Hi Steve
Thank you for your mail, sorry if my description is
confusing, I meant completely same as yours about one
way surge tank operation, I found that I need 800 cu
meter water in one way surge tank to prevent entering
air to pipeline, this is very huge amount of water
which seems impractical, should I put a smaller one?
In this case air will enter to system, I am afraid
about this amount of air in priming.
Would you please let me know your opinion?
Best regards
Omid
> Hi Omid
>
> I am a little confused by your description of a one
> way surge tank. The
> ones I am used to have a check valve which lets
> water into the pipeline
> when the pressure drops below the surge tank static
> head, as described
> in Karassik's Pump Handbook. They are normally
> located below the
> hydraulic grade line to stop them running out of
> water when the system
> is off. The check valve prevents the tank from
> overflowing during normal
> operation. Recharge is normally by a branch off the
> main line and a
> float valve. In many circumstances I have found them
> specified where
> reliable vacuum breakers (or some times a standpipe)
> would work at far
> lower cost. Water hammer software allows for the
> cushioning effect of
> the air, although the exact details are seldom
> forthcoming from the
> software vendors.
> The main problems with vacuum breakers are
> reliability assurance (double
> breakers sometimes used), avoiding hammer in the
> empty pipes on startup
> (prime lines under throttled conditions) and what to
> do with the trapped
> air in the system (two stage air valves or separator
> at discharge if the
> hydraulic gradient permits).
> From what you describe it sounds like your check
> valve lets water into
> the tank but not out. Obviously I am missing
> something here, as such a
> system would not help on a downsurge.
>
> Could you clarify your arrangement please?
>
> Cheers
>
> Steve
>
> -----Original Message-----
> From: Omid Hamlehdar [mailto:omid_7_ae@yahoo.com]
> Sent: Tuesday, December 07, 2004 6:06 PM
> To: PipingDesign@yahoogroups.com
> Subject: RE: [PipingDesign] Surge Tank
>
>
>
> Dear Erik
>
> Thank you for your reply,
>
> As I have mentioned it is a one way surge tank and
> so,
> I have modeled a swing check valve to prevent tank
> from draining back when pump is off.
>
> As you mentioned Surge tank prevents a fluid column
> separation and rejoining but I have modeled a one
> way
> surge tank which is different as you know.
>
> My concern is about this column separation, I
> suppose
> to locate an air valve (twin air valve from Erhard)
> to
> allow this air will be released, but I still want
> to
> know your opinion, do you think it is ok if air will
> enter to system after water has been finished in one
> way surge tank? Actually I have found that I need a
> huge amount of 800 cu meter to prevent air entering
> to
> system but it is impractical, I have decided to
> allow
> air enter to system after water has been finished in
> a
> smaller one way surge tank and locate an air valve
> to
> allow air released in re-starting.
>
> Best regards
>
> Omid
>
> --- Erik Scheir <erik.scheir@pandora.be> wrote:
>
> > What are the boundery conditions ?
> > Is there a receiver at a height over 33ft above
> the
> > level of the tank from
> > which the water is drawn?
> > Is there a valve a the end of the pipeline who
> > closes to prevent the tank
> > from draining back when the pump is off?
> >
> > A surge tank prevents a fluid column separation
> and rejoining.
> >
> > When air enters the pipe and the pump is
> restarted,
> > the column of water will
> > be accelerated into a partial empty pipe. Given a
> > long anough void, the
> > column of water can accelerate to its terminal
> > velocity of perhaps 5 to 10
> > fps before striking the valve face.
> > Upon collision with the valve, the kinetic energy
> of
> > motion is converted
> > into potential energy by compressing the liquid.
> >
> > There should always be water in the surgetank.
> >
> >
> >
> >
> >
> > _____
> >
> > Van: Omid Hamlehdar [mailto:omid_7_ae@yahoo.com]
> > Verzonden: maandag 6 december 2004 11:51
> > Aan: PipingDesign@yahoogroups.com
> > Onderwerp: [PipingDesign] Surge Tank
> >
> >
> > Hi everybody
> >
> > I have a question and will be pleasure to have
> your
> > opinion.
> >
> > After analysis a pipe line for water transfer
> > purpose,
> > I found that I have extreme down surge, to
> suppress
> > this surge I assumed a one way surge tank, my
> > question:
> >
> > 1. Is it ok if air will enter in pipe line
> > after water
> > has finished in one way surge tank?
> > 2. In terms of restarting (priming) the line,
> > if air
> > has entered to system, is there any consideration
> > required regarding probable impact regarding
> column separation in
> > line?
> >
> > Your contribution is highly appreciated
> >
> > Omid
> >
> >
> >
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