COMPOUND LAYER RESIN BONDED FILTER CARTRIDGE

摘要

A hollow, cylindrical, resin-bonded filter cartridge (9) has an inner filter media (13) with a graded density which decreases (becomes more porous) in the radial direction from the inner surface (15) to the outer surface (16). An outer strip (14) of filter media is then wound in a spiral or helix around the inner filter media (13). The outer filter media (14) has uniform density and is wound with adjacent windings abutting one another such that a continuous groove or channel (27) is provided along the length of the cartridge (9). The groove or channel (27) provides a greater effective surface area on the outer surface of the filter cartridge. The outer strip (14) of filter media preferably comprises a lengthwise-extending body panel (18) with a pair of leaves (20) extending along either edge of the body panel (18). The leaves (20) are folded against the lower surface (21) of the outer filter media (14) to provide a multi-layer outer filter media structure.