Fire Protection Total

Emissions, % of  Tg CO2 Total Equivalents Impact  0.3

0.20%

17 13.50% 97.5 77.70% 6.2 4.90% 2.6 2.10% 1.3 1.00% 0.7 0.60% 125.5 100%

Source:EPA(4/15/2009) August 22, 2011

Page 7

NFPA2001Edition2012Review AscanbeseenfromTableA.1.6(A)andTableA.1.6(B),theimpact(inTgofCO2 equivalents)ofHFCemissionsfromfiresuppressionapplicationsrepresents100x (0.7/7150.1)=0.0098%ofthetotalimpactofallGHGs,i.etheimpactofHFC emissionsfromfireprotectionapplicationsrepresentslessthan0.01%oftheimpact ofallGHGemissions.RecentresultsfromtheHEEPprogram,whichestimatesthe emissionsofHFCsfromfiresuppression,areingoodagreementwiththeresultsof EPA'svintagingmodelresultsfortheemissionofHFCsfromfiresuppression applications. Bythesechangesandadditions,theTechnicalCommitteehopedtoclarifywhatwasmeant bytheexistingNFPA2001Edition20081.6Item2whichdirectsthattheenvironmental effectofthecleanagentshouldbeconsideredinadditiontoenvironmentaleffectsofthe fireintheprocessofagentselection.

IV.

NFPA 2001 Chapter 3 Definitions

Newdefinitionsareincludedinthe2012editionofNFPA2001. Final Design Concentration (FDC). Theactualconcentrationofagentdischargedinto

theenclosure. RelatedAnnexMaterial: TheFDCisequalto,orgreaterthan,theAdjusted MinimumDesignConcentration.  Adjusted Minimum Design Concentration (AMDC). Thetargetminimumdesign

concentrationaftertheSafetyFactorandtheDesignFactorshavebeentakeninto account. RelatedAnnexMaterial: ThistermisalsoreferredtoassimplyDesign Concentrationthroughoutthisdocument.IndeterminingtheDurationof Protection(5.6)itis85percentoftheAMDCthatmustbeheldforthe durationoftheretentiontime. ThesedefinitionswereaddedtoaddressincorrectinterpretationsofNFPA2001Paragraph 5.6.Pleaseseediscussionof“DurationofProtection(Holdtime)”onpage14.

V.

NFPA 2001 Chapter 4 System Components

High Pressure FK ‐5‐1‐12 and HFC‐227ea AnnexA.4.1.4.1isexpandedtoincludeFK‐5‐1‐12storedat600psiat70°FaswellasFK‐5‐ 1‐12andHFC‐227eastoredat725psiat70°F

300 bar IG541 IG541atanominalstoragepressureof300barwasaddedtoTable4.2.1.1.1(a)together withcylinderandpipepressurerequirements.Thisrecognizesthetrendinsomelocalesto usehigherstoragepressuresforinertgases. August 22, 2011

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NFPA2001Edition2012Review TableA4.2.3.1(a)includesthefollowinginformationonpipeandfittingsfor300barIG‐ 541: Agent:IG‐541PressureinAgentContainerat70F(21C)4508psig(31,050kPa) MinimumAcceptableFittings: Class3,000lb.thrd.forgedsteelMaximumPipeSize:1in. Class6,000lb.thrd./weldF.S.MaximumPipeSize:All Class2,500flangedjointMaximumPipeSize:All

Manual Control Section4.3.3.6.2whichreferstotheoperationofmanualsystemcontrolswasmodifiedfor sakeofclarityasfollows: 4.3.3.6.2Operationofanymanualcontrolshallcausethecompletesystemto operateasdesignedinitsnormalfashion.

