NIOSHTIC-2 Publications Search
The air flow characteristics of an annular exhaust hood.
Appl Ind Hyg 1988 Apr; 3(4):105-109
The air flow characteristics of an annular exhaust hood were examined at several slot width/flow combinations using a hot wire anemometer and electronic manometer. An annular hood was designed to fit around a 55 gallon drum to simulate a process application; the hood was constructed of sheet metal and had an adjustable slot. The depth and width of the hood were chosen to minimize flow restriction. Nine combinations of slot width and flow were evaluated; these included slot widths of 2.5, 3.8, and 5.0 centimeters and flows of 21.2, 28.3, and 35.4 cubic meters per minute. Values were selected based on obtaining the lowest static pressure possible and an appreciable velocity in the center area of the hood. Measurements included the velocity profile, the hood static pressure, and the air flow patterns (visualized using smoke) for the various slot width/flow combinations. Results indicated that an annular hood could generate an appreciable velocity in the center portion of the drum area; even air distribution could be achieved along the hood's slot using a baffle and variable width slot. The author concludes that designers can use the hood design presented in this paper to control emissions from operations involving 55 gallon drums; the study also provides ideas about how to decrease static pressure losses.
NIOSH-Author; Equipment-design; Exhaust-hoods; Exhaust-systems; Industrial-engineering; Air-flow; Physical-properties; Industrial-design
Issue of Publication
Applied Industrial Hygiene
Page last reviewed: November 20, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division