3 replies to this topic

[Arsal]

Attached sketch shown two pumps,both having the same specification of pump and motor,but one pump deliver maximum 30 bbls flow of naphtha and second deliver 15 bbls flow of naphtha.Suction and discharge line size of both pumps are same..

Difference is that low flow pump (15 BBls) has suction line 1st lift from the main line upto 1.5 ft then connected to pump suction nozzle.

Is any flow difference due to suction line arrangement ??

Attached Files

•  Sketch.docx   51.32KB   17 downloads

[breizh]

Hi ,

Consider reading these  papers .

 

Note : you should check the detailed drawings ( Isometric) and perform hydraulic calculation . Head losses at the suction should be minimized as much as possible and right angles avoided.

 

 

Hope this helps

 

Breizh

Edited by breizh, 10 March 2015 - 08:55 PM.

[Zauberberg]

In a parallel pumping system employing centrifugal pumps, suction and discharge pressure loss due to piping and fittings is the cause of significant flow variations in cases when the pump curve (Head-Flow) has a steep decrease of head with increasing flow. A small change in the head requirements causes relatively big change in developed flow of the pump.

 

Imagine that pump "A" has more pressure/head loss in the suction piping, than the pump "B". This results in lower NPSHA and lower suction pressure of the pump "A". For constant discharge pressure for both pumps, the pump "A" now needs to develop more Head than the pump "B". To develop more Head, the pump operating point has to shift towards left side of the curve, towards higher Head. If the Head-Flow pump curve is relatively steep, shifting towards higher Head means significant decrease of flow developed by the pump. This could be your case, although we don't know the pump details.

 

I suggest you a good reading - articles from Joe Evans available at Pumped 101:

 

http://www.pumped101...llel part 1.pdf

http://www.pumped101...llel part 2.pdf

[Zauberberg]

Apologize - where it says "steep" it should say "flat".