My PVC is going to explode

Would someone please offer some advice before I break something. I have searched around the site for info, but I can't figure out what I'm doing wrong. I have a well which I have been using for a few years for my animals on some rural property. 300 feet deep, 1 1/2 submersible pump around 280 feet, check valve on top of the pump, another check valve 200' up, storage tank at the well casing with a hose bibb, pressure guage, pressure switch. This set up has been working great for my occasional usage. Heres where I created a problem. I set a storage tank 250' +/- away and maybe 75' up in elevation and ran several pipes to and from. I plan to install an ozone setup in the tank and booster pump the water to my houshold usage. My problem is with sub pump filling the storage tank. I removed the pressure tank to use it on my booster setup. I have purchased some tank fill switches, but have not installed them yet , need to pull the wire. I have been trying to throw the breaker to fill the storage tank. When I do there is a large surge as the pump turns on, then the pump runs ok. But when I turn the pump off water hammer hits hard at the well head where I am standing and water starts hammering out of the pressure relief valve. I first had a 1 1/4" pipe from the well to the tank. I thought maybe it was too much additional weight so yesterday I switched to one of the 1" pipes I had installed. Didn't help. I'm at a loss with this and am scared to turn the pump on again in fear that I will break something. Any help would be greatly appreciated.

Smaller pipe just makes the problem worse. It is the high velocity caused by the large flow rate that causes the hammer. Try using a ball or gate valve at the well head and reduce the flow rate to about half. Slowing the velocity or flow rate should help.

Thanks for the reply. I did install a ball valve yesterday at the well head along with a hose bibb. I will try turning it half way I will be amazed and estatic if that is my cure.

Same problem for me, except tank is 140 psi up the hill. But I have long run time and probably a much lower flow than you. My pressure relief valve lets out some water [150] psi when it shuts down.

I think we should both put a pressure tank back into the tank feed to absorb shock. The ballvalve works, but you pay for it in lower flow and longer run. You might try the PRV adjustable, set just below your running pressure and waste some water on the ground.

Be careful where you put that ballvalve valve, so someone does not seperate the pump from the pressure switch, if any.... or close it when its running.

There is a very interesting tank fill valve made in Australia, need no power. Shuts off SLOW - no hammer. I'll look for a link and post it in.

http://www.tdlagritech.com/documents/jobe-valves/more-info-vortex-differential-valve.pdf

Search JOBE valves, several models of great engineering.

http://www.tdlagritech.com/products/jobe-valves.html#

If your Pressure Relief Valve PRV leaks any water, you still have water hammer. A PRV is not fast enough to stop water hammer. It only opens after the water hammer happens, which is too late to stop the damage.

A Cycle Stop Valve or CSV would make the pump start and stop at 1 GPM and there would be no water hammer. The CSV would also open to full capacity while filling the storage tank. If you use a small pressure tank and pressure switch with the CSV, you would not need to “pull” any wires up the hill. Just put in an electric valve or toilet type valve on the storage tank. When the float drops, water from the pressure tank starts filling the storage tank. The pressure switch would then start the well pump and no wires to the storage tank are needed.

Also the second check valve in the well can cause water hammer. If the bottom check is bad or even leaking a tiny bit, the top check is holding water in the pipe like putting your finger on top of a straw full of water. So the pump starts against a negative pressure, then punches the top check like a boxer punching you in the face. This causes water hammer transients throughout the entire pipe system. I would remove the upper check valve at the first opportunity.

Well I temporarily came up with a fix to my water hammer problem. I first tried closing the ball valve half way. At pump shut off the pressure still bounced 0/100+, 0/80, 0/60 etc. Possibly by playing with the ball valve closing it more or less I could have dialed it in. Then I tried opening the hose bibb at pump shut off. 0/20 and no hammering. For the time being I can manually use this method for the low usage, but I will need a better fix for the future. So valveman you recommend the CSV for a solution. I'm going to research some posts to educate myself further on this setup. I am still processing the cause to the whole hammer issue. Almost seems to me that there should be some sort of a checkvalve at the end of my pipe in the storage tank so when the pump shuts off it would close the pipe system. I'm thinking that water is surging back downhill to the well at pump shutoff, thus by opening the hosebibb I gave that pressure a place to release. You mentioned that it is a velocity issue so slowing the water going up with a ball valve would in turn have slower water wanting to return back downhill at shutoff. I could be way off on my thought process. And yes I will remove that second check valve. I am sure I will put it off for a while though because I remember how hard it was to drop those last few sections of pipe by hand with the rig I had set up.

http://www.geminivalve.com/landing/...ctuated.aspx?gclid=CKLc3ZPF7qUCFQ687QodVyB0oQ

Here is a slow close valve that could be controlled by your tank float. [probably more $ than a csv however]

As you research water hammer, you will see that the rate of closing a valve or in your case the flow of water, is critical.

