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Backflow Valve and PVC pipe problems

Discussion in 'Irrigation' started by Tn Lawn Man, Jul 24, 2006.

  1. Tn Lawn Man

    Tn Lawn Man LawnSite Senior Member
    Messages: 479

    In my area it is very common to have the backflow preventer valve approximately 1 1/2 feet above the ground and connected by pvc pipe.

    I am a grass cutter and not an irrigation guy. So, please don't slam me for a stupid question

    My question is: Will this pipe withstand weedeater line hitting it while trimming?

    Thanks Fellas
  2. greenscapes inc.

    greenscapes inc. LawnSite Member
    from Utah
    Messages: 137

    Yeah it will withstand it, just take it easy. It should be galvanized but if it is PVC it should be SCH 40 and it will hold up to the trimmer line. SCH 20 I would be really careful.
  3. justgeorge

    justgeorge LawnSite Senior Member
    Messages: 353

    Are there any markings on the pipe that say what class pipe it is? It could be schedule 40 which is heavier, or class 200 which is thinwall.

    I'll do a test for you tomorrow with class 200 and see how it holds up.

    I always stay with copper pipe above ground on my installs. On most installs though, the backflow is in the landscape bed and not subject to weedwacking anyway.

  4. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    Just don't hit it with a weedeater, your going to encounter everything from thinwall class pipe to SCH 80, to galvinized to copper.

    Best advice is to keep weedeaters away.
  5. Tn Lawn Man

    Tn Lawn Man LawnSite Senior Member
    Messages: 479

    Thanks very much for the replies. I will look today and see if I can tell what sch the pipes tend to be.

    It is frustrating though, that so many are in the turf areas and not hidden in mulch beds or by shrubbery. I think that may be done so that it makes for an easy winterization. ????
  6. jerryrwm

    jerryrwm LawnSite Bronze Member
    Messages: 1,274

    If it becomes a problem, take a couple pieces of PVC pipe, about 6" long, make one saw cut along the length. You can then put it around the standpipe of the backflow device and it will act as a sleeve.
  7. Critical Care

    Critical Care LawnSite Bronze Member
    Messages: 1,654

    The sleeve advice that Jerry mentions is probably your best bet, and not too difficult to do. I have cut through pvc with a line trimmer. If the pvc is egg shell thin, under UV rays, weathered, hit by things in the past, then the risk will be more.
  8. HooKooDooKu

    HooKooDooKu LawnSite Member
    Messages: 70

    I would think the PVC (Sch40 OR class 200) would stand up to the weedwaker... at least a few times.

    My concern would be the repeated beating the pipe would take, Sch40, 80 or class 200). I recall I've read warning not to "hit" pvc pipe and to avoid allowing pipes to slap together when you're handling them because they can crack. So I would imagine repeated abuse from a weedwacker would likely eventually lead to failure.
  9. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Don't get CLASS (I'll use CL 200 as an example) and SCHEDULE (I'll use SCH 40 as an example) mixed up as they don't correlate to each other. SCHEDULE PVC pipe maintains an iron pipe equivilent thickness throughout it's various sizes. SCHEDULE PVC pipe uses SDR (standardized dimension ratio) as its determining wall thickness. As the pipe gets larger its wall gets thicker to maintain the maximum 200 PSI over 10k applications rating. Although small CLASS pipe (under 1-1/4") does have thinner walls, pipe sizes between 1-1/2" and 3" are pretty much the same as SCH pipe. Once you reach 4" in diameter CL 200 pipe actually has a thicker wall that SCHEDULE 40 pipe does.
  10. Mr. Vern

    Mr. Vern LawnSite Senior Member
    Messages: 632

    Well Purp - I am not sure if I will ever use that info, but it sure was a new one on me. I have never seen the larger diameter class pipes so I just assumed that they were always thinner.

    Very interesting!

    Do you ever use CL200 in 1" or smaller installations?

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