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Viscosity
3

Viscosity

Viscosity

(OP)
What is the practical / maximum viscosity limit for centrifugal pumps ?
Please advise.
Thanks

RE: Viscosity

Figures 1.52 and 1.53 in the publication:

ANSI / HI 1.1-1.5-1994
American National Standard for Centrifugal Pumps
for Nomenclature, Definitions, Application and Operation

suggests that you can apply correction factors for performance with viscosities up to 2200 cSt for small pumps (Q<=100 USGPM @ BEP) and about 4000 cSt for larger pumps.  One might infer that these represent industry-accepted practical limitations.

Also, I think I read somewhere that the affinity laws for centrifugal pumps start breaking down when viscosities exceed 50 cP.  Might have been in the Hydraulic Institute Standards.

Regards,

SNORGY.

RE: Viscosity


Sulzer in its Centrifugal Pump Handbook (Elsevier) says:

Quote:

The economical duty limit for centrifugal pumps is about 150.10-6 m2/s. Use of a centrifugal pump is possible up to about 500.10-6 m2/s. but a higher NPSH must be made available for this higher viscosity. Channel impellers and torque flow pumps allow higher values (800 to 1000.10-6 m2/s), depending on size and type.

BTW, 1 cSt = 10-6 m2/s.  

RE: Viscosity

I think ANSI/HI 1.1-1.5-1994 has been now superseded by ANSI/HI 1.1 1.2:2008 ("Rotodynamic (centrifugal) Pumps For Nomenclature And Definitions").

You might also want to consult ANSI/HI 9.6.7 ("Effects of Liquid Viscosity on Rotodynamic Pump Performance"), which presents a revised procedure and equations to predict pumps performance or give a shot to this handy calculator:
 http://www.lightmypump.com/viscosity/Viscosity.html
 

RE: Viscosity

ione:

I am old.  I stopped collecting stuff years ago when it started to hurt too much to bend over to pick things up.

smile

That said, I should (and will) endeavour to get a copy of the more recent publication.  Thanks for letting me know.

Regards,

SNORGY.

RE: Viscosity

(OP)
I would like to thank everyone who provided their valuable input.

RE: Viscosity

Snorgy,

If you find a large print version, post back.

rmw

RE: Viscosity

aiwa7777,

The original question could be a little misleading.  I would be hesitant to answer unless I knew the head and flow required.  Do you have a small pump that only requires 10 GPM with 10 feet of head or are you trying crude oil pipeline pumps?  

Knowing a little more about the application would help.  Economics ultimately should determine the answer.

D23

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