Aiha Combustable Dusts

8/13/2019 Aiha Combustable Dusts

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Combustible DustsCombustible DustsPresented byPresented by

Bruce L. Rottner, CSPBruce L. Rottner, CSPAtAt

AIHce 2006 in Chicago, IllinoisAIHce 2006 in Chicago, Illinois


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First Documented Dust ExplosionFirst Documented Dust ExplosionMr. GiacomelliMr. Giacomellis Bakerys Bakery

Turin, ItalyTurin, Italy December 14 1785December 14 1785

Count Morozzo recounts his investigation as documented in theCount Morozzo recounts his investigation as documented in theMemoirs of the Academy of Science of TurinMemoirs of the Academy of Science of Turin

On the 14On the 14THTH of December, 1785, about six oof December, 1785, about six oclock in the evening, thereclock in the evening, theretook place in the house of Mr. Giacomelli, baker in the city, antook place in the house of Mr. Giacomelli, baker in the city, anexplosion which threw down the windows and windowexplosion which threw down the windows and window--frames of hisframes of hisshop which looked into the street; the noise was as loud as thatshop which looked into the street; the noise was as loud as that of aof alarge cracker, and was heard at a considerable distance. At thelarge cracker, and was heard at a considerable distance. At the

moment of the explosion, a very bright flame, which lasted onlymoment of the explosion, a very bright flame, which lasted only aafew seconds, was seen in the shop; and it was immediatelyfew seconds, was seen in the shop; and it was immediatelyobserved, that the inflammation proceeded from the flourobserved, that the inflammation proceeded from the flour --warehouse which was situated over the back shop where a boy waswarehouse which was situated over the back shop where a boy wasemployed in stirring some flour by the light of a lamp.employed in stirring some flour by the light of a lamp.


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Case HistoryCase History WestWest

Pharmaceutical Services 1/29/2003Pharmaceutical Services 1/29/2003 6 fatalities6 fatalities

38 injuries38 injuries The explosion could beThe explosion could be

heard 25 miles from theheard 25 miles from the

plantplant

Shattering glass injured aShattering glass injured a

student at a school 0.5student at a school 0.5

mile away.mile away.

Flaming debris set woodsFlaming debris set woodson fire as far as two mileson fire as far as two miles

away.away.


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West Pharmaceutical (cont.)West Pharmaceutical (cont.)

Plastic dust was deposited on top of aPlastic dust was deposited on top of a

suspended ceiling.suspended ceiling. toto inch thick on horizontal surfacesinch thick on horizontal surfaces

(e.g., tops of the tiles, lighting fixtures,(e.g., tops of the tiles, lighting fixtures,

beams, conduit, etc.)beams, conduit, etc.)

Estimation was that a ton of powder hadEstimation was that a ton of powder had

accumulated.accumulated.

Accumulated for a period of years.Accumulated for a period of years.


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West Pharmaceutical (cont.)West Pharmaceutical (cont.)

Several Ignition Sources Identified by theSeveral Ignition Sources Identified by the

U.S. Chemical Safety and HazardU.S. Chemical Safety and HazardInvestigation BoardInvestigation Board

Overheated batch of rubberOverheated batch of rubber

Electrical faultElectrical fault

Hot lighting ballastHot lighting ballast

Spark from an electric motorSpark from an electric motor


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MSDS PolyethyleneMSDS PolyethyleneFire and Explosion Hazard InformationFire and Explosion Hazard Information

==================================================================================

