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Do: Implement a preventive maintenance schedule from the unit’s manufacturer or a dust collector expert.


Regular preventive maintenance is key to keeping the


system at near peak efficiency and getting the maximum life out of filters, cages, and pleated filters. It helps the system stay in compliance with environmental health and safety standards and control emissions for air permits.


Do: Consider annual inspections or audits by an outside consultant.


Many qualified baghouse manufacturers and service


providers provide system inspections. Some will make an extensive report on the findings with recommendations for short-term and long-term improvement. Consider having annual inspections to:


ANATOMY OF A PROPERLY DESIGNED SOURCE CAPTURE SYSTEM


A sound dust collection strategy has several goals. It should limit housekeeping and promote a more cleanly and more maintainable workplace. It should remove a portion of fines from the sand system to better manage quality. The system should exhaust heat from castings and heat and moisture from the sand to improve cooling. And it should extract respirable crystalline silica and other contaminants from the environment to protect workers. To achieve these goals, the source capture (or dust collec- tion) system should be properly designed. The two main pieces of a source capture system are the hoods and the ductwork. There are two types of hoods: enclosing hoods and capturing hoods.


Enclosing hoods require less air volume than captur- ing hoods, are restrictive of access and typically used with hazardous substances. There are more design and fabrica- tion costs with enclosing hoods but typically less energy is used for effective capture. They are designed to keep the dust source inside the hood—usually a target of 200-250 ft. per minute (fpm) through the open areas is used. Common enclosing hood locations are bucket elevator taps, taps on day bins, some mold cooling lines, punchout and shakeout enclosures, inoculation booths, most sand coolers and most mullers and mixers.


Capturing hoods can allow for maintenance and production access and have cheaper installation costs but higher operat- ing costs. The source is located outside a capturing hood, and the closer the hood is to the source, the more effective it is. The three main types of capturing hoods are plain operating hoods, slotted hoods, and slotted hoods with plenums. Push/pull hoods are a type of capturing hood. Common locations for capture


In enclosed hoods, the captured source is inside the hood.


Enclosed hoods are designed to keep dust inside the hood. 30 | MODERN CASTING July 2018


Capture hoods are often used in pouring areas.


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