Measuring Dynamic Pressure at the Spray Head

Discussion in 'Irrigation' started by anotherbrian, Jun 9, 2011.


    Messages: 18,668

    Should have used 6inch-valve-box
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  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,071

    I think anyone in Florida would want to have repair capability for indexing valves - elsewhere, meh.
  3. anotherbrian

    anotherbrian LawnSite Member
    Messages: 21

    Meister - Are you suggesting re-plumbing the zone direct into the point of connection thereby bypassing the hydro?

    I tied off the heads to see if I measured a flow of 0 gpm. Instead I measured 1/2 gpm with a visible leak through a crack on the side of the hydro. To bad they stopped making metal ones. That makes me think the lion's share of the lost is occurring through the seals of the popup spray heads or possibly at the riser/spray head connection.

    Are there any rules of thumb on expected leakage amounts for spray head seals?
    I can see that would be distinguishing quality characteristic between product lines. The irrigation engineering manuals don't seem to mention the subject. In practice I replace the seals when they obviously leak.
  4. Mike Leary

    Mike Leary LawnSite Fanatic
    Messages: 23,027

    There should be NO leakage from a wiper seal. They should "lock and load". RB 1800 series have that reputation.

    Messages: 18,668

    I have no clue what this means therefore I will attempt tp flowchart.

    water tower, pump, meter, tap, eliminate hydro indexing valve, pipe in valves for each zone, run wire, install new controller. LIFE IS GOOD
  6. GothamGnome

    GothamGnome LawnSite Member
    Messages: 12

    sorry, but how did you come to that flow rate assumption of 22gpm...bucket test or mathmatics?
  7. Inspired

    Inspired LawnSite Senior Member
    Messages: 544

    I think he said he measured the flow at the meter.
  8. Buck_wheat

    Buck_wheat LawnSite Senior Member
    Messages: 585

    "I measure 22 gpm going into a zone which has 6 half sprayers (number 12H) and 5 full sprayers (number 12H). Assuming all that water makes it to those sprayers, that works out, on average, to be 2.8 gpm for the fulls and 1.4 gpm for the halves. "

    Uh... I dunno, maybe I'm stupid :confused:. If he has 22gpm, do the math on his set up, I think he's got a water deficit .4 glns per minute, assuming I'm reading his post correctly and that's one zone.

    I'm not sure if that's enough to lift the heads and produce the rated radius of throw, let alone produce sufficient pressure to rotate the disk in the valve properly; he may need some more water & pressure to achieve his goal.

    He should call an irrigation designer.

    I love Hydro Indexing valves, everybody here got at least one :laugh:
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,071

    22 gpm is a bit too much to expect from a small residential water meter
  10. Buck_wheat

    Buck_wheat LawnSite Senior Member
    Messages: 585

    I dunno... different communities, different systems; different pressures but 6x1.4= 8.4 & 5x2.8=14 add them up & you come to 22.4 which is .4 more than he says he has. Unless he is using 1.4 GPM per minute for all the 180's combined in which case I want to know what he's using for mist heads and how long the system has to run before he gets .5" precipitation.

    FYI. Metro NYC? I'm from Jamaica Queens in a past life... that be South Jamaica... 103rd precinct BOO!:drinkup:

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