An example embodiment of a filter for a butterfly valve includes an inlet side having an axial inlet port and the first diameter Din, a closed outer side having a second diameter D2, and a filter body disposed between the inlet side and the outer side. The filter body has a filter diameter Dfilter larger than both Din and D2, and includes a cylindrical wall retaining a pleated filter media. A plurality of perforations is formed through a main bore wall to serve as at least one exit for the filter.