3/1/2011 1 Assessing and Managing Combustible Dust Risks ASSE Fire Safety Virtual Symposium March 2, 2011 Ron Allen, CSP, PE - Presenter Presenter’s Experience American Society of Safety Engineers FMC Corporation Monsanto Company Fisher Controls, Inc. Emerson Electric Company Eaton Corporation Imperial Sugar Company Imperial Sugar Company Safety Turnaround Services POLL - Your Background Please indicate your level of combustible dust experience:
Transcript
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1
Assessing and Managing Combustible Dust Risks
ASSE Fire Safety Virtual Symposium March 2, 2011Ron Allen, CSP, PE - Presenter
Presenter’s Experience
American Society of Safety EngineersFMC CorporationMonsanto CompanyFisher Controls, Inc.Emerson Electric CompanyEaton CorporationImperial Sugar CompanyImperial Sugar CompanySafety Turnaround Services
POLL - Your Background
Please indicate your level of combustible dust experience:
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Acknowledgements
Imperial Sugar Company and Its FamiliesChil th
Chemical Safety BoardJ.M. Cholin C lt tChilworth
TechnologiesDennis GroupFluorAlston & Bird
ConsultantsFenwal Protection SystemsFireExploOSHA
DisclaimerThe information in this presentation is provided in good faith. No attempt has been made to treat the topic exhaustively. The information and advice provided in this presentation is provided solely on the basis that users will be responsible for making their own assessment of the matters discussed therein and are advised to verify all relevant representations, statements, and information.This presentation is not a substitute for any of the provisions of the Occupational Safety and Health Act, state and local regulations, or consensus standards. Mention of trade names, commercial products, or organizations does not imply endorsement by the presenter.
AgendaDefinitions and Science of Combustible Dust ExplosionsCombustible Dust Statistics and IncidentsPrevailing StandardsA i Ri kAssessing RiskRisk Reduction Tools and Methodologies
EngineeringAdministrative Controls
Culture ChangeCulture Change
Personal Protective Equipment
Q&A/Discussion
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DEFINITIONS AND SCIENCE OF COMBUSTIBLE DUST
EXPLOSIONSEXPLOSIONS
Fuel Ignition
Dust Fires and Explosions
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Dispersion/Suspension
Confinement
Oxygen
Oxygen
What Makes Dust Explosible1?Flammable or combustible characteristics
~70% of dusts qualifyOrganics, metals, otherMost inorganics, sulfates, carbonates, many halogens, and spent oxides don’t qualify
Particle size (<420 microns2)Caution: Many granular products are >420 µm but have unwanted fines that are <420 µm
1 Capable of being exploded. Considers flammability and combustibility of material.2 OSHA protocols observe 420 µm; ASTM standards require grinding and screening to 75 µm).
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Dust Deposit
Explosible Range
IH Range
Explosible Range
Source: Dust Explosions in the Process Industries, Second Edition, Rolf K Eckhoff
Diagrams Courtesy of John M. Cholin, P.E., FSFPE, J.M. Cholin Consultants, Inc.
How Much Dust Must Be Present to Fuel a Secondary Explosion?
NFPA 654, Chapter 8, D2 Guidelines1:Limit dust layers to 1/32” thick if it exceeds 5% of the building floor area2
Dust accumulations on
Guidance can be confusing and difficult to administer. A “zero tolerance” approach is
Dust accumulations on overhead beams and joists approximate 5% of the floor area and should be considered Dust accumulations exceeding guidance can lead to stoichiometric combustion and worst case explosions OSHA enforces
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recommended
IF YOU CAN READ THIS IT IS
CLEAN ENOUGH
LOCATION # 3 1 Definition changing2 With a bulk density of 75lb/ft3)
COMBUSTIBLE DUST INCIDENTS AND STATISTICSINCIDENTS AND STATISTICS
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A Long History with Worldwide Reach
First documented dust explosion occurred in a Turin, Italy bakery in
fl d l d Blaye, France grain storage complex explosion killed 11 in 19971785. A flour dust cloud was likely ignited by a lamp and blew the windows and their frames from the building.