============== Extinguishing Media: WATER, CARBON============== Extinguishing Media: WATER, CARBONDIOXIDE, DRY CHEMICAL. Fire Fighting Procedures: USE NIOSHDIOXIDE, DRY CHEMICAL. Fire Fighting Procedures: USE NIOSHAPPRVD SCBA & FULL PROT EQUIP (FP N). IF PROT EQUIP IS NOTAPPRVD SCBA & FULL PROT EQUIP (FP N). IF PROT EQUIP IS NOTAVAIL/NOT USED, FIGHT FIRE FROM PROTECTED LOCATION/SAFEAVAIL/NOT USED, FIGHT FIRE FROM PROTECTED LOCATION/SAFEDIST. KEEP PEOPLE AWAY. ISOLATE FIRE AREA & DENY UNNECDIST. KEEP PEOPLE AWAY. ISOLATE FIRE AREA & DENY UNNECENTRY. COOL SURROUND S W/WATER TO LOCALIZE FIRE ZONE.ENTRY. COOL SURROUND S W/WATER TO LOCALIZE FIRE ZONE.HAND HELD CARBON DIOXIDE/DRY CHEM EXTINGS MAY BE USEDHAND HELD CARBON DIOXIDE/DRY CHEM EXTINGS MAY BE USEDFOR SM FIRES. SOAK THORO(SUPDAT) Unusual Fire/ExplosionFOR SM FIRES. SOAK THORO(SUPDAT) Unusual Fire/ExplosionHazard: DENSE SMOKE IS EMITTED WHEN BURNED W/OUTHazard: DENSE SMOKE IS EMITTED WHEN BURNED W/OUTSUFFICIENT OXYG. MECH HNDLG CAN CAUSE FORM OF DUSTS. TOSUFFICIENT OXYG. MECH HNDLG CAN CAUSE FORM OF DUSTS. TOREDUCE POTNTL FOR DUST EXPLO, DO NOT PERMIT DUST TOREDUCE POTNTL FOR DUST EXPLO, DO NOT PERMIT DUST TO

ACCUM. HAZ COMBUST PRODS:UNDER FIRE CNDTNS POLYMERSACCUM. HAZ COMBUST PRODS:UNDER FIRE CNDTNS POLYMERSDECOMPOSE. SMOKE MAY CONTAIN POLYMER FRAGMENTS OFDECOMPOSE. SMOKE MAY CONTAIN POLYMER FRAGMENTS OFVARYING COMPOSITIONS IN ADDN TO UNIDENTIFIED TOX &/ORVARYING COMPOSITIONS IN ADDN TO UNIDENTIFIED TOX &/ORIRRIT (SUPDAT)IRRIT (SUPDAT)


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Industries At RiskIndustries At Risk

AgriculturalAgricultural

ChemicalChemical

PharmaceuticalsPharmaceuticals

WoodWood PlasticsPlastics

FoodFood CoalCoal


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Combustion PrinciplesCombustion Principles Fire is a rapid oxidationFire is a rapid oxidation

process with the evolution ofprocess with the evolution oflight and heat in varyinglight and heat in varyingintensities.intensities.

2C + O2C + O22 2CO2CO

Deflagration is a combustionDeflagration is a combustionreaction in which the velocityreaction in which the velocity

of the reaction front throughof the reaction front throughthe unreacted fuel medium isthe unreacted fuel medium isless than the speed of sound.less than the speed of sound.


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One Explosion or TwoOne Explosion or Two


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Importance of Maintenance (andImportance of Maintenance (and

Inspection) of EquipmentInspection) of Equipment

Identifies problems before they becomeIdentifies problems before they become

disasters.disasters.

Reduces the potential for ignition sources.Reduces the potential for ignition sources.

Reduces the amount of fugitive dust in theReduces the amount of fugitive dust in the

work environment.work environment.


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Definition of aDefinition of adustdust

Combustible DustCombustible DustAny finely divided solidAny finely divided solid

material that is 420 microns or smaller inmaterial that is 420 microns or smaller indiameter (material passing a U.S. No. 40diameter (material passing a U.S. No. 40

Standard Sieve) and presents a fire orStandard Sieve) and presents a fire or

explosion when dispersed or ignited in air.explosion when dispersed or ignited in air.


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Surface Area to Mass RatioSurface Area to Mass Ratio Dust explosion is a rapid oxidation of theDust explosion is a rapid oxidation of the

particle surface.particle surface.

