Length of Funny Pipe

Discussion in 'Irrigation' started by burlap, May 26, 2006.

  1. burlap

    burlap LawnSite Member
    from Indiana
    Posts: 66

    This will be my first experience with funny pipe. I have 1/2" Rainbird pipe and marlex street eels. What determines the length of the pipe? I tried 18" and think that is too unwieldy. A 4-6" piece will work fine- my trench will be 12" and that comes naturally with the Hunter PGP. How much adjusting will be necessary in an unobstructed trench? I didn't think the 18" gave me much flexibility and had to double it back because it wanted to follow its curve. Thanks, burlap
     
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,476

    Are you using poly pipe or PVC? Poly can allow you to use very short lengths of swing pipe, if you install a marlex ell in the head. Between the marlex, the MPTxBarb elbow, and a 3/8 ('funny pipe') side outlet insert tee, the swing pipe itself doesn't need to contribute any flex to the assembly.
     
  3. burlap

    burlap LawnSite Member
    from Indiana
    Posts: 66

    I'm using 1" pvc with the street eel coming out of the side of the 1" tee. I can't think of how much adjusting I would need to do over the years other than an up or down adjustment which the short length will allow for. burlap
     
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,476

    With PVC, you need a bit more pipe, since you don't have the insert fitting to help out. So, if you have the funny pipe terminating with a barbed elbow at both ends, a foot should be plenty. I would avoid assuming that a barbed elbow threaded into a sch 40 fitting will move freely a few years after installation. (but wait to hear from PVC guys)
     
  5. PurpHaze

    PurpHaze LawnSite Fanatic
    Posts: 5,496

    We don't use funny pipe because we build our own swing joints out of Marlex 90s and SCH 80 nipples. We use 6" SCH 80 nipples with 1/2" inlet sprinklers and 8" SCH 80 nipples with 3/4" and 1" inlet sprinklers.
     
  6. burlap

    burlap LawnSite Member
    from Indiana
    Posts: 66

    I'm having trouble visualizing what you're telling me. My problem is that whatever length I make the Rain Bird funny pipe translates into lateral distance. A 12" length means the head will be 12" up stream, down stream, or to either side of the tee. It just seems a shorter length would be easier to work with if I want to set the head into the side of the trench where I can secure it into the side rather than the backfill. Sorry to be so dense about this, burlap
     
  7. greenhorn123

    greenhorn123 LawnSite Member
    Posts: 53

    6-12 inches will be fine.

    if its shorter than 6 inches the head tends rise a bit over time. you can use more if you need.
     
  8. PurpHaze

    PurpHaze LawnSite Fanatic
    Posts: 5,496

    We don't use funny pipe. With proper backfill and compaction around the swing joint the sprinkler will not rise, drop or tilt.

    Swing Joint IV-002.jpg

    Swing Joint IV-003.jpg

    Swing Joint IV-004.jpg
     
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,476

    What lateral distance? If you use a SxSxFPT tee, and thread a funny pipe elbow into that tee, and point the barbs in the direction of the pipe, then the funny pipe runs alongside the PVC. This would mean the sch 40 tee will be about a foot away from where the head gets located.
     
  10. phototropic1

    phototropic1 LawnSite Member
    from MS
    Posts: 118

    Exactly. You have to account for this when you glue your tee. Offset the tee about 7-8 inches or so from the point where the head will be, attach an elbow barb to the tee, funny pipe, elbow barb, street el, then head. Voila! We use about 12" of funny pipe (actually, the length from the hand to the elbow of the employee who is cutting it) for each head.
     

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