Technical Note TN 3/85 Design guidelines for exhaust hoods

Publication Year

1985

Document Status

Current

Abstract

Treats the effective design of exhaust hoods for local exhaust systems. Notes the increasing importance of effective hood design as concerns air pollution and operating costs. States that recent research work has cast doubt on the accuracy of some of the current design equations. Puts forward revised design equations, which experimental evidence shows are more accurate and consistent that those in current use. The equations are for a range of exhaust hoods using the layout of Table B3.5 in the current CIBSE Guide. Further tables present guidance on the selection of control velocities for pollution capture, the heat transfer rates required for assessing the performance of canopies over hot sources and the effects that side walls and adjacent surfaces have on hood performance. Provides general design hints. Discusses the background to the design information in an appendix.

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