dust explosion prevention

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Prevention and Prevention and Control of Dust Control of Dust Explosions In Explosions In

IndustryIndustryRonald C. (Chet) Brandon, Ronald C. (Chet) Brandon, CSPCSP

Dale S. MachirDale S. Machir

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IntroductionIntroduction

Why is this Presentation Important?Why is this Presentation Important?

Many modern industrial operations create dust Many modern industrial operations create dust as either a by-product or an end product.as either a by-product or an end product.

Some dusts can release hazardous amounts of Some dusts can release hazardous amounts of energy when ignited. energy when ignited.

But, which dusts are susceptible? What can be But, which dusts are susceptible? What can be done to reduce the risk of a dust explosion? Why done to reduce the risk of a dust explosion? Why do they occur?do they occur?

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IntroductionIntroduction

What this Presentation will do for You:What this Presentation will do for You:

Knowledge of dust explosions will enable a Knowledge of dust explosions will enable a systematic method of hazard assessment and systematic method of hazard assessment and mitigation providing maximum protection of the mitigation providing maximum protection of the employees and assets. employees and assets.

This training session will focus the application of This training session will focus the application of explosive dust knowledge to your process.explosive dust knowledge to your process.

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Brief HistoryBrief History

First recorded dust explosion First recorded dust explosion occurred in Turin, Italy in 1785 occurred in Turin, Italy in 1785 (flour)(flour)

Other incidents:Other incidents: Stettin - Poland 1858 (grain)Stettin - Poland 1858 (grain) Milwaukee - USA 1860 (flour)Milwaukee - USA 1860 (flour) Hameln - Germany 1887 (grain)Hameln - Germany 1887 (grain)

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Source: Bartknecht, Dust Explosions, 1989.

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Souce: Bartknecht, Dust Explosions, 1989.

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First recorded occurred in Turin, First recorded occurred in Turin, Italy in 1785 (flour)Italy in 1785 (flour)

Other incidents:Other incidents: Stettin - Poland 1858 (grain)Stettin - Poland 1858 (grain) Milwaukee - USA 1860 (flour)Milwaukee - USA 1860 (flour) Hameln - Germany 1887 (grain)Hameln - Germany 1887 (grain) Monongah, WV 1907 (coal)Monongah, WV 1907 (coal)

10 Source: MSHA Web Site, http://www.msha.gov/DISASTER/MONONGAH/MONON1.HTM, 2002.

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First recorded occurred in Turin, First recorded occurred in Turin, Italy in 1785 (flour)Italy in 1785 (flour)

Other incidents:Other incidents: Stettin - Poland 1858 (grain)Stettin - Poland 1858 (grain) Milwaukee - USA 1860 (flour)Milwaukee - USA 1860 (flour) Hameln - Germany 1887 (grain)Hameln - Germany 1887 (grain) Monongah, WV 1907 (coal)Monongah, WV 1907 (coal) De Bruce, USA 1997 (wheat)De Bruce, USA 1997 (wheat)

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Source: Grose, Explosion of the DeBruce Grain Elevator, Grain Elevator Explosion Team, 1998.

13 Source: Grose, Explosion of the DeBruce Grain Elevator, Grain Elevator Explosion Team, 1998.

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Source: Grose, Explosion of the DeBruce Grain Elevator, Grain Elevator Explosion Team, 1998.

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Bremer Roller MillBremer Roller Mill

Bremer Roller Mill, Bremer Roller Mill, Germany 1979Germany 1979

FlourFlour 14 dead, 17 14 dead, 17

injuredinjured 100 million DM 100 million DM

lossloss

Souce: Bartknecht, Dust Explosions, 1989.

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Government InvolvementGovernment Involvement

U.S. Geological Survey (late 1800s)U.S. Geological Survey (late 1800s) Monongah and Darr mining incidents Monongah and Darr mining incidents

left 600 dead (1907)left 600 dead (1907) Bureau of Mines… US Department of Bureau of Mines… US Department of

Interior (1910-1996)Interior (1910-1996) Extensive dust explosion research Extensive dust explosion research

(Hartmann)(Hartmann) NIOSHNIOSH MSHAMSHA

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Hartmann ApparatusHartmann Apparatus

Source: U. S. Bureau of Mines Alumni Association, Online:

http://www.bureauofmines.com/USBMAA.HTM, 2002.

