1 Prev Dust Explosions

7/29/2019 1 Prev Dust Explosions

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Combustible Dust Course for

Die Casting Industry Employees

Preventing Dust Explosions and Fires

Protecting Employees from the Effects of Dust

Explosions and Fires

NADCANorth American Die Casting Association


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Unit 1 Preventing Dust Explosions and Fires in theDie Casting Industry

Unit 2 Protecting Employees from the Effects of

Dust Explosions and Fires in the Die

Casting Industry

Unit 3

Unit 4


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Introductions

Class

Schedule

Instructions


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Terminal objectives for this

Course

Upon completion of this coursestudents should be able to:

1. Explain how the materials used indie casting facilities may cause

dust explosions and fires, theconsequences of these events andhow they may be prevented andmitigated.

2. Implement the work practices andprocedures that will keepemployees in the die castingindustry safe from the hazards of

dust explosions and fire.

Alloydustsexplode!


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Preventing Dust Explosionsand Fires in the Die Casting

Industry

Unit 1



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Enabling Objectives

consequences to employees themselves

and to the die casting plant; and,Identify the materials used in die casting

that may cause dust explosions and/or fires

and how they may be prevented or reducedin severit if the occur.

Students should be able to:

Discuss dust explosionsand fires as a significantsafety problem that mayaffect them;

Explain how these eventsoccur and how they mayhave catastrophic Metal

Dust

Collector

-Exploded

and

Collapsed


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This presentation is based onCombustible Dust in Industry. . . - OSHASafety and Health Information Bulletin (SHIB 07-31-

2005) (download athttp://www.osha.gov/dts/shib/index.html )NFPA 484Standard for Combustible Metals, 2009 Ed.(on-line free viewing athttp://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asp )
http://www.osha.gov/dts/shib/index.htmlhttp://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asphttp://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asphttp://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asphttp://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asphttp://www.osha.gov/dts/shib/index.html


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CombustibleDust

Explosions
http://www.diecasting.org/default.htm


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Background

This section describes a series of horrific dust

explosions that have occurred recently. The US Chemical Safety and Accident

Investigation Board (CSB) and OSHA have

identified these explosions as representative

of a national safety problem.

The list includes a spectacular metal dust

explosion and fire in Indiana that killed one

and injured one employee.


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Metal Dust Fire and Explosion: Indiana(1 killed,1 injured)

Recent Sugar Dust Explosion

Organic Dust Fires and Explosions:

Massachusetts

(3 killed, 9 injured)

North Carolina

(6 killed, 38 injured) Kentucky

(7 killed, 37 injured


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Common Causal Factors

Housekeeping tocontrol dust

accumulations

unacceptable; Ventilation system

design flaws;

Lack ofHazardAssessment;

Lack of explosionprevention and

mitigation.


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Imperial Sugar CompanyPort Wentworth GAExplosion and FireFebruary 7, 2008

14 Deaths and Numerous serious injuries


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US Chemical Safety andHazard Investigation Board Photo


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US Chemical

Safety Board Found a pattern

of catastrophicdust explosions

Recommendedthat OSHA takeaction

MSDS sheetsoften fail toprovide dustexplosioninformation


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U.S. DEPARTMENT OF LABOR Occupational Safety and Health Administration

DIRECTIVE NUMBER: CPL 03-00-008 EFFECTIVE DATE: March 11, 2008

SUBJECT:

Combustible Dust National Emphasis Program

OSHA inspectors are to

go out and inspect

facilities across the US.


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With

confinement

there is an

explosion

Dust Explosion Requirements

Dust is combustible.

It must be dispersed in air or another oxidant,

and

The concentration is at or above the minimum

explosible concentration (MEC).There is an ignition source, such as

an electrostatic discharge,

- spark,

- glowing ember,- hot surface,

- friction heat, or

- a flame

that can ignite the dispersed combustible mixture


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Some event

disturbs the

settled dust

into a cloud

Dust cloud is

ignited and

explodes

Dust explosion in a work area

Dust settles on flat

surfacesDust

Adapted from CSB


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Dust

collectorventingflame jet

Dust explosion in

equipment


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Dust explosion in

equipment

With dispersaland ignition of 2 kg dust

by the flame jet

Dust

Collector

Dust explosion in

equipment


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Dust explosions

damage a containment system (suchas a duct, vessel, or collector).

The additional dust dispersed into the airmay causeone or more secondaryexplosions.

