Air Release / Vacuum Relief Valves provide vital protection to pipeline systems. They allow air to escape during system startup by preventing air restrictions, water hammer caused by large air masses, inaccurate flow meter readings, and explosive conditions from air being compressed by water. 

They also allow air to enter the pipeline during valve closure or system shutdown. This minimizes the collapse of mainline and submain pipes, back siphonage of dirt into emitters, and water hammer caused by sudden reversal of flows.