Prevention of Grain Elevator and Mill Explosions (1982) / Chapter Skim
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Chapter 3: The Explosion Problem
Chapter 3: The Explosion Problem
Pages 13-30
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From page 13... ...
from 1964 through 1973 or an average of more than 2900 fires per year. This is reported to be more than 300 times greater than the average number of grain elevator dust explosions in the same period (Verkade and Chiotti 19761.
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From page 15... ...
This is because the layered dust is the fuel for secondary explosions that occur. GRAIN—HANDLING FACILITIES Figure 3 illustrates the physical construction of an elevator (see Figure 2 for a flow diagram of the functions performed in a grain elevator)
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From page 17... ...
Airborne dust is collected at various points in the elevator to improve the working environment, to reduce the hazard of dust explosions, and to meet Environmental Protection Agency (EPA) requirements concerning ambient air quality.
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From page 18... ...
Dust on some surfaces such as floors, walls, beams, and ductwork is readily visible and can be removed easily. Neglected-'or delayed housekeeping will result in the accumulation of layered dust in an elevator or mill and poor housekeeping methods or an initial explosion can result in the creation of a dust cloud sufficient to be an explosion hazard.
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From page 19... ...
* Dynamics Discussions of dust explosions begin with the concept of an "explosion pentagon.
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From page 20... ...
* See Appendix 8 for a more complete discussion of dust explosions.
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From page 21... ...
Flaming material was discharged into the dust cloud in the basement and there was an explosion in the basement and legwell shaft. Hot gases and burning particles were blown through a distributor system into various bins where they caused secondary explosions fueled by dust that was shaken loose from the walls by the initial explosion.
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From page 23... ...
The examples also identify the locations of the initial explosions. In same cases, secondary explosions have- been triggered by ignition of a dust cloud created within the conveying equipment by layered dust being disturbed and set in suspension in air.
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From page 24... ...
Although the data relative to electrostatics are inconclusive, some believe that low relative humidity can contribute to the dust explosion hazard because the potential for electrostatic sparking increases as relative humidity drops and low relative humidity reduces the moisture content of grain dust, thereby lowering the ignition temperature and energy (Palmer 19731. As a consequence, employees of the Federal Grain Inspection Service (FGIS)
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From page 25... ...
CONTRTBIJTING FACTORS In considering accidents, including grain dust explosions, there is a tendency to focus on immediate physical aspect even thou gb accidents may be recognized as resulting from a combination of causative factors. Thus, the contribution of human operatives and external factors, singularly or collectively, often is overlooked.
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From page 26... ...
Government Interaction The establishment and enforcement of environmental air pollution control regulations in response to the Clean Air Act of 1970 may have had an effect on the dust explosion hazard. The management of grain-handling facilities responded to these regulations in a variety of ways, some of which may have increased the probability of explosions.
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From page 27... ...
This, of course, i Creases the amount of dust to the receiver and thereby increases his hazard especially for the case of export elevators where the grain may have passed through as many as 3 or 4 elevators. Even customers of grain elevators -- those whose grain is processed, stored, or transferred from one transportation mode to another by means of an e~levator -- indirectly influence the probability of dust explosions through economic pressure.
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From page 28... ...
Federal Grain Inspection Service, Policy and Procedures Upon Encountering "Unduly Lazarus Conditions. in Grain Elevators, Instruction 370-3, Revision 2, FGIS, Washington, D.C., 1980.
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From page 29... ...
National Materials Advisory Board, The Investigation of Grain Elevator Explosions, Report GRAB 367-1, National Academy of Sciences, Washington, D.C., 1980. Pa finer, K.N., Dust Explosions and Fires, Chapman and Hall Ltd., London, 1973.
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From page 30... ...
Wade, F.J., Hawk, A.~. and Watson, C.A., Investigations to Determine Dust Concentrations and Characteristics Inside Enclosed Work Areas and Equipment at Large Grain Terminals, final report, USDA/Cargill Cooperative Agreement No.
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