wicked water hammer

Discussion in 'Irrigation' started by Ed G, Oct 16, 2006.

  1. Ed G

    Ed G LawnSite Member
    Messages: 140

    install almost done. Finally

    Haven't put any heads on yet, flex pipe is about 6" above ground and trenches are somewhat backfilled. Need to flush lines completely. I did buy caps to put on flex hose to help flush each line properly.

    Have not connected wiring to control box yet.

    I did activate an existing zone of sprayers that has been unused for the past four months man, sure is throwing out much more water than ever before.

    I'm getting water hammer on every valve using solenoid. They valves do have flow control and I haven't begun to flush completely yet.
  2. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    Seems like you have the reverse problem of what you originally had (decreasing pressure). :)

    If the valves have flow controls on them then throttle them down a little until you get the heads installed. Uncontrolled water running through empty pipes, in this case your lateral lines that were completely empty, can cause water hammer. Air in the lines can also sound like water hammer but it's really a different problem. If the problem continues then you'll have to look at some other issues. However, none of the zones exceed the GPM and 5 feet/second velocity based on your original 1" main line. If you didn't have water hammer with your old system zones then you shouldn't have it now. The 1-14" new main line will not speed up the water any. It just decreases water friction within the piping and combats loss of pressure through this friction.
  3. Ed G

    Ed G LawnSite Member
    Messages: 140

    The PGV valves I selected DO have flow control and I have them cranked wide open.

    The "hammer" seems worse on the zone that was reconnected. When I turn that valve off, you can see the pvc jump. I haven't done a real good job of flushing that line - yet.

    Sure is a big difference in the amount of water going thru those sprayers!

    Can't wait to get those rotators installed.

    I'm dead tired. I did the install with no help and worked 12 hours a day for the last three days.

    I hate to say it, but I didn't want to stop working to take pictures. My wife took a few on trenching day.

    I promise I'll shoot some when the rotators are installed and working.
  4. Ed G

    Ed G LawnSite Member
    Messages: 140


    I bet those those pop-up sprayers were shooting water about 20 feet!

    I turned down the flow until I saw it decrease water flow (which was pretty close to being closed) and backed it off about a half turn.

    No more hammer time.

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