Most all valves over 5" have gearboxes to enforce SLOW close.

Most hydro electric penstocks have open to air pipe risers in case flow is blocked at the outlet quickly. They rise to the level of the tank or pond - surge pipes.

Then they have air intake pipes in case the outflow is blocked quickly at the inlet. Otherwise the vacuum would collapse the pipe.

Interesting business, hydraulics.

No, a checkvalve at the tank will not solve the issue, although a good spring closing checkvalve every 50 or 100' in the line might, though I would not do it.

Try closing your existing ballvalve slowly, say 6 seconds. Do not keep the flow off for long so you do not harm the pump. You should see no hammer in that test. If so the above linked valve would work.

If you use the JOBE valve, you would need a small pressure tank and pressure switch at the bottom. But you do not need wire run to the tank then.

The CSV + the JOBE valve [large adjustable drawdown and no wires] sounds like a certain cure, as I am not sure of the rate of closure of the JOBE valves when they reach high level, though I believe it to be slow like a toilet valve.

http://www.tdlagritech.com/documents/jobe-valves/more-info-topaz-differential-valve.pdf

http://en.wikipedia.org/wiki/Water_hammer

When you moved the tank, did you move the pressure switch with it?
If you didn't, That is the cause of your hammer.
Move the pressure switch with the tank, and all will be back to good.

Yes I did move the pressure switch with the pressure tank. During my troubleshooting I did try putting it back, just resulted in a constant on/off cycling. I also dug up my line to install check valves, but decided after reading on this site that it wouldn't be a good solution. The jobe valve interests me although I'm not sure if I can return the switches I already bought. If the jobe does close slowly that would hopefully do the job. I still need to take the time to understand the advantages of the csv. I could see putting one on the booster pump setup, but at the well head it seems I could reinstall the pressure switch, purchase and install a small pressure tank, and either a JOBE valve or an electric slow close valve. I will try closing the ball valve slowly today, 6 seconds, to see what happens. Thank you all for your input .

If you go with the small tank and a pressure switch, and use your electric switches on the tank, you can set the pump shut off pressure to 70 or 80 or 90 or so. That in itself will reduce the flow to a very low amount upon shut off. No hammer.

In this way you use the lowered output of your pump at higher pressures to reduce the water flow velocity.

Be sure to determine the pressure where there is at least 1gpm still flowing on shut off set point.

And I would'nt worry about the high pressures, unless you have 100psi PE down the well.

And the slow closing of the ballvalve imitates the higher pressure shut off scheme exactly, but you could try 10 to 15 seconds to better imitate it.

A pressure gauge on the pump side of this closed valve will also tell you the maximum pressure the pump will make, and thus your switch setting must be below that number.

ballvalve said:

If you go with the small tank and a pressure switch, and use your electric switches on the tank, you can set the pump shut off pressure to 70 or 80 or 90 or so. That in itself will reduce the flow to a very low amount upon shut off. No hammer.

In this way you use the lowered output of your pump at higher pressures to reduce the water flow velocity.

Be sure to determine the pressure where there is at least 1gpm still flowing on shut off set point.

And I would'nt worry about the high pressures, unless you have 100psi PE down the well.

And the slow closing of the ballvalve imitates the higher pressure shut off scheme exactly, but you could try 10 to 15 seconds to better imitate it.

A pressure gauge on the pump side of this closed valve will also tell you the maximum pressure the pump will make, and thus your switch setting must be below that number.

Click to expand...

That would work because it is imitating all the functions of a CSV. However, it is not as safe, or easy to get right as the CSV. The CSV would not let the mainline work at such high pressures, which could be up to 150 PSI with a submersible. The CSV would also not let the pump work anywhere near its shut off pressure, which would destroy the pump.

It is also hard to make a 1” or even a 2” float valve work slowly. The difference in the size of the opening at 10 GPM compared to 1 GPM is measured in thousands of an inch and happens in a fraction of a second. And if you get the float valve to work very slowly, what the CSV is doing at the other end of the line is still important.

Sounds like he will use electric valves that shut off instantly, so its worse than a float valve.

Certainly the CSV is cheaper and simpler than a slow closing electric ballvalve.

I showed him that scenario because he said he did'nt want or understand the csv on that side of the tank.

Hope he posts back with the amount of time to close the valve and have NO hammer.

