Workbench filtering station and method

Claim 1

A workbench filtering station comprising: an open support frame; a first pair of parallel, spaced vertical panels suspended from said support frame; a second pair of parallel, spaced vertical panels secured to said support frame and perpendicular to said first pair of panels; said first and second pair of vertical panels enclosing said open support frame to thereby define a generally open interior; gas flow inlet means provided on at least one of said panels for communicating with said open interior, said gas flow inlet means including a perforated area having a selected ratio of open area to solid area disposed on a portion of said at least one panel of said first pair of panels, said perforated area regulating the volume of air drawn into the generally open interior; first filter means having a first filtering efficiency arranged in said generally open interior and in communication with said gas flow inlet means for cleaning the gas flow to a first selected particulate level; second filter means having a filtering efficiency greater than said first filter means, said second filter means being supported on said frame and disposed in a chamber in fluid communication with said generally open interior so as to clean the gas flow to a second selected particulate level; fan means mounted on said frame for providing a constant volume gas flow through said generally open interior wherein said fan means maintains a selected static pressure at the outlet thereof; and exhaust means in communication with said chamber in which said second filter means is disposed for discharging a clean gas flow.

Claim 13

A method of filtering a gas flow in a filter device including at least one vertically arranged intake panel, said at least one vertically arranged intake panel including a plurality of perforations therein, a first filter stage having a plurality of bag filters, a second filter stage having HEPA-type filters, and a fan for providing a constant volume air flow through said filter device, said method comprising the steps of: drawing a constant volume gas flow through the perforations in the intake panel so as to maintain a selected static pressure at the outlet of said filter device; passing said gas flow through the first filter stage to clean the gas flow to a desired particulate concentration; passing said partially-cleaned gas flow from said first filter stage through said second filter stage to further clean the gas flow to a desired particulate concentration; and exhausting said clean gas flow to the atmosphere.

Claim 14

A method of filtering a gas flow in a filter device including at least one vertically arranged intake panel, said at least one vertically arranged intake panel including a plurality of perforations therein, a first filter stage having a plurality of bag filters, a second filter stage having HEPA-type filters, and a fan for providing a constant volume air flow through said filter device, said method comprising the steps of: drawing a constant volume gas flow through the perforations in the intake panel so as to maintain a selected static pressure at the outlet of said filter device; passing said gas flow through the first filter stage to clean the gas flow to a desired particulate concentration; passing said partially-cleaned gas flow from said first filter stage through said second filter stage to further clean the gas flow to a desired particulate concentration; and exhausting said clean gas flow to the atmosphere.