I Checked Flow & Pressure

Discussion in 'Irrigation' started by ZX12R, Aug 8, 2008.

  1. ZX12R

    ZX12R LawnSite Senior Member
    Posts: 775

    I checked flow with the bucket method. Meter is 5/8" to 3/4" copper to 3/4" backflow to 1" pvc. In 30 seconds,5.5 gallons of water came out which is 11 gpm.

    Static pressure was 52 psi.

    Can anyone help me with the lawn part of the irrigation system now? Based on earlier reccomendations,I was going to go with Hunter SS I-20's. I was going to use 4 heads per zone. Are my flow and GPM numbers fine for this?

    Also,in reference to total GPM for each zone,do I use the number I got which was 11,or do I use 80% of that which would be 8.8?


    By the way,the main will be 1"poly and all laterals will be kept 1" also.
     
  2. Waterit

    Waterit LawnSite Silver Member
    Posts: 2,879

    It's always best to have some cushion - stay 9GPM or below. That should support your 4 I-20's per zone, although pressure is on the low side. What nozzle and spacing are you using? You have to factor in PSI loss in the piping. I have no idea about poly specs, I'm a PVC guy. If I was installing your system I'd be using a 1" main, 1" DV-100's, and breaking down to 3/4 pipe as fast as I can. Don't see the need for 1" laterals in this case.
     
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,449

    Use PGPs instead. Same gear drive. More useful range of nozzles for a newbie.
     
  4. ZX12R

    ZX12R LawnSite Senior Member
    Posts: 775

    "It's always best to have some cushion - stay 9GPM or below. That should support your 4 I-20's per zone, although pressure is on the low side. What nozzle and spacing are you using? You have to factor in PSI loss in the piping. I have no idea about poly specs, I'm a PVC guy. If I was installing your system I'd be using a 1" main, 1" DV-100's, and breaking down to 3/4 pipe as fast as I can. Don't see the need for 1" laterals in this case."


    Thanks Waterit,maybe I will shoot for 8 GPM to stay on the safe side. A couple questions if you dont mind. What are DV-100'S? Why would you break down to 3/4" laterals? I thought that 1" laterals would have more water available to use than 3/4"? Am I wrong on that?

    I do not know what nozzles I should use as I have not mapped out my lawn just yet. I was thinking of putting heads 20-25 feet apart to be safe.

    You said you think my pressure is low.I went to hunters site and it looks like my pressure falls in line with their specs.Please take a look at the specs below and let me know what you think.Thanks

    • Recommended pressure range:
    40 to 60 psi (2.8 to 4.1 bars; 275 to 413 kPa)
    • Operating pressure range: 20 to 100 PSI (1.4 to 6.9 bars; 137 to 689 kPa)
     
  5. ZX12R

    ZX12R LawnSite Senior Member
    Posts: 775

  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,449

    52 psi is not enough. Be kind to yourself and stick with PGPs.
     
  7. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,603

    Static don't mean diddly squat; got to measure zone need + friction lossl
     
  8. ZX12R

    ZX12R LawnSite Senior Member
    Posts: 775


    OK,I will take your advice.I am dissapointed I won't get to use the pretty I-20's. :cry:

    What kind of spacing would you suggest? Also,should I stay away of full circles if I can?
     
  9. ZX12R

    ZX12R LawnSite Senior Member
    Posts: 775

    Do I measure zone need by figuring out my GPM usage for each zone?
     
  10. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,603

    Yup, then you figure the pressure loss thru the pipes & fittings. 50 psi static
    is not something to celebrate; be carefull. I bet you get around 6 gpm
    @ 35 psi.
     

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