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PSI for irrigation system

Discussion in 'Irrigation' started by Ray Kane, Dec 30, 2006.

  1. Ray Kane

    Ray Kane LawnSite Member
    Messages: 16

    first post so bear with me. 1.5 hp sta-rite pump with 2" suction and 1.5" output. I have a 1.5" "T" at the output with a hose bib for priming and a 1.5" ball valve. I have not hooked up any of the irrigation as of yet. At the hose bib I screwed on a "Y" and attached a pressure guage to one side and a garden hose to the other.

    My question is what type of PSI should I have if I were to shut off the 1.5" ball valve and runthe pump thru the garden hose?
  2. laylow1994

    laylow1994 LawnSite Member
    Messages: 114

    probably like 40-50 psi
  3. Ray Kane

    Ray Kane LawnSite Member
    Messages: 16

    The needle is rapidly moving between 35-40 psi and can run a pretty steady stream thru a 50 ft garden hose.
  4. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    Did you inherit the pump? or install it? What KIND of pump? Specs on the pump? 1.5hp doesn't tell me much. Is it a high volume? or high pressure pump? Close the valve going to the garden hose (what size hose? 3/8, 5/8, 3/4???) until the pressure gauge holds stead. Maybe 50psi.......then time the flow from the choked hose bib. I would prefer w/o the 50' of who knows what size hose, but either way, you will get some idea of what is going on this way. A 1.5" outlet w/ a 2" suction should be able to move 20-30 gpm and your not going to do that through a hose bib and garden hose. Some pumps designed for "lawn irrigation" won't create more than 60 psi and the specs will talk about an operating pressure of 40-45 psi, BUT you could be looking at 30gpm.
  5. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    Ok, Sta-rite has a web site. IF it is a PD series pump, then your looking at 40psi max and between 10 and 20gpm dependng on amount of lift. The other "question" you didn't answer. How far below pump level is the water level? are we lifting 5 ft? or 20?
  6. Ray Kane

    Ray Kane LawnSite Member
    Messages: 16

    Sta Rite DS2HF-192PL - won at a charity auction
    Garden hose is 3/4" and 44' long - I temporarily attached the hose to take the water AWAY from the foundation of my house.
    Amount of lift is unkown - The 2" vertical pipe comes up to a foot underground and makes a 90* - travels 8' horizontally underground, makes another 90* then up 2' to the pump.

    Guy across the street has the same pump and THINKS he is lifting 30'
  7. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    Specs for your pump say 10gpm at 20' of lift w/ 40 psi. Pump specs don't suggest more lift that 20'. I hope your neighbor is incorrect about the 30' of lift. The MAXIMUM lift by suction using any device is just short of 34'. This is a sea level standard (Fla should be real close to that). Reduced atmospheric pressure (being above sea level) decreases this ever so slightly. ANY suction leak reduces pump performance. The more lift, the more important it becomes for your suction line to be "tight". I don't think this pump would lift 25'.
  8. brookviewlawncare

    brookviewlawncare LawnSite Senior Member
    Messages: 378


  9. Ray Kane

    Ray Kane LawnSite Member
    Messages: 16

    Iis there a glossary where I can learn what these terms are - for instance "total head" and what they mean to me?
  10. drmiller100

    drmiller100 LawnSite Senior Member
    Messages: 562

    the further you pump the water up hill, the more work your pump has to do, which means the less gallons per minute, OR the less pressure you will have.

    head typically is measured from where the water starts uphill until it comes out, then add the pressure equivalent on top of that.

    With 1.5 hrose and a garden hose, you are probably cavitating your pump.
    As an example, take a hair dryer, turn it on, and plug the end. The dryer motor speeds UP becuase air isn't flowing.
    Likewise your pump. a garden hose is like trying to pee through a syringe.

    a horse and a half in good shape with no restrictions is a ton of water. I would GUESS 20 gpm.
    I'm a chicken. I would make a bunch of runs to the main valve box, hook up the zones at 20 gpm, then run it. if you have less, redistribute your zones.
    Don't mix spray heads with gear drives unless you are using MP rotors. Use a 50 micron filter. You can run up to 3 valves at one time off of a clock.

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