Pump suction pipeline size less than pump suction nozzle
Pump suction pipeline size less than pump suction nozzle
(OP)
Is it acceptable if the sizing of pipeline size at pump suction less than pump suction nozzle size?My case is the designer selected to use suction pipe of 2 inch,but the pump suction nozzle is 3 inch.The pump is normal centrifugal type,suction size on the front and dischrage on the top.Please advise the reason if reject or accept.





RE: Pump suction pipeline size less than pump suction nozzle
Offshore Engineering&Design
RE: Pump suction pipeline size less than pump suction nozzle
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pump suction pipeline size less than pump suction nozzle
A.
RE: Pump suction pipeline size less than pump suction nozzle
Bear in mind that quite often the inlet flange size has nothing to do with the impeller eye diamater - if the impeller eye is lets say 2.375" diameter it stands to reason you would have a 3" flange.
RE: Pump suction pipeline size less than pump suction nozzle
RE: Pump suction pipeline size less than pump suction nozzle
RE: Pump suction pipeline size less than pump suction nozzle
RE: Pump suction pipeline size less than pump suction nozzle
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"Pumping systems account for nearly 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Pump suction pipeline size less than pump suction nozzle
Consider that a pump with a 3" suction could (in a 60HZ world) be operating at 3600 rpm, or 1800, or 1200....
While a 4" pipe would probably be required while running at 3600 rpm, if the pump is running at 1200 rpm, the flow rates are possibly low enough that a 2" pipe would not cause problems.
But that requires input on flow rates, pressures, viscosity, pipe runs, etc etc. One would hope that the piping designer did actually check this, but that's certainly not a given.
RE: Pump suction pipeline size less than pump suction nozzle
Why did the Designer deviate from textbook recommendations? Many good points have been made on why it may be ok to deviate, but what was the rational of the Designer?
RE: Pump suction pipeline size less than pump suction nozzle
Perhaps he actually made the system curve and it showed that the operation point and NPSHr was satisfied with a smaller suction pipe. What's the problem with that?
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"Pumping systems account for nearly 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Pump suction pipeline size less than pump suction nozzle
BigInch, agreed, it is conceivable that the Designer has done his/her due diligence, but how probable? A quick look at my Goulds Pump Manual states that reducing the suction line size "should never be smaller than the suction connection"; I would think that would be a typical requirement of any OEM. The OP should have his bases covered well if he is going to lift OEM liability.
RE: Pump suction pipeline size less than pump suction nozzle
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pump suction pipeline size less than pump suction nozzle
Even if it works, its not something I would want to do anyway, unless GREAT advantage were to be had, as process systems always tend to increase their flowrates eventually. Why make expansion at a later date so difficult, unless you could really save a tonne of money today. Possible, but probably not much is going to be saved by changing an 8" suction to a 6" inch, etc. But stranger things have happened, right? All I'm saying is that there could be a very real and valid reason as to why it was made that way.
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"Pumping systems account for nearly 20% of the world's energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Pump suction pipeline size less than pump suction nozzle
I agree re shooting in the dark - but before we lay this to rest the point regarding suction lines should be clarified for those others who might be interested now or in the future.
The sizing of a pumps inlet pipework is solely a function on NPSHa / Npshr, OEM and text books don't ensure that the margin is correct.
However, common sense usually prevails and the same size or the next size line is normally used and in most cases sufficient- although in a case of a long inlet line even the next size up could be a problematic, NSPHa always needs to be checked.
RE: Pump suction pipeline size less than pump suction nozzle
Like BigInch, Artisi et al have said, it could well be that the system has been designed adequately to accept the smaller pipe, so we cannot comment too much, but the above are potential resultant factors...
...as well as that, you will give the manufacturers ample opportunity to reject any potential warranty claims that may come out of what they would deem to be "not a recomended installation" - Most IOM manuls would state pipework being ideally 1 size larger than the flange size !!
Ash Fenn
www.cdrpumps.co.uk