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Amateur needing help

Discussion in 'Irrigation' started by swbhog, Jun 17, 2007.

  1. swbhog

    swbhog LawnSite Member
    Posts: 10

    Hi I'm new to this sight but hope someone can enlighten me.I am a landscaper,mainly maintenance but I dabble when needed.I need help with an install irrigation. I have done numerous installs mainly for friends throughout the 16 years I,ve been Landscaping. I do this work part time and have no interest in doing irrigation for a living. Enough of my background.I have studied the hydraulics theories till I'm blue in the face and still barely get by.This job I am doing is a little bigger than I usually take on but you got to help friends in need.
    My system needs to cover 900' long and 140' wide.Drafting from a lake the intake side is 100' out in lake to deep water.Maybe 5' drop from dock.This is a new install with about 25,000 in plant material so I must not fail.

    Please feel free to critique this mess its how I learn.
    My problem is what pump,main line size,valvin etc. FIS irrigation has directed me to this set up.

    Sta-rite 5hp 230v DHJ
    Esplxm clock
    PESB series electric valves-self cleaning because of lake sediment.
    2 1/2 160 pipe mainline
    Rainbird Maxipaws or 5000 series or Hunter pcp,s
    I know what your thinking what PSI and GPM. I was guessing at 83 gpm at 50 psi on my worksheet but I suck at math.

    Am I overkilling this beast or what.Also do I really need to dropdown my pipe sizes every 30' or so to maintain psi after my valves.I didn't do it for my house and it works well.Sorry for the long 1st post but my head hurts from contemplating this and I need help.
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    5HP pumps will provide enough water to fill a 4" main :)

    I think your supplier really wants to sell you an expensive pump.

    Work backwards to the pump. Design your system, figure out how many heads, and how much water you will need, size pipe accordingly, when you get back to the pump, find the pump that matches the desired output and pressure.

    The main reason to downsize pipe is cost. Big pipe is expensive. There is no need to have a section of pipe that is only moving 10 GPM be larger than 1". So you step it down as the flow decreases. Stepping down pipe has nothing to do with raising the pressure, don't listen to the old timers.

    Also, why the modular LX timer? Plan on expanding this any time soon? If not, don't waste your money on the modular. I think your supplier wants to sell you some stuff.
  3. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    Ok, In this day and age, I wouldn't go maxi-paws, even with dirty water. Is the water source murky most of the time? PGP's should still be OK, but if the water is VERY turbid, you might be back to maxi's. Either way, plan for 27x5 if your area is square, so 135 heads. 40 of those are perimeter heads. 4 90's and 36 180's. So, if we nozzle correctly, we have the equivalent of 105 full circle heads. IF we do 6gpm fulls, we have 630gpm with heads that will run 60 min to achieve about .5" of precip. If we want to be able to do this in one "night" cycle, then figure 10 hours of run, so 10 zones. You need 63gpm with this figure. If we decide we only need to run every other day, we can get by w/ 20 zones. Now we are down to 32gpm. I have designed for every three days (30zones) and you could get by on 21gpm. Try to achieve these gpm's w/ an operating pressure of 60psi (system would "work" w/ 50psi at pump, but......). I have done systems with only 4gpm full circle heads. If you maintain the 60psi, you can still get coverage w/ 4gpm nozzles. Your going to end up with longer run times per zone, but more heads per zone. What are your choices w/ costs for a pump? What are your costs per zone in addition lateral piping (zone valve and stations on the controller). Designing your system for 30 zones means smaller (and therefore cheaper) valves, but a much more expensive controller. 10 zones means larger valves, but a much more economical controller. A pump setup to push over 60gpm is pricey, but might balance out. If you go 4gpm rotors and longer runs, you can still do 10 zones but only need a 40+gpm pump. Many, many variables here. Also, do you have good access to 230v power? Any chance you have access to 3 phase power (doubtful, but sometimes, it is available).

    See guys, I can be helpful, and believe it or not, I'm not in a good mood. Also please note *****
    I did NOT jump his case for being a MORON and suggesting he could CREATE pressure by downsizing pipe!!
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,642

    Since this is about 3 acres in Florida (sandy soil, no doubt) I can see bumping up the water supply. But the suction side would have to be larger than 2 1/2, if it's 100 feet long. 3 inch for a minimum.

    Is there a limited time window to do the watering? Is the pump located near the midpoint of the 900 foot dimension? A pump like the DHJ (or is it now the Berkeley LTH?) can push way more than that 83 gpm, so you would be running it somewhat inefficiently.

    Maxipaw heads (wait for the collective groan to die down) are a good choice for cruddy lake water. That they can water effectively at lower pressures than gear-drive rotor heads may allow you to use a less expensive pump. Just be aware that you don't want to be sloppy with your pressure-loss numbers. You could cover 3 acres with 50 gpm, and that might be pumped with a 2 HP pump.
  5. swbhog

    swbhog LawnSite Member
    Posts: 10

    I get it I am a bit ignorant on some of this but I keep getting different ways to do everything.An old guy that worked for the city for 26 yrs told me to step down the pipe thats why I asked.I have never done it and they work fine. Another guy with lots of time in field talked me into the 5 h.p pump.I already had the 230v wire ran so I hope this pump will work.Also I use hunter heads always but someone recommended the maxi paws.See how confused I am.The lake is tanic like tea and shallow.The pump is 800' from the furthest heads. I have an open budget but I want to save them if I can.Also I noticed 2" pipe is 6.00 a stick less than 2 1/2". Can I use 2" for mainline and how much reduction would that be.I really appreciate the help I am learning the hard way and trying not to make any major mistakes.One more thing.I'm not getting the whole work from the end back.Could I hook up the pump find out my gpm and design the system to flow 60% of gpm at 50psi.Come on experts set me straight.
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,642

    More information, please. What is the time window for the watering?

    Using 2 inch pipe from a DHJ is not going to work. You go in the other direction, especially if you have 800 feet to travel. Read your friction loss tables. Run the numbers.
  7. swbhog

    swbhog LawnSite Member
    Posts: 10

    What does a time frame have to do with it. I have 8 zones on my own house and they run for about 4 hrs every third day.I'm missing something here.I will go and review friction loss for pipes though.
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,642

    Time Window relates to flow required. If you could water 24/7, then you could get by with a smaller pump. You might even use a Sta-Rite SSHM-2 multistage pump, and get enough pressure to compensate for the long runs.
  9. Keith

    Keith LawnSite Gold Member
    Posts: 3,977

    Unless Orlando is under a rule that is even more strict right now, they are limited to two days a week max (either Wed and Sat, or Thur and Sun based on odd/even address), and no watering between 10am and 4pm.
  10. swbhog

    swbhog LawnSite Member
    Posts: 10

    Keith are you serious.I water as needed only no specific days unless the water police get me but they never come out here ,these guys in my neighborhood water these big yards all the time and never turn there system off. I've watered Once this week, probably none for the next several months so I,m banking my days for future use.:laugh:

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