Abstract: A filtration assembly may comprise first and second end pieces having inner and outer faces, at least one filtration unit between the inner faces of the first and second end pieces, and at least one compression rod arrangement extending between the end pieces. The compression rod arrangement may comprise an unthreaded compression rod and a locking device mounted to the compression rod to maintain compression of the filtration unit between the end pieces. A method of maintaining compression of filtration units may comprise installing at least one filtration unit between a first end piece and a second end piece and maintaining compression of the end pieces and the filtration unit, including mounting a locking device to an unthreaded compression rod.

Abstract: The present invention relates to microporous and ultrafine polytetrafluoroethylene (PTFE) membranes of high permeability, excellent mechanical strength, and good chemical inertness, and to methods for their preparation. According to the method of the present invention, a porous PTFE substrate having a first pore rating is compressed to provide a porous membrane having a second pore rating, wherein the second pore rating is smaller than the first pore rating. The PTFE substrate can be contacted with one or more fibrous sheets during the compression step, which is preferably performed by passing the substrate, and fibrous sheets, if appropriate, between two calender rolls. The resulting porous PTFE membrane then can optionally be stretched and/or sintered, and preferably has a water permeability of at least about 0.5 l/hr/m2/kPa.

Abstract: The present invention relates to microporous and ultrafine polytetrafluoroethylene (PTFE) membranes of high permeability, excellent mechanical strength, and good chemical inertness, and to methods for their preparation. According to the method of the present invention, a porous PTFE substrate having a first pore rating is compressed to provide a porous membrane having a second pore rating, wherein the second pore rating is smaller than the first pore rating. The PTFE substrate can be contacted with one or more fibrous sheets during the compression step, which is preferably performed by passing the substrate, and fibrous sheets, if appropriate, between two calender rolls. The resulting porous PTFE membrane then can optionally be stretched and/or sintered, and preferably has a water permeability of at least about 0.5 l/hr/m.sup.2 /kPa.