The air relief valve installed with a drip line or drip tape for sub-surface installations allows air into the drip line or zone when the system it is not operating. It is not required for above the surface installations. The air relief valves can reduce the chance of water hammer damage caused by a sudden reversal of water flow. The air relief valve allows air to escape during system start-up and prevents air restrictions within the system.
In any irrigation system trapped air bubbles can damage pumps (via cavitation) and disrupt the flow rate and pressure in the system. The two main reasons we suggest installing an air relief valve in an irrigation system are:
1.They provide a means of releasing large volume of air from the drip line when the system is turned on and can eliminate any air pockets.
2.They allow air to freely enter the system when it is shut down, ensuring a vacuum does not draw debris into the drip line via the drip emitter outlets. This condition is known as "suck back". Suck back can cause the drip line to collapse or draw in dirt and debris that clog the drip emitters.
To install an air relief valve, ensure you have a 1" FPT tee at the start of your system (such as model P100). The air relief valve then threads into the 1" FPT of the tee. The air relief valve connection is normally located near the pressure regulator assembly as this is often the highest point in the drip system. If your water connection and filter are lower than the irrigated landscape, ensure your air relief valve is suitably located at the highest point. Install one air relief valve for every 40 LPM of water flow used in your system.