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Evaluation of a local exhaust ventilation system for controlling refractory ceramic fibers during disc sanding.

Dunn-KH; Shulman-SA; Cecala-AB; Venturin-DE
J Occup Environ Hyg 2004 Oct; 1(10):D107-D111
In 2002, the National Institute for Occupational Safety and Health (NIOSH) conducted an engineering control evaluation at an Ohio company that produced vacuum-formed ceramic fiber parts. The evaluation was conducted at the request of the company to examine the efficacy of a local exhaust ventilation system they had developed to capture and collect airborne refractory ceramic fibers (RCFs) during the sanding of vacuum-formed parts. This case study describes the process and evaluation methods and presents data that demonstrates dramatic reductions in airborne refractory ceramic fiber concentrations. This is a small company that manufactures vacuum-formed ceramic fiber parts using RCF materials obtained from a vendor. At the time of the survey the company employed 67 workers; 50 worked in the plant and 17 worked in the office. The plant operates 3 shifts with most workers (34) on the first shift. The sanding area is staffed 24 hours a day by one worker. A second worker packs the final product for shipping. The manufacture of RCF products comprises a number of tasks including: part forming; drying; and finishing, which involves sanding, sawing, or other processes according to customer specifications. The company purchases RCF in bulk and vacuum forms the material into various shapes according to customer specification. Brass-screened dies with perforated screen reinforcements are made to produce the variously shaped vacuum-formed RCF parts. The die is mounted on a dip machine that is operated by a foot pedal-activated control switch to lower the die into the ceramic fiber slurry tank. When the die reaches the bottom of the tank a limit switch is triggered and the vacuum is activated. The dip machine operator sets a timer according to the part being formed. The timer activates a switch to remove the die from the slurry tank after the part has been formed. The part is then removed from the die by hand and placed on a tray that is placed on a conveyor belt that moves the parts to an oven for drying. After drying, the parts are transferred to the sanding station. All RCF parts are finished on the disc sander designed and fabricated by the company. Once sanded, the part is removed from the station, inspected, and packed into a cardboard tray for shipping.
Engineering-controls; Exhaust-ventilation; Refractories; Ceramic-materials; Ventilation-systems; Airborne-fibers; Vacuum-equipment; Control-technology; Electrical-equipment
National Institute for Occupational Safety and Health, Division of Applied Research and Technology, 4676 Columbia Parkway, Cincinnati, OH 45226
Publication Date
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Journal Article
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NTIS Accession No.
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NIOSH Division
Priority Area
Research Tools and Approaches: Control Technology and Personal Protective Equipment
Source Name
Journal of Occupational and Environmental Hygiene