EFFECT OF BAFFLES AND A LOUVERED BYPASS ON THE AIR-FLOW AND THE CONVECTIVE PATTERNS OF CONTAMINANT INSIDE A FUME HOOD

Various numerical predictions are given for the containment testing of fume hoods with internal baffles of different sizes and at different locations and with a louvered bypass. The numerical predictions were c ompared with experimental data and a fairly good agreement for the air velocity was found, although there was only qualitative agreement for the concentration of the contaminant. It was found that the level of contaminant leakage at the working aperture depended not only on the s ize of the recirculating airflow behind the fume hood sash but also on the blockage caused by the baffles inside the fume hood near the exha ust duct. Finally some new suggestions for the design of the fume hood have been proposed. However, before implementing these suggestions it is essential that either experimental testing be performed, or the co st-effective alternative of using numerical predictions for containmen t testing, to determine accurately the level of contaminant leakage fr om the working aperture.