# Irrigation pipe sizing.



## uts

Hey everyone,

Il start by saying I have read through the tutorials a while back but it seemed simpler to ask this question here rather than going through everything again.

I will be adding some zones to my existing sprinkler system coming spring. I will be doing most of the work myself. My mainline is PVC and laterals are poly. My flow right now is around 10GPM. My laterals are 0.75" (I think) and riser pipes are 0.5".

I saw a good deal on BlueLock (1" 100ft=$50) and was looking at buying just 1" pipe for the laterals and maybe some 0.75" for the risers because the area will be more open and I will be running i20 with 360 deg rotation so I need the flow.

Does that sound right?

Thanks.


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## burntfire

Sorry I missed this post @uts

Running 360 i20s is really going to depend on the nozzles... you're not going to be able to run many of them with 10 GPM available.

I like to run my laterals in 1" and risers in the inlet size; mostly 1/2".

I would really need to see a layout.


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## uts

burntfire said:


> Sorry I missed this post @uts
> 
> Running 360 i20s is really going to depend on the nozzles... you're not going to be able to run many of them with 10 GPM available.
> 
> I like to run my laterals in 1" and risers in the inlet size; mostly 1/2".
> 
> I would really need to see a layout.


Thank you for this. The area is a big rectangle. The width is about 120' so I plan to run 5 rotors in one zone, with the first and last being 180deg. So only 3 will be 360. I am comfortable with the nozzle chart and the outputs (I think) so my plan was to put a size 1 in the corners, size 2 in th middle and a 3 on the 2 sides. This helps with minimizing wet spots with overlaps sometimes (or a combination of this). So this should keep me with in the GPM.

My question for piping was more to see I wasn't crazy in terms of oversizng and cost as well.

I was planning to put 1" laterals and 0.75"riser pipes to mitigate any resistance issues. The 1" pipe is costing me $50 for 100'.


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## burntfire

uts said:


> burntfire said:
> 
> 
> 
> Sorry I missed this post @uts
> 
> Running 360 i20s is really going to depend on the nozzles... you're not going to be able to run many of them with 10 GPM available.
> 
> I like to run my laterals in 1" and risers in the inlet size; mostly 1/2".
> 
> I would really need to see a layout.
> 
> 
> 
> Thank you for this. The area is a big rectangle. The width is about 120' so I plan to run 5 rotors in one zone, with the first and last being 180deg. So only 3 will be 360. I am comfortable with the nozzle chart and the outputs (I think) so my plan was to put a size 1 in the corners, size 2 in th middle and a 3 on the 2 sides. *This helps with minimizing wet spots with overlaps sometimes (or a combination of this). So this should keep me with in the GPM.*
> 
> My question for piping was more to see I wasn't crazy in terms of oversizng and cost as well.
> 
> I was planning to put 1" laterals and 0.75"riser pipes to mitigate any resistance issues. The 1" pipe is costing me $50 for 100'.
Click to expand...

So this isn't how you design a system. You want overlap as that's the fundamentals of irrigation design. What you're doing is simply getting the turf wet and not actually irrigating it.

At this point I would suggest sending in your layout to Rain Bird or a local designer to come up with a system.

120' area is going to require a LOT more sprays and zones.

Off the top of my head I would suspect at least 10 - 13 rotors and 3 zones.

Side note, don't size systems based off maximum available GPM... you always want a buffer of 10-20%... at least I do.


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## uts

@burntfire I think I didnt explain my setup I guess. Attached is a picture. The blue lines are my existing irrigation.

I'm clearing the trees and will be adding the new zones, red lines. The new area is in orange. Zones are spaced 30ft apart currently and that's what I will continue to do so.


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## bernstem

Irrigating a 120x120 foot space with heads that throw 30 feet would need 25 rotors in 5 rows of 5 heads. 
Irrigating a 90 x120 foot space would need 5 rows of 4 heads = 20 heads total.

Assuming you are 90x120 feet, you are going to be at 5+ zones for the system with 10GPM.


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