Thank you guys for the possible solutions for me. I have't tried closing the valve slowly yet to see what results we get. Between the heavy rains I have been installing the booster pump set up. Guess what. Yep, problems with that too. I called the guy I bought the pump from and he said I should put my checkvalve on the intake side of my pump. I put it on the discharge side just like my submersible pump. The problem I am having is once the pressure gets to 60 the pump shuts off and cycles on/off/on/off. at first I thought maybe the contacts in the pressure switch got wet in the rain, but after talking to the pump supplier I guess not. I have purchased the larger check valve just wanted to run it by you guys before cut my pipes apart again. I have
: 1 1/4" line up out of the storage tank to the booster pump, 1" line out of the booster to a check valve, then the line goes back to 1 1/4" to a tee, one leg of the tee goes to a pressure tank and the other leg of the tee goes 300' slightly down hill and over to the house. Not a lot to it, but I managed to do something wrong. I now have a manually operated water system. Good thing I have two boys. One can turn the submersible pump on and off and the other can run the booster pump. I have a new appreciation for pump setups. I'm gunna stick to what I know and hang some doors today.

Check valve needs to go before the booster pump. Because the check has to go before the pressure switch, which is mounted on the side of the pump.

That makes complete sense thank you for clarifying that.

How are you electrically feeding your pumps? Sounds like you might have some long runs of wire. I can't quite figure out where the pump and pressure switch are in relation to each other but sounds like you have some significant voltage drops on motor startup. That is the cause of the "surge" as you describe it when the sub pump starts. If the controlling switch is up on the hill you will probably have to use a motor contactor at the well head or use some pretty big wire.

When the sub pump shuts off there is going to be a lot of energy in the column of water going up the hill that will have to go somewhere. For that reason I think part of the solution to your water hammer is going to be a water hammer suppressor (a big one) or a tank with an air space at the well head. Does your tank have a bladder or is it air over water? Can you post a sketch of your system? Your narrative makes it a little unclear.

Ichabod

I will double check my electrical to eliminate that possibility. If I remember correctly I ran #6 aluminum overhead 250'.
At the moment there are no tanks installed at the well head. I am starting to think that is part of my problem. I have the sub plumbed straight to the storage tank with no pressure tanks and an open ended pipe at the storage tank. I planned to install float switches to turn the sub on and off to fill the tank. Since this pump only serves to fill the tank I didn't think I would need a pressure switch or pressure tank.
I did do the slow closing of the ball valve test. As I slowly closed the ball valve the pressure went up to where the pressure relief was spraying hard and the guage hit 100 psi as I turned the power off at the closing of the ball valve no hammer occured. Not too excited at putting my system at these pressures evertime I fill my tank. I believe this is how the slow closing valve would work. So I would have to dial in a pressure switch at the same pressure created at the closing of the valve. Seems to me that exposing the system to those extreme pressures constantly will lead to component failures. I would much rather try to slow down the velocity and create less pressure if possible.

Small wire size does not cause water hammer. It will actually give you a soft start, which helps eliminate water hammer. See quote from Franklin Electric below.

“Reduced-voltage starters may not be required if the
maximum recommended cable length is used. With
maximum recommended cable length there is a 5%
voltage drop in the cable at running amps, resulting in
about 20% reduction in starting current and about 36%
reduction in starting torque compared to having rated
voltage at the motor. This may be enough reduction in
starting current so that reduced-voltage starters are
not required.”

From this link:
http://www.franklin-electric.com/bu...ervice/AIM/docs/M1311_60HzAIMManual_08-09.pdf

Small pipe causes water hammer because of the increased velocity. Decreasing or stopping the water velocity before shutting off or starting the pump will eliminate water hammer. The CSV does this and the only place there is high pressure is before the CSV. You don’t want your PRV prior to the CSV, and the high pressure just makes your pump think it is in a deeper well. Contrary to popular belief, higher pressure is actually easier on a pump than low pressure. High volume from low pressure puts more load on the pump than low volume from high pressure.

Don't worry about the pressure. Test it without the relief valve and see what the maximum is. What kind of pipe goes down the well?

And he may have a unintended soft start, but its irrelevant in this situation.

So power isn't crucial and high pressure is preffered, got it. Ballvalve when you say "test it without the relief valve" my pressure guage only goes to 100 should I get a higher one, and you say what is the max. I turned the pump off as soon as the ball valve is closed to keep from building a damaging pressure. Are you recommending that I cap off the pressure release, do the same test again, and see what the pressure is at when I have completey shut off the valve just before I turn off the pump? Just want to double check because it's gunna be pretty high. I have 1 1/4" PVC threaded going down the well. I have both 1" and 1 1/4" from the well to the storage tank. At first I tried the 1 1/4 then switched to the 1" to try and remedy. Seems to me I should switch back to the 1 1/4 for lower velocity.
Valveman my boys thank you. They can now take swing shifts down at the sub. I moved the checkvalve and all is good. I know that's kindergarden stuff for you, but i didn't think that all the way through. Thank you guys for your input, seriously.