Effect of Viscosity on pump performance

[Sawsan311]

Dear All,,

I was going through the below TOTM by Jon Campell discussing the impact of viscosity increase on pump performance curves. Figure 2 in below post is discussing that for flow of 0.6& Q BEP, there will be a comparative increase in the delivered head compared to the base case curve. Do you agree that in this case, the delivered pump's discharge pressure could be higher for the same suction pressure.

can we rely on suction correction figures and factors for estimating the viscosity effect while having a base case pump curve represented based on water test.
I understand we have to go back to vendor to check, however, there are situations where overcooling may cause wax formation in crude and exponential increase in viscosity that needs to be checked with respect to the impact on system's hydraulics.

regards,

http://www.jmcampbell.com/tip-of-the-month/2006/08/effect-of-viscosity-on-pump-performance/

 

[TiCl4]

Sawsan,

By my reading, the C factors in figure 2 are correction factors, not actual head. In all cases, the correction factors are less than unity, meaning in all cases a higher viscosity will result in a lower head delivered, no matter where the pump is on its curve.

The C factors being higher at 0.6 BEP than at 1.0 BEP just means that pump head is not as much affected at 0.6 than 1.0 BEP.

 

[Latexman]

Look at Figure 1 for the typical viscosity effect on a centrifugal pump’s capacity, head and efficiency.

can (sic) we rely on suction correction figures and factors for estimating the viscosity effect while having a base case pump curve represented based on water test.

What else is one to do? Don’t correct for viscosity and be off the design? The previous correction method has been used successfully for decades, and the new method is improved. Yes, I will rely on it. The previous method worked okay for me.

Good Luck,
Latexman

 

[pierreick]

Hi ,
A good booklet for centrifugal pumps from KSB .
Pierre

 

[pierreick]

Hi,
You may find some interest in the doc attached (similar to one from Campbell ).
Good luck
Pierre

 

[Sawsan311]

Thanks all for your replies,

@TiCL4, Thanks for the clarification, I misread the solid black curve in figure 2 thinking it is the base curve case but it is only at the BEP