Water Hammer Problems

Install an SMC with pump control and it will eliminate all water hammer and protect your pumps, pipes, valves and motor.

GA!

What is SMC please?

The hammer could be the check valve closing if there is a great back flow after the pump stops. Change the type of check.

The changing the check valve will not solve the problem, but it is part of the problem. Pepsi had a very similar problem with water hammer so bad they were breaking pipes. I had them install an Allen Bradley SMC with pump control and it solved their problem 100% and in fact Guy said that when the system shut down, he could hear the check valve close and no water hammer at all. They have since installed many of these on all of their pumps and have 0 water hammer.

It's a very cheap way to eliminate water hammer, save your pipes, valves, motors and any other equipment you have in your system.

Check out www.ab.com look for SMC's, but also SQD makes them Benshaw makes them. You don't have to use AB, this is just what I used to handle. Just make sure you add the pump control and you will be all set.

Also you don't need to remove current motor starter, actually it is advised to keep the existing motor starter in place with the heaters.

GA!

Agree. Change it with Disk Check Valve(spring actuated).

ducon(am on somebody's elses computer n not logged in)

Dear Anthony:

Thanks a lot for your detail explainations.

I will try to do what you suggested, and send any results if it is available.

Regards

Robert Su 090318

GA!

GA!

Robert

You have not specified the elevations of various items in the water circuitary. As water hammer phenomenon occures after about 15 seconds of stopping motor, I think, it is nothing to do with pump starting method (SMC). I suppose, the cooler should be at higher elevation than the pump and the sump, and the water must be reversing its direction towards pump and sump. In this reversal, obviously the check valve will close and water is forced to stop suddenly creating water hammer.

If this is the reason, closing the check valve little slowly will solve the problem, Or else, you may provide some buffer air chamber to absorb the water hammer energy, which should solve the problem. (This is very old technology, still best technology)

Use the axial flow check valve (NozzleCheck valve) to eliminate the water hammer. The NozzleCheck uses a short stroke, fraction of an inch movement and springs to close the disk at the Vmin (minimum velocity as the fluid reverses). This solution is minimum cost and most troube free. No motor control or power.

Hi Robert

Placing a piece of flexible rubber hose in the line often solves the problem, as it is caused by the liquid trying to expand the tubing and then the tubing contracting back.

Tony

GA from me. It is full description of what I suggested in my post.

Let's cut the crap and all the fancy names............install a suitably sized pneumatic or bladder type accumulator!!!!!!!

I have solved the same problem in a slightly larger system with an 8 mile pipe run. The water hammer takes place across a little time and the reaches a quik apex. I used a Cla-Val pilot operated pressure relief valve, I was pumping 3500 GPM in a 24 inch Diameter pipe. I used a 10 inch relief in the middle of the system and a 12 inch valve near the recieving end of the flow. The hammer never happened again.

Dear Robert SU,

As Mechanical Engineers, the other responders to this query know more than me. I do know on Civil Engineering pump applications, we use a dampener on all our check valves to delay closing time from 30 60 seconds. In a municipal distribution system, the rebound of the pressure wave from closing may take from 60 to 120 seconds. However, the longer the rebound time, generally, the more the pressure wave is reduced due to the numerous pipes and interconnections the wave travels through in a normal urban distribution system. If this is a one pipe system with few fittings, the returning pressure wave can be significant and return time would likely be rapid.

Respectfully Yours,

Christian Cooper

Put into perspective, even if a small reverse flow is allowed by the check valve, it will create a significant force when the check valve slams closed. With 300 m of pipe downstream, there is roughly 15,000 kg of water in the pipe coming to an abrupt stop!

DEAR HI,

YOU HAVE NOT MENTIONED THA YOU HAVE INSTALLED A PRESSURE TANK PARALLEL TO THE SYSTEM OR NOT?

IF NOT THEN INSTALL A PRESSURE TANK OF SUITABLE SIZE ( AS TO BE CALCULATED) OF GET VERIFIED WITH ANY PLUMBING ENGINEER TO SELECT APPROPRIATE SIZE OF PRESSURE TANK.

Try using air cushion check valve, this will solve your problem. I suggest you may contact the supplier or manufacturer for further information.

graysurpa