18 Source: U. S. Bureau of Mines Alumni Association, Online: http://www.bureauofmines.com/USBMAA.HTM, 2002.

19 Source: U. S. Bureau of Mines Alumni Association, Online: http://www.bureauofmines.com/USBMAA.HTM, 2002.

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Testing ApparatusTesting Apparatus

1.2 liter Hartmann test apparatus1.2 liter Hartmann test apparatus Siwek 20 liter sphere - ASTM Siwek 20 liter sphere - ASTM

Standard of todayStandard of today

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Eramet 1.2 l HartmannEramet 1.2 l Hartmann

Source: Eramet-Marietta, 2002.

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Fike 10 mFike 10 m3 3 SphereSphere

Source: Fike Corporation, Fike Explosion Protection Solutions, 1999.

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Fike 20 l SphereFike 20 l Sphere


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Fike 20 l Sphere Fike 20 l Sphere InstrumentationInstrumentation


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Anatomy of a Dust Anatomy of a Dust ExplosionExplosion

Understanding Understanding dust reactionsdust reactions

Dust reaction Dust reaction demonstrationdemonstration

Secondary Secondary explosionsexplosions

Identification of Identification of explosive dustsexplosive dusts

Source: Fike Corporation, Fike Explosion Protection Solutions,

1999.

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Understanding Dust Understanding Dust ReactionsReactions

Prerequisites:Prerequisites: Finely divided solids that pass through a Finely divided solids that pass through a

No. 40 USA Standard sieve or less that No. 40 USA Standard sieve or less that 425 micron425 micron

Five Parameters for a reactionFive Parameters for a reaction A dust capable of propagating a burning A dust capable of propagating a burning

reactionreaction

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Material SizeMaterial Size Finely divided materials have a high total Finely divided materials have a high total

contact surface area with oxygen in the contact surface area with oxygen in the atmosphereatmosphere

The large surface area of finely divided The large surface area of finely divided materials allows rapid oxidation to occurmaterials allows rapid oxidation to occur

The relatively low mass particles are more The relatively low mass particles are more easily suspended in aireasily suspended in air

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Reactive DustsReactive Dusts Dusts which react exothermically with airDusts which react exothermically with air Exothermic reaction: Exothermic reaction: fuel + oxygen fuel + oxygen oxides oxides

+ heat+ heat Typical reactive dusts:Typical reactive dusts:

Natural organic materialsNatural organic materials Synthetic organic materialsSynthetic organic materials Coal and PeatCoal and Peat MetalsMetals

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Five Parameters of Dust ExplosionsFive Parameters of Dust Explosions Dust Concentration (Fuel)Dust Concentration (Fuel) Ignition Source (Energy)Ignition Source (Energy) Atmosphere (Oxygen)Atmosphere (Oxygen) ConfinementConfinement SuspensionSuspension

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FuelOxygen

Ignition

Susp

ensio

nConta

inm

ent

Dust ExplosionPentagonFu

el

Ignition

Oxyg

en

Fire Triangle

From the Fire TriangleTo the Dust Explosion Pentagon

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Dust Explosion Dust Explosion ParametersParameters

FuelOxygen

Ignition

SuspensionCon

tain

men

t

Dust ExplosionPentagon

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Explosion AnatomyExplosion Anatomy

All five parameters are met All five parameters are met Point of IgnitionPoint of Ignition Flame FrontFlame Front Pressure Wave of Cool Compressed GasPressure Wave of Cool Compressed Gas High pressure generated in containing High pressure generated in containing

vesselvessel

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Dust Explosion Dust Explosion MechanismMechanism

Spark

Flame Front

Pressure Wave

Fuel

Containment

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Pressure Wave Pressure Wave DemonstrationDemonstration

Source: Discovery Channel, World of Wonder Segment: Dust Explosions, 1998.