These can befar more destructivethan a primary explosion.

An initial (primary)

explosion in processing equipment or

in an areawhere fugitive dusthas accumulated:

may shake loose moreaccumulated dust; or,


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Time, msec.

(Timing of actual events may vary)

0 25 50 75 100 125 150 175 200 225 250 300 325

Primary deflagration inside process equipment


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Shock wave caused

by primary deflagration

Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Shock waves reflected by surfaces within

the building cause accumulated dust to gointo suspension


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Dust clouds thrown in the air by the shock waves


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Primary deflagration breaks out of the equipment

enclosure - creating a source of ignition


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Secondary deflagration ignited


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Secondary Deflagration is propagated

through the dust clouds


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Secondary

deflagration bursts

from the building


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Time, msec.

0 25 50 75 100 125 150 175 200 225 250 300 325

Collapsed building with remaining fires

Adapted from OSHA diagrams prepared by

John M. Cholin, P.E., FSFPE, J.M. Cholin Consultants, Inc.


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Combustible dust explosion hazard may

exist in a variety of industries

dyes, coal, metals (e.g.,

aluminum,chromium,iron,

magnesium,and zinc), and fossil fuel power

generation.

food (e.g., candy,

starch, flour, feed),

plastics,

wood,

rubber,

furniture,

textiles, pesticides,

pharmaceuticals,


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. . .any industrial process that reduces a

combustible material and some normallynoncombustible materials

to a finely divided state

presents a potential for a serious fire or

explosion. (NFPAs Industrial Fire HazardsHandbook)


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Combustible Dust ExplosionsPractice Quiz

1. A combustible dust explosion or deflagration mayoccur when combustible dust, an ignition source, airor other oxidant, ______________ are present.A. Dispersion of the dust

B. ConfinementC. A. and B. aboveD. None of the above

2. Combustible dust explosion hazards frequently

exist in which of the following industrial activities?A. Collecting beach and lake bottom sandB. Mixing cementC. Manufacturing and finishing magnesium and

aluminum alloy castings.

D. All of the above


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3. A combustible dust explosion in a piece ofequipment or area where dust has accumulated:A. May shake loose more accumulated dustB. Damage a containment system

C. Cause one or more destructive secondaryexplosions

D. All of the above


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1. A combustible dust explosion or deflagration mayoccur when combustible dust, an ignition source, airor other oxidant, ______________ are present.A. Dispersion of the dustB. Confinement

C. A. and B. aboveD. None of the above

2. Combustible dust explosion hazards frequentlyexist in which of the following industrial activities?

A. Collecting beach and lake bottom sandB. Mixing cement

C. Manufacturing and finishing magnesiumand aluminum alloy castings.

D. All of the above


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3. A combustible dust explosion in a piece ofequipment or area where dust has accumulated:A. May shake loose more accumulated dustB. Damage a containment system

C. Cause one or more destructive secondaryexplosions

D. All of the above


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Combustible Dust Explosions

In this section, we described a series of

horrific dust explosions that have occurredrecently. Common causes were identified

How the explosions occurred was outlined

The factors needed to produce anexplosion and the explosion process

was discussed in detail.


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Particles

In this section,particles thatparticipate in theexplosion process are

discussed. Theircharacteristics

are identified.

How they form in anindustrial process isoutlined Metal Dust Particles


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Particles

Size

Pellets > 2mm diameter Granules 0.42mm - 2mm dust particles < 0.42mm (420m)

Hazard increases as particlesize decreases

larger surface area for

combustion Fine particles may have a larger

role in dust cloud ignition and

explosion propagation.


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Particle Size of Common Materials

Common Material Size (microns)

Table salt 100

White granulated sugar 450 - 600

Sand 50+

Talcum (baby) powder 10

Mold spores 10 30

Human hair 40 - 300Flour 1 - 100

Source: OSHA and Filtercorp International Ltd.

P ti l


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Particles

Dusts may occur in the process streamand cause a hazard, regardless of

starting particle size of the materialmay

break

into

or


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ParticlesPractice Quiz

1. Regarding combustible dust particles grinding andpolishing waste:A. Hazard decreases as particle size increasesB. Hazard increases as particle size decreasesC. They produce no hazardD. None of the above

2. Dusts may occur in the process stream and cause ahazard, regardless of starting particle size of thematerial :

A.TrueB.False


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ParticlesPractice Quiz

1. Regarding combustible dust particles grinding andpolishing waste:A. Hazard decreases as particle size increases

B. Hazard increases as particle size

decreasesC. They produce no hazardD. None of the above

2. Dusts may occur in the process stream and cause ahazard, regardless of starting particle size of the

material :

A.TrueB.False


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Particles

In this section,particles thatparticipate in theexplosion process

were discussed. Theircharacteristics

were identified.

