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aerodan1

Active Member

1

Sunday, August 30th 2015, 1:19am

Sprinkler head layout

[img]https://www.dropbox.com/s/hxs2vbclin6chu1/Head%20layout.pdf?dl=0[/img]

Please see attached for the Rainbird Design for sprinkler head layout for my house. I numbered the zones on page 2 for reference. I also made a few edits in PDF to block off areas or move boundaries for where the lawn will actually be (denoted by red lines). Right now I'd like to focus on zones 1 and 2, which is the front left yard (you can ignore the strip sprays, it will just be rotors or rotators). I have 10 - 11 gpm to work with, about 40 psi as well. I have two areas of concern with the zone layout provided:

- On the far left side of zone 1, there is not head to head spacing between the 90 degree sprinklers in the bottom left and upper left. Perhaps a half circle sprinkler in between would be good?
- There is a tree in the middle of zone 2, indicated by the circle in the middle of the lawn. Moving the sprinkler head nearest the tree either right or left kind of screws things up, not sure how best to approach this.

I was thinking either Rainbird 3500, Hunter PGP or MP Rotators would work best for these two zones. I've played around with some calculations, even mixed PGPs with 3500s on zone 2 to get a decent matched precip. rate. Overall, MP rotators are on low end of GPM, so wind distortion is a concern and less margin for error with the spacing. 3500s would be on the high end of available GPM and higher precip. rates, PGPs also on low end of water usage. I just wanted to get the ball rolling on finalizing the design. I mixed 3500s and PGPs on zone two in my initial design but I'm not sure it's a good idea to do so. Any thoughts are welcome, thanks

Wet_Boots

Supreme Member

Posts: 5,288

Location: Metro NYC

2

Sunday, August 30th 2015, 8:18am

Trade in the 3500 heads for 5000 series, would be my first thought. Better nozzle selection, especially low-trajectory-angle sprays, for windy conditions. Don't worry about that supposed gap you see, and for which you want to add a sprinkler. There is enough overlap, and you could always upsize one or more of the corner nozzles, if you wanted heavier coverage there. The zone with the big tree is more complicated. I will assume you don't want to try to dig anywhere close to it. That would have you adding one more head, and spacing them so that the tree is about ten feet away from any of the heads nearest to it.

aerodan1

Active Member

3

Sunday, August 30th 2015, 9:57pm

Thank you for the follow up. Regarding zone 1, does it sound like I'm calculating the precip. rates correctly?

- 1.5 LA nozzle @ 40 psi has a radius of about 30 ft. per the spec. sheet. If I want it at 25 ft., I divide 25 squared by 30 squared, giving me 0.65. Then divide 1 by 0.65 and multiply by the spec'd precip. rate of 0.31 inch/hour to arrive at 0.48 in/hr, then of course multiply by 2 since it's a corner sprinkler to end up at 0.95 in/hour.

Regarding zone 2, not sure I'm understanding - I modified and attached a new layout, having deleted out two heads and adding two heads. I don't want overspray onto the driveway or house/flower beds, so this makes it a little tougher also. Thanks [img]https://www.dropbox.com/s/hxs2vbclin6chu1/Head%20layout.pdf?dl=0[/img]

Trade in the 3500 heads for 5000 series, would be my first thought. Better nozzle selection, especially low-trajectory-angle sprays, for windy conditions. Don't worry about that supposed gap you see, and for which you want to add a sprinkler. There is enough overlap, and you could always upsize one or more of the corner nozzles, if you wanted heavier coverage there. The zone with the big tree is more complicated. I will assume you don't want to try to dig anywhere close to it. That would have you adding one more head, and spacing them so that the tree is about ten feet away from any of the heads nearest to it.

Wet_Boots

Supreme Member

Posts: 5,288

Location: Metro NYC

4

Monday, August 31st 2015, 9:43am

That wasn't quite what I was getting at, but rather than kick around guesses, why not explain why you don't want to work near this tree.

As for the other corner, it probably isn't impressing on you that there is an 'extra' head spraying into the area you think will be too dry. Note that two rotor heads are less than ten feet from each other, and they duplicate some of their coverage.

aerodan1

Active Member

5

Monday, August 31st 2015, 5:27pm

Thanks for the follow up once again. I don't have a preference for putting sprinklers around / away from the tree but the design called for one right in front of it, so most of the spray would be just hitting the bark - not good for the tree or the lawn, I also thought you mentioned avoiding the tree and staying 10 feet on both sides. I have seen design workarounds for shrubs / trees by putting heads in a triangle essentially around the tree, but not sure if it's practical or necessary in this case. It's the only real obstacle in the middle of any of my lawn and given it's right in front of the house by the road I wanted to make sure I get it right.

I get the other corner has the coverage from the two half-circles in zone 1, it was really just along the edge of the border in the middle I thought may be a weak spot since the half-circles don't reach there and there isn't head to head spacing with the corner sprinklers, but a 6th sprinkler in that zone may be unnecessary...I could always add a head later if it looks terrible and playing with different nozzles doesn't work.

That wasn't quite what I was getting at, but rather than kick around guesses, why not explain why you don't want to work near this tree.

As for the other corner, it probably isn't impressing on you that there is an 'extra' head spraying into the area you think will be too dry. Note that two rotor heads are less than ten feet from each other, and they duplicate some of their coverage.

Wet_Boots

Supreme Member

Posts: 5,288

Location: Metro NYC

6

Monday, August 31st 2015, 8:15pm

Don't worry about the tree and a sprinkler head near it. You will not have enough pressure to harm a tree, and you can always diffuse the spray with the radius adjusting screw.

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