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Dust Deflagration Dust Deflagration DemonstrationDemonstration

1.2 l Hartmann Apparatus1.2 l Hartmann Apparatus Small scale reaction of Small scale reaction of

finely divided flourfinely divided flour Demonstrates the 5 key Demonstrates the 5 key

parameters of dust parameters of dust reactionsreactions

Source: U. S. Bureau of Mines Alumni Association,

Online: http://www.bureauofmines.com/USBMAA.HTM, 2002

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Eramet 1.2 l HartmannEramet 1.2 l Hartmann

Source: Eramet-Marietta, 2002.

37 RCB

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Secondary ExplosionsSecondary Explosions

Can create the greatest injury and damage

Associated with dust accumulated on the horizontal surfaces

Occur when dust becomes suspended by the pressure wave and is ignited by the flame front of the primary explosion

Source: Elkem Metals Co., LP, 2002.

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40



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Secondary Explosion Secondary Explosion MechanismMechanism

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Pressure PilingPressure Piling

Primary Reaction in one containment Primary Reaction in one containment vesselvessel

Flame Propagation to secondary Flame Propagation to secondary containment preceded by the cool containment preceded by the cool pressure wavepressure wave

Raises pressure in secondary before flame Raises pressure in secondary before flame front arrivesfront arrives

Secondary containment starts reacting at Secondary containment starts reacting at a high initial pressure creating a higher a high initial pressure creating a higher ending pressureending pressure

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Pressure PilingPressure Piling

Source: Cashdollar, Industrial Dust Explosions, ASTM, 1987.

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Prevention of Secondary Prevention of Secondary ExplosionsExplosions

Proper Design ContainmentProper Design Containment Elimination of one or more of the five Elimination of one or more of the five

parametersparameters VentingVenting Barriers and LocationBarriers and Location Stop gatesStop gates

Housekeeping - KEEP IT CLEANHousekeeping - KEEP IT CLEAN

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Identification of Identification of Explosive dustsExplosive dusts

Fuel + oxygen = oxides + energyFuel + oxygen = oxides + energy Must rapidly oxidizeMust rapidly oxidize Typical reactive dusts:Typical reactive dusts:

Natural organic materialsNatural organic materials Synthetic organic materialsSynthetic organic materials Coal and PeatCoal and Peat MetalsMetals

If you are unsure….If you are unsure…. Reference materialsReference materials GET IT TESTEDGET IT TESTED

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Fuel ParametersFuel Parameters

SizeSize Concentration (MEC)Concentration (MEC) PurityPurity TurbulenceTurbulence Get YOUR our material tested Get YOUR our material tested Don’t used information from books Don’t used information from books

for your design parametersfor your design parameters

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Prevention of a Dust Prevention of a Dust ExplosionExplosion

Use of the pentagon to help prevent dust explosions

Engineering out the dust explosion hazard

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Dust Explosion Dust Explosion ParametersParameters

FuelOxygen

Ignition

SuspensionCon

tain

men

t

Dust ExplosionPentagon

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Elimination of Dust Elimination of Dust Explosion ParametersExplosion Parameters

Eliminate one or more of the 5 Eliminate one or more of the 5 parametersparameters Fuel – Reduce concentration below MECFuel – Reduce concentration below MEC Oxygen – Use inerting agentsOxygen – Use inerting agents Energy – Control ignition sources Energy – Control ignition sources Suspension – Control suspension of dust Suspension – Control suspension of dust

in airin air Containment – Design vessels for Containment – Design vessels for

explosionsexplosions

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Use of the pentagon to help prevent dust explosions

Engineering out the dust explosion hazard dust explosivity results equipment quality control system housekeeping

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Generation of Design Generation of Design Data For Explosion Data For Explosion

ProtectionProtection Data generated in the 20 l sphere Data generated in the 20 l sphere

tend to be more accurate than those tend to be more accurate than those from the Hartmann test apparatus from the Hartmann test apparatus

ASTM Standard E-1226-00ASTM Standard E-1226-00 Data generated using ASTM methods employs precise standards for preparation and testing of samples that include concentrations, size, and ignition energy

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Generation of Design Data Generation of Design Data For Explosion ProtectionFor Explosion Protection

The spherical test The spherical test chamber of the 20-Liter chamber of the 20-Liter Apparatus avoids the Apparatus avoids the nonsymmetrical energy nonsymmetrical energy waves that are developed waves that are developed in the tubular apparatus. in the tubular apparatus.