How they form in anindustrial process wasoutlined Metal Dust Particles

Facility Analysis Components


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In this section, the variouscomponents of facility

analysis are discussed.

Several factors are

identified as critical to theanalysis:

Material combustibility;

Electrical classification;

Dust control;

Ignition control; and,

Damage control. Hazard Analysis Couch

Dust



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Carefully identify:

Materials that can becombustible when finely divided;

Processes which use, consume,

or produce combustible dusts;

Open areas where combustibledusts may build up;

Hidden areas where

combustible dusts may

accumulate;

Means by which dust may be

dispersed in the air; and

Potential ignition sources.

D t C b tibilit


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See

Explosives

regulations

Dust Combustibility

The primary factorin anassessment of thesehazards is whether thedust is in factcombustible.

Determine if a dust cloudwill:

Detonate

Deflagrate

Present a fire hazard Or will Not burn or

ignite

Testing may be necessary

D t C b tibilit


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See

Explosives

regulations

Dust Combustibility

A detonation is a combustion

event that burns fasterthanthe speed of sound:

Not common in industry;

Not generally theproblem in an industrial dustexplosion.

A deflagration is a combustionevent that burns slower thanthe speed of sound:

A pushing force;

The mechanism of destructionin most

combustible dust explosions.

D t C b tibilit


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Dust Combustibility

Combustible dust per NFPA 654

Prior to 2006 - Any finely divided solidmaterial that is 420 microns or smallerindiameter (material passing a U.S. No. 40 StandardSieve) and presents a fire or explosion hazardwhen dispersed and ignited in air.

2006 Edition A combustible particulate solid thatpresents a fire or deflagration hazardwhen suspended in air or some other oxidizingmedium over a range of concentrations, regardlessof particle size or shape.


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Dust Combustibility

0

2.5 ug/m315 mg/m3

15 g/m31200 g/m3

ExplosibleRange

IHRange

Concentration1000X

Dust Combustibility


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25 watt light bulb probably can not be

seen through six feet of a mixture ofcombustible dust in air> Minimum

Explosible Concentration

Dust Combustibility

Whatbulb

?

25 watts

2 meters

Glass

40 g/m3 concentration ofcomb. dust suspended in air

Glass


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What is wrong here?

Dust Combustibility


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Dust Combustibility

Information sources

Best to rely on As used test data

Chemical supplier test data

MSDS sheets Published tables

Variables Particle size,

Shape

Changes in the materialproduced by process

equipment.

Many others

Dust from Die Casting Alloys


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Dust from Die Casting Alloys

ChipsProduced

Dust

Resulting in



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Dust Combustibility

Practice Quiz

1. The primary factor in an assessment of a materials dustexplosion hazard is to:A. Determine whether the dust is in fact combustibleB. Measure the size of the particles

C. Determine if the dust will pass through a #40 USGscreen

D. None of the above2. A deflagration is a combustion event that:

A. Burns at a rate slower than the speed ofsound

B. Provides a pushing force

C. Is the mechanism of destruction in most industrialdust explosions.

D. All of the above



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Dust Combustibility

Practice Quiz

3. Dust produced in die casting plants is almost alwayscombustible when dispersed in air at the correctconcentration::

A. TrueB. False



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Dust Combustibility

Practice Quiz

1. The primary factor in an assessment of a materials dustexplosion hazard is to:

A. Determine whether the dust is in factcombustible

B. Measure the size of the particlesC. Determine if the dust will pass through a #40 USGscreen

D. None of the above



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Dust Combustibility

Practice Quiz

2. A deflagration is a combustion event that:A. Burns at a rate slower than the speed of soundB. Provides a pushing force

C. Is the mechanism of destruction in most industrialdust explosions.

D. All of the above3. Dust produced in die casting plants is almost always

combustible when dispersed in air at the correct

concentration:

A. TrueB. False

Other Hazard Analysis


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Considerations

Electrical equipment and facilities at the plant


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Magnesium Alloys

Aluminum Alloys Zinc-Aluminum and Zinc Alloys

(For Zinc alloys utilize as used

test data or treat as Class II)

Dust Areas

NEC Class II Group E

Electrical classification


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Electrical classification

OSHAElectrical standard(29 CFR Part 1910 Subpart S)

NFPA 70, the NationalElectrical Code. (NEC)

NFPA 499, . . . Classificationof Combustible Dusts and ofHazardous (classified)

Locations for ElectricalInstallations in ChemicalProcess Areas.

