Abstract: A combined air release and vacuum breaker valve for pipelines has a ball float that acts directly upon both the vacuum breaker and air release valves which are concentric with one another and axially aligned with the ball float. To avoid adverse effects of high velocity flow of water into the float chamber, which tends to initially counteract buoyancy of the ball, a flow disturbing screen is connected to the lower end of the ball. The direct acting ball is connected to the pressure release valve member by means of a resilient lost motion connection, so that slight bouncing of the ball caused by turbulent flow in adjacent areas of the pipeline will not cause the air release valve member to bounce on and off its seat.

Abstract: A radially inner portion of a flat annular elastomeric washer is inserted and retained in a frustoconical annular groove formed in a cylindrical valve seat of an inline disc check valve. The groove is positioned and dimensioned so that it grips the washer and holds it in a radially stretched, axially skewed configuration wherein one of the washer's outer peripheral corner edges forms a leading sealing edge of the valve seat. At low back pressures in the valve, a line seal is formed between the leading washer edge and the valve's closure disc. High back pressures cause the disc to rearwardly deflect the protruding radially outer portion of the washer and engage the valve seat itself. Because the installed washer is both radially stretched and axially skewed, forward flow through the valve does not tend to dislodge the washer, and reverse flow around the washer portion within the groove is prevented.