Dust Control Handbook for Industrial Minerals Mining and Processing

RECOMMENDATIONS FOR FILTRATION/PRESSURIZATION SYSTEMSBased on the knowledge gained from both laboratory and numerous field studies, the practicesrecommended in this section need to be incorporated in order to achieve an effective filtrationand pressurization system.Ensuring Enclosure Integrity by Achieving Positive Pressurization against WindPenetrationEnclosure integrity is necessary in order to achieve pressurization, which is critical for aneffective system. Testing has shown that the installation of new door gaskets and plugging andsealing cracks and holes in the shell of the enclosure have a major impact on increasing theenclosure pressurization. To prevent dust-laden air from infiltrating into the enclosure, theenclosure's static pressure must be higher than the wind's velocity pressure [Heitbrink et al.2000]. Equation 9.3 is used to determine the wind velocity equivalent for an enclosure (the windvelocity at which the cab is protected from outside infiltration as determined by the staticpressure):Wind velocity equivalent( 4000 pcab) fpm x 0.011364 mph/fpm(9.3)where Δр = cab static pressure in inches wg.@ standard air temperature and pressureFigure 9.3 provides a graphical display of this wind velocity equivalent. This shows that anenclosure pressure of 0.05, 0.1, 0.25, 0.5, and 1.0 inches wg would be able to withstand windvelocities of 10.2, 14.4, 22.7, 32.1, and 45.5 mph from penetrating dust into the enclosure.Although minimum pressurization has been shown to have positive results from field studies, agood rule of thumb is to have at least 0.05 inches wg of positive pressure in enclosures. Areasonable range of enclosure pressure is between 0.05 to 0.25 inches wg.230 Operator Booths, Control Rooms, and Enclosed Cabs