End Cap (DOE / SOE)
Definition
The molded or welded cap that seals each end of a filter element and defines how it interfaces with the housing.
DOE (Double Open End) elements are open at both ends and sealed by compression between housing plates. SOE (Single Open End) elements have one open end with an O-ring interface (e.g. code 226) and a closed opposite end.
End-cap geometry must match the housing exactly — fin, bayonet, spring seat and O-ring positions all determine fit and prevent unfiltered bypass.
Relevance for high-flow filtration
R+F replicates the exact OEM end-cap type (DOE or SOE with the correct code) for a leak-free drop-in replacement.
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Related terms
A common cartridge end-cap connection using dual 226-code O-rings with a locating fin or bayonet, sealing the element into the housing tube sheet.
Outside-to-Inside FlowA flow configuration in which liquid enters the outer surface of the element and exits through the core, using the full pleat area for filtration.
6-Inch Filter HousingThe predominant high-flow housing standard, accepting elements of roughly 6.0" (152 mm) outer diameter across most major OEM platforms.
Verified FitAn R+F designation confirming that a replacement element has been matched to the OEM part on dimensions, media, and end-cap/seal interface.
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