2 replies to this topic

[stianhp]

Hello everyone.

 

I have been working as a process engineer for about 6 months so my skill level is fairly limited.

 

My company is recieving a centrifugal pump from our HQ in Germany and I need to figure out the size of the motor. We are going to pump 50 % KOH (potassium hydroxide).

 

Parameters 50 % KOH:

 

rho = 1510 kg/m3

Dynamic viscosity = 6 - 6.5 cP @ 30^oC

Kinematic viscosity = 4.3 * 10^-6 m²/s (6.5 cP / 1,51 = 4.3 cSt, 4.3 cSt = 4.3 *10^-6 m²/s)

 

According to KSB (Pump manufacturer), the viscosity only has to be corrected using empirical correction factors for kinematic viscosities above 20 * 10^-6 m²/s.

 

Since I don't need to make any corrections regarding the viscosity, do I still need to make corrections regarding the specific gravity of the fluid ?  (I have a feeling that I might)

 

Any help will be appreciated.

 

Stian

[xavio]

stianhp,

 

The calculation of centrifugal pump power requirement is quite straightforward, abundant information can be easily found.

This is one of them  http://www.engineeri...ower-d_505.html

 

P_h = q ρ g h / (3.6 10⁶)           

where

P_h = power (kW)

q = flow capacity (m³/h)

ρ = density of fluid (kg/m³)

g = gravity (9.81 m/s²)

h = differential head (m)

 

 

P_s = P_h / η          

where

P_s = shaft power (kW)

η = pump efficiency

 

 

Your liquid is not viscous, do not bother with the viscosity corrections.

 

What do you mean by correcting the specific gravity?

 

To size the motor you will need more than just rho and viscosity, you lack many basic data.

Once you get the Ps (= brake power), you can add some margin and select suitable standard size motor.

Remember to specify the motor rpm as indicated on the pump curve.

 

I suggest you to let KSB guys help you.

Good luck.

 

xavio

 

[breizh]

_Hi,

 

_{On top of what Xavio  explained , you can use this handbook to support your query .}

 

_Breizh