Cotton Gin Dust Explosibility Determinations
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Following the recent Imperial sugar dust explosion in 2008, a comprehensive survey of past dust explosions was conducted by the Occupational Safety and Health Administration (OSHA) to determine potential explosible dusts. After the survey, OSHA personnel listed dust found in cotton gins, or gin dust, fueled two explosions in the past. OSHA is required by law to regulate facilities handling explosible dusts to provide a safe working environment for employees. The dust handling facilities must test the dust for explosibility based on the American Society for Testing and Materials (ASTM) E 1226 to ensure proper regulation of facilities. Dusts found in cotton gins were tested to determine if they are explosible. Safety Consulting Engineers Inc. (SCE) personnel tested gin dust in accordance with the ASTM method and reported that gin dust (GD) was an explosible dust. However, personnel from the Center for Agricultural Air Quality Engineering and Science (CAAQES) utilized the CAAQES test method and reported that gin dust was non-explosible. The goal of this research was to analyze the two different test methods and determine if gin dust should be regulated as an explosible dust. It is assumed that either the ASTM or CAAQES test method had incorrectly classified gin dust. The CAAQES test method was analyzed and tests were conducted on multiple dusts to the accuracy of the test procedure. A theoretical analysis of the ASTM test method was conducted to determine potential flaws in the test method. The ASTM test method was found to be flawed. It used pressure as the only criterion for a dust explosion, utilized high energy ignition sources, limited the amount of oxygen, and had no requirement for a dust to have a minimum explosible concentration (MEC) to be classified as explosible. Utilizing high energy ignition source can result in a determination that a dust explosion occurred when the measured reaction was actually due to the ignition source and not a dust explosion. This type of test is referred to as an overdriven test. The CAAQES test method utilizes three criteria: a ruptured diaphragm, flame front leaving the chamber, and a characteristic pressure versus time curve to determine if a dust has a MEC. If a dust has a MEC, it is an explosible dust. By determining the MEC a more accurate classification of a dust can be made by utilizing the CAAQES test method, as CAAQES personnel did to determine that gin dust is not an explosible dust. An analysis of the ASTM and CAAQES explosible dust testing protocols was conducted to determine proper classification of gin dust. Primary dust explosions occur in the process stream of facilities at locations where an explosible dust is entrained at concentrations above the MEC. A primary dust explosion may result in a series of secondary dust explosions. For a dust explosion to occur four criteria must be met simultaneously: there must be containment, a dust entrained in the air at or above the MEC, oxygen must be present, and there must be an ignition source. A theoretical analysis was conducted to determine if a MEC exists in a cotton gin. The results indicated that there were no locations in a cotton gin where aMEC existed. It was concluded that gin dust is not an explosible dust and that dust explosions are not possible in cotton gins.
Vanderlick, Francis Jerome (2014). Cotton Gin Dust Explosibility Determinations. Master's thesis, Texas A & M University. Available electronically from