To avoid general equipment failure, pipe rupture or pipe blockage, A/V relief valves are used to expel air that builds up in the pipeline network during startup and operation. A/V relief valves are also used to allow air to enter the pipeline network as water exits at shutdown. This avoids undesirable vacuum suction in both the pipelines and the emission devices. A/V relief valves are typically installed at high elevation points, at control points, and at periodic pipeline intervals.