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Starting Member


Wednesday, November 1st 2017, 3:04pm

Variable Water pressure

I have 3 zones of sprinklers for a moderate size California backyard. As I turn the first zone on, the pressure is low and the automatic valve sounds like there is air in the line. After 2-3 minutes, the pressure increases and the sound stops. Same thing with zone 2 but not with zone 3. I have normal 50psi pressure. I have 3 year old Rain Bird automatic valves, 1/2" pvc throughout with approximately 5-7 heads per zone. Any suggestions????


New Member


Tuesday, December 26th 2017, 5:35pm

Sounds like your system's pipe sizing could be part of the problem. The pipe size addressed is most likely undersized if the sprinklers addressed have flows in excess of 1 GPM. Small pipe such as 1/2" will able to manage only flows up to 5 GPM as long as the pipe sections from sprinkler to sprinkler are not long. Friction losses in small diameter piping build up very quickly.
If the sprinklers' nozzles are large coverage diameter such as 12' to 17' radius, you could replace them w/ multi-stream rotating nozzles such as MP Rotators. The flow will be reduced significantly; this will help to get the operating pressure up to a level that is within the manufacturer's recommended operating pressure range. The only thing is that due to the change in flow volume and application rate reduction your zones will have to operate for longer periods of time. Good luck.

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