Abstract: A flap valve comprising an annular frame (10) defining an opening (11) through which liquid may flow in one direction, a closure flap (14) for said opening connected to the frame (10) by a hinge member (15), and a valve seat (12) against which the closure flap (14) may close to prevent reverse flow of liquid through the opening. The frame (10) may be bolted (at 18) to a wall or pipe flange, with integral sealing ribs (24, 25) on the rear face of the frame avoiding the need for a separate gasket. The entire assembly comprising frame, closure flap, hinge, valve seat and sealing ribs, is integrally moulded from a plastics material and is reinforced where appropriate by embedded steel plates (19, 20 and 21).

Abstract: A valve such as penstock with a gate (13) which slides across an opening in a frame (10, 11, 12). On at least one side of the gate (13) is a two-part sealing strip consisting of resilient layer (22) and a superimposed bearing portion (23). Attached to or integral with bearing portion (23) is a thickened part (24) which limits the maximum compression of the resilient layer (22) when the valve is closed.