by the National Institute for Occupational Safety and Health (NIOSH) have shown that
excessive concentrations of respirable silica are produced when cleaning castings are made
from sand molds. Use of the local exhaust ventilation (LEV) system described below
significantly reduced worker exposures to respirable dust by 59% to 77% for various
cleaning tools. This system may keep worker exposures to respirable silica below
permissible limits and eliminate the need for workers to wear respirators.
LOCAL EXHAUST VENTILATION (LEV) SYSTEM
The LEV system
consists of a downdraft ventilation booth outfitted with a turntable for manipulating the
castings. This system is designed to enclose and draw air contaminants downward through a
grate opening at the working surface of the table for cleaning small castings. The table
surface opening for this booth is approximately 5 ft long and 1.5 ft deep; airflow rate
for the system was about 5,600 ft/3 min. This LEV system exceeds the minimum recommended
face capture velocity of 200 ft/min. The turntable allows the worker to have easy access
for cleaning multiple surfaces and directing the dusts generated from the tools toward the
grate opening, away from the breathing zone. (see ILLUSTRATIONS)
Downdraft ventilated casting-cleaning workstation. Casting-cleaning turntable.
WORKSTATIONS WITH TURNTABLE
U.S. Patent 5569074. For other than single use, contact NIOSH Technology Transfer Coordinator (513/841-4321)
For problems with accessibility in using figures and illustrations, please contact the OSHA Directorate of Technical Support and Emergency Management at (202) 693-2300.