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Risks Associated To Combustible Dust Handling

Risks Associated To Combustible Dust Handling . Sponsorship. Department of Labor Occupational Health and Safety Administration (OSHA) Susan Harwood Training Grant

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Risks Associated To Combustible Dust Handling

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  1. Risks Associated To Combustible Dust Handling

  2. Sponsorship Department of Labor Occupational Health and Safety Administration (OSHA) Susan Harwood Training Grant This material was produced under Susan Harwood grant number 19480-09-60-F-72 Occupational Safety and Health Administration, U.S. Department of Labor. The contents in this presentation do not necessarily reflect the views or policies of the U.S. Department of Labor, nor does the mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

  3. Work Team UNIVERSITY OF PUERTO RICO Río Piedras Campus Division of Continued Education and Professional Studies (DECEP) Migdalia Ruiz, MS – Project Director Lymari Orellana, MS, Trainer Adaliz López, MS, Trainer Carmen Vázquez, BSSI, CIHT, Trainer

  4. Purpose The purpose of this presentation is to compile within one document the hazards present while handling combustible dusts in industrial processes. The following will be discussed: • Hazard characteristics and behavior of Combustible dusts. • How to perform risk assessments to recognize hazards associated with combustible dusts, and • Suggested Control Methods.

  5. Objectives • Define combustible dust and its impact on industry • Mention loss statistics due to dust explosions • Identify risk areas • Discuss available controls • Identify applicable associated standards • Briefly introduce the proposed regulation

  6. Topics to be discussed • Historical background • Definitions • Related risks • Facility evaluation • Controls • Prevention • Mitigation 6. Training 7. Proposed Rule 8. References

  7. Industrial Explosions HISTORICAL BACKGROUND

  8. Are These Materials Explosive? coal sugar metal plastic wood medicines

  9. Imperial Sugar Company • February 7, 2008 • Port Wentworth, Georgia • 14 deaths and numerous injured persons • A spark started the fire and explosion of the sugar cloud

  10. Fire and Explosion by Metal Powder : Indiana October 23, 2003 Huntington Indiana 1 dead, 6 injured Aluminum powder caught fire in a dust collector, from there the flame spreads generating the explosion 10

  11. Fire and Explosion in “CTA Acoustics” February 20, 2003 • Corbin, Kentucky, • 7deaths, several injured • An poorly worked oven lit a cloud of phenolic resin dust, causing the explosion. 11

  12. West Pharmaceutical January 29, 2003 • Kingston, North Carolina • 6 deaths, 38 injured • Phenolic resin dust accumulation enabling false ceiling fire and dust explosion 12

  13. Fire and Explosion in Malden Mills December 11, 1995 Methuen, Massachusetts 37 workers injured Destruction of the polar fabric manufacturing company (nylon fibers)

  14. Grain Handling During the 70s there were several explosions in grain silos. This led to implement a specific standard 1910.172, for that industry, which has significantly reduced the explosions in this industry. 14

  15. Definitions IMPORTANT CONCEPTS

  16. Definitions • Combustible dust: Very small particles (<420 microns) that when dispersed in air have the ability to ignite under certain conditions. • The NFPA 654 (2006) defines combustible dust as a particulate solid that presents a fire hazard or deflagration when suspended in air (or other oxidant) at various concentrations independent of size or shape.

  17. pellet Combustible Solid Particulate Any combustible solid material composed of particles or different pieces independent of the size, shape or chemical composition Includes: DustFines (coal dust)fibersFlakesFragmentsBitsMixture of any of the foregoing

  18. Particle Size of Common Materials Source: OSHA y Filtercorp International Ltd.

  19. Combustible Dust Fires and Explosions Fire Triangle

  20. Fires and Explosions of Combustible Dust Confinement For a combustible dust explosion to happen, it requires the presence of all these factors Dispersion Ignition Source Fuel (dust) Oxidant

  21. Dispersion • It is the effect of moving the cloud of dust from one place to another, may it be by mechanical processes (transport, ventilation, vibration, improper cleaning) or as the result of a primary explosion.

