Experimental Study on the Performance of a Benchtop Enclosing Hood – Effects of Face Velocity and Cross-Draft Velocity

Details

• Personal Author:
  Guffey S ; He X ; Lewis B
• Description:
  In the industrial field, benchtop enclosing hoods are critical for protecting workers from airborne contaminants. Face velocity and cross draft velocity are assumed to be two dominant factors affecting the performance of benchtop enclosing hood. However, there is little published research on the effectiveness of these hoods. Almost all enclosing hood research has been done on laboratory fume hoods. Objective: To determine the effects of face velocity and cross-draft velocity on the efficiency of a 36'x30' enclosing hood. Methods: This study is a factorial study design with two replications of each treatment combination. The study tested the effects of five levels (111, 140, 170, 200, and 229 fpm) of hood face velocity and five levels (14, 26, 36, 46 and 57 fpm) of wind tunnel cross-draft velocity on the plain benchtop enclosing hood performance. Freon-134a concentrations were measured on an anthropometrically correct, heated, breathing manikin holding a source between its hands while standing at the enclosing hood face. Samples were taken simultaneously at the nose, mouth, outside the wind tunnel, downstream of the wind tunnel and the exhaust duct. Every location was sampled at 0.15 LPM for 20 minutes. Results: Higher values of face velocity were associated with higher hood protection efficiency at each value of cross-draft velocity. Surprisingly, effectiveness was generally greater for high levels of cross-draft velocity than low ones. The median level of face velocity (170 fpm) and the median level of wind tunnel cross-draft (36 fpm) produced the best hood protection efficiency. Conclusion: is that interaction of cross-draft velocity and face velocity strongly affect the concentrations at the sampling sites. [Description provided by NIOSH]
• Subjects:
  Air Pollutants, Occupational Laboratories Occupational Health Particulate Matter Safety Ventilation
• Keywords:
  Airborne Particulates Exhaust Hoods Exposure Assessment Laboratory Equipment Ventilation Hoods
• Publisher:
  American Industrial Hygiene Association
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  80
• NIOSHTIC Number:
  nn:20070221
• Citation:
  AIHce 2010: American Industrial Hygiene Conference and Exposition, May 22-27, 2010, Denver, Colorado. Falls Church, VA: American Industrial Hygiene Association, 2010 May; :80
• Federal Fiscal Year:
  2010
• Performing Organization:
  West Virginia University
• Peer Reviewed:
  False
• Start Date:
  20050701
• Source Full Name:
  AIHce 2010: American Industrial Hygiene Conference and Exposition, May 22-27, 2010, Denver, Colorado
• End Date:
  20100630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:4f69239ea55bf97003e1c18b7e725110d3d42fd0e8ded4accf06a92b0d444bb03816aa22b231c6e23a08062655868186234966741c9218a89045babf7a9e0e30
• Download URL:
  https://stacks.cdc.gov/view/cdc/208474/cdc_208474_DS1.pdf
• File Type:
  [PDF - 1.37 MB ]