Abstract: A filter assembly to remove impurities from a pressurized fluid stream comprises:(a) a longitudinally elongated barrel, first and second end structures at opposite ends of the barrel, said structures including end caps, and elongated tie members spaced about the barrel and removably interconnecting said end caps,(b) the barrel adapted to receive flexible container means containing fluid stream filtering material, and a spring located within the barrel between one of said end structures and said flexible container means to pressurize the latter for expanding same sidewardly against the barrel, and(c) the first end structure containing a fluid inlet and an annular plenum communicating with said inlet, said first end structure having an annular wall extending about a cavity in endwise longitudinal alignment with the barrel interior, said plenum extending about said wall which contains multiple through openings angled to pass pressurized fluid from the plenum to the cavity in sub-flow streams which are caused to