Abstract: A filtration apparatus for use in polymer processing includes a housing having an internal bore for directing polymer flow and a channel oriented transversely to the bore. A slide plate for supporting filters is movable through the channel and across the bore. An annular upstream seal ring sealably contacts the slide plate. A surface of the upstream seal ring facing the upstream direction is angled with respect to the bore. A plurality of ring segments are arranged to form an annular segmented ring. The segmented ring presents a tapered ring surface that is generally complimentarily angled relative to the angled surface of the upstream seal ring. Pressurized polymer flowing through the bore imparts radially forces on the ring segments, causing the ring segments to impart axial forces on the upstream seal ring to enhance the seal interface between the upstream seal ring and the slide plate.