Design Problems

Discussion in 'Irrigation / Sprinkler Forum' started by ivseenbetter, Mar 27, 2007.

  1. ivseenbetter

    ivseenbetter New Member

    Messages:
    2
    I have been trying to figure out what to do in order to design my home sprinkler system. Basically, I am stuck on figuring out GPM. I did the bucket test coming from the spicket on the side of the house and the best I came up with is 5.5 GPM with 70 PSI. But when I called the water company to come out and test my flow because I thought that was way too low they told me that I have a flow of 25 GPM up to the meter after they tested it themselves. If I was to tap the waterline right after the meter for my irrigation system, would I basically be getting 25 GPM or does the meter slow down my flow to 5.5 GPM somehow?

    Any info is helpful. Thanks.

    Chris
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Testing at the hose bibb..likely fed on a 1/2" line a long way from the meter, gave you the expected results. By the way, 70 PSI was the static pressure, but I suspect the dynamic pressure was substantially lower. This would NOT be a good place to tap off for the sprinkler.

    If you tap near the meter, and ran 1 1/4" pipe from there to the manifold, you could get your 25 GPM with very little pressure loss and an acceptible water velocity of around 5 FPS.

    By the way, at any supply store or even the depots, you can by a testing manifold rig which measures GPM and dynamic PSI. This could give you definitive results before you finalize your design. http://www.toro.com/sprinklers/irrmisc/pressuregauges/53351.html
    Last edited: Mar 28, 2007
  3. ivseenbetter

    ivseenbetter New Member

    Messages:
    2
    Thanks Jimbo. I appreciate the info. I thought it was crazy to believe that I was really only getting 5.5 when the water company is telling me 25. I will probably do my plan based off of 20 GPM. That way I have a little bit of buffer built into it.
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