Manifold design

Discussion in 'Irrigation' started by drmiller100, May 13, 2005.

  1. drmiller100

    drmiller100 LawnSite Senior Member
    Posts: 562

    pretty fundamental question, but what is the best way to build a manifold. PVC? Glued? Threaded? Iron?

    If it matters, I'm using Irritrol valves where the top unscrews very easily. We are in freezing areas.

    Thanks.
     
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,992

    In freezing climates, it might be assumed that poly pipe is being used, and that, in turn, points to using threaded valves.
     
  3. drmiller100

    drmiller100 LawnSite Senior Member
    Posts: 562

    ok, yes, i'm using threaded valves.

    that doesn't mean the whole manifold needs to be threaded, does it?

    i'm getting really tired of my threaded plastic manifolds leaking when i put them together. i'm wondering if i should build them so that i can unscrew the valves, but the rest of the manifold is glued.

    thanks much in advance,
    doug
     
  4. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    I build all of my manifolds out of 1" or 1 1/4" Glued PVC.
     
  5. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    I don't like manifolds (got to be the service guy in me). I firmly believe in the hydraulic placement of valves. That being said, have you tried the RB manifold w/ the built in unions. I'm not sure how old a product this is. I saw my first one in the field last year, and IF I could have found one in a parts house, I would have just replaced it. This spring, I see them available at my supplier. I haven't priced it out, but it looks user friendly. I couldn't believe they offer the mainline side poly adapter for it. I take great exception to those who run poly mains. Best thing about my local PI. He won't sign off on them :)
     
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,992

    is the best advice I can think of, assuming you use valves with female threads, with a pipe-thread to poly adapter on the valve outlet. (valves with male threads use a softer plastic, and aren't as risky as they would be if they were made of PVC) Each threaded connection is a bit of 'wiggle room' to relieve strain, so I favor their use. More temperate climates don't see so much frost and heave in the soil, so an all-PVC system doesn't face the same risks as it would in colder areas.
     
  7. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Posts: 2,697

    I've pondered this same question myself. I've had to replace a couple PVC manifolds in the last couple of seasons and they were all cracked at the first valve. I thought to myself "what a waste, there has to be a better way". I did one with all threaded sch80 fittings and one in all sweated copper fittings. So far, I'm leaning towards doing them in all copper from now on.
     
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,992

    The broken manifolds I saw (on systems I personally winterized, so freezing wasn't a consideration) were at female threads on a schedule 40 fitting. Constructing manifolds without those female-threaded fittings seems to eliminate the problem. I think sweated copper is overkill, but you might combine it with brass zone valves as an upgrade.
     
  9. YardPro

    YardPro LawnSite Gold Member
    Posts: 3,563

    you're not gluing them correctly.
     
  10. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,992

    I suspect the OP was using all-threaded manifold fittings, which piggyback onto each other, using O-rings for sealing. O-rings can fail. Better to build your own manifolds from standard fittings.
     

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