Vented flexible filtration device for use in administering parenteral liquids

A vented filtration device for use in the filtration of parenteral liquids comprising:

• a closed, flexible and compressible housing including a pair of flexible sheets sealed together around their peripheries except for a liquid inlet and a liquid outlet, said housing including a passage within connecting said inlet and outlet;
• a filter assembly disposed within said passage between said inlet and said outlet thereby defining an upstream pressure section between said inlet and said assembly and a downstream pressure section between said assembly and said outlet, said filter assembly including a flexible, porous bacteria retentive filter membrane having a pore size not greater than 0.22 microns, a flexible, porous support material having pores generally greater in size than those of said filter membrane overlying one surface of said filter membrane, a flexible frame overlying the surface of said filter membrane opposite said supported surface, said assembly being folded at least three times and sealed to form a flexible pouch having one liquid opening in one ene thereof, said outlet communicating with the interior of said pouch through said liquid opening, said frame having one more central opening than the number of folds to expose a substantial surface area along each leg of said folded filter, said assembly including a porous scrim fabric on the innermost and outermost layers thereof so that collapse of said folded pouch on itself is prevented during use, said filter assembly adapted to filter all liquid passing from said inlet to said outlet during use;
• and a gas vent opening through one of said flexible housing sheets communicating with said upstream pressure section of said passage and a hydrophobic filter medium attached to said housing sheet to cover said opening to thereby allow gas not liquid to pass from said upstream section out of said housing, said filter assembly providing a sufficiently low pressure drop thereacross, so as to eliminate the requirement of a pump to force said fluid through said assembly.