Electrical

EquipmentClass II

Division 1

Group EF

GE

El t i l Cl ifi ti d Cl i


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Electrical Classification and Cleaning

If Clean-up is constant and

Dust layer is not apparent; Surface color is discernible;

e.g.: Storage area with bags,

drums, or closed hoppers; No dust around.

Ordinary

ElectricalEquipment

See NFPA

499 Figure

5.8(e)

Ledge Dust Surfacecolor obscured with

Group E metal dust

A hazard and NEC Class

II location

Fire Codes* speak plainly


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Fire Codes speak plainly

Group E dusts

. . . could cause a short inthe electrical equipment . . .

. . . (electricity may find) the

path of least resistance

through a dust layer, heatingup the dust particles in it pathand thus providing a

source of ignition. The

resulting electric arc couldignite a dust layer or dust

cloud.

*NFPA 499 . . . Hazardous (Classified) Locations (2008) Sec 4.4

Fire Codes* speak plainly


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Fire Codes speak plainly

Dusts containing magnesium or aluminum are

particularly hazardous, and the use ofextremeprecaution is necessary to avoid ignition andexplosion.

Group E. Atmospheres (contain) combustible

metal dusts, includingaluminum,

magnesium, and

theircommercial alloys, or

othercombustible dusts whose particle size,abrasiveness, and conductivity present similarhazards. . .

*NFPA 70 National Electrical Code (2005) Article 500

NEC Electrical Classification


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Indoor unrestrictedarea

Open or semi-enclosedequipment

Source

Moderate or Dense

Dust Cloud

Dust Layer

Class II Group E Metal Dust Areas



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Plan/Top

ViewElevation/SideView

Dust Source

Moderate or

Dense Dust

Cloud or

Layer>1/8inch

Dust Layer


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Group E - Metal Dust Areas

Switches and Motor Controllers in Class II, Div.

1 areas provided with identified dust-ignition proof

enclosures

for Mg or Al - dust enclosures to be identified for

such locations.Motors and Generators must be

identified for Class II, Div. 1

or totally enclosed pipe-ventilated

Electrical Equipment for Class II


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q p

Group E - Metal Dust Areas

Lighting Fixtures IDd for hazardous locations

marked to indicate the maximum lamp wattage

for Mg or Al dust - IDd for the specific location

Receptacles and Attachment Plugs three wire plug-in type

identifiedfor Class II locations.



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y y p

Electrical Equipment

Practice Quiz

1. When dust of the following material has built up arounda work area, that location is considered a Class II GroupE Hazardous location by OSHA and the NEC:A. Aluminum alloy.

B. Magnesium alloy.C. Aluminum-Zinc alloy.D. All of the above.

2. In Class II, Div. 1 Group E areas, Switches and MotorControllers, Motors and Generators, Lighting Fixtures,Receptacles and Attachment Plugs must be:A. Identified (labeled) as suitable for those areas.B. Open sparking type.C. Vapor proof type.

D. All of the above.



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y y p


Practice Quiz

3. In general, ordinary general service electricalequipment may be installed where:.A.A dust layer is not apparent.B. It is a storage area with bags, drums, or closed

hoppers and there is no dust around.C. The surface color is discernible on all

equipment, floors, overhead beams and similaritems.




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y y p


Practice Quiz

1. When dust of the following material has built up around awork area, that location is considered a Class II Group EHazardous location by OSHA and the NEC:A. Aluminum alloy.

B. Magnesium alloy.C. Aluminum-Zinc alloy.

D. All of the above.2. In Class II, Div. 1 Group E areas, Switches and Motor

Controllers, Motors and Generators, Lighting Fixtures,Receptacles and Attachment Plugs must be:

A. Identified (labeled) as suitable for those areas.B. Open sparking type.C. Vapor proof type.D. All of the above.



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Practice Quiz

3. In general, ordinary general service electricalequipment may be installed where:.A.A dust layer is not apparent.B. It is a storage area with bags, drums, or closed

hoppers and there is no dust around.C. The surface color is discernible on all

equipment, floors, overhead beams and similaritems.




