Flow Coefficient for fluid other than water 2

[jfaucher]

I'm currently doing pump sizing calculation, so I have to determine the total pressure loss of my piping system. Most of commercial components like ball valves, check valves, strainers, etc. have experimental data from suppliers indicating the flow coefficient (Cv) for water at 60degF. If I want to calculate the resulting pressure loss, I get it from following formula:

deltaP (psi) = GPM^2 * Specific Gravity / Cv^2

My problem is that the fluid in my system is oil. How to evaluate the Cv factor for other fluid than water? I assume it should depend at least on fluid viscosity?

If it is not possible to determine the Cv factor for other fluids without practical experimention, how to determine the pressure loss through the valves and other components?

Thanks for your help!

Jean-Pierre Faucher, ing.

http://www.cel-aerospace.ca

 

[racookpe1978]

6 gpm through 3/4 inch pipes?

I'm overseas, and don't have my usual references, but you need to really justify any assumption of laminar flow.

My opinion? Not laminar by any measure. 1/2 to (maybe) 1 gpm in a 1 inch to 1-1/2 pipe "might" be laminar.

 

[BigInch]

This case obviously isn't laminar. He's just making generalizations of viscosity correction factors to use, if you happen to have laminar flow in some other problem.

(Know the feeling. I'm always overseas).

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[LSThill]

jfaucher (Mechanical) and Team members

Technical Reference
ASME CONTINNUING EDUCATION INSTITUTE
Introduction to Unsteady Thermofluid Mechanical PD 382 Textbook

Frederick J. Moody
General Electric Company
San Jose, California
and
Mechanical Engineering Department
San Jose State University
San Jose, California
ISBN 0-471-85705-X


ALSO, PLEASE DO GOOGLE SEARCH
Frederick J. Moody Introduction to Unsteady Thermofluid Mechanical




L S THILL

 

[jfaucher]

racookpe1978,

My flow is laminar because I'm working with oil (not water) and the liquid temperature may average -20 degC. For example, at this temperature, the kinematic viscosity of my oil is 891 cSt, which gives me a Re = 35 at 6 GPM in a 3/4" pipe. Even at room temperature, my fluid has a viscosity of 56 cSt, giving Re = 551 (still laminar).

By the way, thank you everyones for the very helpful tips! It's a pleasure to see people sharing their experience.

Jean-Pierre Faucher, ing.

http://www.cel-aerospace.ca

 

[BigInch]

Yup. That's laminar.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[racookpe1978]

Laminar?

Heck, at -20 C it's tar! Not oil. 8<)