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• Review the ongoing maintenance program. • Generate a list of maintenance goals/recommendations for the following quarter or year.


• Receive expert advice on how to increase efficiency, decrease operating costs, improve reliability and expand capacity, as needed.


Do: Invest in maintenance and operations training. To effectively maintain and operate a dust collection sys-


tem, the personnel must be properly trained. A well-trained team can better identify areas for improvement to increase efficiency, lower emissions, improve reliability, cut operating costs, and expand capacity.


Ductwork needs to be properly designed for a facility’s specific operation to be most efficient.


hoods are most furnace collection areas, manual grinding stations, pick and sort areas, and pouring areas.


The ductwork of a dust collection system has several design considerations. What is conveyed in the airstream? Is it abrasive or corrosive? What pressures will the ductwork see? The live loads will also effect the decision—will there be wind or snow loads and will people be walking on the duct? The temperature inside and outside the duct should also be considered. Typically, mild steel or stainless steel construction is used in foundries. Foundry construction usually has a minimum 14 gauge thickness, and the ductwork should be supported adequately to handle potential material buildup, such as a 30 in. diameter duct 70% full of shot.


For air with common densities, volumetric flow rates are cumulative at branches of the system. The ductwork should transition in size as branches are added to the main. The sizing


Table 1. Selecting a Proper Transport Velocity Nature of Contaminant


Examples


Vapors, gases, smoke Fumes, metal smokes Very fine, light dusts Dry dusts and powders


Average industrial dusts Heavy dusts Heavy/moist dusts Welding Cotton lint, wood flour, litho powder


Fine rubber dust, Bakelite molding powder dust, jute lint, cotton dust, shavings (light), soap dust, leather shavings


Grinding dust, buffing line (dry), wool jute dust (shaker waste), coffee beans, silica flour, general material handling, brick cutting, clay dust, foundry (general), limestone dust, packaging, and weighing asbestos dust in textile industries


Sawdust (heavy and wet), metal turnings, foundry tumbling barrels and shakeout, sand blast dust, wood blocks, hog waste, brass turnings, cast iron boring dust, and lead dust


Lead dust with small chips, moist cement dust, buffing lint (sticky), and quick-lime dust Proper sizing of ductwork is important to minimize wear and limit buildup.


of the duct is important to minimize wear, limit buildup in the ductwork and aid in balancing.


The transport velocity of a source capture system depends on the nature of contaminant being collected (Table 1). Higher velocity systems (3,000-4,500 fpm and 34-51 mph) have higher static pres- sure, lower initial cost, higher operational cost and more abrasion. Low velocity systems (greater than 1,800 fpm and 20 mph) have a lower static pressure, larger diameter, higher initial cost, lower operational cost and less abrasion. —Matt Diestler, IVI Inc. (Greenville, Wisconsin)


Design Velocity 1,000-2,000 fpm 2,000-2,500 fpm 2,500-3,000 fpm 3,000-3,500 fpm


3,500-4,000 fpm 4,000-4,500 fpm 4,500 fpm and up July 2018 MODERN CASTING | 31


Information in this table is from the ACGIH ventilation manual.


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