Increasing the surface to mass ratio allowsIncreasing the surface to mass ratio allowsless heat to dissipate into the mass.less heat to dissipate into the mass.

The less heat absorbed by the mass of theThe less heat absorbed by the mass of theparticle, the more that heat acceleratesparticle, the more that heat acceleratesthe reaction.the reaction.


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Optimum Cloud DensityOptimum Cloud Density

An optimum cloud density allows sufficientAn optimum cloud density allows sufficient

distance between the particles to allowdistance between the particles to allow

access of oxygen around the particles; butaccess of oxygen around the particles; butclose enough so that the heat of oneclose enough so that the heat of one

ignited particle can initiate reactions inignited particle can initiate reactions in

nearby particles.nearby particles.


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Ignition of Dust LayersIgnition of Dust Layers Ignition of a dust layer is a function of the typeIgnition of a dust layer is a function of the type

of dust, its physical and chemical properties, andof dust, its physical and chemical properties, andthe depth of the layer.the depth of the layer.

The ignition of a dust layer usually occurs at aThe ignition of a dust layer usually occurs at a

lower temperature than a dust cloud.lower temperature than a dust cloud. Once the material is ignited it then can serve asOnce the material is ignited it then can serve as

an ignition source for a dust cloud.an ignition source for a dust cloud.

The ignition temperature of a layer can decreaseThe ignition temperature of a layer can decreaseover time when subjected to constant heating.over time when subjected to constant heating.


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Ignition of Dust CloudsIgnition of Dust Clouds

Ignited dust particlesIgnited dust particles

Mechanical sparksMechanical sparks

Static electricityStatic electricity Electrical sourcesElectrical sources

Heat sourcesHeat sources

Open flamesOpen flames


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General ParametersGeneral Parameters Average minimum concentration of aAverage minimum concentration of a

combustible dust is approximately 0.05 ozs / ftcombustible dust is approximately 0.05 ozs / ft33

or 50 g / mor 50 g / m33

Materials that ignite above 0.50 joules are notMaterials that ignite above 0.50 joules are notconsidered sensitive to ignition by electrostaticconsidered sensitive to ignition by electrostaticdischarge.discharge.

Draft System +,Draft System +, --, and ?, and ?

Min. Ignition Temp. of a Cloud < 400Min. Ignition Temp. of a Cloud < 400 CC

Min. Ignition Temp. of a Layer 5mm < 300Min. Ignition Temp. of a Layer 5mm < 300 CC

Min. Ignition Energy of a Cloud < 15 mJMin. Ignition Energy of a Cloud < 15 mJ


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Laboratory TestsLaboratory Tests Minimum Explosive Concentration (MEC)Minimum Explosive Concentration (MEC)

Minimum Ignition Temperature (MIT)Minimum Ignition Temperature (MIT)cloud or a layercloud or a layer

Minimum Ignition Energy (MIE)Minimum Ignition Energy (MIE) Maximum Explosion Pressure and Rate ofMaximum Explosion Pressure and Rate of

Pressure RisePressure Rise


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Factors Effecting Laboratory TestsFactors Effecting Laboratory Tests

Variation of apparatus *Variation of apparatus *

Ability to achieve perfect dispersion of theAbility to achieve perfect dispersion of thedust.dust.

Particle SizeParticle Size

Moisture ContentMoisture Content


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Minimum Explosive ConcentrationMinimum Explosive Concentration

Hartmann Apparatus (Vertical tubeHartmann Apparatus (Vertical tube

apparatus)apparatus) Positive result is the bursting of a paperPositive result is the bursting of a paper

diaphragm at the top of the apparatus.diaphragm at the top of the apparatus.

Quantity of dust is decreased 5 mg untilQuantity of dust is decreased 5 mg until

no explosions occurs in four successiveno explosions occurs in four successive

trials.trials.


