Water Hammering when valves open

[ABADI8891]

Hi Gents;

I'm facing a burning issue here in the facility that I'm working in. It's something happening since plant start-up, but no one picks it up.

however, in one of the water feed lines to a 72m3-4 to 5 bar pump, we are observing a very high and annoying hammering issue, and due to this issue, one of the pipe support broke.

Usually, hammering happened when we close valves, but in my case, this hammering happens when our pneumatic valve open to feeds the above pump. Mainline can supply>75m3 with 5 bar from water treatment plant located approximately 100 m away.

* How to eliminate this issue?
* Why it's happened only when the valve opens, not when it's close!!!

Many thanks

Side note:
*

I could not slow down the opening speed of pneumatic valve.​

 

[davefitz]

perhaps there is ocurring a closure of a check valve in another part of the system that occurs when that isol valve opens.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[LittleInch]

Same effect, I.e a sudden increase in pressure. I can't really understand what this second pump is doing though as flow and pressure seems to be the same.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[GD2]

OP,
A change in direction (change in momentum) is also a cause of water hammmer. Post a layout of the piping to understand more on the cause.

GDD
Canada

 

[btrueblood]

Open the valve first, then start the pump?

 

[RVAmeche]

How quickly is this valve opening? We had an experience where the contractor forgot to install speed control mufflers on the solenoid vents of 12" butterfly valves, so they were opening/closing very rapidly causing lots of water hammer issues.

 

[ABADI8891]

Hi gents;

Many thanks to you for your valuable input.

perhaps there is ocurring a closure of a check valve in another part of the system that occurs when that isol valve opens.

it's checked but we did't find what you mentioned. thanks

Same effect, I.e a sudden increase in pressure. I can't really understand what this second pump is doing though as flow and pressure seems to be the same.

You are correct, no need for this pump if supplied water came with parameters i gave. (BUT) there is a branch in the same header connected to tanks. Refer to attached Flow chart.

A change in direction (change in momentum) is also a cause of water hammmer. Post a layout of the piping to understand more on the cause.

you are correct, we have to many elbows and pipe fittings all the way. what should be done to reduce this effect rather that change whole system

Open the valve first, then start the pump?

Yes, this is what happening.

How quickly is this valve opening? We had an experience where the contractor forgot to install speed control mufflers on the solenoid vents of 12" butterfly valves, so they were opening/closing very rapidly causing lots of water hammer issues

From fully close to fully open i would say 1 Sec or less.. in your case after you installed the muffler, have the issue disappeared? how quick your valve was closing and how quick is now? what is the Air pressure supply to your valve?

 

[danschwind]

Well, if you are closing your valve in less than a second, I highly suspect that is the issue.

There are some applications where such a fast closing is desirable, but I don't think this is the case here. Try fiddling with the closing times and see if your problem disappears.

 

[RVAmeche]

Yeah speed of operation definitely needs to be slower. We had ~100 psi air to the valves and they were operating in less than a second as well resulting in significant hammering. Once we installed the mufflers and got the speeds to ~4 seconds (I think) things were a lot smoother, but the time for your valves will be system dependent.