More accurate More accurate measurements for rate of measurements for rate of pressure rise and pressure rise and maximum pressure maximum pressure developed in the test developed in the test vessel.vessel.

vs

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Generation of Design Generation of Design Data For Explosion Data For Explosion

ProtectionProtection Information generated in the Information generated in the

Hartmann Test Apparatus and Hartmann Test Apparatus and published in the majority of older published in the majority of older reference manuals.reference manuals.

When using information generated When using information generated from the Hartmann Test Apparatus, from the Hartmann Test Apparatus, it should be tempered with additional it should be tempered with additional safety factors to compensate for the safety factors to compensate for the inaccuracies of the technique.inaccuracies of the technique.

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Importance of Testing Specific Importance of Testing Specific MaterialsMaterials

It is essential to use data generated It is essential to use data generated for specific productsfor specific products

Use of explosion data from what are Use of explosion data from what are believed to be believed to be similarsimilar dusts to those dusts to those in question is in question is not recommendednot recommended

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Tests using scientifically valid procedures Tests using scientifically valid procedures quantifies 6 key explosion quantifies 6 key explosion characteristics for your dust:characteristics for your dust:

Maximum Pressure DevelopedMaximum Pressure Developed Maximum Rate of Pressure RiseMaximum Rate of Pressure Rise Deflagration IndexDeflagration Index Minimum Ignition EnergyMinimum Ignition Energy Minimum Explosive ConcentrationMinimum Explosive Concentration Maximum Limiting Oxygen ConcentrationMaximum Limiting Oxygen Concentration

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Maximum Pressure Maximum Pressure DevelopedDeveloped

Greatest pressure Greatest pressure generatedgenerated

Measured in barsMeasured in bars Determines max Determines max

pressure exposure pressure exposure to a containing to a containing vessel vessel

Predicts likelihood Predicts likelihood of vessel failureof vessel failure

PPmaxmax

Explosion Pressure vs. Concentration

Dust Concentration (g/m3)

Pre

ssur

e (b

ar)

Pmax

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Maximum Rate of Maximum Rate of Pressure RisePressure Rise

The rate of pressure increase over time at the steepest part of the pressure-versus-time curve

Measured in bar/s Used to determine

necessary venting capacity of closed vessels

(dP/dt)(dP/dt)maxmax

Rate of Pressure Rise

Time (milliseconds)

Pre

ssu

re (

bar

s)

(dP/dt)max

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Deflagration IndexDeflagration Index

The maximum dP/dt normalized to a 1.0 m3 volume

Measured bar-meters/second

Allows a comparison of data from different sized test vessels

KKstst

KKstst = V = V1/31/3 (dP/dt) (dP/dt)maxmax

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Minimum Ignition Minimum Ignition EnergyEnergy

The minimum amount of energy released in a cloud of suspended dust causing indefinite flame propagation

Measured in millijoules

Determines what energy sources must be controlled to prevent ignition of a dust cloud

MIEMIE

Source: Fike Corporation,

Fike Explosion Protection Solutions, 1999.

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Minimum Explosive Minimum Explosive ConcentrationConcentration

The lowest concentration of a dust that can support a self-propagating reaction

Measured mg/m3

Used in designing and operating explosive dust systems below the level of suspended fuel required for combustion

MECMEC



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Maximum Oxygen LevelMaximum Oxygen Level The level of oxygen at

or below which a dust is not capable of sustaining reaction

Reported as a percentage of oxygen in a given volume

Used in designing inerted atmospheres for systems processing reactive dusts

OO2 max2 max



DSM

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Engineering Out the Engineering Out the HazardHazard

Assume an explosion will occurAssume an explosion will occur Select proper equipment for use Select proper equipment for use

with explosive dustswith explosive dusts Follow existing design standardsFollow existing design standards Include safe maintenance capability Include safe maintenance capability

in system designin system design Utilize explosion protection systemsUtilize explosion protection systems

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Types of Explosion Protection SystemsTypes of Explosion Protection Systems IsolationIsolation VentingVenting SuppresionSuppresion ContainmentContainment


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Isolation

Mechanical

ChemicalSource: Fike Corporation, Fike Explosion Protection Solutions, 1999.

