Master Valve Installation
Zone valves are the individual valves that operate a group of sprinklers or drip emitters. A typical irrigation system has several zone valves. Typically one zone valve is turned on at a time, and controls the irrigation in a specific area of the yard.
Whenever one of the irrigation zone valves is told to open by the controller, the controller also signals the master valve to open. So the master valve is a little like a back up valve, or a fail-safe valve.
The purpose of the master valve is to shut off the water to the irrigation system when none of the zone valves are operating.