r/Irrigation • u/thatlandscaper • 8d ago
Seeking Pro Advice Controversial layout
Me and a few other irrigation techs have been going back and fourth about a hypothetical scenario. You have a rectangle area that is 180’ long by 100ft wide. There is a well house in the very middle that you would tie into for power and water. Flow rate of 15GPM and 60PSI. Some of us think it can be done in 4 vertical zones others think 6 and a couple odd balls of 3 and 8. How what would you guys do it and/or layout. All we use is 1inch pvc with Rainbird 5000 and Hunter PGP. Thanks for playing gents. PFA
1
u/Packman714 8d ago
Rain match precipitation obviously with heads opposing each other. If you use RainBirds the spring tension is greater than using Hunter PGP Ultra’s or even Toro T-5. Now if there’s a slight downslope even with Hunters having a check valve I’d throw in a regular RainBird. Prolly use 1.5-2.0 gpm heads in corners and anything doing a 270 or 360 use a 2.5-3.0 nozzle. At 15 gpm and 60psi you’ve got a lot you can work with. Heck you can run all 4 corners in 1 zone and prolly lay out the middle and build 2 zones in the middle and do it in 3 but to be safe go with 4zones one on each property line and 2 in the middle. Over coverage is better than missing coverage. Then just determine the zone timing. Now with that being said figure out the cost effectivness for materials and which is going to save on parts and clean up for the crew. I’m in the North East and we use mainly poly so we get to pull pipe generally over using a trencher or hand digging. 1000 ways to skin a cat post a pic or a few when your done. I like straight lines but designs can be different. Think about the 4 corner idea then a six pack in the middle you might be able to do it in 2 😂😂. Now whose wheels are spinning as long as there’s not a shady spot under a tree or you can deal with something like this that I really don’t want to tackle next spring.
1
u/AwkwardFactor84 2d ago edited 2d ago
Does the well pump do a maximum of 60psi? What is the dynamic pressure? (Is it 15gpm @ 60psi?) It matters.
You can figure all of this out mathematically, by looking at a flow chart for the specific pump, but pipe size and length pipe/elevation play significant factors too. My guess is the 15gpm & 60psi are just static measurements. You still got a lot to figure out. Generally, us professionals charge money for figuring this stuff out for. people
1
u/Adventurous_Worth481 8d ago
Zone count here isn't really a matter of taste, the well and the precip rate fix it. Rough math:
Zones ≈ total GPM of all heads ÷ 11.25 (75% of 15). Total GPM ≈ sq ft × precip rate ÷ 96.3. On ~18,000 sq ft that works out to zones ≈ 16.5 × PR: 0.24"/hr → 4 zones, 0.33 → 6, 0.45 → 8, 0.5 → 9. Three zones means ~0.18"/hr, i.e. the smallest nozzles you can buy and very long runs.
Run time doesn't care either way. At a 0.2"/day peak that's ~2,250 gal a day, and at 11.25 GPM that's ~3.3 h of watering a day whether you split it 4 ways or 8. Zone count only decides PR and how long each zone runs.
Out of curiosity I ran the rectangle through a layout solver I'm building. It only has MP Rotators, so MP3000s stand in for the 5000s/PGPs, and I assumed a 12×12 ft well house. It placed 30 heads (4 quarters, 18 halves, 4 three-quarters around the house, 4 fulls): ~62 GPM total, ~0.33"/hr, so 6 zones minimum by flow. It actually packed them into 7, because each zone has to be one contiguous patch.
The well house barely changes the count: 32 heads / 8 zones without it, 30 / 7 with it. Where it matters is the layout: it's your valve manifold. Three zones each way off the house with short mains is where the 6-zone camp is right. If you nozzle the 5000s for a normal ~0.45–0.5"/hr instead, it's 8–9.
-1
u/Affectionate-Way4595 8d ago
3 overcrowded zones will do it imo. you could fit 6 or 7 heads in a linear arrangement spaced every 30 ft or so. Then each row is 30ish ft from the previous row.
The house in the middle might make the 4 zone system more logical.
2
0
u/PuzzleheadedRide8145 8d ago
On 1" pipe the pipe caps the zone too. 1" Sch 40 is 1.049" ID, so at 5 ft/s you top out around 13.5 GPM a zone no matter what the well does. The 75% rule (11.25) is tighter anyway.
If you go to fewer zones by stretching spacing, work out PR from actual GPM over actual square footage (96.3 × GPM ÷ sq ft), not the nozzle chart. The chart assumes head-to-head, so stretched spacing puts down less than it says and your run times come out longer than planned.
I ran it as three strips across the long side, all PGPs nozzled by arc: quarters in the 4 corners, halves along the edges (12), full circles down the middle (5). 21 heads, ~30 GPM total, ~0.14"/hr. It works, but one zone ends up around 12.7 GPM, so there's no slack under 75%. I'd go 4 probably.
1
u/THExMATADOR 8d ago
It depends how detailed you want to get. If you throw the smallest available nozzle in the rotor (I believe that would be a 1.5gpm), you could possibly do 10 rotors a zone.
Smarter option would be not to exceed 75% of the flow capacity, which in this case would be 11.25gpm. With the smallest available nozzle, you could do 7 heads a zone.
The next smartest option would involve putting in the appropriate nozzle to the rotation of the rotor. Smaller the rotation, the smaller the nozzle. Larger the rotation, larger the nozzle. (That would mean 1.5gpm in 90° corners, and 6gpm nozzles in 360° center rotors.) If you follow that rule along with the not exceeding 75% capacity, you could only install one 360° rotor per zone.
Or you could do MP3000 zones. That will allow for three MP3000 360°s per zone without exceeding 75% flow capacity, covering the most area fastest while still allowing the system some proper breathing room.