A filter assembly including a filter screen (27) comprising a band (27′) of porous material extending between two axially aligned opposing ends (38, 38′) and defining a cylindrical periphery (29), wherein the ends (38, 38′) are each secured to a dynamic tensioning mechanism (46) that permits the ends (38, 38′) to move bi-directionally relative to one another about the periphery (29) of the filter screen (27).