Qinhuangdao, China starch plant explosion killed 19 in 2010
USA Combustible Dust Incidents 1980 to 20051
281 combustible dust fires and explosions in general industry2
44 different states affected119 workers killed718 injuredSeven of the explosions were catastrophic, involving multiple fatalities and a significant community economic impact
Under-reporting and incomplete reporting a concern
1 Source: Chemical Safety Board Report 2006-H-12 Excludes grain handling, coal mining, transportation, and non-manufacturing incidents.
Ford Power Plant– Dearborn, MIFebruary 1, 19996 Deaths, 30 InjuriesSecondary Explosion ofExplosion of Coal Dust
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Incidents/Year
Fatalities by State – 1984 - Present
MASS
MAINEMONTANA
WYOMING
IDAHO
WASHINGTON
OREGON
NEVADA
UTAH
NORTH DAKOTA
SOUTH DAKOTA
NEBRASKA
IOWA
MINNESOTA
WISCONSIN
ILLINOIS INDIANA OHIO
NEW YORK
PENNSYLVANIA
DELAWARE
NEW JERSEY
CONN
VT
NH
RI
9
611
63
1
5
3461
MICHIGAN
UTAH
CALIFORNIA
ARIZONA
COLORADO
NEW MEXICO
TEXAS
OKLAHOMA
KANSAS
ARKANSAS
MISSOURI
KENTUCKY
MISS ALABAMA GEORGIA
FLORIDA
SOUTHCAROLINA
NORTH CAROLINA
VIRGINIAWVMARYLAND
2
9
8 95
8
1
2
6
LOUISIANA
15
5
4
3
32
1
2
12
1
11
6
1
Source: 2006 CSB Dust Study
No Incidents
Known Deaths Including Since
CSB Study
Deaths Cited by CSB Study
Incidents Occur in Many Industries
Food products18%
Fabricated metal
Rubber & plastic products
7%
Equipment manufacturing
6%
Furniture & fixtures5%
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Lumber & wood products
13%
Chemical manufacturing
12%Primary metal industries
11%
Other10%
Electric services9%
Fabricated metal products
9%
2006 CSB Dust Study
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Common Factors in Dust Explosions
Engineering controls inadequate
Dust collector and process equipment design and maintenance inadequate
Dust explosion hazard not recognized
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Dust explosion hazard not recognized
Change management inadequate
Hazard awareness training inadequate
Rigorous housekeeping practices not applied
Source: Chemical Safety Board
Administrative
Controls
ProbabilitiesSixteen of 281 incidents
involved multiple deathsRisks present in “low volume” dust operations“What we have is a dust explosion that happened in the two dust collectors. We are not exactly sure what triggered it.”
PREVAILING STANDARDS
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General Industry Standards1910.22 - Housekeeping 1910 Subpart E - Means of Egress 1910.94 - Ventilation 1910.119 - Process Safety Management 1910.145 - Warning Signs 1910.146 - Permit-Required Confined Spaces1910.157 - Portable Fire Extinguishers 1910.176 - Handling Materials 1910.178 - Powered Industrial Trucks1910.252 - Welding, Cutting and Brazing1910.307 - Hazardous (Classified) Locations 1910.1200 - Hazard Communication 5(a)(1) - General Duty Clause
Special Industries—1910 Subpart R
1910.263 - Bakery Equipment
1910.265 - Sawmills
1910.269 - Electric Power Generation, Transmission and Distribution (Coal Handling)
1910.272 - Grain Handling Facilities
Applicable NFPA StandardsStd Title Latest61 Standard for Prevention of Fires and Dust Explosions in Agricultural and
Food Processing Facilities2008
68 Guide for Venting of Deflagrations 2007
69 Standard on Explosion Prevention Systems 2008
70 National Electrical Code 2008
77 Recommended Practice on Static Electricity 2007y
101 Life Safety Code 2009
484 Standard for Combustible Metals 2006
499 Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations
2008
654 Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids
20111
655 Standard for Prevention of Sulfur Fires and Explosions 2007
664 Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities
2007
1 Not yet effective; 2006 standard observed and enforced.
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ASSESSING RISK
Is Action Needed?
1. Is the dust combustible?
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Class II Test1
Dust properties can be used to exempt an area from electrical area classification if it can be shown that the dust explosion hazard is not significant as defined by NFPA 499 section A.4.5.2
IF
When Is Action Required?