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Venting


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Suppression


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Containment

Source: Eckhoff, Dust Explosions in the Process Industries, 2nd Ed, 1997.RCB

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Risk Reduction with Human Risk Reduction with Human FactorsFactors

Operators have the greatest impact on Operators have the greatest impact on operation safetyoperation safety

Carefully design human interactions with Carefully design human interactions with systemsystem Employee knowledgeEmployee knowledge Employee behaviorEmployee behavior Design of process controls and displaysDesign of process controls and displays Task analysisTask analysis Proper job designProper job design

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Management of RiskManagement of Risk

Standard Operating ProceduresStandard Operating Procedures Maintenance Operating proceduresMaintenance Operating procedures Complete set of written procedures Complete set of written procedures

BEFORE turning first switchBEFORE turning first switch TrainingTraining AuditsAudits Operator - Maintenance involvement Operator - Maintenance involvement Checks and balances by the safety Checks and balances by the safety

personnelpersonnel

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SummarySummary Elimination of dust explosion Elimination of dust explosion

parametersparameters Engineering out the hazardEngineering out the hazard Human Factors Human Factors Risk reduction through management Risk reduction through management

systemssystems

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Damage Control: Damage Control: Considerations Considerations

Regarding Explosive Regarding Explosive Dust FiresDust Fires

Develop detailed emergency Develop detailed emergency response plans in advance of system response plans in advance of system start-upstart-up

Train and retrain on the plansTrain and retrain on the plans Execute the plans during actual Execute the plans during actual

emergencies with patients and emergencies with patients and diligencediligence

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Regarding Explosive Regarding Explosive Dust FiresDust Fires

Probable scenarios:Probable scenarios:

1)1) Smoldering or unreacted pile of Smoldering or unreacted pile of dust remaining after an explosiondust remaining after an explosion

2)2) Smoldering pile of dust not yet Smoldering pile of dust not yet involved in an explosion.involved in an explosion.

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Regarding Explosive Regarding Explosive Dust FiresDust Fires Important Considerations for fighting Important Considerations for fighting

dust firesdust fires De-energize all energy sourcesDe-energize all energy sources Field assessment of structureField assessment of structure Current level of dust suspensionCurrent level of dust suspension Potential for primary or secondary Potential for primary or secondary

explosionsexplosions Determine proper fire fighting mediaDetermine proper fire fighting media Do notDo not use high pressure streams of water use high pressure streams of water

directed at piles of dustdirected at piles of dust

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Key Point SummaryKey Point Summary

Understand your materials characteristics Understand your materials characteristics through proper testingthrough proper testing

Seek help from dust explosion expertsSeek help from dust explosion experts Seek experienced design companies for Seek experienced design companies for

engineeringengineering Develop management systems to control riskDevelop management systems to control risk Maintain good housekeepingMaintain good housekeeping Audit aggressively to verify adherence to risk Audit aggressively to verify adherence to risk

control practicescontrol practices Have an effective emergency planHave an effective emergency plan

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Sources of HelpSources of Help

Fike Explosion Protection SystemsFike Explosion Protection Systems Fenwal Safety SystemsFenwal Safety Systems References in the Proceedings PaperReferences in the Proceedings Paper World Wide Web searchWorld Wide Web search OSHAOSHA NIOSHNIOSH MSHAMSHA

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Special ThanksSpecial Thanks

Fike Explosion Protection SystemsFike Explosion Protection Systems Elkem Metals Company, LPElkem Metals Company, LP Eramet-Marietta, LPEramet-Marietta, LP

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Questions?Questions?

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Thank You!Thank You!

dust explosion prevention

Documents

recorded dust explosion

dust capable

knowledge of dust explosions

control of dust explosions

hartmann source

dust reactions prerequisites

sphere source

explosion anatomy