A water treatment cartridge includes a base having a recess therein. One outlet is located in the recess in the base and at least one further outlet is located away from the recess in the base. The outlet located in the recess in the base may be surrounded by an annular wall which projects away from the base of the water treatment cartridge to cooperate with a hopper in which the cartridge is fitted. The outlets can be designed to restrict the flow of water through the cartridge independently of any hopper in which the cartridge is mounted.

An electronic system providing unique identification of a genuine filter system assembly to the engine control unit (ECU). A resistor is made to be an integrated part of the filtration system hardware such that when connected through a wired connection, the ECU detects a particular voltage signal and identifies the system as a genuine filter. The resistor could be integrated in. any part of the filter system such that it could be used to recognize the filter or the cartridge. The resistor connection could be made via male/female pins, conducting wires, plates, conductive plastic material or other mechanisms.

A filter element for filtering liquids has a folded filter medium with outer fold edges and inner fold edges, wherein the inner and outer fold edges extend along a longitudinal axis of the filter element. A support body is provided with a first support body section and a second support body section, wherein the first support body section is facing the inner fold edges and hugs closely an envelope of the inner fold edges. An envelope of the outer fold edges and the second support body section hug closely at least sectionwise an outer circumferential surface of the filter element.

An electronic system providing unique identification of a genuine filter system assembly to the engine control unit (ECU). A resistor is made to be an integrated part of the filtration system hardware such that when connected through a wired convection, the ECU detects a particular voltage signal and identifies the system as a genuine filter. The resistor could be integrated in any part of the filter system such that it could be used to recognize the filter or the cartridge. The resistor connection could be made via male/female pins, conducting wires, plates, conductive plastic material or other mechanisms.

A filter assembly includes a cylindrical filter housing, a filter element housing plate positioned between a high pressure and a low pressure side of the filter housing, the filter element housing plate having a plurality of one female cavities, and a plurality of replaceable filter elements within the filter housing. Each replaceable filter element has an endcap with an external rounded polygon shaped sealing surface engaging peripheral surfaces of an associated female cavity of the filter element housing plate and sealing against peripheral surfaces of the female cavity of the filter element housing plate.

A filter element includes a filter media having opposite first and second faces, and an outer face extending in a longitudinal direction perpendicular from the first face to the second face. An undulating sealing element is directly bonded to the outer face at a location closer to and offset from the first face. The undulations of the sealing element define an offset region of the outer face of the filter media from the first face, the offset region being defined by an amplitude of the undulations. The filter element may be incorporated into a filter assembly including the filter element enclosed by a filter housing. The sealing element may be made of urethane and be compressible within a mating groove in the filter housing.

A water filter system includes a removable filter unit having a body portion including a proximal end and a distal end. The proximal end is adapted to be inserted into a filter head assembly. A laterally extending key member is disposed on the body portion and adapted to engage a key slot in the filter head assembly. An engagement protrusion extends from the proximal end. The engagement protrusion includes a first portion that has a first radius of curvature and a second portion opposing the first portion that includes a second radius of curvature that is larger than the first radius of curvature.

A water filter system includes a removable filter unit having a body portion including a proximal end and a distal end. The proximal end is adapted to be inserted into a filter head assembly. A laterally extending key member is disposed on the body portion and adapted to engage a key slot in the filter head assembly. An engagement protrusion extends from the proximal end. The engagement protrusion includes a first portion that has a first radius of curvature and a second portion opposing the first portion that includes a second radius of curvature that is larger than the first radius of curvature.

A water filter system includes a removable filter unit having a body portion including a proximal end and a distal end. The proximal end is adapted to be inserted into a filter head assembly. A laterally extending key member is disposed on the body portion and adapted to engage a key slot in the filter head assembly. An engagement protrusion extends from the proximal end. The engagement protrusion includes a first portion that has a first radius of curvature and a second portion opposing the first portion that includes a second radius of curvature that is larger than the first radius of curvature.

A filter apparatus has a filter housing (1) accommodating at least one filter element (17) having an inner filter cavity (23) enclosed by a filter medium (27). The housing (1) contains an element bolder (19) that interacts with the filter element (17) located in its functional position. The element holder (19) has a projecting accommodating part (43) with an outer configuration adapted to the shape of an opening (37) located at the end of the filter element (17) to be secured to the element holder (19). The accommodating part (43) fits through the opening (37) of the filter element (17) located in the functional position.