Balancing Axial Thrust

[PalomaP]

I would like if someone could clarify my doubts...

when a multistage pump has a balance axial thrust device (drum, sleeve or combination of both), is the axial thrust eliminated to the extend that it is not required axial thrust bearings?
If it should be required thrust bearings, what type of bearings? Hydrodinamic (kingsbury) or ball bearing? and the radial bearings?

I have a cross sectional drawing of a multistage pump with a hydraulic balance system and the only bearings that i can see are journal bearings, so It seems there is not any thrust bearings?¿?

thanks again in advance!

 

[JJPellin]

There are some pump designs that do not require any true thrust bearing. These pumps use a type of balance compensating device that completely cancels out the thrust. However, this is unusual. Most pumps have some thrust bearing. The decision to use ball bearings or hydrodynamic bearings is based on the requirements for long term reliability (favors hydrodynamic), up-front costs (favors ball), operating costs (favors ball) and condition monitoring (ball bearings allow for case readings, hydrodynamic bearings require non-contacting proximity probes.) There is a thread under the Pump Engineering forum FAQ, that provides some additional information about thrust compensation.

Johnny Pellin

 

[stgrme]

If the thrust is fully compensated, you may not need a thrust bearing to carry a large thrust load, but you do need one to ensure the proper location of the rotating element relative to the stationary parts.

You might want to look a little more closely at that cross-sectional drawing.

Regards,

stgrme