The Ignition Sensitivity2 is less than 0.2
ANDThe Explosion Severity2 is less than 0.5
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1 NFPA 499 reference to locations that are hazardous because of the presence of combustible dust. Further subdivided into two divisions that consider the frequency of exposure and 3 groups that consider the types of dust.2 As defined by the U.S. Bureau of Mines (see NFPA 499 section A.3.3.9). OSHA also observes this definition.
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Class II Test
The U.S. Bureau of Mines defined ignition sensitivity and explosion severity as follows:
CoalPittsburgMECMITMIES iti itI iti
][ ××
When Is Action Required? (Con’t)
If the ignition sensitivity is less than 0.2 and the explosion severity is less than 0.5, electrical area classification is not required
( )( ) CoalPittsburg
Sample
Sample
CoalPittsburg
dtdPP
dtdPP
SeverityExplosion
MECMITMIEySensitivitIgnition
][
][
][
maxmax
maxmax
×
×=
××=
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Is Action Needed?
1. Is the dust combustible?2. Are dust accumulations present?
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Presence of Dust – Nothing’s EasyAccessible and inaccessible surfaces, crevices, enclosures
Fine dusts can take extended time to settle and may travel vast differences (e.g., 3µm particles of sugar descend ~5’/minute in undisturbed atmospheres)Consider highest surfacesConsider interior and exterior surfaces of ductwork and processConsider interior and exterior surfaces of ductwork and process equipmentMultiple samples may be needed to properly characterize and consider representative accumulations
Air filtration devices criticalSample from “dirty side” of filters
Sample size: ≥ 2 kg
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Is Action Needed?
1. Is the dust combustible?2. Are dust accumulations present?3 Wh t th b tibl d t
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3. What are the combustible dust characteristics?
How Explosible is the Dust?Ignition Sensitivity
Minimum Ignition Energy (MIE)Minimum Ignition Temperature (MIT)
Explosion SeverityMaximum Explosion Pressure (PMax)Maximum Rate of Pressure Rise ([dp/dt]Max)Dust Deflagration Index (KSt)
Bearing temperatureElevator speedElevator belt alignment
Fan bladesFlightsDucts
Tramp Metal*ScreensMagnetsDetectors
* Examples forthcoming
Electrical ClassificationEngineering Study NeededCareful DocumentationMay Include “Bubbles”Cl II C t fClass II Components for Appropriate Division and Group
Electrical Grounding & Bonding
Transportation Protection
63Railcar and Truck Grounding Systems
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Building and Floor Grounding & Testing
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Static Dissipative Floor Test Connection Testing Equipment
Bearing Temperature
Heat Generation Monitoring Equipment
Must be:• Interlocked• Alarmed• Tested• Maintained
Speed Switch Monitor
Belt Alignment Switches
Properly Rated Industrial Trucks
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Non-Sparking Process Components
Synthetic Buckets Aluminum Fan Blades
Magnetic Control
Tramp Metal Control
Metal Detectors Mechanical Screens
Dust Fires and Explosions
Fuel Ignition
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OxygenDispersion/Suspension
Confinement
Oxygen
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Control or Eliminate Confinement
Process ReviewEliminate or seal unnecessary enclosures (e.g., false ceilings, concealed areas)
Process Design*P tiPneumatic conveyanceLocal exhaust ventilationMonitoring and alarms
Fortify Confinement*Prevents propagationReduces structural damageAllows relief devices to function
* Examples forthcoming
Pneumatic ConveyanceMinimize Screws and ScrollsControl Fines
Dense Phase Conveying: Comparison
Control FinesPneumatic Conveyance Options
Click here for a video demonstration…
Local Exhaust VentilationTransportation Protection Must be:
Guidance in NFPA 69Common gas inerts1: N, CO2, ArUnlikely to propagate <8% oxidant concentration; can be
Gas Inerting MethodsPressure purgingVacuum purgingFlow through purgingPartial purging in combination with other layer(s) of safety
effective as high as 16%Must know LOC (Limit of Oxygen Concentration) for specific productMust know properties of oxidant and inertantNot a candidate for many combustible dust processes (examples of exceptions – coal pulverizers and mills, metal dust transferring and blending)
y ( ) y
PrecautionsUnsafe for human occupancyContinuous monitoringSafety factor (60% LOC limit if not monitored)
1 Can also inert with solids
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Dust Fires and Explosions
Fuel Ignition
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OxygenDispersion/Suspension
