Capture efficiency of flanged circular local exhaust hoods.

Details

• Personal Author:
  Ellenbecker, Michael J. ; Flynn MR
• Description:
  An idealized theoretical model of capture efficiency for Local Exhaust Ventilation (LEV) systems was developed based on the modified potential flow solution. A model was developed for the flanged circular hood operating in the presence of a cross draft perpendicular to the hood centerline. The model was based on computer generated streamline maps and the assumption that capture efficiency depends upon the interaction of three flow fields, generated by the hood, the contaminating source, and due to any perturbing cross drafts. A point source of gaseous contaminant of low strength was assumed. The predicted capture efficiencies were in close agreement with measured values, with a maximal error of about +/-25 percent at the critical distance. The authors identify the need for further research to determine the applicability and accuracy of the theory in estimating adjustments to LEV systems which will facilitate desired levels of control and in accounting for possible effects of flows around objects and people. The authors conclude that models of breathing zone concentration may be derivable from capture efficiency. [Description provided by NIOSH]
• Subjects:
  Aerosols Air Pollutants, Occupational Air Pollution, Indoor Hazardous Substances Occupational Health Safety Ventilation Workplace
• Keywords:
  Air-contamination Control-technology Exhaust-hoods Exhaust-ventilation Mathematical-models NIOSH-Grant NIOSH-Publication Toxic-gases Toxic-vapors Ventilation-hoods Ventilation-systems Workplace-studies

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• ISSN:
  0003-4878
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Massachusetts ; OSHA Region 1
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  497-513
• Volume:
  30
• Issue:
  4
• NIOSHTIC Number:
  nn:00165865
• Citation:
  Ann Occup Hyg 1986 Nov; 30(4):497-513
• Contact Point Address:
  Physiology Department, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115
• Federal Fiscal Year:
  1987
• Performing Organization:
  Harvard University, Boston, Massachusetts
• Peer Reviewed:
  True
• Start Date:
  19770930
• Source Full Name:
  Annals of Occupational Hygiene
• End Date:
  19940630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:fc2e7b38f6a729addacad8a8d713d4b31b762925ca600735ee1cf2c0331c70964ee4b64bcfc495f16a19f9efbaa6578318e8f599e7e93501caa8fca0cb7103d6
• Download URL:
  https://stacks.cdc.gov/view/cdc/185079/cdc_185079_DS1.pdf
• File Type:
  [PDF - 764.02 KB ]