Well done, water hammer

Discussion in 'Pumps and Tanks Well Forum & Blog' started by WellHead, Oct 22, 2010.

  1. WellHead

    WellHead Mechanical Engineer

    Messages:
    34
    Location:
    Arizona
    Hi all,

    New pump is about 10 times faster at filling than the old one and now I have some serious hammer at pump on and off.

    I did a search here but did not find anything related to pump turn/off one. I am blaming my Search terms more than the Search system. :)

    I have a WellMate WM-25 pressure tank with the air pressure set at 28-psi for 30-50. If I turn off the power to the pump and let the tank empty, I hear the pressure switch click at 30 and right about 28, the flow from the tank drain bib cuts out. Not sure if that is important but thought it might save a question from the experts.

    What are my options?

    Thanks

    Harry
  2. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,246
    Location:
    Land of Cheese
    If the piping is not properly supported in the building it can cause a banging noise. Water hammer in a well system is commonly caused by a faulty check valve or a check valve installed in the wrong place.
  3. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Try turning up the shut off pressure to about 75 or 80 and report if the the OFF hammer stops. And or try 40 to 75 as your switch setting. Fast moving water does not like to be stopped quickly. You will have a harder time with the ON noise, which if not some weird check valve issue, is simply loose pipes absorbing a hydraulic shock.

    Maybe you have too much pump for your system....
  4. WellHead

    WellHead Mechanical Engineer

    Messages:
    34
    Location:
    Arizona
    Thanks for the replies. I will check the pipes for loose attachments and saddles.

    To much pump? The one taken out was a 19-gpm and this is a 10, so I am thinking probably not, but I am not knowledgeable in this area.

    I'd rather not try the 75-psi thing as the copper and PVC plumbing in this place was installed in 1978. The DIY owner/builder had limited plumbing skills and it is a mess of pipes. Probably 50% of the joints and valves have leaks that have calcified and sealed. I fear bumping the pressure may present we with a wonderland of small fountains.

    One of these days I will re-do it all.

    Harry
  5. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Water hammer can [will] produce shock pressures of 150 to 500 psi and more. Pipes are certain to leak with that impact, but they are designed to live forever with consistent pressures under their rating.

    "hammer" if that is what it is, will open those leaks and provide a shower stall long before a 25 or 30 PSI increase in constant pressure.

    Most PVC and copper can easily see 120 psi forever, and not be compromised. I believe 1" PVC is rated for 450PSI. And thats max working pressure. Those little rubber hoses on excavators run happily for years on 4500 PSI.

    You might consider a dole valve to reduce flow a bit, or a CSV. If you have a valve between the pump and the tank, throttle back the flow as a test. Be sure you have a pressure relief valve inside that circuit.

    10 times faster fill rate on a 19 vs 10 gpm pump tells me something is wrong with your calcs, or you have far too much Horsepower under the pump head.
  6. WellHead

    WellHead Mechanical Engineer

    Messages:
    34
    Location:
    Arizona
    ..10 times faster fill rate on a 19 vs 10 gpm pump tells me something is wrong with your calcs,

    Nope, the 19-gpm is 20 years old -- plus -- there was a small hole about 3' above it. As the hole got bigger the flow reduced and then finally the pressure started dropping as the hole got even bigger.

    Harry
  7. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Okay, forgot your hole. What is the flow rate at your shut off pressure setting according to the pump chart? How many HP? Pumping depth? If you have a real impact and noise at shut off, you should try some of the ideas above.
  8. WellHead

    WellHead Mechanical Engineer

    Messages:
    34
    Location:
    Arizona
    For the depth etc, the 10GS15 is right on it's sweet spot of 9.4gpm at 50-psi shut-off.

    I am going to try a Sioux Chief hammer arrestor at the top of the lift pipe. It has a Tee sitting vertically with a plug in it. I will replace the plug with an elbow and then the arrestor. I can't sit the arrestor straight up because of the lid on the well head housing. But Pascal pretty much assures me the elbow will be OK.

    Harry
  9. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    One of the best hammer arrestors Sioux does not want you to know about is a soft 100' garden hose left on with a shut off valve on the end.

    Cheaper and even more useful than a 30 dollar stick of copper. .... Even better if you drain it now and then, close the hose end valve and re-open the hose bib.

    Saw a hammer arrestor - 4" pipe riser full of rubber balls. worked great.

    One last arrestor is a adjustable pressure relief valve for 7$ set to drip at 50PSI and then add 1/4 turn to the spring. No more 400PSI surges, just a little leak for a moment.
  10. WellHead

    WellHead Mechanical Engineer

    Messages:
    34
    Location:
    Arizona
    Interesting, but I am guessing (from your avatar) you live in CA. That hammer arrestor would only work 6 months of the year here. :)

    The hammer is not going beyond the two filters and so they are obviously taking care of part of it.

    Interesting thought on the pressure relief though. To be fair, the Sioux arrestor is only $12 and no leaks.

    Harry
  11. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    It freezes here nicely, but for only a week at a time, then its sping again for a few weeks. I leave the hose cracked and build a nice ice sculpture with it. Thats my windshield defroster hose.

    I would call Sioux and ask about the flow rate of 10gpm - remember these are for fixtures, and I know I don't get 10 gpm out of my sink or washer. Certainly don't try their "mini's"

    Those clear plastic filters will not tolerate any hammer for long. And the PRV could be hosed off to a drain.

    What you really want is a valve that SLOWS the flow to 1 or 3 gpm just before shutoff, but outside of a CSV - whole different story - I cannot think of one.....
  12. WellHead

    WellHead Mechanical Engineer

    Messages:
    34
    Location:
    Arizona
    Ha! Good thought Dude, **but** I seem to be being ignored by Sioux head-office. I also asked two of their dealers and got the old, "we just sell them, we don't know s..t about them" reply. Guess which two dealers will not see my credit card number? :)

    The PRV could dribble on the garage floor. Our humidity rarely gets about 30% so it would evaporate before hitting the floor. :)

    It looks like a PRV or CSV then. I will check with the well guy who put the pump down there. When I told him about the hammer, he didn't seem very interested or concerned. It's a third generation drilling company so I am sure he must have heard of the issue.

    Harry
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