NFPA 2001 Edition 2012xd

August

August 22,22, 20112011

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Firir e Se Suppupp ression Sysression Systt ems Asems Associatisociati onon 5024

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Baltlt imore, Maryland 21236-5974imore, Maryland 21236-5974

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Phone: (410) 931-hone: (410) 931- 81008100 F

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 ... 8

Final Design Concentration (FDC). ... 8

Adjusted Minimum Design Concentration (AMDC)... 8

V. NFPA 2001 Chapter 4 System Components... 8

High Pressure FK_‐5_‐1_‐12 and HFC_‐227ea ... 8

300 bar IG541... 8

Manual Control ... 9

Supervision of Electric Actuators ... 9

Disconnect Switch ... 9

VI. NFPA 2001 Chapter 5 Design Considerations... 10

Protection of Rooms having Subfloors ... 10

Extent of Protection... 10

Agents for Protection under Subfloor Only ... 11

Minimum Design Concentrations ... 12

Class A fuels... 12

Class C fuels... 12

Deep Seated Class A... 13

Duration of Protection (Hold Time) ... 14

Discharge Time (Inert Agents) ... 14

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.

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.

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.

 Annex 1.6:

_

Table A 1.6  Agent  GWP (IPCC 2007) ODP FIC‐13I1 0.4 0* FK‐5‐1‐12 1 0 HCFC Blend A 1550 0.048 HFC Blend B 1540 0 HCFC‐124 609 0.022 HFC‐125 3500 0 HFC‐227ea 3220 0 HFC‐23 14800 0 HFC‐236fa 9810 0 IG‐01 0 0 IG‐100 0 0 IG‐541 0 0 IG‐55 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,

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

_

Emissions, Tg CO2 Equivalents % of  Total Impact  CO2 6103.4 85.40% CH4 585.3 8.20% N2O 311.9 4.40% HFCs 125.5 1.70% PFCs 7.5 0.10% SF6 16.5 0.20% Total 7150.1 100% Source:EPA(4/15/2009)

Table A.1.6 (B): Impact of HFC Emissions

Source

_

Emissions, Tg CO2 Equivalents % of  Total Impact  Semiconductor Industry 0.3 0.20% HCFC‐22 production 17 13.50% Refrigeration/AC 97.5 77.70% Aerosol 6.2 4.90% Foams 2.6 2.10% Solvents 1.3 1.00% Fire Protection 0.7 0.60% Total 125.5 100% Source:EPA(4/15/2009)

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

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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.

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.

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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

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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

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

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Protection of Rooms having Subfloors

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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:

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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.

 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.

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

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

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.