In-depth survey report: control technology for bag filling operations at Manville Products Corporation, Lompoc, California, report no. CT-112-23b.
A control technology survey was conducted at Manville Products Corporation (SIC-3295), Lompoc, California, on January 17 to 21, 1983. The survey was conducted as part of a study to document and evaluate effective control techniques for potential health hazards. The facility was chosen because it had exemplary controls for packaging calcined and flux calcined diatomite. An epidemiological study indicated that the dust was well controlled by various dust control hoods and their related ventilation systems, the automated ventilation system, and other controls in the bag filling and packaging and conveying and palletizing operations. Concentrations of total dust containing 16 percent cristobalite (14464461) were bag recycling, 0.04 to 0.09mg/m3 at the conveyer line, 0.02, 0.03, and 0.04mg/m3 for three samples in the palletizing area. A suggested permissible exposure limit (PEL) was 0.30mg/m3. For cristobalite, no concentrations were higher than 0.03mg/m3 in the areas. The author concludes that Manville has effective dust controls, with a well designed ventilation system that captures most of the dust before it enters the workers' environment. The company also makes use of controls such as spillage hoppers and wet sweeping of paved areas to help control dusts.