Design/gpm Help!!

Discussion in 'Irrigation' started by offshore1234, Jul 11, 2008.

  1. offshore1234

    offshore1234 LawnSite Member
    Posts: 17

    I am starting a homeowner system and need some help getting started. I was told to cut into the 1 inch copper line just ahead of my 3/4 meter. I put a "T" in the line. From that I ran a psi gauge and down from that a stop valve. Then another right angle down to drain into a 5 gal bucket. I ran 3 tests. The static pressure is 56 psi. I tested the flow at 50 psi = 12.5 gpm, 45 psi = 16.5 gpm, and 40 psi = 21.4 gpm. QUESTIONS: First was I correct to do this, if so, now what do I do. Which of these numbers do I use to configure the system. I was going to run the system main with 1 inch copper and the laterals with 3/4 poly. Is that correct? What should I use? I read that the gpm should be around 18. I have glanced at the irrigation tutorial and it is alittle confusing. Any advice to get me in the right direction would be greatly appreciated.

    I tried to attach a drawing of what I did.
     

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  2. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,308

    Have you considered hiring soimeone for this?
     
  3. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,909

    I thought she was busy with with the SHESHOVEL project.
     
  4. offshore1234

    offshore1234 LawnSite Member
    Posts: 17

    Yes I have considered it, however I would like to try this on my own. Thanks for the comments, however any comments that might help out would be greatly appreciated. Thanks in advance.
     
  5. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,909

    You might understand that the guys that really know their stuff are in the
    middle of the season & don't have time to spit. The only comments you're
    going to get are from we hacks.
     
  6. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    I'm assuming you got the lowest PSI (40 psi) with the stop valve wide open, so I'd design the system around 14 GPM, because you will have friction loss from the pipe runs. You want to keep your running pressure above 40 psi if at all possible.
     
  7. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,909

    Hack.........
     
  8. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    Don't make me hop on the ferry and kick your old ass :)

    Want to quantify your response to my answer?
     
  9. offshore1234

    offshore1234 LawnSite Member
    Posts: 17

    At 40 psi the stop valve was not fully open.
     
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,363

    How many acres are you watering?

    By the way, "just ahead of" means "upstream of" ~ if you bypass the water meter, things could get ugly.
     

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