Abstract: A method and apparatus for the leak testing of one or more filters, and comprising a housing adapted to sealably mount the filters, means for introducing DOP particles within the housing and immediately upstream of each of the filters, and means for imparting a like electrical charge to the particles such that the particles repel each other and rapidly disperse within the airstream so as to be substantially uniformly dispersed upon reaching the face of each filter. A collecting surface may be disposed downstream of the filters for detecting any of the charged particles to thereby permit a determination as to whether the filters are leaking. Alternatively, a collapsible panel system may be positioned immediately downstream of the filter to condense and impart turbulence to the airstream to thereby permit a sample to be withdrawn for analysis from a point closely adjacent the filter.

Abstract: A sliding plate air flow control valve adapted for use in a high efficiency air filter system of the type used in clean rooms and the like. The sliding plate valve is preferably positioned on the downstream side of each filter, and includes a highly viscous, non-evaporating fluid positioned between the plates to thereby prevent the air from flowing laterally between the plates, whereby the volume of air flow may be accurately controlled over the full area of the clean room as well as the full area of each filter.

Abstract: A high efficiency air filter system of the type used in clean rooms and the like, and having a sliding plate valve associated with each filter. The sliding plate valve is positioned on the downstream side of each filter, and includes a highly viscous, non-evaporating fluid positioned between the plates to thereby prevent the air from flowing laterally between the plates, whereby the volume of air flow may be accurately controlled over the full area of the clean room as well as the full area of each filter.

Abstract: A portable apparatus for directing a filtered stream of air downwardly over a predetermined area such as a hospital bed or the like. The apparatus includes a cantilevered plenum chamber adapted to be positioned horizontally over the bed, the plenum chamber comprising two segments hingedly interconnected so that the forward segment thereof may be dropped downwardly to facilitate movement and storage. The bottom wall of the plenum chamber comprises an openwork screen bounded by a peripheral slot, and a layer of filtering media overlies the screen such that a first portion of the air entering the plenum chamber is directed downwardly through the filtering media and screen at a relatively low velocity and in a substantially laminar flow pattern, and a second portion of the air is directed through the open slot to define a peripheral air curtain of relatively high velocity. The air curtain thereby serves to prevent the incursion of unfiltered air from the surrounding environment.