Dimensional specifications, pressure classes and engineered jointing for specialized infrastructure service.
Air Release, Pressure Reducing & Control Valves
Why irrigation lines need air valves
Air trapped at high points reduces flow and can cause water hammer; an air valve releases it as the line fills. When the line drains, it lets air in so no vacuum forms and the pipe or drip tape does not collapse.
Air valves are usually fitted at high points of the main, after the pump and at the head of each block, on PE pipe with a threaded tee or clamp saddle. An irrigation designer sets their number and size.
Single or combination air valve?
A single-function air valve releases small amounts of trapped air while the line runs. A combination valve also lets out large volumes of air while the line fills and lets air in while it drains, so no vacuum forms.
A combination valve is usually chosen for the start of the line after the pump and for high points on the main. In drip-tape networks, an air valve at the head of each block stops the tapes collapsing when the water is shut off.
Fitting and maintaining an air valve
Fit the air valve vertically on the highest point of the pipe; a valve fitted at an angle or on the side of the pipe will not release air properly. Put a small isolating valve under it so it can be taken off and cleaned without draining the line.
At the start of each irrigation season, check that mud or scale has not jammed the float inside the air valves. An air valve that leaks water is usually fixed by cleaning its seat.
Air Release, Pressure Reducing & Control Valves — Frequently Asked Questions
Where is an air valve fitted?
At high points of the main, after the pump and at the head of each block.
Which sizes are supplied?
From 3/4 to 2 inch.
What does a combination air valve add?
It releases air on filling, admits air on draining and releases air during operation.
Where should air valves go on the line?
On high points of the main, after the pump and at the head of each irrigation block; the irrigation designer sets the exact number and size.
What happens without an air valve?
Trapped air reduces the flow and can cause water hammer, and when the line drains a vacuum can collapse the pipe or the drip tape.
Can't find what you need?
If you require specific sizes, custom fittings or specifications not listed in the catalog, our technical team is ready to assist and review custom requests.