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Pump Suction Line


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#1 DANA-IF

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Posted 14 September 2015 - 09:50 AM

Hello friends 

 

Im sizing liquid line , and I would ask if a pump suction line includes all lines and manifold before  pump or a pump suction

 

 

is just the last line before the pump ?

 

Thanks a lot !

 

Regards !



#2 fallah

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Posted 14 September 2015 - 10:09 AM

DANA-IF,

 

The pump suction line includes the line (pipes, valves, fittings,...) between the exit nozzle of the relevant suction drum/vessel/tank and suction nozzle of the pump...



#3 DANA-IF

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Posted 14 September 2015 - 10:34 AM

Thanks a lot MR.FALLAH 

 

REGARDS !



#4 DANA-IF

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Posted 15 September 2015 - 02:12 AM

I'm wondering Mr. Fallah, if you can explain more why the pump suction line includes the line (pipes, valves, fittings,...) between the exit nozzle of the relevant suction drum/vessel/tank and suction nozzle of the pump ; Is it for NPSH calculation ?

 

 

regards !



#5 samayaraj

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Posted 15 September 2015 - 03:34 AM

I could not understand your query. Upstream to the pump, valve will be provided for isolating the pump during shutdown/ maintenance job. Other fittings such as bends/ reducer etc are used to route the piping from vessel to pump suction.


Edited by samayaraj, 15 September 2015 - 03:40 AM.


#6 fallah

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Posted 15 September 2015 - 04:16 AM

DANA-IF,

 

It is for NPSHA calculation and whatever matter relevant to suction line...!  In fact, a line includes all pipes, piping components, valves, inlines .... by which that line has been formed and integrated ....
 



#7 farid.k

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Posted 20 September 2015 - 04:52 AM

For me, pump suction is any component in between the main outlet of reservoir i.e. tank outlet, vessel outlet, up to the inlet nozzle of the pump. Anythings in between them is pump suction.



#8 DANA-IF

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Posted 07 October 2015 - 02:35 AM

Hello,

 

I have calculated the first  line size from the tank and its 6 " in diameter.

 

My question: Does the total equivalent length have any influence on the calculated pipe diameter since this line contains 1 tee brunch (equivalent length = 28 ft and total pressure drop = 0.09 psi)?

 

Thanks a lot !

 

REGARDS !



#9 breizh

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Posted 07 October 2015 - 07:42 AM

Hi DANA-IF ,

 

Consider this document to support your work .

 

good luck.

Breizh


Edited by breizh, 07 October 2015 - 07:43 AM.


#10 samayaraj

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Posted 07 October 2015 - 10:41 AM

Hi,

 

After calculating the pipe size, you need to calculate the pressure drop for the line. If the pressure drop is within the limit, then you no need to change the line size. If pressure drop exceeds the limit, then change the line size and do the calculation again until the pressure drop is within the limit.

 

In pressure drop calculation you need to add the equivalent length of fittings to pipe length i.e. Ltot = Lpipe + Leqt length of fittings. Ltot need to used in pressure drop calculation.


Edited by samayaraj, 07 October 2015 - 10:45 AM.


#11 Art Montemayor

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Posted 08 October 2015 - 01:57 PM

The Scope of Work for ANY pump is to allow the pump in question to receive all the liquid necessary at its design working point (and sometimes more than that) without causing the resulting NPSHa to be less than the pump's NPSHr.  THAT is the number one priority design point to consider when selecting the appropriate - and required - pump suction line size (together with all required fittings, instrumentation, etc. required).  Because of this priority design criteria, the correct and recommended size for the suction piping should be that corresponding to the correct and necessary NPSHa that should be above the NPSHr by a safe and acceptable factor.

 

Contrary to what Samayaraj states, the pressure drop resulting from the suction piping is an academic one and is over-ruled by the size required to meet the NPSHr demands of the pump.






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