General advice: do these pipe sizes seem okay?

Discussion in 'Irrigation / Sprinkler Forum' started by CliffK, Dec 26, 2013.

  1. CliffK

    CliffK New Member

    Messages:
    3
    Location:
    CA
    Hi Folks,
    this is my first post, and I am hoping to learn a little in regards to an irrigation system. I want to start to rebuild the badly corroded steel pipes that are on my property. I have a small orchard that that has a 1.5" main pipe coming from the water main, and between the rows of trees there are six 300' parallel lines of 1" steel pipe coming off of the main pipe, and each of the 1" pipe lines has small 1/2" steel risers with little brass sprinkler heads spaced about every 10'. My goal right now is to start replacing the 300' lines with PVC pipe and plastic risers.

    My first question is for pipe size: I was thinking of using 1" Schedule 40 PVC pipe for the 300' lines (six of them), with 1/2" plastic risers spaced about every 10' - 15'. So, it would be the 1.5" main line, feeding into six rows of 1" PVC with 1/2" risers.

    Does this sound like an okay set-up?

    I'm ready to go to the store to get the pipe, just want to make sure the sizes will work okay.

    Thank you!
  2. dj2

    dj2 Member

    Messages:
    437
    Location:
    California
    That sounds OK. Do you have good water pressure?
  3. CliffK

    CliffK New Member

    Messages:
    3
    Location:
    CA
    It's pretty good. Even with the old pipes which are very corroded and restricted.

    Thanks
  4. CliffK

    CliffK New Member

    Messages:
    3
    Location:
    CA
    One more question:

    Assuming that there is good water pressure, it it generally better to use a larger diameter pipe? Is 1.25" or even 1.5" (same size as the pipe coming off of the main water line) better than 1", or is 1" accepted as a good standard size for sprinkler lines? My lines will vary between 100' to 300'.

    Thanks
  5. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,398
    Location:
    Yakima WA
    I'm not an expert on the subject, but 1" seems woefully small for such a long run and with as many sprinklers as you will have. I believe you need more volume than the 1" can supply, and for that long of a run, friction will cut the pressure a bunch. You are in California and I know there are numerous irrigation system installers that can do the math and give you professional advice. There's a lot of work and expense to install what you are doing, you sure don't want to get it done and then find out it's too small. I think your question is far more complex than a short answer can provide.

    If you do go to a professional, take as much data as possible. A scale drawing, water source, # of sprinkler you want to run, size of the nozzles, and anything else that might be of use. Years ago, I had my home system designed professionally for free with the agreement that I would buy all of my supplies from them. As it turned out, their prices were better than the box stores and often the quality of the material was better as well.
    Last edited: Jan 11, 2014
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