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Considerations

After hazards have been

assessed,

One or more of the

following prevention,protection and/or

mitigation methods

Dust Control

Ignition Control

Damage Control

Training



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Considerations

in which dustcan be disbursed, The normal process and Potential failure modes

such as dust collectors, acombustible mixture could be presentwhenever the equipment is operating.

to consider are those, both

in occupied areas and

in hidden concealed spaces.

Dust ControlC i


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NFPA 484 - contains

comprehensive

guidance

Some

recommendations:

Minimize the escapeof dust from process

equipment or

ventilation systems;

Use dust collectionsystems;

Casting

Remelt

Shop

area

Dust Control


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NFPA 484

guidance Inspect for

dust residuesin open andhidden areas,at regularintervals;

Cleandustresidues atregularintervals;

Dust Control


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Dust Control

NFPA 484 Use cleaning methods

that do not generatedust clouds;

Only use vacuumcleaners approvedfor dust collection;

HAZ LOC

Dust Control


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Dust ControlNFPA 484

Locate relief valves awayfrom dust hazard areas; and

Develop and implement ahazardous dust

inspection,testing,

housekeeping, and

control program

(Written with

established frequency and

methods).

Dust Control


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Dust Control

OSHA discusses

housekeeping in detail. Inspection program

provides insight on how

they interpret housekeeping

The program is listed on

the web at

http://www.osha.gov/pls/osh

aweb/owadisp.show_document?p_table=DIRECTIVES&

p_id=3830

OSHA NEP H k i


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OSHA NEP on Housekeeping

Clean immediatelywhenever a dust layer of1/32-inch thickness

accumulates (the thicknessof a paper clip wire) over a surface area of at

least 5% of the floorareaof the facility or any givenroom.

Not to exceed 1,000 ft2

Taking a

sample in a

dusty area

OSHA NEP H k i


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Include:Overhead beams, joists,

ducts,

The tops of equipment,

and other surfacesEven vertical surfaces if

they are dusty

OSHA NEP on Housekeeping

Rough calculations may show surface area of bar joists is approximately 5% of

the floor area and

the equivalent surface area for steel beams can

be as high as 10%.

Areas to observe for dust > 1/32


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Inch

Structuralmembers

Conduit and

pipe racks

Cable trays

Floors

Above ceiling

Equipment(leaks around

dust collectors

and ductwork.)

Other Hazard Analysis Considerations


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Dust ControlPractice Quiz

1. One of the most important factors for the preventionof dust explosions in the die casting industry is:A. Removal of any fugitive dust through systematic,effective housekeeping.

B. Excellent housekeeping.C. Planned, thorough and frequent regularhousekeeping activities.



D t C t l


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2. An important component of any good housekeepingprogram involves:A. Allowing waste and scrap from machining operations toaccumulate around equipment.B. Inspect for dust residues in hidden areas, at regular

intervals and, if necessary, removal of any dust.C. Blowing down, or aggressively knocking, or sweepingdown any dust.D. All of the above.

2. OSHA inspectors have been instructed that a combustibledust layer of 1/32-inch thickness exceeding 5% or 1000 sq.ft. or room area may indicate that the employer hasviolated the housekeeping regulations.A. True B. False


D t C t l


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1. One of the most important factors for the preventionof dust explosions in the die casting industry is:A. Removal of any fugitive dust through systematic,effective housekeeping.

B. Excellent housekeeping.C. Planned, thorough and frequent regularhousekeeping activities.



D t C t l


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2. An important component of any good housekeeping

program involves:A. Allowing waste and scrap from machining operations toaccumulate around equipment.

C. Blowing down, or aggressively knocking, or sweepingdown any dust.D. All of the above.

2. OSHA inspectors have been instructed that a combustibledust layer of 1/32-inch thickness exceeding 5% or 1000 sq.ft. or room area may indicate that the employer has violatedthe housekeeping regulations.

B. False


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NFPA 484

Use appropriateelectrical equipmentand wiring methods;

Control staticelectricity, including

bonding of equipment

to ground; Control smoking,

open flames, and

sparks;

No!

Ignition Control


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Separate heatingsystems from

dusts; Proper use of

cartridge activatedtools; and

Adequatelymaintainequipment.

