Water Hammer Help

Discussion in 'Irrigation' started by Summett, May 29, 2008.

  1. Summett

    Summett LawnSite Member
    Posts: 72

    Here's my situation...

    Newly constructed home [entirely finished] with a dedicated line that was installed for a future irrigation system. Well, the future has arrived, and had an irrigation specialist over for a bid. He ran some gpm tests, and upon checking the water pressure with the test being run, he shuts off the line valve and we get an Extreme water hammer [only when it was shut off abruptly]. if he slowly shut the valve...no hammer.

    His opinion that was there was a problem with the dedicated supply line (which was the new 1" plastic line) and that it wasn't large enough to handle the 18 gpm flow that he said was running thru the line. And, he had a concern that he said at that rate, the valves would probably close quickly causing the hammer.

    So, had the plummer over today and only real suggestion that he could give was that he didn't think the irrigation valves would close that quick to create the hammer, but if they did, that he would install an arrestor.

    My fear is having an irrigation system installed, along with an arrestor, and the water hammer continues...then what??? My house is completely finished, so an increased 1 1/4" line option is probably not viable.

    What options do i have?

    I realized that many of you experts may need more info to help me out, so ask away.

    thanks much in advance for all the advise.

    [signed]
    "A guy who REALLY wants an irrigation system."
     
  2. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    More than likely you'll be fine with no hammer. Make sue to NOT use the Rainbird DV series valves. They close very abruptly and may cause hammer. Go with either Irritrol, Hunter, or WeatherMatic valves. I've also found that valves with flow controls, even if they are not adjusted, tend to close slower.

    Good luck!
     
  3. No Rush

    No Rush LawnSite Member
    Posts: 203

    what size is your water meter? what is your static pressure? what type of 1" pvc do you have (sch 40, class 200)? also, you could get another opinion from another irrigator in your area.
     
  4. Summett

    Summett LawnSite Member
    Posts: 72

    Thanks DM...that's encouraging. I believe he'll use Hunter valves (as that's the heads he's using) but i'd have to double-check.

    It was just a WICKED hammer. I mean, even the plummer looked at his other plumber when i showed it to him and he said..."have you ever heard a hammer like that?" It wasn't something that i really cared to hear. :dizzy:
     
  5. Summett

    Summett LawnSite Member
    Posts: 72

    It's on a well w/ 1hp pump. Not sure if i follow you on static pressure, need a little help on that question. Pipe is a ViegaPEX Ultra 1" SDR-9. Doesn't list a "class #" on it.
     
  6. lowvolumejeff

    lowvolumejeff LawnSite Member
    Posts: 72

    I bet the solution is based ion the velocity thru the 1" plex when running such a high GPM. I went to the PEX makers site, and the download shows the velocity is too high. www.viega-na.com/downloads/1201798836TD-PFVPU 0307 ViegaPEX Ultra.pdf
    Might want to limit your zones to less tahn 16 GPM (Velocity = 8 FPS) or better yet, 14 GPM to be safe.

    Jeff
     
  7. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,301

    Hunters will close a lot faster then a RB dv. RB,s take about 30 seconds , Hunter is almost immidiate.

    Putting check valves in all the heads will also help to control it ,as the zones will not be empty thereby slowing water speed when a zone turns on.
     
  8. No Rush

    No Rush LawnSite Member
    Posts: 203

  9. Ditto... I'd stay away from the Hunter valve line. The SRV is junk in my opinion.
     
  10. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,301

    They stopped making the srv. To answer my own question from last week, no other hunter valve will screw to a srv body.
     

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