500 foot mainline

Discussion in 'Homeowner Assistance Forum' started by DarrylT, Mar 20, 2018.

  1. DarrylT

    DarrylT LawnSite Member
    Messages: 2

    I have decided to do the project with my son, about 1acre of lawn and 50 fruit trees to water. Its a large rectangle like a football field but slightly sloped. We haven't researched this part yet but should be working with 65 or 75 psi and 15 gpm and coming off a 5/8 copper pipe. Thats what a landscaper told me is normal but i will get it checked.

    Now the issue is the water box is 450 feet away, is there going to be issue running a main that long and can i get bigger pipe to run off the 5/8 copper. Is there anything i can do to nake sure there is enough pressure travelling the long distance
  2. BrendonTW

    BrendonTW LawnSite Bronze Member
    Male, from Oklahoma City
    Messages: 1,011

    Size up your main line to reduce friction loss over a distance. Are you familiar with friction loss charts?

    Do a quick google “friction loss charts for schedule 40 PVC” or whatever you’re using, and it will tell you how many PSI you will lose per 100 foot run at your given GPM for various sizes of pipe.
    DarrylT likes this.
  3. stebs

    stebs LawnSite Senior Member
    Messages: 553

    You sure about that 5/8" pipe? That's an oddball size. 1/2" copper has an approximate outside diameter of 5/8" inch, and if you actually have 1/2" copper, I'd venture to guess that 15gpm is a bit extreme.
    Mdirrigation, DarrylT and 1idejim like this.
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 52,353

    Confirm your water supply first, in the form of combined flow and pressure, like 8 gpm at 55 psi, for instance. You will first be choosing your desired operating pressure, and then measuring the flow at that desired pressure. Then move on to the friction loss charts.
    DarrylT likes this.
  5. DarrylT

    DarrylT LawnSite Member
    Messages: 2

    I looked at the pressure loss charts and looks like i could lose about a third of my pressure. How do i get the flow and psi without tapping into the water line? If i end up with 6gpm and 45psi or something im going to be looking at something like 4 low flow rotors or 2 larger ones per station?
    I found a post here and ran two 5 gallon buckets off 2 spigots and both filled in less than a minute so i dont think the 5/8 supply line is correct.
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 52,353

    If you are going to do this project, you are going to have to make a connection for the supply. That means you might just as well make that connection, then proceed to flow-and-pressure testing on your actual supply plumbing, as opposed to filling buckets and making guesses.

    Understand that pressure loss in a long supply line can be almost zeroed out by oversizing the pipe diameter. Costs money, but it isn't impossible.

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