Confinement
Oxygen
Reduce Dispersion and Suspension
Sealed Process and EquipmentLocal Exhaust VentilationControl Product TransfersAdd Moisture*Limit Agitation
Investment and ExecutionIncident Investigation*Visibility and Communication
Training and knowledge*Postings
Housekeeping*Equipment shutdownInspections and audits*Hot workZero tolerance*
IntegrationSOPsPMs*MoCPHAs*
Meeting reference
Involvement and OwnershipEmpowerTeamsContractors*Reporting mechanisms*
* Examples forthcoming
TrainingAll Levels of Organization
Tailoring requiredVary content to audienceInclude contractors
NFPA 654 Requirement“ l d ” d“Knowledge” required
Periodic Refresher (Annual or When Process Change Occurs)Supervisory ReinforcementComputer Based Training (CBT) a Convenience
Summary of NFPA 654 Required Training Topics
(1) Hazards of their workplace(2) General orientation, including plant safety rules(3) Process description(4) Equipment operation, safe startup and shutdown, and response to
upset conditions(5) The necessity for proper functioning of related fire and explosion(5) The necessity for proper functioning of related fire and explosion
Regular cleaning frequencies shall be established for walls, floors, and horizontal surfaces (lengthy list of examples).Surfaces shall be cleaned in a manner that minimizes the generation of dust clouds.Vigorous sweeping or blowing down with steam or compressed air produces dust clouds and shall be permitted only where the following requirements are met:(1) Area and equipment shall be vacuumed prior to blowdown.(2) Electrical equipment not suitable for Class II locations and other sources of
ignition shall be shut down or removed from the area.(3) Only low-pressure steam or compressed air, not exceeding a gauge
pressure of 15 psi.(4) No hot surfaces or flames capable of igniting a dust cloud or layer shall
exist in the area.
Only Class II vacuum cleaners permitted.
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Cleaning ToolsWet MethodsCarbon-Impregnated brushes availableN C d tiNon-Conductive Shovels and ToolsClass II Approved Vacuum Cleaners
Air poweredElectrically powered
Inspections and Actions
•Consider Actions and Conditions•Employee Involvement•Rely on All Senses•Ask “Why?”•Document & Correct
Incident Investigation
Near miss = exceedance of NFPA accumulation limitsLocal definitions of “reportable releases” ( b k FIBC t b k b f il d(e.g., broken FIBC, two broken bags, failed dust collector)Team approachDisciplined problem solving methodsRecommendations consider design, SOPs, maintenance, and training
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Reporting Mechanisms
PrimaryEmpowermentImmediate action
SecondarySupervisorHot LineSuggestion BoxSafety CommitteeRecognition Program
Contractors and Visitors
Define Training Requirements by Tasks Performed
Equally intensive as employee trainingq y p y g
Specify Compliance and Code Requirements or ReferencesHire for Success
Process Hazard AnalysesProcess:
Logic based analysis of each process and sub-process that could harbor, transfer, or produce combustible dust
NFPA 654:The design of the fire and explosion safety provisions shall be based on a process hazard analysis of the facility, the process, and the
Multidisciplinary
RigorousCorrective Actions Documented
associated fire or explosion hazards.Repeat every 5 years
Common Findings:Additional samplingRedesignMitigationProcedures and training
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OSHA HazCom Guidance –August 2008
“Regarding dusts and other particulates, a hazard evaluation must be conducted taking into consideration all discernible hazards, including that of explosibility. It is incumbent upon manufacturers and importers to provide information on the potential for and control of combustible dusts.”pote t a o a d co t o o co bust b e dusts“This evaluation of hazards ensures that downstream employers and workers are provided MSDSs with complete and accurate information regarding dust explosion hazards, appropriate information is included on labels, and that workers are properly trained regarding workplace combustible dust hazards.”
Section 5: FIRE FIGHTING MEASURES
This material can form explosible dust/air suspensions that are ignitable under some conditions. Dust accumulations should be avoided to prevent secondary dust explosions. Avoid generating dust; fine dust dispersed in air in sufficient concentrations, and in the presence of an ignition source, is a potential dust explosion hazard. Refer to NFPA 61 for procedures regarding fire and explosion hazards relating to sugar dust.
Suitable Extinguishing Media: Class A stored-pressure wet-water or water-mist extinguishers or extinguishing media that are appropriate for the surrounding fire and materials.
