Clearing The Air With Cartridges (continued)

Indoor Air Quality Improvements

The Occupational Safety and Health Administration (OSHA) has not established a permissible exposure limit (PEL) for refractory ceramic fiber (RCF). However, the Refractory Ceramic Fibers Coalition, an association of the leading RCF manufacturers-through its voluntary Product Stewardship Program, PSP2002-has established a recommended exposure guideline (REG) of 0.5 fibers per cubic centimeter (f/cc), based on eight-hour time weighted average (TWA) emissions testing, and OSHA supports this guideline. Based on dozens of air samples collected at Thermal Ceramics between 1994 and 2001, when the baghouse collector only was in use, the mean TWA was 0.593 f/cc-slightly above the industry's current REG. As a result, respirators were required in the workplace.

After installing the Farr cartridge dust collector, Thermal Ceramics also instituted work practice improvements to further improve air quality in the finishing area. These practices include manually repositioning floor fans in the summer to avoid disrupting airflow into the collection system and more careful handling of finished boards after sanding and during packaging to minimize the potential for dust generation. "Through this combination of higher efficiency dust collection and work practice improvements, we cut our emissions in half," Criss says.

Recent air sampling data has shown a mean TWA of 0.272 f/cc-an approximate 55% reduction in exposures. "After documenting that we were well below the industry REG, we allowed our workers to take off their respirators-though they still have the individual option of using these devices if they wish," says Criss.

Operator Robert Gilchrist loads boards onto the inlet rollers for the cross-cut saw.

According to Criss, "The new system provides better airflow than we achieved previously." The system has also operated at low differential pressure in the 2.0-3.0 in. water gauge range. When the differential pressure rises, maintenance crews can wash down the cartridges if desired and reinstall them for extended service life. When filter maintenance or replacement is needed, the collector has a patented cambar system that allows fast cartridge removal with no tools required.

"Our air flow is better and our air quality is better, and that makes for a cleaner and more pleasant work area with enhanced process reliability," Criss says.

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