How it connects
Slip insertion of a hollow cylindrical molded boss into the center bore / rubber grommet gasket of an open-ended water filter cartridge, compressed axially when the housing bowl is threaded onto the head.
Male and female halves
Male locating boss / spigot protruding upward from the bottom of the housing sump bowl that inserts into the female annular center core / end cap gasket of the cartridge.
Usually connects to
- DOE (double open end) filter cartridge center core (e.g. GE FXHTC, FXHSC, standard 10x4.5 inch 'Big Blue' style sediment/carbon blocks)
Common sizes
- Approx. 27 mm outer diameter boss with 18 mm hollow bore and 16 mm engagement height for nominal 1-inch to 1-1/8-inch ID filter cartridge cores (standard for 10-inch x 4.5-inch 'Big Blue' / high-flow filter formats).
Where it is used
residential plumbingwater filtration systems
Variations
- Molded transparent polycarbonate/SAN bowl center post
- Opaque polypropylene sump post
How to recognise it
An upright hollow cylindrical plastic post molded centrally into the bottom interior of the transparent or opaque water filter canister bowl.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| standard 10x2.5-inch slim housing locating seat | Standard slim filter housings use a smaller post (approx. 20-25 mm) designed for standard 2.5-inch OD cartridges, whereas the high flow FXHTC/FXHSC housing is designed for nominal 4.5-inch OD heavy duty cartridges. |
Also called
cartridge centering seatfilter cartridge locating bossfilter housing bottom postcartridge guide post
Good to know
Internal mechanical alignment seat rather than an external plumbing port; it centers the cartridge to ensure the filter end gasket seals properly against bypass when the housing collar is tightened.
Related connections
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