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Monday, May 17th 2010, 3:29pm

Help with low pressure design

Has anyone done a sprinkler design that started with only 45 psi? If so what where the result? Any info would be great

pass1

Active Member

Posts: 34

Location: east coast

2

Monday, May 17th 2010, 8:23pm

45 psi static is going to be tough to work with.
i'll give you some thoughts
1. design around the lowest expected pressure
2. figure pressure losses on your service line size and length, based on your expected flow (gpm)
3. figure losses through your meter, any check valves etc
4. losses through an appropriate backflow device. If a RP assy. is required, forget it.
5. losses through your valves and zone piping to the heads.
6. losses due to elevation
7. add another 10% for misc.


After you add all that together, you'll probably find there is not much left to operate a sprinkler zone. I don't know what your property size is and what you want to water, so these are general pressure losses to take into account on any system. For a diy person as you are, I'd be wary!

HooKooDooKu

Supreme Member

3

Tuesday, May 18th 2010, 2:09pm

The biggest issue might be what sort of backflow preventer is required in your area. If it happens to be RPZ level, that's going to suck another 12-16 psi from your already load pressure.

If not, then I would suggest you look into MP Rotators.
http://www.sprinklerwarehouse.com/Hunter-Rotary-Nozzles-Bodies-s/7572.htm
They are sort of like a rotor that goes in a spray body. They are designed to work on as little as 30psi, with many models designed to work on as little as 25 psi.

Even though I didn't have a pressure problem, I decided to use the MP Rotators to make double darn sure I wouldn't run into flow rate issues. Because I used the rotators, I've got the lawn zones and drip zones on seperate controllers, never have an issue with running both a lawn zone, a drip zone, and use water in the house.

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