Abstract: A filter assembly wherein a housing seat (220) and a cartridge cap (330) are keyed to insure correct filter replacement procedures. The seat (220) can comprise a family of pedestals (270) and the end cap (330) can comprise a corresponding family of pedestal-insertion pockets (370). The correct filter cartridge can be easily installed (e.g., periodically replaced), by aligning the pockets (370) of the end cap (330) with the pedestals (270) in the housing seat (220), and inserting the pedestals (260) into the pockets (370).

Abstract: A filter assembly wherein a housing seat (220) and a cartridge cap (330) are keyed to insure correct filter replacement procedures. The seat (220) can comprise a family of pedestals (270) and the end cap (330) can comprise a corresponding family of pedestal-insertion pockets (370). The correct filter cartridge can be easily installed (e.g., periodically replaced), by aligning the pockets (370) of the end cap (330) with the pedestals (270) in the housing seat (220), and inserting the pedestals (260) into the pockets (370).

Abstract: A hollow, cylindrical, resin-bonded filter cartridge has an inner, depth-type filter media with a graded density which decreases (becomes porous) in the radial direction from the inner surface to the outer surface. An outer strip of filter media is then wound in a spiral or helix around the inner filter media. The outer filter media is also a depth type of filter media and has uniform density and is wound with adjacent windings abutting one another such that a continuous groove or channel is provided along the length of the cartridge. The groove or channel provides a greater effective surface area on the outer surface of the filter cartridge. The outer strip of filter media preferably comprises a lengthwise-extending body panel with a pair of leaves extending along either edge of the body panel. The leaves are folded against the lower surface of the outer filter media to provide a multi-layer outer filter media structure.