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Minimum Ignition TemperatureMinimum Ignition Temperature --

CloudCloud

Conducted in a GodbertConducted in a Godbert--GreenwaldGreenwald

FurnaceFurnaceAir dispersion of dust into the furnace.Air dispersion of dust into the furnace.

Positive result is the observation of a flame atPositive result is the observation of a flame at

the bottom of the furnace.the bottom of the furnace. Standard quantity of dust 0.1 g. (0.05 andStandard quantity of dust 0.1 g. (0.05 and

1.0)1.0)

Increments of 5Increments of 5

C.C. Positive results in one or more trials in aPositive results in one or more trials in a

group of four.group of four.


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Minimum Ignition TemperatureMinimum Ignition Temperature

LayerLayer

Hot PlateHot PlateA metal ring is placed on a hot plateA metal ring is placed on a hot plate

and filled with the dust. Thermocouples recordand filled with the dust. Thermocouples recordthe temperature of the hot plate and the dust.the temperature of the hot plate and the dust.

If the dust temperature exceeds the hot plate byIf the dust temperature exceeds the hot plate by

2020 C then an ignition is recorded.C then an ignition is recorded. US Bureau of Mines test involves a metal meshUS Bureau of Mines test involves a metal mesh

basket which is filled with the dust. Air of abasket which is filled with the dust. Air of a

known temperature is flowed across the powder.known temperature is flowed across the powder.An ignition is when the temperature of theAn ignition is when the temperature of the

powder exceeds the surrounding air.powder exceeds the surrounding air.


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Minimum Ignition EnergyMinimum Ignition Energy US Bureau of Mines conducted the test inUS Bureau of Mines conducted the test in

the Hartmann Apparatusthe Hartmann Apparatus Multiple trials are used to determine aMultiple trials are used to determine a

minimum energy discharge for ignition.minimum energy discharge for ignition.

The minimum spark ignition energy is theThe minimum spark ignition energy is the

lowest setting at which a positive result islowest setting at which a positive result is

obtained in one out of at least four trials.obtained in one out of at least four trials.


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Maximum Pressure (PMaximum Pressure (PMAXMAX) and) and

Maximum Rate of Pressure Rise (RMaximum Rate of Pressure Rise (RMAXMAX))

Hartmann ApparatusHartmann Apparatus

2020--Liter SphereLiter Sphere


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KKSTST

KKSTST is an index used to classify the explosionis an index used to classify the explosion

severity of a combustible dust.severity of a combustible dust.

It is based on the maximum rate of pressureIt is based on the maximum rate of pressure

rise, (dP/dt)rise, (dP/dt)MAXMAX and the units areand the units arebar/second.bar/second.

KKSTST = (dP/dt)= (dP/dt)MAXMAX * V* V1/31/3 (V is the vessel(V is the vessel

volume ~ mvolume ~ m33))


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KKSTST

IndexIndex

> 300> 300StSt -- 33

201201 -- 300300StSt -- 22

Up to 200Up to 200StSt -- 11

KKSTST

(bar(bar--m/s)m/s)

Dust ClassDust Class


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Explosion Severity IndexExplosion Severity Index

(US Bureau of Mines)(US Bureau of Mines)

>10>10>2.0>2.0>5.0>5.0SevereSevere

1.01.0 -- 10101.01.0 2.02.01.01.0 5.05.0StrongStrong

0.10.1 1.01.00.50.5 1.01.00.20.2 1.01.0ModerateModerate


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Explosion SeverityExplosion Severity

(Maximum Explosion Pressure X Maximum Rate of(Maximum Explosion Pressure X Maximum Rate of

Pressure Rise) Sample dustPressure Rise) Sample dust

(Maximum Explosion Pressure X Maximum Rate of(Maximum Explosion Pressure X Maximum Rate of

Pressure Rise) Pittsburgh Coal dustPressure Rise) Pittsburgh Coal dust


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Index of ExplosibilityIndex of Explosibility

Ignition Sensitivity X Explosion SeverityIgnition Sensitivity X Explosion Severity


