Indepth survey report: Macawber Engineering, Inc., Maryville, Tennessee, report no. CT-144-21a.
An indepth survey of control technology for reducing limestone (1317653) exposure during bag opening operations at Macawber Engineering, Incorporated (SIC-3535), Maryville, Tennessee was conducted in April, 1984. The ability of an automatic bag slitter to open bags of very fine limestone (mass median diameter less than 4.0 micrometers) without becoming a dust emission source was evaluated. Total and respirable dust concentrations before and during bag slitting operations were measured under the bag disposal chute, above the bag disposal tube, at the outlet of the automatic unbagger, next to the bellows, or at a position next to the storage bins. Total dust concentrations when the machine was off ranged from 0.01 to 0.45 milligram per cubic meter (mg/m3). When the slitter was operating, total dust concentrations were 0.02 to 5.4mg/m3. The highest concentration occurred above the bag disposal tube. Respirable dust concentrations when the machine was off ranged from 0.08 to 0.65mg/m3. When the slitter was operating, respirable dust concentrations were 0.11 to 3.83mg/m3, the highest concentration occurring next to the bellows. The author suggests that the bag slitter leaks dust. As tested, the automatic bag opening machine is probably suitable only for handling relatively nontoxic dusts.