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CombustibleDust
Hazard
Recognition
and
Control
NFPAStandardsforCombustibleDusts
DerekDuval
FireProtection
Engineer,
NationalFireProtectionAssociation
PelletFuels
Institute
Conference
PonteVedraBeach,Florida
July26,2011
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Outline: NFPA Anoverview
CombustibleDustHazard Explosionv.FlashFire
IdentifyingHazards
MitigatingHazards
NFPAResources
NFPA664 NewChangesfor2012Edition
NFPA656(NewStandard) OtherDustStandards:NFPA484,654,655
PreventionandProtectionStandards:NFPA68,69
Symposiums,Seminars,Handbooks
2
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NationalFireProtectionAssociation
(NFPA) An
Overview
WhatisNFPA?
Foundedin
1896
Mission
Internationalnonprofit membershiporganization
(75,000members
worldwide)
Developcodesandstandards,protectpeople,their
property,andtheenvironmentfromdestructivefire.
Consensusbased
NFPAcodeandstandard developmentprocess
3
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WoodPelletProcessing:
GeorgiaBiomass
Explosion
WaycrossWareCounty,GA
Startup:
May
12th,
2011
Explosion:June20th,2011
Noinjuriesorfatalities
DustInvolved:Wooddust
IgnitionSource:overheatedroller/bearing
assembly
4
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CSBCombustible
Dust
Study
281combustibledustfiresandexplosions
between1980
and
2005
119fatalitiesand718injuriesintheUnited
States;
Sevencatastrophicdustexplosionsinthepast
decade
Widerange
of
industries
and
many
types
of
combustibledusts
5
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6
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7
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8
Wood
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Whatis
Combustible
Dust?
WhatisCombustibleDust?
Whereis
it
found?
WhatmakesitaHazard?
Whatcan
be
done
to
prevent
and
Protect
againstaCombustibleDustHazard?
9
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CombustibleParticulate
Solid
Anycombustiblesolidmaterial,composedof
distinctparticles
or
pieces,
regardless
of
size,
shapeorchemicalcomposition.
(NFPA6542006)
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CombustibleDust
CombustibleDust* Acombustible
particulatesolid
that
presents
afire
or
deflagrationhazardwhensuspendedinairor
otheroxidizingmediumoverarangeof
concentrations,regardless
of
particle
size
or
shape. [NFPA654]
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ParticleSize
Influence
on
Explosibility
420*micronsthreshold
500micronsthreshold(New,NFPA664,2012)
Smallerparticles
more
easily
lofted
Flakesorfibersbehavedifferently
Consideraspectratiofordifferentsolidforms
Dustsofcriticalsizecreatedfromanysizeparticulatesolid 12
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DeflagrableWoodDust
ExistingDefinition
Woodparticulatewithmediandiameterof
420microns
or
smaller
(i.e.,
material
that
will
passthroughaU.S.No.40StandardSieve),
havingamoisturecontentoflessthan25
percent(wet
basis).[NFPA
664,
2007]
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DeflagrableWoodDust
NEWDefinition
Woodparticulatethatwillpropagateaflame
front,thus
presenting
afire
or
explosion
hazard,whensuspendedinair,ortheprocess,specificoxidizingmediumoverarangeof
concentrations,regardless
of
particle
size
of
500micronsorsmaller(i.e.Sieve),havingamoisturecontentoflessthan25percent(wet
basis).[NPFA
664,
2012] (AdditionalExplanatorymaterialaddedinAnnexAfor2012
Edition)
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Property Definition ASTMTestMethod
Application
KSt Dustdeflagration
index
ASTME1226 Measures relative
explosion severity
Pmax Maximum
explosion
overpressure
ASTM
E1226 Used
for
enclosure
designandpredict
explosionseverity
(dp/dt)max Maximumrateof
pressurerise
ASTME1226 Predictexplosion
violence;used
to
calculateKSt
MIE MinimumIgnition
Energy
ASTME2019 Predicteaseand
likelihoodofdust
cloudignition
MEC Minimum
Explosible
Concentration
ASTME1515 Minimumamount
ofdustdispersedin
air;likeLFLfor
gasesand
vapors 15
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CombustibleDust:
ProtectAgainst
Two
Hazards
Fires
Flashfire
hazard
Threattoproperty
Thermalexposureextremelydangerousfor
workers
Explosions
Overpressureimpacts
structure
Primaryandsecondaryexplosions
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Conditionsfor
aDust
Explosion
17
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DustExplosion
Pentagon
18
Confinement
Fuel Ignition
Dispersion
Oxygen
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AirborneDustandExplosible
Concentration
Minimum
Explosible
Concentration
(MEC)Determinedbytesting
Averagevalue400to500gramspercubicmeter
19
ExplosibleDustCloudConcentration
DustConcentration(g/m3)
Explosion
Violence
0 250 500 750 1000
10
5
0
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20
Acloudof40g/m3 ofcoaldustinairissodensethataglowing25Wlightbulbcan
hardlybeseenthroughadustcloudof2mthickness (Eckhoff)
25W
Glass Glass
40g/m3 CoalDust
2m
?
