Keyed system for connection of filter cartridge to filter holder

A keyed system for a filtration unit, the keyed system comprising:

• a filter and a cooperating holder, wherein the filter holder has a tubular outer surface having a radially-outward-extending key protrusion and the cooperating filter has a tubular inner surface having a radially-inwardly-extending lock recess adapted to receive the key protrusion of the cooperating holder, so that the filter is insertable into the holder because the key protrusion of the holder slides into the lock recess of the filter;
• wherein the locations of the key protrusion and the lock recess on said tubular outer and inner surfaces are selectively locateable to different circumferential locations on said tubular outer and inner surfaces to prevent said filter from being installed in any but its cooperating filter holder.

In a filtration assembly including the subassembly of a keyed filter and the subassembly of a cooperating holder, wherein the cooperating holder has a holder surface with a circumferential perimeter having a first cooperating recess structure having a plurality of axial portions separated by radially-protruding ridges, and the cooperating recess structure further having one circumferentially-extending lock portion having an open end near, and in mechanical communication with, said axial portions and having a closed opposite end;

• the filter subassembly comprising:
• a filter surface with a perimeter having a first set of a plurality of key protrusions, wherein said key protrusions slide through the axial portions during axial insertion of the filter into the holder and, upon angular rotation of the filter in the holder, said first set of a plurality of key protrusions are received in the one circumferentially-extending lock portion.