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dynamite

New Member

1

Monday, June 18th 2018, 11:00pm

How do I determine if I have enough GPM to add new heads to this zone?

I would like to add a few new heads to a zone in my sprinkler system. I'm not completely sure how to determine if it has the flow rate capacity to add a few more heads. What more do I need to measure and calculate to determine if I can add the extra heads?

Sprinkler Design Paperwork says:
  • 1" Class 200 PVC main lines
  • 1/2" Class 315 PVC lateral lines
  • Zone is designed at 13 GPM

I Observed / Measure
  • Zone has 13 heads which are a combination of 8QFLT, 8HFLT, 15Q, 15H, 15VAN, and HE-VAN-10 nozzles
  • I measured the pressure at the closest (38 PSI) and farthest (37 PSI) heads from the valve with the zone running using a Hunter MP Guage.



So given that, if I understand correctly. I have the current PSI and GPM, and I need to calculate the PSI given additional GPM. What is the formula I would use? Or am I approaching it wrong?

This post has been edited 4 times, last edit by "dynamite" (Jun 18th 2018, 11:19pm)


mrfixit

Moderator

Posts: 2,188

Location: USA

2

Tuesday, June 19th 2018, 12:04am

I don't design sprinkler systems. I only repair them.
I can only make suggestions.
I'd use schedule 40 for all my piping. I even question the 1/2" laterals.

13 gallons per minute seems like a lot to me. So you're going to fill up 2 2/3 five gallon buckets in a minute. Do the test below to see if you have the water.

As far as determining your water flow. Click on this to determine how many heads to use.

What's the static pressure? How many heads do you want to put on one line? And what did you determine on the water flow?
Who designed the system?

dynamite

New Member

3

Tuesday, June 19th 2018, 10:44pm

The system was designed and installed by a local sprinkler company. The 13 GPM of the zone is what is listed on the paperwork for the system.

This afternoon I measured the static pressure at the closest hose faucet at 60 PSI, although the sprinkler system is tapped into the main line before it goes into the house, and it also has a pressure regulator on it so i'm not entirely sure the pressure to the system itself. The flowrate I measured at 10 GPM at the same faucet.


I want to add 2 heads, both rainbird 8QFLT nozzles.

This post has been edited 1 times, last edit by "dynamite" (Jun 19th 2018, 10:52pm)


mrfixit

Moderator

Posts: 2,188

Location: USA

4

Tuesday, June 19th 2018, 11:08pm

I'd go ahead and add the sprinklers. Two 8 foot 1/4's use hardly any water.

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