1. Combustible Dust National Emphasis Program March 10, 2008 Combustible Dust Oxygen in Air Ignition Source Dispersion Confinement Explosion FIRE Deflagration
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4. Malden Mills Methuen, MA December 11, 1995 37 Injured Nylon Fiber Combustible Dust Explosions History
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6. Combustible Dust Explosions History Jahn foundry Springfield, MA February 26, 1999 3 dead 9 Injured Phenolic resin dust
7. Ford River Rouge: Secondary Coal Dust Explosion February 1, 1999 Combustible Dust Explosions History Killed six workers and injured 36
8. Combustible Dust Explosions History May 16, 2002 Rouse Polymerics Vicksburg, Ms 5 dead, 7 injured Rubber Dust
23. Class II locations are those that are hazardous because of the presence of combustible dust. The following are Class II locations where the combustible dust atmospheres are present: Group E. Atmospheres containing combustible metal dusts, including aluminum, magnesium, and their commercial alloys, and other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment. Group F. Atmospheres containing combustible carbonaceous dusts that have more than 8 percent total entrapped volatiles (see ASTM D 3175, Standard Test Method for Volatile Matter in the Analysis Sample of Coal and Coke, for coal and coke dusts) or that have been sensitized by other materials so that they present an explosion hazard. Coal, carbon black, charcoal, and coke dusts are examples of carbonaceous dusts. Group G. Atmospheres containing other combustible dusts, including flour, grain, wood flour, plastic and chemicals . Class II Locations Definitions and Terminology
24. Deflagration Vs. Explosion Deflagration . Propagation of a combustion zone at a speed that is less than the speed of sound in the unreacted medium. Detonation . Propagation of a combustion zone at a velocity that is greater than the speed of sound in the unreacted medium. Explosion . The bursting or rupture of an enclosure or a container due to the development of internal pressure from deflagration. Explosion Deflagration Detonation Definitions and Terminology
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26. Source: Dust Explosions in the Process Industries, Second Edition, Rolf K Eckhoff Explosible Range
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28. Deflagration Index - Kst Kst = (dP/dt) max V 1/3 (bar m/s) where: (dP/dt) max = the maximum rate of pressure rise (bar/s) V = the volume of the testing chamber (m 3 ) Very strong explosion >300 St 3 Strong explosion >200 and <=300 St 2 Weak explosion >0 and <=200 St 1 No explosion 0 St 0 Characteristic Kst (bar.m/s) Dust explosion class
29. The “Typical” Explosion Event Process Equipment Initial Internal Deflagration Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325
30. The “Typical” Explosion Event Time, msec. Process Equipment Initial Internal Deflagration Shock Wave 0 25 50 75 100 125 150 175 200 225 250 300 325
31. The “Typical” Explosion Event Process Equipment Initial Internal Deflagration Elastic Rebound Shock Waves Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325
32. The “Typical” Explosion Event Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325 Process Equipment Initial Internal Deflagration Dust clouds caused by Elastic Rebound
33. The “Typical” Explosion Event Process Equipment Containment Failure from Initial Deflagration Dust Clouds Caused by Elastic Rebound Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325
34. The “Typical” Explosion Event Process Equipment Secondary Deflagration Initiated Dust Clouds Caused by Elastic Rebound Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325
35. The “Typical” Explosion Event Process Equipment Secondary Deflagration Propagates through Interior Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325
36. The “Typical” Explosion Event Process Equipment Secondary Deflagration Vents from Structure Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325
37. The “Typical” Explosion Event Diagrams Courtesy of John M. Cholin, P.E., FSFPE, J.M. Cholin Consultants, Inc. Secondary Deflagration Causes Collapse and Residual Fires Time, msec. 0 25 50 75 100 125 150 175 200 225 250 300 325