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Pressure in the system

Discussion in 'Irrigation' started by Bunton Guy, Sep 22, 2001.

  1. Bunton Guy

    Bunton Guy LawnSite Bronze Member
    Messages: 1,917

    What makes the pressure to really get the water to shoot far ? I made a small system that has 5 heads that rotate 190 degrees...its for in my moms front garden only its got low pressure i didnt do it with all these valves and stuff...just PVC with the T's with heads attached to them...and then the pvc comes up out of the ground to attach to the garden hose...how can I make more pressure I want to make another 6 heads but when I turn on the current 5 heads it barely has enough pressure to get the water out of the heads... ? I dont do irrigation for a living...just wanted to water the front beds on the house .
  2. longslawn

    longslawn LawnSite Member
    Messages: 201

    You can only get about 5-6 gallons per minute through the garden hose if it is 5/8 inch. The layout and pipe size will effect the pressure. Need a little more info.

    Pressure and flow at spigot
    Pipe size
    gpm each head uses

    Would do much better if connected to main supply line.
  3. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Messages: 1,712

    Depending on what nozzles you have on the heads you might have demand of 10-11 GPM on those 5 heads and a supply only good for 5 GPM off a hose bibb. This is assuming city water supply @ 50-60 PSI.

    Rather than ask a lot of questions that you probably can't answer, try capping off heads till the pressure is good. Then just run that many at one time.

    Make no mistake that irrigation systems are engineered products. They can be succesfully done by do-it yourselfers IF you get pamphlets or design books from manufacturers telling you how to design and install.

    Why nobody reads these pamphlets and follows directions or seeks advice before starting is way beyond me.
  4. racerdave

    racerdave LawnSite Senior Member
    Messages: 260

    Volume. You need a minimum amount of water flow per head plus frictional piping loss. A conservative design would establish a system using 85% of the available supply (pressure/flow or if using a dedicated pump, 85% of it's BEP)
    don't be confused about pressure, flow is your best friend or worst enemy.

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