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Protection MethodsProtection Methods Deflagration Pressure ContainmentDeflagration Pressure Containment

Deflagration VentingDeflagration Venting SuppressionSuppression

Oxygen ReductionOxygen Reduction

Deflagration venting through a listed dustDeflagration venting through a listed dust

retention and flameretention and flame--arresting devicearresting device

Isolation (prevent propagation)Isolation (prevent propagation) chokes, rotarychokes, rotary

valves, flame front diverters, fast acting valvesvalves, flame front diverters, fast acting valves


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NEC ClassificationsNEC ClassificationsArticle 500Article 500Class II, Division 1 and 2 locations where fire or explosionClass II, Division 1 and 2 locations where fire or explosion

hazards may exist due to combustible dust.hazards may exist due to combustible dust.

Division 1Division 1

Combustible dust in air under normal operating conditions inCombustible dust in air under normal operating conditions inquantities sufficient to produce an explosive or ignitiblequantities sufficient to produce an explosive or ignitiblemixture.mixture.

Division 2Division 2

Combustible dust due to abnormal conditions in quantities,Combustible dust due to abnormal conditions in quantities,

Dust accumulation on, in, or in the vicinity of the electricalDust accumulation on, in, or in the vicinity of the electrical

equipment could be sufficient to interfere with the safeequipment could be sufficient to interfere with the safedissipation of heat from electrical equipment, or could bedissipation of heat from electrical equipment, or could beignitible by abnormal operation or failure of electricalignitible by abnormal operation or failure of electricalequipmentequipment..


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Group EGroup E Group EGroup EAtmospheres containing combustibleAtmospheres containing combustible

metal dusts, including aluminum, magnesium,metal dusts, including aluminum, magnesium,and their commercial alloys, or otherand their commercial alloys, or other

combustible dusts whose particle size,combustible dusts whose particle size,

abrasiveness, or conductivity present similarabrasiveness, or conductivity present similarhazards in the use of electrical equipment.hazards in the use of electrical equipment.

Aluminum, Chromium, Ferromanganese, Iron,Aluminum, Chromium, Ferromanganese, Iron,Manganese, and MagnesiumManganese, and Magnesium


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Group FGroup FGroup FGroup FAtmospheres containing combustibleAtmospheres containing combustible

carbonaceous dusts that have more than 8carbonaceous dusts that have more than 8percent total entrapped volatiles or that havepercent total entrapped volatiles or that have

been sensitized by other materials so that theybeen sensitized by other materials so that they

present an explosion hazard.present an explosion hazard.

Coal, carbon black, charcoal, pitch, and coke dustCoal, carbon black, charcoal, pitch, and coke dust


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Group GGroup GGroup GGroup GAtmospheres containing otherAtmospheres containing other

combustible dusts, including flour, grain,combustible dusts, including flour, grain,wood flour, plastic, and chemicalswood flour, plastic, and chemicals


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Housekeeping as it Relates to NECHousekeeping as it Relates to NEC Assume a bulk density of 75 lbs/ftAssume a bulk density of 75 lbs/ft33 (1200 Kg /(1200 Kg /

mm33

) and assumed concentration of 0.35 oz /ft) and assumed concentration of 0.35 oz /ft33

(350 g/m(350 g/m33) it has been calculated that a dust) it has been calculated that a dust

layer averaging 1/32 inch is sufficient to form alayer averaging 1/32 inch is sufficient to form a

combustible dust cloud.combustible dust cloud. Reference Section 5.2.2 of NFPA 499 whichReference Section 5.2.2 of NFPA 499 which

states: When a dust layer is greater than 1/8states: When a dust layer is greater than 1/8

inch thick (3mm) is present under normalinch thick (3mm) is present under normalconditions, the location should be classified asconditions, the location should be classified as

Division 1.Division 1.