Supervision of Electric Actuators Anewsectionrequiring“supervision”ofelectricactuatorshasbeenaddedtothestandard. ThisrequirementwillbecomeeffectiveJanuary1,2016.JimKiddsubmittedtheoriginal proposalforthisrequirementwhichwasacceptedbytheTechnicalCommitteeduringROP development.JohnSpalding,representingtheFSSA,contributedsomeclarifying modificationsasacommenttotheROP.Theresultingnewtextisasfollows: 4.3.4.1* Removalofanelectricactuatorfromtheagentstoragecontainerdischarge valvewhichitcontrolsshallresultinanaudibleandvisualindicationofsystem impairmentatthesystemreleasingcontrolpanel. 4.3.4.1.1 Section4.3.4.1shallbecomeeffectiveJanuary1,2016. 4.3.4.1.2 Section4.3.4.1shallnotapplytosystemscoveredunderChapter8 ofthisstandardwiththeexceptionofthosesystemsincludedunder8.6. 4.3.4.2 Removalofanelectricactuatorfromtheselectorvalvewhichitcontrols shallresultinanaudibleandvisualindicationofsystemimpairmentatthesystem releasingcontrolpanel. 4.3.4.2.1 Section4.3.4.2shallbecomeeffectiveJanuary1,2016. 4.3.4.2.2 Section4.3.4.2shallnotapplytosystemscoveredunderChapter8 ofthisstandardwiththeexceptionofthosesystemsincludedunder8.6. Annexmaterialdiscussingthisnewrequirementisincludedinthe2012Standard.

Disconnect Switch Therequirementforadisconnectswitchisnotnew.Thetechnicalcommittee,however, addedtherequirementthattheswitchmustbelocatedinsidealockablecabinetorrequire akeytooperateitinordertosecuretheswitchagainstun‐authorizedoperation.Itis

August 22, 2011

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NFPA2001Edition2012Review clarifiedthatasupervisorysignalshalloccuratthereleasingcontrolunitwhenthe releasingcircuittothesuppressioncircuitisdisconnectedfromthecontrolunit. 4.3.6.1 Toavoidunwanteddischargeofacleanagentsystem,asupervised disconnectswitchshallbeprovided.Thedisconnectswitchshallinterruptthe releasingcircuittothesuppressionsystemandshallcauseasupervisorysignalat thereleasingcontrolunit. 4.3.6.2 Thedisconnectswitchshallbelocatedinsidealockablefirealarmcontrol panel,insidealockableenclosure,orrequireakeyforactivationoftheswitch. 4.3.6.3 Whenthedisconnectswitchrequiresakeyforactivation,theaccesskey shallnotberemovablewhiledisconnectedsothatthesuppressionsystemcanbe quicklyreturnedtotheoperationalconditionintheeventofafire. 4.3.6.4Suppressionsystemsdisconnectachievedviasoftwareprogrammingshall notbeacceptableforuseinlieuofaphysicaldisconnectswitch. 4.3.6.5Thedisconnectswitchshallbelisted.

VI. NFPA 2001 Chapter 5 Design Considerations Protection of Rooms having Subfloors  Extent of Protection

Reportsfromthefieldindicatedthatcleanagentsystemwerebeinginstalledinroomswith raisedfloorsandthespaceundertheraisedfloorwasnotaffordedsimultaneous protection.Section5.3.5isaddedtothe2012editionofthestandardtomakeitclearthat whentheroomabovearaisedfloorisprotectedbytotalfloodingwithacleanagent,the spaceundertheraisedfloor(withinthesubfloor)mustbesimultaneouslyprotectedbya cleanagentsystem. 5.3.5 Whenacleanagenttotalfloodingsystemisbeingprovidedfortheprotection ofaroomwitharaisedorsunkenfloor,theroomandraisedorsunkenfloorshallbe simultaneouslyprotected.Eachvolume,roomandraisedorsunkenfloortobe protected,shallbeprovidedwithdetectors,pipingnetworkandnozzles. Weparaphrasesubstantiationprovidedbythesubmitteroftheoriginalcommentwith whichthetechnicalcommitteeagreed: Evenifthereisnoairfloworcablinginthelowerspace,theagentswilleventually leaktothelowpointandmayprematurelycausetheconcentrationintheroomto decay.Iftherehappenstobeafirebelowtheraisedfloor,theconcentrationofagent leakingdownwardmaynotbeenoughtodevelopanextinguishingconcentration, andtherefore,couldpossiblyproducegreatamountsofproductsofagent decomposition.

