NPSH and the validity of siphoning effect 1

[JessCalizar]

We have a project which is to construct and additional storage tank for sulfuric acid adjacent to the existing tanks. It has been proposed that the existing transfer pumps be used for the additional tank so as to avoid additional cost. It turned out that the said proposal is plausible because the available NPSH is still greater than the NPSH required by the pump. This calculation is based on the fact that the height of the suction pipeline is constant from the tank to the pump, what will happen if there is a need to construct an overhead piperack for the suction line, and the said piperack is higher than the low-low level of the tank?, what is the static head to be considered, will it still be the low level of the tank (and holding siphoning effect to be valid) or the height of the pipe rack?

-Thanks in advance, hope you understood the situation

 

[Latexman]

The line will get longer, more frictional losses, more fitting losses, and less NPSH_A. You also have to know the pressure at the highest, furtherest away point up in the pipe rack. Calculate this "pressure at a point" and see if it will be a subcooled liquid or a boiling liquid. If a boiling liquid or close to boiling, I would advise you seek alternative approaches.

Good luck,
Latexman

 

[BigInch]

You will kick yourself for not putting a booster at the tank.

What would you be doing, if you knew that you could not fail?

 

[Latexman]

What kind of transfer pump is it? Self-priming? Centrifugal? PD? Details?

Good luck,
Latexman

 

[JessCalizar]

Thanks Latexman, the one thing i ignored was taking the pressure at the highest point in the piperack, i will look into that.
By the way, the pump is centrifugal.
BigInch, please elaborate on putting a booster at the tank

 

[Latexman]

Let us know the situation at the high point!

Good luck,
Latexman

 

[BigInch]

I don't consider siphons reliable.


What would you be doing, if you knew that you could not fail?

 

[Latexman]

BI you are right. I've heard many operators say, "the pump lost prime" when there was no flooded suction.

Good luck,
Latexman