An apparatus such as a multiple orifice valve (MOV) for controlling a flow of pressurized fluid. A housing directs the flow from an inlet to an outlet and supports an interior stationary surface. A moveable surface selectively impedes the flow and is disposed in facing relation to the stationary surface to form a leakage path therebetween. A sealing member is disposed in a medial portion of the leakage path so that a leakage portion of the flow passing along said path compresses the sealing member against a shoulder portion of one of the surfaces to urge the sealing member across the path and form a mass seal. Preferably, the leakage path comprises a first portion in a first direction and a second portion in a different, second longitudinal direction, and the sealing member is compressed against the shoulder portion adjacent a junction between said first and second portions.