August 22, 2011

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NFPA2001Edition2012Review  Agents for Protection under Subfloor Only

Subsection5.3.5.1wasaddedtomakeitclearthatwhenasystemisarrangedtodischarge onlyinthespaceundertheraisedfloor,aninertgasmustbeused.NFPA75requireseither automaticsprinklerprotectionoragaseousextinguishingsystemtobeinstalledunderthe raisedfloorofadatacenter.Gaseoussystemsprotectingonlythespacebelowaraised floorarenotuncommon.ThenewlystatedrequirementinNFPA2001isbelowandnew Annexmaterialexplainsthereasonfortherequirement. 5.3.5.1 Ifonlythespaceundertheraisedflooristobeprotectedbyatotalflooding system,aninertgasshallbeusedtoprotectthatspace.  Annex 5.3.5.1 NFPA752009edition8.1.1.2requires“Anautomaticsprinkler system,acarbondioxideextinguishingsystem,oraninertagentfireextinguishing systemfortheprotectionoftheareabelowtheraisedfloorinaninformation technologyequipmentroomorinformationtechnologyequipmentareashallbe provided.”NFPA752009editionA.8.1.1.2notesthatHalocarbonagentsshouldnot beusedtoprotectthespacebelowaraisedfloorunlessthespaceabovetheraised floorislikewiseprotectedbythesystemandthesystemisdesignedtodischarge simultaneouslyintoboththespacebelowtheraisedfloorandtheroomabovethe raisedfloor. Duringandafteradischargesomeoftheagentfromthespaceundertheraisedfloor willmigrateintotheroomabovetheraisedfloor.Ifanyfireexistsintheequipment abovetheraisedfloor,theagentataconcentrationbelowtheextinguishing concentrationmaybeexposedtothefire.Iftheagentwereahalocarbon, considerabledecompositionoftheagentcouldoccur.NotethatNFPA12A2009 5.3.1.2alsoprohibitstheuseofHalon1301forfloodingthespaceunderaraised flooriftheroomabovetheraisedfloorisnotsimultaneouslyprotectedbytheHalon 1301totalfloodingsystem. Note from the FSSA Technical Director:Inacloselyrelatedaction,NFPA75has proposed a clarificationtoitsrequirementforprotectionofspaceunderraisedfloorsindatacenters. CurrentlyNFPA75edition2009states: 8.1.1.2* Anautomaticsprinklersystem,acarbondioxideextinguishingsystem,or aninertagentfireextinguishingsystemfortheprotectionoftheareabelowthe raisedfloorinaninformationtechnologyequipmentroomorinformation technologyequipmentareashallbeprovided. ThisprovisionhasbeenincorrectlyinterpretedbysometomeanthateveniftheentireIT roomorareaandsubfloorareaareprotectedbyatotalfloodcleanagentsystem,the subfloormustbeprotectedseparatelyby“anautomaticsprinklersystem,acarbondioxide system,oraninertagentfireextinguishingsystem...” TheROCforNFPA75edition2012waspublishedonAugust8,2011.Ifadopted,the requirementforprotectionofthespaceundertheraisedfloorwillbeclarifiedasfollows: 8.1.1.3 Whereagaseousfireextinguishingsystemisprovidedonlyunderaraised floor,thegaseoussystemshallbeeithercarbondioxideoraninertgas.

August 22, 2011

Page 11

NFPA2001Edition2012Review 8.1.1.4Whereacleanagentfireextinguishingsystemsisprovidedtoprotectthe spaceabovetheraisedfloor,thespaceundertheraisedfloorshallbe simultaneouslyprotectedbythecleanagentfireextinguishingsystem. FromtheReportonCommentsF2011 —Copyright,NFPA

UnlessAmendingMotionsarecertifiedforthisdocument,thechangessetforthintheROP andROCforNFPA75edition2012willbeincorporatedinthestandardandreleasedthis comingwinter.ThedeadlineforfilingNITMAMsonNFPA75isOctober21,2011.

