Numerical and Experimental Investigations on Hood Capture and Protection Efficiencies Available to Purchase

Effective hoods are critical for the protection of workers from airborne contaminants. The aim of this study is to determine the effects of cross-draft and presence of a worker on the effectiveness of the bench-top enclosing hoods, which, unlike laboratory fume hoods have no sash and have a constant cross-sectional area. The computational fluid dynamics (CFD) software, FLUENT, with shear-stress transport (SST) k-ω turbulence model was used to investigate the effect of orientation of the manikin and hood with respect to cross-draft on the flow and contaminant concentration field. Experiments were conducted using a manikin and a fume hood in a wind tunnel and the flow around the manikin and inside the hood was investigated via particle image velocimetry (PIV) measurements. The correlation of contaminant leakage with the turbulent intensity and recirculating vortices at the hood face were observed. The hood and manikin orientation was found to change the exposure level significantly. Maximum contaminant leakage from the hood to the working environment has been found when the hood and manikin were placed 30 degrees to the cross draft. Maximum containment was observed when the manikin and hood were oriented in the same direction as the cross draft and perpendicular to the cross draft.