Filtration Device with Pressure-Activated Means for Bypassing Serial Filter Layers

Abstract

A serial-flow filtration device is provided with pressure-activated means for by-passing at least one of its constituent layer (or layers) of filtration material. The filtration device comprises a housing, a fluid inlet, a fluid outlet, and at least an upper and a rearmost filter layer. The upper filter layer divides the interior of the housing into an upstream zone and a downstream zone, with the rearmost filter layer residing in the downstream zone. The fluid inlet enables the introduction of fluid into said upstream zone. The fluid outlet enables releases of the fluid from said downstream zone. The upper filter layer, but not the rearmost filter layer, has integrated thereinto a pressure-activated means capable of allowing substantially non-selective passage of fluid from the upstream zone into the downstream zone upon the attainment of a predetermined pressure differential across said upper filter layer. The bypass means can be embodied, for example, as a pressure-breachable seal or as a pressure-activated gate.

1 . A serial-flow filtration device comprising:
 a housing,   a fluid inlet,   a fluid outlet, and   a stack of serially-arranged filter layers including at least an upper filter layer and a rearmost filter layer, and an additional filter layer or layers between the upper and rearmost layers, each filter layer comprised of a filter medium being made from the same or different selectively-permeable filtration material, each adjacent filter layer being separated proximately either by an air space or by a spacer comprising a screen capable of allowing substantially non-selective passage of fluid therethrough and laterally;   the upper filter layer dividing the interior of the housing into an upstream zone and a downstream zone, the fluid inlet capable of introducing fluid into the upstream zone, the fluid outlet capable of releasing fluid from the downstream zone out of the housing;   the upper filter layer being held by a substantially rigid framework, the upper filter layer and the substantially rigid framework combining to form an upper filter component, wherein the upper filter layer abuts the housing to form a seal therewith, the seal being breathable upon attainment of a predetermined pressure differential, thereby allowing the substantially non-selective passage of fluid; and   the rearmost filter layer being positioned in the downstream zone and configured such that. upon attainment of the same aforementioned pressure differential across the rearmost filter layer, the rearmost filter layer will not allow non-selective passage of fluid therethrough or beyond.   
     
     
         2 . The filtration device of  claim 1 , wherein the seal is a friction-based seal. 
     
     
         3 . The filtration device of  claim 1 , wherein the seal is an adhesive-based seal. 
     
     
         4 . The filtration device of  claim 1 , wherein the housing is substantially cylindrical in shape, and each of the filter layers is substantially disc-shaped. 
     
     
         5 . The filtration device of  claim 1 , wherein the nominal pore size of each of the filter layers ranges from about 0.1 microns to about 5 microns. 
     
     
         6 . The filtration device of  claim 1 , wherein the filtration material is made from a material selected from the group consisting of polypropylene, polyester, glass, polyvinylchloride, polycarbonate, polytetrafluoroethylene, polyvinylidene fluoride, cellulose, asbestos, nylon, and polyethersulfone.