Hotwork

permit_________

_________

_________

_________

Grinder

Kaboom!

Ignition Control


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g t o Co t o

Other ignition sources

OSHA regulates poweredindustrial trucks 29 CFR

1910.178 (c): Does not permit powered

industrial trucks where combustiblemetal dust is present in hazardous

concentrations; e.g.: Heavy dust concentrations, or

Thick dust layer;

See NFPA 505.


I iti C t l


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Ignition Control

Practice Quiz

1. Many activities that must occasionally be done industy areas produce arcs, sparks and hot surfaces:A. They must be done, so do them as fast aspossible.

B. Implementing a hot work permit system andfollowing it will control any of these hazards.

C. Uncontrolled these ignition sources may causean explosion.

D. A. and B. above.


Ignition Control


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Ignition Control

Practice Quiz

1. Many activities that must occasionally be done industy areas produce arcs, sparks and hot surfaces:A. They must be done, so do them as fast aspossible.

B. Implementing a hot work permit system andfollowing it will control these hazards.

C. Uncontrolled, these ignition sources may causean explosion.

D. A. and B. above.

Damage Control


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g

Methods controlling and reducing hazard

of the hazard (isolate with distance); of the hazard (isolate with a

barrier);

Metal

DustHazard

Not

< 30

feet

Offices and shops

Equipment Rooms

Blast barrier

Damage Control


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gof the hazard (isolate with a barrier);

contd.

Electric

initiator

Pressurized

reservoir

Gate

Pneumatic

actuator

Automatic, fast-

actingisolation

valve

Flame

front

diverter

Roof Line

Air

Damage Control


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Isolation of Equipment

Automaticfast acting

valve

Damage Control


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Diverter

valve

Airflow control valves

Diverter valves are to seal mechanicallyand close all other directions from air or

material leakage

Normal flow

of material

Positive shut

off flap

Flame

front

Hinged

device

Damage Control


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g

Deflagration venting ofa building, room, or

area;

Damage Control


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Damage ControlDeflagration venting is

required for rooms orbuildings containing a dust

explosion hazard .

Vent closures:Must be directed toward a

restricted area;

Closure must not be a

missile hazard;

Blast pressure and fireball

must not impinge on

unrestricted personnel

pathways.

Explosion

hazardbuilding

Blast resistantconstruction

Ventwall

Blast barrier

Damage Control


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g

NFPA 654(7.1.2)

Explosionprotection system

requirements

NFPA 69, Standardon ExplosionPrevention

Systems);

Fire ball expands at 30 feet per second

Pressure wave expands at 1100 feet per second

Ignition

0 Mil/sec

Total

Suppression

50 Mil/Sec

Damage Control


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g

Damage Control


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Explosion protection

NFPA 654 (7.1.2)

Dust collector

suppression system

Mechanical

isolation

valve

Deflagration

pressure

detectors

Deflagration

suppression

device

Damage Control


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>8 ft3

Outsidelocation

Engineered

containment

Venting to

outside

Suppression

In general dry dust collectors greater

than 8 cubic feet in volume located mustbe located outside.

Damage Control


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OSHA has fined facilities

where

Dry dust collectors

located inside the

building (some

exceptions) and/or dust collectors returning

air back inside the

building Ductwork

not grounded

not constructed of metal

Outsidewall

Damage ControlD t t b d i d t i t i


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>1068 meters minute

Dust

built

up

Dust

flowing

E.G.: Ontario Fire Code (5.10.1.10) requires

velocity to exceed 1068 meters minute


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In this section, the variouscomponents of facility

analysis were discussed.

Several factors were

identified as critical to theanalysis:

Material combustibility;

Electrical classification;

Dust control; Ignition control; and,

Damage control.

