Has anyone seen this before?

Discussion in 'Irrigation' started by Dirty Water, May 23, 2006.

  1. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,794

    I did some work on a system thats new to us. The front yard was about 50'x30'...The original installer uses sprayheads, and only 6 of them to do it. Needless to say it wasn't exactly head to head :laugh:

    Anyways, we needed to move two heads because they were actually in the cities right of way, so I had one of the guys dig it up. Found the head, attached to funny pipe. Started following the funny pipe and after about 4' we find a funny pipe tee, heading towards another head. Turns out the original installer was running 2 heads off one run of funny pipe about 10' from a 3/4" lateral.....:Laugh:

    Anyways, thats only the first weird thing.

    In the side yard, I had to move a few more heads and discover that they ran funny pipe down the length of the yard, and tee'd each head into it with about 4" of funny pipe on each tee. I'm guessing that its being fed by a PVC line in a few spots, because it actually had pressure....but still weird. I've never seen anyone use funny pipe for more than one head, or run it more than 2'-3'.
     
  2. Desertdweller

    Desertdweller LawnSite Member
    Posts: 159

    I used to go through rolls of FP each week. I've run 2 rotors off one FP line with a T and 25' from the poly line. Could not tell any difference in distance or coverage from the heads mounted on the 1" poly line. Have easily run 3 sprays off 1 FP line. Not a normal installation technique but sometimes you have to do what you do.
     
  3. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,794

    Have you ever looked at the pressure loss from FP and what the water velocity would be?
     
  4. greenhorn123

    greenhorn123 LawnSite Member
    Posts: 52

    sure

    funny pipe tees, usually to add a head in a bed.

    ive pulled up to 20 feet of funny pipe with the machine, but i build poly manifolds.

    your guy was probably the home owner
     
  5. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,794

    You guys are forgetting how thick of a wall funny pipe has. Take a look at the charts, you will exceed 5 FPS very easily.


    Nope, local landscrape "pro"
     
  6. greenhorn123

    greenhorn123 LawnSite Member
    Posts: 52

    "it'll be alright"

    ive seen someone tuck some funny pipe in that little crack between the conrete stairs and the foundation being used as the mainline.
     
  7. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,794

    Alright does not equal right in my book.

    But I'm picky.
     
  8. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    The 5 fps velocity rule applies to solvent welded PVC. It is used as a rule to reduce the effects of water hammer to a closed piping system when a valve closes.

    On the lateral or open end of a pipe system the kinetic energy has a way to easily dissipate by flowing out of the nozzles. Water hammer is negligible on open piping.

    Agricultural designers regularly use velocities that exceed 8 fps on large drip systems that use 125 psi PVC pipe for sub mains and laterals that may be 4" or 6". Their thinking is that with as many as 3000 emitter orifices on the system there is plenty of outlets for the energy dissipation.

    And the ASIC design criteria calls for a maximum of 6 fps.

    Also, pressure loss in funny pipe at 3 gpm is not going to be critical in a system that has adequate pressure. There may be a loss of 2-4 psi in a piece of funny pipe 15' long at that flow. So one or two heads on the funny pipe will still give proper performance without undo damage or stress on the system.
     
  9. Desertdweller

    Desertdweller LawnSite Member
    Posts: 159

    I'm impressed. All I know is it works without any problems.
     
  10. I'm quite sure we have fixed some of your stuff....:)

    Poly in Phoenix? Or another transplant?
     

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