Flow induced vibration 1

[S4in]

Hello everybody!
Do any of you have any tips on how to calculate vibrations caused by pressuredrop over an orifice?
It now seems that higher backpressure leads to heavier vibrations.
The flow is also fluctuating, reprociating pump.

Any tips on litterature would also be welcome!

Cheers,
Sai

 

[MJCronin]

S4in...

In piping systems, a vibration problem is usually encountered and addressed. It is rarely evaluated before the system is started-up.

General pipe support schemes have been developed for supporting control valves and orifices. Usually these involve pipe anchors and rigid, 2-way guides near the components. Alternately, there are piping "fixes" to be designed into the system, such as spargers downstream of control valves for the high pressure drop situations.

Wit regard to recommendations on literature, I have always been fond of Mary Shelly (Frankenstein), George Orwell (1984, Animal Farm, and many others),Daniel Defoe (Last of the..) and of course, my hero... the venerable and acidic PJ O'Rourke ("Parlament of Whores" and "Give War a Chance" and many, many sarcastic articles)

http://en.wikipedia.org/wiki/P._J._O'Rourke

-MJC

 

[S4in]

heh, Thank you MJCronin.
and yes, this problem was discovered after startup.. now i need to explain why.
it´d be nice to have some calculative figures to back it up with, not just saying: "It´s there"

Thank you also for the excellent literature recommendations, but I would also like some textbooks or articles discussing this problem

 

[BigInch]

Cavitation related? You don't give info, so I can't tell.
Check this,

http://www.neng.usu.edu/cee/faculty/rahm/CAVITER.pdf

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[btrueblood]

As BigInch alludes, you need to tell us more info. What frequency are the vibrations, what are the fluid & properties, pipe size, orifice dia. & length, what material...

 

[BigInch]

Its cool. I didn't want to work it out anyway.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[hydtools]

This may lead you somewhere:

http://www.cuservices.net/products_c500.html

Ted

 

[Artisi]

As it's a (reprociating)reciprocating pump, I would suggest you look at the acceleration / deceleration of flow in the inlet line as a starting point.

 

[chief]

Get hold of a hand held vibration meter and take your readings before moving fluid, and after on both sides of the RO. Calculations are not feasible in this situation

Offshore Engineering&Design

 

[hacksaw]

plate type RO's with recip's are not a good idea. they wont last and they are noisy

you need go variable speed or use a kickback valve arrangement

 

[S4in]

Thank you all for your answers!

I need to get some more data before I can come back to you, but now I have some guidlines!

Many thanks to you all!!

Best regards,
Sai