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Capture efficiency of local exhaust hoods.
Environmental and Occupational Health Sciences, School of Public Health, University of Illinois at Chicago, Chicago, Illinois 1993 May; :1-144
A semiempirical model for capture efficiency of local exhaust hoods was developed from wind tunnel experiments. Crossdraft experiments considered the effects of crossdrafts generated by cooling fans, crossdrafts generated through doorways, disruptions to air flow patterns caused by the presence of a mannequin in the flow field, and drafts caused by a mannequin moving through the workplace. Wind tunnel experiments included velocity measurements and capture efficiency measurements. Measured crossdrafts ranged from 0.2 foot per second (fps) for the mannequin moving at 1 mile per hour (mph) to 14fps for the cooling fan operating at medium speed at a distance of 2 feet. Measured turbulence intensities ranged from less than 1% for a draft through a doorway generated by a room pressure differential of 0.001 inch of water to 86% for a mannequin moving at 3mph. Power spectra were generated for the experimental conditions. Qualitative analysis showed that higher power levels occurred at lower frequencies and larger vibration magnitudes occurred at lower velocities. The effects of turbulence intensity on contaminate dispersion were included in the model; the results indicated that better predictions were obtained of capture efficiency than with the previously developed model which did not include turbulence intensity.
NIOSH-Grant; Control-technology; Exhaust-hoods; Indoor-air-pollution; Mathematical-models; Exhaust-ventilation; Indoor-environmental-quality
Enzyme Laboratory University of Illinois Eohs (M/c 922), Box 6998 Chicago, IL 60680
Final Grant Report
NTIS Accession No.
Environmental and Occupational Health Sciences, School of Public Health, University of Illinois at Chicago, Chicago, Illinois
University of Illinois at Chicago, Chicago, Illinois
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division