The Cla-Val Model 100-42 Roll Seal valve is a hydraulically operated valve used to control liquid flow by means of a flexible control element: the liner. The basic valve consists of only two parts: a one-piece, investment cast body and an elastomeric liner. The valve body is constructed with internal ribs and slots forming a grillwork that surrounds the liner to provide support. A normally closed type valve is formed by the installed liner which covers the grillwork and seats against the raised seating surface in the valve body.