Unsuitable Extinguishing Media: Avoid use of pressurized dry-chemical extinguishers on powdered materials to prevent dust suspensions and dust explosion hazards. Hose streams should be used with great care to avoid creating dust clouds. Fog nozzles should be used.
Section 6: ACCIDENTAL RELEASE MEASURES
Methods for Clean-Up: Airborne sugar dust may form explosible dust clouds and dust accumulations should be avoided to prevent secondary dust explosions. Sugar dust can accumulate on floors, equipment, and overhead structural members and can become airborne, and accordingly must be removed concurrently with operations. Avoid dispersal of dust in the air (i.e., clearing dust surfaces with compressed air). Non-sparking tools should be used. Sugar dust should not be allowed to accumulate in quantities that when suspended could create an atmosphere above the Minimum Explosible Concentration (MEC) of 50 to 60 g/m3. Spills should be cleaned up and dust accumulations should be removed promptly. Surfaces should be cleaned in a manner that minimizes the generation of dust clouds. Refer to NFPA 61 for procedures regarding fire and explosion hazards relating to sugar dust.
Section 7: HANDLING AND STORAGE
Section 1: PRODUCT AND COMPANY IDENTIFICATION
Section 2: HAZARDS IDENTIFICATION – WARNING
WARNING! MAY FORM COMBUSTIBLE DUST CONCENTRATIONS IN AIR
Explosion: This material is friable and can create small dust particles during any handling, processing, and transfer operations. This material can form explosible dust/air suspensions that are ignitable under some conditions. Dust accumulations should be avoided to prevent secondary dust explosions.
Fire: Sugar is a combustible material and could contribute to a fire, once started and, therefore, normal fire prevention practices should be followed.
Imperial Sugar Company: (800) 727-8427 Plant Emergency: (281) 491-9181 (8am to 5pm, Central Time Zone, Monday to Friday)
Product Name: Granulated Sugar Trade Names/Synonyms: Sucrose, Sugar, Cane Sugar, A Coarse, Fine Sanding, Bakers Special, Fruit Granulated, Medium Granulated, Extra Fine Granulated
Issue Date: 09/01/2009 Supersedes Date: January 2008
Reference to
MSDS for Granulated Sugar
104
Section 7: HANDLING AND STORAGE
Precautions to be taken in Handling and Storing: Airborne sugar dust may form explosible dust clouds. To minimize dust generation and accumulation, spills should be cleaned up, and, dust accumulations should be removed promptly.
Other precautions: Provide adequate (local exhaust) ventilation to prevent the spread of dust clouds. Dry powders can build static electricity charges when subjected to the friction of transfer and mixing operations. Provide adequate precautions, such as electrical grounding and bonding, or inert atmospheres. Avoid all potential ignition sources including smoking, open flames, static electricity and sparks in areas where airborne sugar dust may be possible. Ensure that electrical equipment meets the Class II, Group G classification for sugar-handling areas, particularly where dusts having average particle sizes less than 400 microns could be released or could accumulate.
Employ effective housekeeping practices and exhaust ventilation, electrostatic grounding of all metal equipment and operators, management of electrical devices, maintenance of mechanical equipment (e.g. mills, rotary valves, screw feeders, conveyors, and elevators), and explosion protection and isolation provisions in accord with accepted engineering practices in any process capable of generating dust. Refer to applicable NFPA standards including:
NFPA 61 “Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Products Facilities” NFPA 68 “Guide for Venting of Deflagrations” NFPA 69 “Standard on Explosion Prevention Systems” NFPA 70 “National Electrical Code (NEC)” NFPA 77 “Recommended Practice on Static Electricity” NFPA 499 “Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas”
NFPA 101 "Life Safety Code" NFPA 654 “Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids" NFPA 2112 “Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire” NFPA 2113 “Standard on Selection, Care, Use, and Maintenance of Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire”
Effects of Overexposure: Prolonged exposure to nuisance dust could result in temporary, reversible respiratory irritation. Prolonged contact may cause skin sensitization or inflammation (reddening, scaling, or itching). No other effects have been reported in humans.
This product does not contain any carcinogens or potential carcinogens as listed by OSHA, IARC or NTP.
