PURPOSE: To efficiently seal a disposable cartridge and to secure the cartridge to a base member so as to be reliably and efficiently replaced.

CONSTITUTION: A fuel filter assembly 10 has a spring-loaded collar 16 which retains the disposable cartridge 14 to the base member 12. The collar carries a wave spring 80 and incorporates followers 82, 84 which are shifted along a spiral ramp of the base member for retaining the cartridge to the base member in a positive fixed position. The fuel filter assembly also has an efficient bleed orifice 34 and a pair of mutually axial spaced seal rings 42, 44 for implementing a fluid seal with the cartridge.