Patent ID: 7753977

Claim:
An air filtration system comprising: (a) a support structure; (b) an enclosure coupled to the support structure and including an air outlet; (c) an air filter housed in the enclosure; (d) a fan operatively coupled to the enclosure; (e) a screen frame; and (f) a unidirectional flow screen spanning the screen frame, the unidirectional flow screen having a downstream side defined along a single plane, the unidirectional flow screen covering the air outlet to result in unidirectional filtered air flow; the unidirectional flow screen: (i) being spaced from the air filter; (ii) consisting of a single layer of polymeric fabric constructed and arranged to provide unidirectional filtered air flow from the air outlet such that filtered air flows in a single direction with generally parallel air streamlines; (iii) having a weave pattern with pore sizes of 50-200 micrometers; and (iv) creating only unidirectional parallel air streamlines across the flow screen, to shield a work area from unfiltered air surrounding the work area to result in filtered air that travels further to the work area with lower levels of cross-contamination from particulates present in the surrounding unfiltered air than filtered air from an air filtration system without a unidirectional flow screen.