Minimum Design Concentrations Class A fuels

Themethodfordeterminingtheminimumdesignconcentrationforextinguishingfirein ClassAfuelshasbeenmodifiedasfollows: 5.4.2.4* TheminimumdesignconcentrationforaClassAsurfacefirehazardshall bedeterminedby5.4.2.4.1or5.4.2.4.2,whicheverisgreater. 5.4.2.4.1 Theextinguishingconcentration,asdeterminedin5.4.2.2,timesasafety factorof1.2 5.4.2.4.2 Equaltotheminimumextinguishingconcentrationforheptaneas determinedfrom5.4.2.1. TheneteffectofthischangeistheminimumdesignconcentrationforClassAfuelsmaynot belessthantheminimumextinguishingconcentrationfornormalheptanedetermined fromthecupburnertest.ThecurrentClassAminimumdesignconcentrationsforinert gaseswillnotchange.TheClassAMDCformosthalocarbonagentswillbeincreasedtothe MECforheptane.Designersandinstallersshouldconsultwiththesystemmanufacturerto obtainthecorrectMDCforhazardsinwhichClassAfiresaretobeextinguishedwithtotal floodcleanagentsystems. Class C fuels

Inthe2008editionofNFPA2001,theminimumdesignconcentrationforaClassChazard was“atleastthatforClassAsurfacefire.”The2012editionwillmandatethefollowing minimumdesignconcentrationsforClassChazards: 5.4.2.5 TheminimumdesignconcentrationforaClassChazardshallbethe extinguishingconcentration,asdeterminedby5.4.2.2,timesasafetyfactorof1.35. 5.4.2.5.1 Theminimumdesignconcentrationforspacescontainingenergized electricalhazardssuppliedatgreaterthan480voltswhichremainspoweredduring andafteragentdischarge,shallbedeterminedbytesting,asnecessary,andahazard analysis. ThediscussionofClassCminimumdesignconcentrationshasbeenongoingforseveral revisioncyclesofNFPA2001.Therequirementwhichwillbesetforthinthe2012edition isaresultofthisongoingdiscussionaswellasdebatewhichtookplaceattheNFPA technicalreportsessionthisJuneinBoston.Designersandinstallersshouldconsultthe

August 22, 2011

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NFPA2001Edition2012Review systemmanufacturerfortheminimumdesignconcentrationsrequiredtomeetNFPA2001 Edition2012. Deep Seated Class A

Section5.4.2.6anditsrelatedAnnexwilladdressdeepseatedClassAhazardsasfollows: 5.4.2.6Theminimumdesignconcentrationforasmolderingcombustionhazard (deepseatedfirehazard)shallbedeterminedbyanapplicationspecifictest.  A.5.4.2.6FiresinSolidMaterials.Twotypesoffirescanoccurinsolidfuels:onein whichvolatilegasesresultingfromheatingordecompositionofthefuelsurfaceare thesourceofcombustion;andanotherinwhichoxidationoccursatthesurfaceof, orwithin,themassoffuel.Theformeriscommonlyreferredtoas“flaming” combustion,whilethelatterisoftencalled“smoldering”or“glowing”combustion. Thetwotypesoffiresfrequentlyoccurconcurrently,althoughonetypeofburning canprecedetheother.Forexample,awoodfirecanstartasflamingcombustionand becomesmolderingasburningprogresses. Conversely,spontaneousignitioninapileofoilyragscanbeginasasmolderingfire andbreakintoflamesatsomelaterpoint.Flamingcombustion,becauseitoccursin thevaporphase,maybeextinguishedwithrelativelylowlevelsofcleanagents.In theabsenceofsmolderingcombustion,itwillstayout.Smolderingcombustionis notsubjecttoimmediateextinguishmentasisflamingcombustion.Characteristicof thistypeofcombustionistheslowrateofheatlossesfromthereactionzone.Thus, thefuelremainshotenoughtoreactwithoxygen,eventhoughtherateofreaction, whichiscontrolledbydiffusionprocesses,isextremelyslow.Smolderingfirescan continuetoburnformanyweeks,forexample,inbalesofcottonandjuteandwithin heapsofsawdust. Asmolderingfireceasestoburnonlywheneitheralloftheavailableoxygenorfuel hasbeenconsumedorwhenthefuelsurfaceisattoolowatemperaturetoreact. Thesefiresareusuallyextinguishedbyreducingthefueltemperature,either directlybyapplicationofaheat‐absorbingmedium,suchaswater,orbyblanketing withaninertgas.Theinertgasslowsthereactionratetothepointwhereheat generatedbyoxidationislessthanheatlossestosurroundings.Thiscausesthe temperaturetofallbelowthelevelnecessaryforspontaneousignitionafterremoval oftheinertatmosphere.Forthepurposesofthisstandard,smolderingfiresare dividedintotwoclasses:(1)wherethesmolderingisnot“deepseated”and(2) deep‐seatedfires. Whetherafirewillbecomedeepseateddepends,inpart,onthelengthoftimeithas beenburningbeforeapplicationoftheextinguishingagent.Thistimeisusually calledthe“preburn”time.Anotherimportantvariableisthefuelconfiguration. WhilewoodcribsandpalletsareeasilyextinguishedwithClassAdesign concentrations,verticalwoodpanelscloselyspacedandparallelmayrequirehigher concentrationsandlongholdtimesforextinguishment.Firesinboxesofexcelsior andinpilesofshreddedpaperalsomayrequirehigherconcentrationsandlonghold timesforextinguishment.Inthesesituations,heattendstoberetainedinthefuel August 22, 2011

