Derek Duval

8/13/2019 Derek Duval

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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

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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

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WoodPelletProcessing:

GeorgiaBiomass

Explosion

WaycrossWareCounty,GA

Startup:

May

12th,

2011

Explosion:June20th,2011

Noinjuriesorfatalities

DustInvolved:Wooddust

IgnitionSource:overheatedroller/bearing

assembly

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CSBCombustible

Dust

Study

281combustibledustfiresandexplosions

between1980

and

2005

119fatalitiesand718injuriesintheUnited

States;

Sevencatastrophicdustexplosionsinthepast

decade

Widerange

of

industries

and

many

types

of

combustibledusts

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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?

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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

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DustExplosion

Pentagon

18

Confinement

Fuel Ignition

Dispersion

Oxygen


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AirborneDustandExplosible

Concentration

Minimum

Explosible

Concentration

(MEC)Determinedbytesting

Averagevalue400to500gramspercubicmeter

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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

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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

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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

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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

[email protected]

34

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Derek Duval