Drip Tip:  When and Where To Use Air Relief Valves

The use of air relief valves for some dripline applications is essential to keep the entire system running efficiently and minimize maintenance costs for your customer. However, when you use Rain Bird® XFS-CV dripline you can eliminate the air relief valves and the necessary valve box required to install these devices.

Air Relief Valves – What’s the Benefit?

First, at the start of the watering cycle the air relief valve releases air from the dripline zone eliminating air pockets, which speeds up the fill time and increases watering uniformity across the zone. Secondly, air relief valves in subsurface dripline installations allow air into the zone at the end of the watering cycle which ensures that a low-head drainage vacuum (back-siphoning) doesn’t draw debris into the dripline through the emitters.  

Finally, the air relief valve minimizes water hammer at the start of the watering cycle allowing air to release. The effects of water hammer in dripline applications are less destructive than in spray or rotor systems however, water hammer can still cause pipes to wiggle and work their way to the surface.

How Many Air Relief Valves Are Needed

One air relief valve per irrigation valve may be enough, but in some cases system efficiency can be improved when multiple air relief valves per irrigation valve are utilized. Air relief is needed most at the highest point of the drip system layout. The air relief valve should be placed in an exhaust header or a line that runs perpendicular to the lateral rows at the furthest distance possible from the water source to ensure all rows of the dripline can take advantage of the air relief valve.

How to eliminate the need for Air Relief Valves?

Rain Bird’s new XFS-CV dripline with heavy-duty check valve can handle elevation changes up to ten feet, holding back water in the dripline preventing low point drainage. XFS-CV’s true emitter check valve maximizes water savings and ensures no air is drawn back into the dripline. What does this mean relative to air relief valves? When the dripline zone stays charged with water, there is no need to displace the air. Therefore, the installation of air relief valves and the associated valve boxes is eliminated by using XFS-CV dripline. The result is an easier, lower cost installation with fewer valves boxes to degrade the appearance of the finished landscape.