Gentlesweeping

only


Damage Control


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Practice Quiz

1. The following dry filter type dust collectors larger than 8 cu. ft.in volume may be located inside the plant:

A. Cyclone and bag house collectors.

B. Collectors that exhaust inside the plant.

C. Collectors with explosion relief panels venting inside thework area.

D. None of the above.

2. The following dust properly engineered dust collectors maybe located inside the plant:

A. Wet collectors.

B. Dry collectors venting outside to a safe area.

C. Dust collectors protected by an explosion suppressionsystem.


Damage Control


Damage Control


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Practice Quiz

3. It is sometimes not possible to suppress a deflagration incombustible metal dust because:

A. Flame speed is too fast and too much heat is produced bythe expanding fire ball after ignition.

B. Not enough heat is produced.

C. Flame speed is to slow and the suppression systemactivates too quickly.


Damage Control


Damage Control


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Practice Quiz

1. The following dry filter type dust collectors larger than 8 cu. ft.in volume may be located inside the plant:

A. Cyclone and bag house collectors.

B. Collectors that exhaust inside the plant.

C. Collectors with explosion relief panels venting inside thework area.

D. None of the above.

2. The following dust properly engineered dust collectors maybe located inside the plant:

A. Wet collectors.

B. Dry collectors venting outside to a safe area.

C. Dust collectors protected by an explosion suppressionsystem.


Damage Control


Damage Control


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Practice Quiz

3. It is sometimes not possible to suppress a deflagration incombustible metal dust because:

A. Flame speed is too fast and too much heat isproduced by the expanding fire ball afterignition.

B. Not enough heat is produced.

C. Flame speed is to slow and the suppression systemactivates too quickly.


Damage Control

Training


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Hazardousvertical surfaceaccumulation

Employees need

to be trained

To recognize and

prevent hazards

associated withcombustible dust:

In taking

preventative action;and/or,

How to alert

management.

Training

Training


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g

They need to know The safe work practices applicable to

their job tasks,

The overall plant programs for dust

control and ignition source control.

Training must be

Before they start work

Periodically to refresh their knowledge

When reassigned

When hazards or processes change

TrainingManagement Responsibility


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Management Responsibility

Comply with the Hazard Communication

Standard

Have a qualified team conduct a facility

analysis (or have one done by qualified outside

persons) prior to the introduction of a hazard and

Develop a prevention and protection scheme

tailored to the operation.

List of

Chemicals

Training


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a g

Supervisors and managersshould be aware of and

support the plant dust and

ignition control programs.Their training should include

identifying how they can

encourage the reporting ofunsafe practices and

facilitate abatement

actions

Training


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Necessary training andeducation for dust explosionprevention were discussed in thissection.

Training needs were identified for:Employees;

Supervisors;

Managers.

Training

Training


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gPractice Quiz

1. Who must be trained and educated regardingcombustible dust explosions?A.EmployeesB. SupervisorsC. ManagersD. All of the above

2. When must training and education be givenregarding combustible dust explosions?

A. Before they start work and periodically torefresh their knowledge

B. When reassignedC. When hazards or processes change

D. All of the above

Training


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gPractice Quiz

1. Who must be trained and educated regardingcombustible dust explosions?A.EmployeesB. SupervisorsC. Managers

2. When must training and education be givenregarding combustible dust explosions?

A. Before they start work and periodically torefresh their knowledge

B. When reassignedC. When hazards or processes change

Guidelines and Standards


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The Dusty BIG 10 from NFPA61 . . .Agricultural and Food Processing . . .68 . . . Venting of Deflagrations69 . . . Explosion Prevention Systems70 . . . National Electrical Code, Articles 500, 502, 503

91 . . . Exhaust Systems for Air Conveying . . .484 . . .Combustible Metals499 . . . Classification of Combustible Dusts and of

Hazardous (Classified) Locations . . .

654 . . .Manufacturing, Processing, and Handling ofCombustible Particulate Solids

655 . . . Sulfur Fires and Explosions664 . . .Wood Processing and Woodworking Facilities

Guidelines and StandardsNumerous other references are commonly available:


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Numerous other references are commonly available:

Prevention and Mitigation of Combustible Dust

Explosions and Fire FM Global Data Sheet No. 7-76, 2008. (download at

www.fmglobal.com/fmglobalregistration/ )

Guidelines for SafeHandling of Powders and

Bulk Solids Center for

Chemical Process Safety

(CCPS) AIChE 2005.

29 CFR 1910.272 - GrainHandling FacilitiesOSHA

General Industry Standard

6 inches

of metaldust and

chips

SummaryIn this section of the program we discussed the
http://www.fmglobal.com/fmglobalregistration/http://www.fmglobal.com/fmglobalregistration/


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Materials used in

particular die casting

operations that may beinvolved in dust

explosions and/or fires;Methods to reduce

dust explosion severity;

and,

In this section of the program, we discussed thecauses and occurrence of dust explosions and

fires including:Catastrophic consequences;

Documents

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