There are many types of open and enclosed exhaust hoods including canopy hoods, equipment hoods, biological safety cabinets, and chemical fume hoods. Laboratory-type facilities primarily utilize chemical fume hoods and biological safety cabinets. Fume hoods currently being manufactured incorporate entrance airfoils, beveled sidewall entrances, internal baffles, and sash options to provide both safety and energy efficiency. Fume hoods typically have either a vertical sash or a horizontal sash arrangement. The horizontal sash can reduce exhaust air volume by 50 percent over the vertical sash system. Because these features are important to insure safe and energy-efficient operation, old fume hoods without them should not be reused. [SEFA…, 2002] [Neuman and Guven, 1994; Ruys, 1990; Suhail, 1989]