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Housekeeping as it Relates to NECHousekeeping as it Relates to NEC

(continued)(continued)Table A.5.2.2(a) Division Determination GuidelinesTable A.5.2.2(a) Division Determination Guidelines

Based on Dust Layer ThicknessBased on Dust Layer Thickness

Greater than 1/8 inch (3.0mm) Division 1Greater than 1/8 inch (3.0mm) Division 1

Less than 1/8 inch, but surfaceLess than 1/8 inch, but surfacecolor not discernable Division 2color not discernable Division 2

Surface color discernable underSurface color discernable underthe dust layer Unclassifiedthe dust layer Unclassified


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Fire Brigades and EmergencyFire Brigades and Emergency

ResponseResponseA dust explosion can be initiated by anA dust explosion can be initiated by an

incipient fire.incipient fire. Incipient Fire Brigades:Incipient Fire Brigades:

Have limited training.Have limited training.

Can use hose streams to fight fires.Can use hose streams to fight fires. Have little or no Personal ProtectiveHave little or no Personal Protective

Equipment (PPE).Equipment (PPE).

A dust explosion can be initiated byA dust explosion can be initiated byan incipient fire.an incipient fire.


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Emergency Response PlanningEmergency Response Planning

PrePre--ExplosionExplosion

Dust ExplosionDust Explosion

PostPost--ExplosionExplosion


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Determining the CauseDetermining the Cause Ignited materials can travel throughIgnited materials can travel through

process equipment far from its ignitionprocess equipment far from its ignitionsource until it reaches a combustiblesource until it reaches a combustiblecloud.cloud.

Fire and explosions destroy some of theFire and explosions destroy some of theevidence necessary to make aevidence necessary to make adetermination.determination.

For the most part, determining cause isFor the most part, determining cause isonly achieved in about 50% of the cases.only achieved in about 50% of the cases.


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Post Event Working EnvironmentPost Event Working Environment Community and regulatory industries haveCommunity and regulatory industries have

a renewed interest in your facility.a renewed interest in your facility. Facility personnel have a perceived risk ofFacility personnel have a perceived risk of

an elevated hazard.an elevated hazard.

Strong push to rebuild and resumeStrong push to rebuild and resumeoperations.operations.

EHS personnel along with facilityEHS personnel along with facility

management must decide when to resumemanagement must decide when to resumenormal operations.normal operations.


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Resuming Normal OperationsResuming Normal Operations Rebuilding equipment and facilities onceRebuilding equipment and facilities once

thought to be safe but led to a dustthought to be safe but led to a dustexplosion.explosion.

The exact ignition source of a dustThe exact ignition source of a dust

explosion is only identified approximatelyexplosion is only identified approximately

50% of the time.50% of the time.

Theories and solutions are numerous andTheories and solutions are numerous andvaried.varied.


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StandardsStandards NFPA 61, Standard for the Prevention of Fires and DustNFPA 61, Standard for the Prevention of Fires and DustExplosions in Agricultural and Food Product FacilitiesExplosions in Agricultural and Food Product Facilities

NFPA 70, National Electrical Code (2005)NFPA 70, National Electrical Code (2005)

NFPA 499, Recommended practice for the ClassificationNFPA 499, Recommended practice for the Classificationof Combustible Dusts and of Hazardous (classified)of Combustible Dusts and of Hazardous (classified)Locations for Electrical Installations in Chemical ProcessLocations for Electrical Installations in Chemical ProcessAreas (2004)Areas (2004)

NFPA 654, Standard for the Prevention of Fire and DustNFPA 654, Standard for the Prevention of Fire and Dustexplosions from the Manufacturing, Processing, andexplosions from the Manufacturing, Processing, and

Handling of Combustible Particulate Solids (2006)Handling of Combustible Particulate Solids (2006)

NFPA 664, Standard for the Prevention of Fires andNFPA 664, Standard for the Prevention of Fires andExplosions in Wood Processing and WoodworkingExplosions in Wood Processing and Woodworking

FacilitiesFacilities

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