AppearanceofanExplosibleDustCloud
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NFPA664
StandardforthePreventionofFiresandExplosionsinWoodProcessingandWoodworkingFacilities,2012
Scope:
Appliestofacilitiesthatprocesswoodormanufacturewoodproducts,usingwoodorothercellulosicfiber
Appliestowoodworkingoperationsthateither:
Occupyareasofmorethan465m2 (5000ft2),or
Requirean
aggregate
dust
collection
flow
rate
of
more
than
2549
m3/hr(1500ft3/min)
NewEdition,2012
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Chapter4General
Requirements
DeflagrationHazard(New)
ProcessAnalysis
ManagementofChange
Objectives
Lifesafety
Structuralintegrity
Mission
continuityMitigationoffirespreadandexplosions
Options performancebasedorprescriptive
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Chapter6Building
Construction
Compartmentation firewalls,firepartitions,
firebarrier
walls
Protectionofopeningsandpenetrations
Life
safety
and
means
of
egress Surfacesandledges
Damagelimitingconstruction
Dustaccumulation
threshold
established
Draftcurtains
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Chapter7 Ignition
Control
Hotwork
Electricalsystems
Hotsurfaces
Industrialtrucks
Lighting Fuelfiredequipment
Lightningprotection
Staticelectricity
Smoking
Machinesand
processing
equipment Foreignmaterial
Friction
Fans Spontaneousignition
andchemicalaction
Propellant
actuated
tools
Portableelectrictools
24
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Chapter8 Processes,Operations,and
SpecialSystems
Particulateconveyinganddustcollection HazardDetermination
2012Change:8.2.1.5:75%>25%ofMEC 2012Change:AdditionalHazardDeterminationRequirements
Pneumaticconveying seeNFPA654
Ductsystem 2012Change:Clarificationondustcollectioncapacitycalculations
Hoodsandenclosures
Fansorblowers(airmovingdevices)
Dustcollectors(airmaterialseparators)
Recyclingexhaustair 2012Change:AdditionalSafeguards
25
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Chapter10
Human
Element
Inspectionandmaintenance
Recordretention
Employeetraining
Contractorsandsubcontractors
Portableappliances
Incidentinvestigation
Impairmentsoffireprotectionsystems
Hotwork
Emergencyplanningandresponse
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Chapter11
Housekeeping
Eliminatedustaccumulations
Vacuumingis
preferred
Sweepingorwaterwashdownisacceptable
Vigoroussweepingcangeneratedustcloud
Blowingdown
with
steam
or
compressed
air
leastpreferable
Afterothermethodsusedandonlytoaccesshardto
reachareas
Limitsonairpressure
Shutdownotheroperationsifignitionsource
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NFPA
656,
Standardfor
Combustible
Dusts*
BrandNewStandard
Fundamentalsand
General
Requirements
CorrelatesGeneralRequirementsfrom: NFPA61,StandardforthePreventionofFiresandDustExplosionsinAgriculturalandFoodProcessingFacilities,2008
NFPA484,
StandardforCombustibleMetals,2012
NFPA654,StandardforthePreventionofFireandDustExplosionsformtheManufacturing,Processing,andHandlingofCombustibleDusts,2006
NFPA655,StandardforPreventionofSulfurFiresandExplosions,2012
NFPA664,StandardforthePreventionofFiresandExplosionsinWoodProcessingandWoodworkingFacilities,2012
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AdditionalReferences
NFPA68,StandardforExplosionProtectionbyDeflagrationVenting,2007
NFPA69,StandardonExplosionPreventionSystems,2008 NFPA91,StandardforExhaustSystemsforAirConveyingof
Vapors,Gases,Mists,andNoncombustibleParticulateSolids,2010
CombustibleDustGuidebook(tobereleasednextyear)
NFPA
Fire
Protection
Handbook
20
th
Edition
Seminars
29
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PHAPrimer
Howmuchdoyouknowaboutyoursolids
processing?Whichmaterialsarecombustible?
Ifnotknown,butsuspected,thendataare
needed TestingofDust(2012:Addedannexmaterialtoaddress
testingmethods)
Dontoverlook
any
combustible
particulate
solids
Dust formationoftencomeswithmaterialhandling
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PHAPrimer
(continued)
Wherearesolidsproducedand/orhandled?
Closedor
open
processes?
Rateofgenerationorreleaseofsolidstoan
environment?
Anycollection
methods
in
place?
Conclusion:processgeneratesorhandles
solids
and
dusts
are
formed
in
process,
potentialexists
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Questionsto
Consider
Hazardanalysisincludesmaterialproperty
input Basisforsafety
Collectdustsandminimizeaccumulation
Controlignitionsources
Protectequipmentandstructuresfromexplosion
Limitimpact
on
facility
through
design
or
isolation
measures
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DustSymposium
NFPAandFireProtectionResearch
Foundationpresenting
2day
dust
symposium,
September20212011
Detroit,MI
Registration
informationwww.nfpa.org
NFPA1dayCombustibleDustSeminar
September19,
2011
preceding
the
dust
symposium
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ThankYou!
Questions?
DerekDuval
34
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