Experimental and numerical studies on the impact of work practices used to control exposures occurring in booth-type hoods.
Flynn-MR; Lackey-BD; Muthedath-P
Am Ind Hyg Assoc J 1996 May; 57(5):469-475
A numerical and experimental analysis of the influence of worker position on breathing zone exposure to airborne contaminants in booth type hoods was performed. Velocity fields were computed around a simulated worker in a booth type hood holding a contaminant source (such as a paint sprayer) with the air flow coming from behind (configuration-A) or from the side (configuration-B) using the discrete vortex method for solving the flow equations. The concentrations of the contaminant in the breathing zone were computed for air flow rates of 100, 150, and 250 feet per minute (ft/min). The flow patterns of the two configurations were experimentally measured using a mockup of the booth and a mannequin placed in a wind tunnel. Sulfur-hexafluoride was used as the tracer gas. The average concentrations of sulfur-hexafluoride in the mannequin's breathing zone in the configuration-A mockup measured at flow rates of 100, 150, and 250ft/min were 83.2, 53.7, and 18.2 parts per million (ppm), respectively. The breathing zone concentrations measured at 100, 150, and 250ft/min in configuration- B were 0.44, 0.05, and 0.13ft/min, respectively. The breathing zone sulfur-hexafluoride concentrations measured in configuration-B with the mannequin turned sideways to the air flow represented 137 to 944 fold decreases compared to configuration-A where the air flow came from behind the mannequin. The breathing zone contaminant concentrations calculated by the numerical simulation showed very good agreement with the experimental values in the case of configuration-A. Agreement between the simulated and experimented values in the case of configuration-B was good when the near wake region was selected as the breathing zone. The predicted flow fields showed good qualitative agreement with the experimental data. The authors conclude that the worker's position relative to the air flow plays a significant role in exposures generated by a handheld contaminant source in a booth type arrangement.
NIOSH-Publication; NIOSH-Grant; Grants-other; Air-flow; Ventilation-hoods; Work-practices; Control-technology; Mathematical-models; Simulation-methods; Industrial-hygiene
Environmental Sciences & Engr University of North Carolina CB 7400 Rosenau Chapel Hill, NC 27599-7400
Other Occupational Concerns; Grants-other
American Industrial Hygiene Association Journal
University of North Carolina Chapel Hill, Chapel Hill, North Carolina