  22. Confinement • Occurs when the fire occurs in a confined space, where the rapid change in temperature causes a rapid change in pressure. • This change in pressure or shock wave can be more or less destructive depending on the magnitude of the explosion and how the structure is closed

  23. Deflagration In the deflagration the flame advances as the material is consumed creating a fire front, with pressure changes

  24. Detonation • The combustion speed advances faster than the speed of sound generating an audible event. • Dificult to control once it has begun

  25. Minimum Explosive Concentration (MEC) The minimum amount of dust suspended in air that will support deflagration. It is estiamted that this concentration (MEC) can reduce the visibility of a 25 wat bulb in a room to only 6 feet of distance 25 watts 6 feet = 2 meters Combustible dust concentration suspended in air > MEC Source: Course 7120 OSHA Training Center

  26. dispersion fire Explosion Results from the combination of these factors: • fire • dispersion of solid particulate material • in a more or less enclosed space Explosion + = + confinement

  27. Primary Explosion from dust in equipment Dust Colector Fuente: Curso 7120 OSHA Training Center

  28. Secondary Explosion Mechanism 1. Dust accumulates on work surfaces 2. An event disperses dust creating a cloud 3. The cloud ignites and explodes

  29. Dust Colector Expansive wave Secondary Explosión from dust in area DustAccumulation (onfloor and surfaces) Fuente: Curso 7120 OSHA Training Center

  30. Industries ¿Who IS at risk?

  31. Industries that Generate or Handle Combustible Dusts • Textiles • Forest Products • Wastewater Treatment (used) • Recycling of metal, paper, plastic • Coal Metalworking Pharmaceutical products Food Paper products Wood products Agriculture Chemical Manufacturing

  32. Metal Powders Aluminum Iron Carbonile Zinc Bronze Magnesium

  33. Plastic Powder/ rubber Molded Cellulose Polyethylene Melamine and its resin Polypropylene Polyacrylamide Epoxy or phenolic resin

  34. Food Cotton Rice starch, corn, wheat Sugar Coffee Cocoa Powder Coconut shell Spice powder Potato starch

  35. Food Rice flour, oats, corn, potato, wheat Lime Walnut powder Soybean powder Seeds of raw cassava Sunflower SeedsTomatoe Carrot

  36. Chemicals Sodium stearate Ascorbic Acid Carboxymethyl Cellulose Lactose Calcium Acetate Methylcellulose Dextrin

  37. Powders Containing Carbon (Carbonaceous powders) Cellulose paste Activated charcoal Black charcoal Bituminous coal Petroleum coke Wood charcoal Pine soot Petroleum Celullose Lignin Dry chemical

  38. Agricultural Products Rice starch Celullose Dry powdered milk Wheat starch Egg white Barley Lactose

  39. Area Assessment Risk Analysis

  40. RisksFactors ¿ What factors should I consider for preventing explosion? Major Factors: • Dust Combustibility • The accumulation of dust in areas and work surfaces • Presence of ignition sources.

  41. Combustibility Determination The first step in the risk analysis should be todetermine if the powder is combustible

  42. Powder Combustibility • Verifiy if the presence of dust increases the risk of fire, explosion and / or a detonation within the workspace. In some cases it will be determined by an specific flammability test. • Consider: • Particle size and shape • relative humidity and oxygen present in the environment • Minimum explosive dust concentration (MEC).

  43. Accumulation

  44. Ignition Sources

  45. Contributing Factors EXPLOSION

  46. Other Considerations in Risk Analysis • Must assess the electrical ratings of the areas • Consider the scenario in which dust may be generated as a result of equipment failure or operating procedures Fuente: Curso 7120 OSHA Training Center

  47. Hazards Analysis • Determine if a combustible dust is potentially dangerous in a work area • Look for accumulations of fine dust • Find ways in which the powders are dispersed in the air • Possible sources of ignition • Consider dust collectors, hoppers and other equipment that can confine a cloud of dust. • Investigate possible ignition sources

  48. Prevention & Mitigation Principal Methods of Control

  49. Principal Methods of Control Both OSHA and NFPA established that the best way to prevent the combustible dust hazard is using engineering controls such as; • Design of pipes and equipment capable of containing the dust or a dust explosion safely • Reduction of work surfaces where dust can accumulate • Control of ignition sources

  50. Principal Methods of Control Control methods are devided: Prevention of fire and / or explosion, this mean, to prevent it from happening either of these situations by; Dust accumulation control • Ignition sources control • Reduction in the concentration of oxidant (NFPA 69 Chap.7)

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