Section 3: COMPOSITION/INFORMATION ON INGREDIENTS
Component CAS No. % by Wt. Sucrose 57-50-1 100%
β-D-fructofuranosyl-α-D-glucopyranoside Formula: C12H22O11 Chemical Family: Carbohydrate Description: Odorless, hygroscopic, dry, white crystals with a sweet taste Melting Point: 365°F (185°C) Bulk Density: 49-56 Lbs./Cu.Ft. Solubility in Water: 200 gm per100 ml @ 20°C Percent Moisture by Weight: 0.05 Specific Rotation: (Not Less Than +65.9) @ 20°C & 589.44 ηm (c=26) Specific Gravity: 1.59 (H2O = 1) Molecular Weight: 342.3
Section 4: FIRST AID MEASURES
Emergency and First Aid Procedures: Ingestion: If swallowed in large amounts and the person is conscious, immediately give large amounts water. Get medical attention. Inhalation: If a person inhales a large amount of sugar dust, move the exposed person to fresh air. Get medical attention. Eye Contact: Wash the affected area with large amounts of water for at least 15 minutes and obtain medical attention. Skin Contact: Wash the affected area with large amounts of water for 15 minutes.
Conspicuous warnings about combustible and explosible properties
applicable NFPA standards
Material Safety Data SheetsSection 9: PHYSICAL AND CHEMICAL PROPERTIES The following guidance is given concerning the properties and usage of Extra Fine Granulated (EFG) sugar:
PROPERTY [and approximate values]
FINE a FRACTION [8% smaller
than 75 microns]
COARSE b FRACTION [50% larger
than 450 microns] Minimum Ignition Energy [MIE] 4 millijoules 10 joules
NOTES: a – Locations where the fine-fraction data would be applicable: within dry dust collectors; for accumulations on elevated surfaces; in exhaust-ventilation ducts; in downlegs of bucket elevators; in dilute-phase pneumatic conveyors; in head spaces in blenders and mixers; in trucks and railcars during loading; in bags, drums, FIBCs, bins, and silos during filling. b – Locations where the coarse-fraction data may be applicable: during bottom unloading from trucks and railcars; during dumping
ACGIH TLV = As Sucrose, 10 mg/m3, 3 mg/m3 (Respirable); A4 Not classified as a human carcinogen
NIOSH REL = TWA 10 mg/m3 (Total Dust), TWA 5 mg/m3 (Respirable Dust) LD50 = 29.7 g/kg (oral, rat)
Establish and maintain good housekeeping practices. Follow dust control practices outlined in NFPA 61, “Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities.” Accumulated dust on floors, structural members, and other surfaces should be removed concurrently with operations.
Respiratory Protection: Local exhaust ventilation or other site specific engineering controls are recommended if visible dust emissions are present. Please refer to the ACGIH document, Industrial Ventilation, A Manual of Recommended Practices, most recent edition, for details. If dusty conditions exist, wear appropriate respiratory protection based on industrial hygiene exposure monitoring assessment until engineering controls reduce dust concentrations to an acceptable level If the exposure
Reference coarse fraction and fine fraction particles
Reference explosion
MSDS for Granulated Sugar
105
b Locations where the coarse fraction data may be applicable: during bottom unloading from trucks and railcars; during dumping from hoppers, bins, bags, and FIBCs; on belt conveyors; in screw conveyors; in dense-phase pneumatic conveyors; and in elevator buckets. a and b – Locations where intermediate values of the data could be applicable, depending on the dispersability or stickiness of the materials and the extent of segregation of the fine and coarse fractions: in rotary driers and coolers; in mixers, blenders, and tumblers; and at transitions between conveying systems, such as belt conveyors, bucket elevators, screw conveyors, and chutes. Caution: Dust cloud explosion properties are very dependent on particle properties such as average particle size, particle-size distribution, particle shape, and moisture content. Therefore, if the as-received physical or chemical properties are modified by the user – during handling or processing – and if such dusts are accumulated in cyclones or dust collectors, it is important that explosibility data be obtained from tests on representative samples of the modified material.
Section 10: STABILITY AND REACTIVITY Stability: Stable under normal temperatures and pressures.
Conditions to Avoid: Keep away from heat, sparks and flames.
