IPS PE 1.25 supply line from well- a few questions.

[raymond c slack]

I have a campground that I'm replacing the main water supply to the RVs with PE pipe.
The PE pipe running from the well to the 2 pressure tanks is 1.25" POLY an then it attaches to copper 1" pipe that goes into the 2 pressure tanks.. Then goes from those 2 tanks back to 1.25" out to the RV sites. I'm going to have a few main line runs off 500-800 ft.
My questions.
1. Is the 1" copper pipe bottlenecking the flow since it's 1.25 before and after the pressure tanks? or do does the size of the pipe really only matter after the pressure tanks?
2. Am I correct in assuming that attaching any larger PE pipe (2" or 1.5") to the 1.25" line coming out of the pressure tanks not really have any increased affect on flow since it's bottlenecked at the 1.25" coming out of the pressure tanks? (Other than maybe a reduction in friction for the longer runs)

Thanks for any input

 

[Reach4]

1. Is the 1" copper pipe bottlenecking the flow since it's 1.25 before and after the pressure tanks? or do does the size of the pipe really only matter after the pressure tanks?

reduction before the pressure tank matters less than after, since the pressure tanks with pressure switch are your regulation.

2. Am I correct in assuming that attaching any larger PE pipe (2" or 1.5") to the 1.25" line coming out of the pressure tanks not really have any increased affect on flow since it's bottlenecked at the 1.25" coming out of the pressure tanks? (Other than maybe a reduction in friction for the longer runs)

No.

"(Other than maybe a reduction in friction for the longer runs)" Pipe size is all about friction/pressure drop, so to eliminate thinking about friction would lead to silly conclusions.

My suspicion is that after doing some calculations you may bump up to 2 inch or 1.5 inch for your mains.

Pipe resistances add, and flow resistance is not primarily determined by the smallest path. Add the sections.
http://irrigation.wsu.edu/Content/Calculators/General/Pipeline-Pressure-Loss.php is a fairly simple friction loss calculator.
http://www.pressure-drop.com/Online-Calculator/ is more complex. It can model elbows and changes in size and more. With the simpler one, I would just increase the distances entered by maybe 15% to account for elbows, etc.

What do you know about your pump and depth to water?

 

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[John Gayewski]

Once you get to 1.25" the friction loss compared to 1.5" and 2" won't be all that much. It's primarily the load (gpm) or available volume that could be helped by using bigger pipe.

1" copper and 1.25" poly are close in size you aren't losing a lot with the run of copper. ( edit : strike this I realized you have ips poly)


I would use the sizing guidelines in the upc code book based on what you have in place. Meaning from your start point (meter) find out your pressure, length of run, and fixture unit load. Also and relevant elevation changes.