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NFPA2001Edition2012Review arrayratherthanbeingdissipatedtothesurroundings.Radiationisanimportant mechanismforheatremovalfromsmolderingfires.

Duration of Protection (Hold Time) Thisisaclarificationofanexistingrequirement. 5.6*DurationofProtection.Aminimumconcentrationof85percentofthe Adjusted  Minimum DesignConcentrationshallbeheldatthehighestlevelofcombustiblesfor aminimumperiodofl0minutesorforatimeperiodtoallowforresponseby trainedpersonnel.Itisimportantthattheagent Adjusted MinimumDesign Concentrationnotonlyshallbeachieved,butalsoshallbemaintainedforthe specifiedperiodoftimetoalloweffectiveemergencyactionbytrainedpersonnel. Thisisequallyimportantinallclassesoffires,sinceapersistentignitionsource(e.g. anarc,heatsource,oxyacetylenetorch,ordeep‐seated”fire)canleadtoresurgence oftheinitialeventoncethecleanagenthasdissipated. Thischangemakesitclearthattheintentofthisrequirementwasandistohold85percent oftheadjustedminimumdesignconcentration(AMDC).Theadjustedminimumdesign concentrationmaydifferfromthefinaldesignconcentration(FDC),thatis,theagent concentrationactuallyprovided.Forexample,iftherequireddesignconcentration(AMDC) is42%,buta50%concentration(FDC)isprovided,then85%of42%shallbeheldatthe highestlevelofcombustibles“foraminimumperiodofl0minutesorforatimeperiodto allowforresponsebytrainedpersonnel.”

Discharge Time (Inert  Agents) WhenClassAsurfacefireorClassCfirehazardsareprotectedbyinertgasagents,the dischargetimerequiredtoachieve95percentoftheminimumdesignconcentrationmay beextendedtoamaximumof120seconds. 5.7.1.2.2Forinertgasagents,thedischargetimerequiredtoachieve95percentof theminimumdesignconcentrationforflameextinguishmentshallnotexceed60 secondsforClassBfuelhazards,120secondsforClassAsurfacefirehazardsor ClassChazards,orasotherwiserequiredbytheauthorityhavingjurisdiction. Theapprovedlimitsforagiveninertgassystemmustbefollowed.Designersandinstallers shouldseekandfollowtheguidanceofthesystemmanufacturerinapplyingtherevised 5.7.1.2.2.

VI.

 Annex C Enclosure Integrity Procedure

Inthe2012editionofNFPA2001,AnnexChasbeenre‐writtenforclarityandanumberof errorsintheformulascontainedinthe2008editionofNFPA2001havebeencorrected.

August 22, 2011

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