The Impact of Flow Separation on Exposure and Hood Capture Efficiency

Details

• Personal Author:
  Flynn MR
• Description:
  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. [Description provided by NIOSH]
• Subjects:
  Environmental Monitoring Laboratories Occupational Health Safety Ventilation
• Keywords:
  Air-quality-control Air-sampling Control-technology Laboratory-workers NIOSH-Grant Ventilation-systems
• Series:
  Grant Final Reports
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  North Carolina ; OSHA Region 4
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-155
• NIOSHTIC Number:
  nn:00197948
• NTIS Accession Number:
  PB91-188615
• Citation:
  Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 1990 Feb; :1-155
• Contact Point Address:
  Environmental Sciences & Engr University of North Carolina Rosenau Hall 201H Chapel Hill, NC 27514
• Federal Fiscal Year:
  1990
• NORA Priority Area:
  Research Tools and Approaches: Control Technology and Personal Protective Equipment
• Performing Organization:
  University of North Carolina Chapel Hill, Chapel Hill, North Carolina
• Peer Reviewed:
  False
• Start Date:
  19870929
• Source Full Name:
  Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina
• End Date:
  19890928
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:baf45db62109e9005bb8289e679dfd2025ea6e50b55dea9f049d002c756eb44a588fe1c7b8d851ab7428d1fd7457a947e9f075c3e19fb8737255557e68a9e2ea
• Download URL:
  https://stacks.cdc.gov/view/cdc/217798/cdc_217798_DS1.pdf
• File Type:
  [PDF - 5.33 MB ]