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Funny pipe max length

Discussion in 'Irrigation' started by F6Hawk, Jul 2, 2005.

  1. F6Hawk

    F6Hawk LawnSite Member
    Posts: 195

    If I have a 1" lateral that has 3 I20's on it, and the feed is between head 2 & 3, how long of a feed can the funny pipe be? Do I NEED to go with 1" PVC until about 2' from the head, or will 4-5' of FP be ok? Also, on the other end, do I really need to go from 1" to 3/4" between heads 1 & 2, or would it be ok to stay 1" all the way? (Particularly if head 3 has the longer FP on it).

    I guess what I am asking is will it hurt anything to use about 5' of FP to feed a rotor?

    What about a spray (1804's)?


    P.S. Got all the trenches dug today, 1-1/4" mainline halfway ran, had to stop for the night. Tomorrow, the manifolds!
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    I don't like to run more than 2'. Funny pipe is very flow restrictive.

    I also like to bush down to 3/4" in your situation, though for a homeowner, your fine not doing it and saving a few bucks on some fittings.
  3. F6Hawk

    F6Hawk LawnSite Member
    Posts: 195

    At this point, bucks is not the issue. I have all the fittings already, just wasn't sure if I needed to do it. I know on a long run, the last section should be narrowed from 1" to 3/4", just wasn't sure about a 3-rotor zone. Almost seems to me that the flow would be ok with 1" to the end (with the tee soming in between heads 2 & 3, then feeding down to 1), but that is why I am asking the experts.

    Thanks for the advice, you are always fast on the replies, I really appreciate your assistance, as well as all the pros on here. I truly believe my system will be the best in the county, thanks to all the help here. The guy who bid my job last month came by yesterday and sneered at my SS I20's, my DVF-100s, my Modular controller, and my 1-1/4" mainline feeding 1" lats & 3/4" ends. Said it was way overkill, and that 7 zones was too much, as well. Said he could have done it in 4. Oh well, my money, my system!
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,650

    The fine folks at Toro, who originated funny pipe, have a pressure loss table in their catalog, and it gives the pressure loss for a flow of 4 gpm as 0.09 psi per foot. That would allow you to run more than a few feet, without adverse affect. For contrast, the pressure loss for a 3/4" funny pipe elbow is 0.80 psi at 4 gpm. Change that 4 gpm to 3 gpm (or 5 gpm) and the flow losses become 0.06 (0.15) and 0.41 (1.42) psi.

    Something curious, that you might not expect, just by looking at the fittings, is that more pressure is lost in a 3/4" funny pipe elbow than in a 1/2" funny pipe elbow.
  5. JB926

    JB926 LawnSite Member
    from NJ
    Posts: 150

    for just one head it will be fine

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