Incompatible Materials (Materials to Avoid): Strong oxidizers, such as potassium permanganate, potassium chlorate, potassium nitrate, potassium perchlorate, and nitric acid. Strongly hydrophilic liquids such as sulfuric acid can release carbon monoxide upon contact with sugar. Carbon dioxide, flammable aldehyde, and carbon monoxide may form when heated to decomposition, or heated with strong, concentrated alkalis. This reaction is exothermic.
Hazardous Decomposition Products: Thermal decomposition, at temperatures in excess of 365°F, may release flammable gases and acrid fumes and smoke, including aldehydes, carbon monoxide, carbon dioxide, and steam. If confined, the decomposition gases can exert considerable pressure.
Polymerization: Will not occur.
assessment until engineering controls reduce dust concentrations to an acceptable level. If the exposure limit is exceeded and engineering controls are not feasible, a half face elastomeric respirator (with NIOSH type N95 filters or better) or NIOSH approved disposable particulate respirator (filtering facepiece or dust mask) may be worn for up to ten times the exposure limit. A full-face elastomeric respirator (with NIOSH type N100 filters) may be worn up to 50 times the exposure limit. If oil particles are present or suspected to be present, use a NIOSH type R100 or P100 filter. For emergencies or instances where the exposure levels are not known, use a full-face positive-pressure, air-supplied respirator. Air-purifying respirators do not protect workers in oxygen-deficient atmospheres. If employees are required to wear respirators, they should be included in a written respirator program, trained in the use of respirators, medically qualified to wear respirators, and fit-tested to ensure proper fit of the respirator worn.
Other Protective Clothing or Equipment: Protective clothing and gloves are not required for ordinary operations but may be desirable from a sanitation aspect. Eye protection is recommended to avoid eye irritation. Where dusty conditions are unavoidable, flame-resistant, antistatic outer clothing and conductive shoes should be worn and used.
It is recommended that all dust control equipment such as local exhaust ventilation and material transport systems involved in handling of this product contain explosion relief vents or an explosion suppression system or an oxygen-deficient environment. Ensure that dust-handling systems (such as exhaust ducts, dust collectors, vessels, and processing equipment) are designed in a manner to prevent the escape of dust into the work area. Use only appropriately classified electrical equipment and appropriately rated powered industrial trucks.
pprotection equipment
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Warning Signs
CAUTION
Classified Hazardous Location
Class II, Division 2, Group EMetal Blender
No Open Flames, Spark Producing Equipment , or
Electrical Equipment That Does Not Meet Class II, Division 1,
Group E Requirements(including Cell Phones)
Procedures & Equipment Standards
ProceduresNFPA 654
Operating and maintenance proceduresEmergency procedures
MoC considerationTraining & knowledgeRecords maintainedTypes of equipment:
(1) Fire and explosion protection and
Specific:Material feeding devicesAir-moving devicesAir–material separatorsAbort gates and abort dampersFire and explosion protection(1) Fire and explosion protection and
prevention equipment in accordance with the applicable NFPA standards
(2) Dust control equipment(3) Housekeeping(4) Potential ignition sources(5) Electrical, process, and mechanical
equipment, including process interlocks(6) Process changes(7) Lubrication of bearings
requirementsVariation in screw diameterMinimum clearance between screw and trough
Experience Actions
Unusual noiseHot spots (>4º F variation)Reduced gap between screw and troughPhysical damage
REDUCING RISK THROUGH PERSONAL PROTECTIVEPERSONAL PROTECTIVE
EQUIPMENT
Personal Protective EquipmentOSHA 1910.132Careful consideration of garment styles and ratingsPractical consideration and experienceNFPA 654 id d/ id iNFPA 654 considered/considering changes: :
Requirement for operating and maintenance procedures to address PPE for tasks involving processing and handling of combustible dusts, including:
a) PPE shall include flame-resistant garments in accordance with the workplace hazard assessment required by NFPA 2113; and
b) Where a dust deflagration hazard exists, flame-resistant garments shall be required for all exposed personnel.
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PPE Static Protection ConsiderationsRisk Greatest with Low MIE Materials (>25 mJ) + High Probability of Dust Cloud (e.g., Class II, Division 1)Workers Can Generate And Accumulate Electrostatic Charge B
SD Shoe and Glove Programs Can Be Complicated to Administer
By:Clothing changes (including outer garments)Pouring or dumping materialsContact with equipment or material charged by movement of belts, powders, or dustWalking or working on non-conductive flooring with non-conductive shoes
