Filter cartridge system

A filter cartridge system comprising:

• a filter housing including
• an inlet connection for receiving unfiltered air;
• an outlet connection for filter air arranged in a first end wall of said filter housing;
• a second opposing end wall of said filter housing including
• an anti-rotation opening provided in a central portion of said end wall and extending from an interior of said filter housing to an exterior of said filter housing;
• a plurality of inwardly extending end wall projections arranged on an inner surface of said end wall encircling said anti-rotation opening;
• an annular inwardly extending annular sealing projection;
• a substantially cylindrical main filter cartridge arranged within said filter housing between said inlet connection and said outlet connection, wherein said main filter cartridge includes
• a substantially rigid support tube having an axially extending sidewall with airflow apertures therethrough, said sidewall defining an axially aligned open interior therein;
• a filter media arranged on, surrounding and secured onto said outside surface of said support tube;
• an annular end cap having an open aperture in air flow communication with said open interior, said end cap secured to a first axial end of said support tube sidewall and/or said filter media;
• a closed end cap secured to an opposing second axial end of said support tube sidewall, said closed end cap including
• a centrally arranged axially outwardly extending dome member arranged in said closed end cap;
• an anti-rotation engagement housing member arranged on an outward facing surface of said dome member and extending axially outwardly and received into said anti-rotation opening of said filter housing, said anti-rotation engagement member having a radially elongated or polygonal radial cross-section configured to be received into and rotationally lock to said anti-rotation opening, said rotational lock operative to lock rotational alignment of said first filter cartridge to said filter housing end face;
• a plurality of arcuate axially extending projections on an outward facing surface of said closed end cap encircling said dome member with circumferential gaps between said projections, said arcuate axially extending projections received into gaps between said inwardly extending end wall projections of said filter housing, said arcuate projections together with said inwardly extending end wall projections each having pre-defined keying characteristics including
• a pre-defined and arc length, wherein different ones of said projections can have different arc lengths;
• a pre-defined projection length, wherein different ones of said projections can have different projection lengths;
• a pre-defined projection width, wherein different ones of said projections can have different projection widths;
• a pre-defined gap spacing between adjacent projections, wherein different pairs of said projections can have different gap spacings;
• a pre-defined number of said arcuate projections on said closed end cap;
• wherein said pre-defined characteristics key particular intended type of said main filter cartridge for use in said filter housing where said filter cartridge type is intended,
• wherein said pre-defined characteristics are operable to prevent accidental use of a non-intended type of said filter cartridge;
• a continuous annular seal arranged radially between said plurality of arcuate axially extending elastomeric projections and said dome member and projected axially outwardly from said outward facing surface of said second end cap layer, said annular seal forming a radial seal sealing against an outward facing surface of said annular sealing projection of said second end wall of said housing.