NIOSHTIC-2 Publications Search
The Impact of Flow Separation on Exposure and Hood Capture Efficiency.
Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 1990 Feb:155 pages
A mathematical model was developed which could predict breathing zone concentration for a worker operating in the vicinity of a local exhaust hood. As part of this effort, a mathematical model was developed to predict breathing zone concentration for a mannequin when a point source of tracer was located downstream. The model was extended to include the situation with a mannequin positioned in front of a flanged circular hood and to include cross drafts and mannequin position with respect to the hood. The results of the study indicated that where workers hold contaminant generating sources and operate in front of or within large booth type hoods, the phenomenon of boundary layer separation was of major importance in determining exposure. Where possible the worker should maintain an orientation such that the line connecting the source and worker is a right angle to, not parallel to, the air stream. Vortex shedding plays the primary role in contaminant transport from the separated recirculation zone. The author concludes that ventilation when used as an engineering control must be used in conjunction with, and not in exclusion to, work practices.
NIOSH-Grant; Control-technology; Air-quality-control; Control-technology; Air-sampling; Ventilation-systems; Laboratory-workers;
Environmental Sciences & Engr University of North Carolina Rosenau Hall 201H Chapel Hill, NC 27514
Final Grant Report;
NTIS Accession No.
Control Technology and Personal Protective Equipment; Research Tools and Approaches; Control-technology;
Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina
University of North Carolina Chapel Hill, Chapel Hill, North Carolina
Page last reviewed: September 11, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division