Absorbing thrust on a vertical pumpset

[impeller1]

Good day people,

Another question here, we're looking at purchasing a spare vertical pump for an existing service we have. However, the current pumpsets we have are all designed whereby the pump is equipped with thrust bearings which handle all the thrust..the unit the manufacturer in question is supplying as the spare is designed whereby the motor carries the thrust bearing and thus absorbs the thrust. Now in order for us to use this unit as our spare, it must be modified so that the pump can carry the thrust as we already have a spare motor which is not designed to carry thrust. The manufacturer is stating that their design is better by having the motor carry the thrust..I would just like to know if there is any truth to this?????

Thank You..

 

[desertfox]

Hi

impeller1 have you asked the supplier why their design is better?

desertfox

 

[MartinSr00]

Not sure about your situation, but my experience is that with most vertical pumps (say vertical turbine pumps) the thrust bearing is in the motor. It simplifies the pump and seems to result in a more compact design. If your pump is a classic vertical turbine pump, and the pump has a thrust bearing, I'd say it's a bit of an odd-ball.

If this is another type of vertical pump, say with bearings on both ends, and not with one end in a pit or a can, then I can see your problem.

Don't know the horsepower for your new pump, but you may be money ahead by purchasing a motor with a thrust bearing in it. If you want to use the motor with the thrust bearing for both pumps, all you need is a coupling with some end-float in your existing pumps.

Or, simply purchase another copy of your existing pump if it's still available.

Before adding a bearing to your new pump that doesn't have one, you may wish to make sure that you haven't converted a spare pump problem into a bearing design problem. That could get expensive!

 

[JoeySoap]

I use both types perfectly satisfactorily. I'd be very tempted to just buy a pump/motor set as the spare and change them out as a complete unit I think.

 

[dabluffrat]

It's not that the design is better, it depends on the application and thrust load.

If the motor bearing is carrying the thrust, then the pump/motor coupling must be a rigid style coupling to transfer the thrust, if the pump has a thrust pot/bearing below the coupling, then the design allows for a flexible spacer type coupling. Typically a flex type coupling will run with less vibration, but it's a pain in the a$$ to disassemble and reset the thrust bearing every time you need to change out the seal. There's also consideration for the size of the thrust bearing, cooling methods available on site, and thrust direction.



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[hbw]

It is a question of magnitude. Thrust applied to a motor bearing must be within the allowable thrust load for that bearing. The pump manufacturer should advise you of the pump thrust and the motor thrust capacity.

Both types can be successful but keep in mind that the motor bearing is not specifically designed for your thrust load whereas the pump thrust bearing is specifically selected for this thrust.