Abstract: A low air volume exhaust hood is based on the concept of zone laminar flow through the hood as the hood sash is raised to different levels. Laminar flow is achieved through a plurality of plenum zones constructed at the rear of the cabinet. Preferably the zones are created by utilizing different sized openings in a rear baffle of the cabinet which presents the plenum chamber. Alternatively, distinct independent plenums may be formed and coupled with a common exhaust structure. By utilizing laminar flow which is directed through different zones corresponding to different open positions of the sash, a lower volume of air can be moved through the hood while achieving desired levels of evacuation. Performance of the hood is further enhanced by a novel air foil design at the floor of the hood which promotes a sweeping flow of air across the floor.

Abstract: A laboratory fume hood has a cabinet structure, which defines an enclosed work area, and a primary exhaust assembly. The primary exhaust assembly serves to contain fumes within the work area and then exhaust the fumes. It effects a flow of a volume of air through the work area and in many instances is designed to maintain a constant face velocity across an access opening in the front wall of the fume hood. A secondary collection device is disposed within the fume hood for removing a concentration of fumes from a small portion of the work area. The secondary collection device includes a collector head disposed in the work area and a conduit connected to the primary exhaust assembly. A portion of the air flowing through the work area is directed to the primary exhaust assembly through the secondary collection device. The volume of air passing through the secondary device should not be high enough to adversely affect the containment capabilities of the primary exhaust assembly.

Abstract: A fume hood for venting fumes comprising a cabinet, a venting system, and a split sash. The cabinet defines a working area. The cabinet has a front face which comprises an opening for providing access to the working area. The venting system is connected to the cabinet and vents fumes that collect in the working area of the cabinet. A split sash is movably secured to the front face of the cabinet for selectively opening and closing the opening to the working area of the cabinet. The split sash comprises at least two panels that move in unison between closed and open positions. Further, the fume hood comprises a bypass having an opening formed in the face of the cabinet for controlling the face velocity of the cabinet and means for selectively adjusting the size of the bypass opening.