You are not logged in.

Dear visitor, welcome to SPRINKLER TALK FORUM - You Got Questions, We've Got Answers. If this is your first visit here, please read the Help. It explains how this page works. You must be registered before you can use all the page's features. Please use the registration form, to register here or read more information about the registration process. If you are already registered, please login here.

jsbeckton

Active Member

Posts: 27

Location: Pittsburgh

1

Wednesday, December 2nd 2015, 6:16am

Help with Rainbird Design

I submitted my property information and just received my design from Rainbird. I have about 23GPM at the mainline at about 100 psi which they are recommending that I add an inline pressure reducing valve right after the POC to drop the pressure down to 40 psi but then they show all of the sprinklers using 45psi, some of them 150ft+ downstream of the POC. Will the far end sprinklers really see the correct pressure?

Another thing that troubles me is that it seems like I should have more zones than I do so I added up the sprinklers on each zone along with their spray patterns and found that my 4 sprinkler zones have 5, 18.5, 12.3 and 15.7 GPM demands. Given that my service line is 3/4" copper and my meter is 5/8" I thought this was way too high? This will give me up to 12.3 feet/sec through the service line?

I am going to try to give them a call later this week but wanted to see if I could get any feedback here in the meantime.

Wet_Boots

Supreme Member

Posts: 5,255

Location: Metro NYC

2

Wednesday, December 2nd 2015, 7:56am

Did you give them the info about the meter and supply line sizes? If you tried to employ 23 gpm of flow, you would be setting yourself up for some significant water hammer.

jsbeckton

Active Member

Posts: 27

Location: Pittsburgh

3

Wednesday, December 2nd 2015, 8:14am

Yes, that is part of the input information that they request on the form. I was expecting to be held to about a 10 GPM max per zone so I was shocked to see nearly double that.

Wet_Boots

Supreme Member

Posts: 5,255

Location: Metro NYC

4

Wednesday, December 2nd 2015, 1:18pm

Well, I don't get it. I'd stick with 10 gpm, or maybe even less. And still, your best option is to first do your supply plumbing with a PRV in it, all as close as you can get to the water meter, and then to run some bucket tests, and see the actual numbers you can rely on.

jsbeckton

Active Member

Posts: 27

Location: Pittsburgh

5

Wednesday, December 2nd 2015, 2:01pm

Yeah, I have the POC done expanded to 1" copper and run outside to a 1" PVB before going 18" underground to a PVC transition (stopped there). What PRV should I use? They suggested at 40 psi max but that seems so restrictive given they are showing all of my heads running 45psi. Is there any way to control the pressure to each zone with the zone valves or do I need a separate PRV on each zone?

Wet_Boots

Supreme Member

Posts: 5,255

Location: Metro NYC

6

Wednesday, December 2nd 2015, 3:52pm

I wouldn't worry about precise regulation. This would be more about water-hammer control. Indeed, if you skipped worrying about water hammer, you could just go with flow-control valves on every zone.

jsbeckton

Active Member

Posts: 27

Location: Pittsburgh

7

Wednesday, December 2nd 2015, 6:04pm

So would I be ok using the one 40psi PRV that they suggested upstream of all valves? Should I still make sure the valves that I get have flow control?

Wet_Boots

Supreme Member

Posts: 5,255

Location: Metro NYC

8

Thursday, December 3rd 2015, 10:40am

Yes to flow-control valves, and avoid potentially fast-closing models like the Rainbird DV series.

No to a 40 psi regulator. Best is still a standard brass PRV installed as physically close as possible to the water meter. Water hammer is a function of pipe length, and you want the shortest possible length between water meter and PRV. Your PRV pressure setting will probably start at 50 psi and adjust up from there (this is something you can figure out during repeated bucket tests, at different PRV pressure settings)

Similar threads

Rate this thread