# are valves operable



## bbqbrisket (Oct 27, 2019)

If the water supply is shut off, will valves electronically open with Rainbird zone is activated and release water in the line from the shutoff?


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## Prospect (Mar 19, 2019)

bbqbrisket said:


> If the water supply is shut off, will valves electronically open with Rainbird zone is activated and release water in the line from the shutoff?


The Water supply is shut off. No water can flow. The valves will open and some water may in theory move in the lines if any resides after the shutoff and before the valve, but it will not be under any pressure (gravity).


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## hsvtoolfool (Jul 23, 2018)

Yes and no. Irrigation valves cannot open without water pressure. Valves actually use the water pressure to open the valve. The electrical solenoid only opens a small orifice which allows water to flow behind the main diaphragm. Eventually, the water pressure behind the diaphragm exceeds the main spring pressure and the valve fully opens.

If you're blowing out your lines, the air pressure will also open the valves the same way as water. If there's neither water nor air pressure behind the valve, then the valve won't open. But that's kind of a "if a tree falls in the forest" question. Why do we care about the valve if there's no air or water pressure?


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## Prospect (Mar 19, 2019)

hsvtoolfool said:


> Yes and no. Irrigation valves cannot open without water pressure. Valves actually use the water pressure to open the valve. The electrical solenoid only opens a small orifice which allows water to flow behind the main diaphragm. Eventually, the water pressure behind the diaphragm exceeds the main spring pressure and the valve fully opens.
> 
> If you're blowing out your lines, the air pressure will also open the valves the same way as water. If there's neither water nor air pressure behind the valve, then the valve won't open. But that's kind of a "if a tree falls in the forest" question. Why do we care about the valve if there's no air or water pressure?


I stand corrected. That does make perfect sense knowing what the inside of the valve looks like. That you would need some sort of pressure to "open" the diaphragm. I don't mind being wrong but I hate it when I give wrong information.


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