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Associate

Join Date: Jul 2008
Posts: 29
Good Answers: 1

Pump NPSHA and TDH

09/15/2017 2:19 AM

Hi,

A pleasant day to every one . . .

Can somebody direct me to a website were i can use to compute for the NPSHA and TDH of pump to be used in Petroleum.

or, perhaps, you can suggest on what should i do to compute for the NPSHA and TDH

Many thanks

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Power-User

Join Date: Feb 2007
Location: Aberdeen, Scotland
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#1

Re: PUMP NPSHA and TDH

09/15/2017 3:07 AM

I typed in "net positive suction head online calculation" and found this

http://irrigation.wsu.edu/Content/Calculators/General/NPSHA.php

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Guru
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Join Date: Mar 2011
Location: Lubbock, Texas
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#3

Re: PUMP NPSHA and TDH

09/15/2017 11:39 AM

It depends a lot on the layout of any storage tanks, height offsets relative to the pump, pipe sizing, and the layout and sizing of pump discharge.

You usually take these numbers off "good" working areas for the pump, and then design the system around the pump, not the other way around.

Have people forgotten how to "think and work backwards" in order to go forwards?

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Anonymous Poster #2
#7
In reply to #3

Re: PUMP NPSHA and TDH

09/18/2017 2:33 AM

I would assume that he needs to do these calculations on a system in order to acquire a suitable pump, not the other way round.

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Guru

Join Date: Oct 2009
Location: sometimes Wales,UK.. was Libya, now Oman!
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#4

Re: PUMP NPSHA and TDH

09/16/2017 8:43 AM

a bit more info required,, what is the application of this pump?
What are you going to pump, well fluid, light crude, water????
What will be the total height of the lift of the fluid, or distance, what size tubing/pipework.
What type of pump are you thinking of using, single stage or multi-stage centrifugal pump.

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Associate

Join Date: Jul 2008
Posts: 29
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#5
In reply to #4

Re: PUMP NPSHA and TDH

09/16/2017 9:52 AM

its actually Diesel, and the suction line has 145 m of 12 inch header pipe, there will be 2 units of pump (size 6x5) parallel installed and a possibility of the the third pump rated @ 180 m3/h capacity.

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Power-User

Join Date: Jul 2016
Posts: 371
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#6
In reply to #5

Re: PUMP NPSHA and TDH

09/16/2017 11:21 PM

This website does a good job of getting the friction losses taken care of, you need to know the liquid properties, temperature/viscosity/density, then add the static components (elevation differences) to get the total head at your suction and discharge. In addition to your piping components, wherever you have a velocity change, you should have a component selected, such as entrance or exit loss when going between a tank and a pipe.

The NPSHA includes elevation difference from pump c/l to liquid level, and is in absolute pressure units, so you start with 1 bar/ 14.696 PSIA if the tank is vented, for instance.

http://www.freecalc.com/fricfram.htm

The TDH includes the vertical distance from pump centerline to the same pressure reference as your suction side, also usually atmospheric.

Cameron Hydraulics has a step by step process, pages 1-10 and 1-11 show NPSH procedures.

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