run out of vertical shaft 2

[pradeep4u]

Dear all
we have vertical cooling tower pump which is supported on bearing at top and impellers supported by hanging at bottom. How to check run out of shaft of this pump or it is not required to check run out of shaft of this vertical pump. If it is not required then why if run out to be checked then how much run out is acceptable
Regards
Pradeep

 

[Artisi]

Why do you want to check run-out, are you experiencing any operating problems?
Depending on pump configuration /type it may not be possible.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[pradeep4u]

We are making new CT pump assembly in workshop so we are tHinking to start from beginning like checking the run-out of shafts. I just wanted to know whether run out should be checked in vertical pump or not. If run-out is checked then what is permissible run out tolerance.

 

[Artisi]

Google is your friend.
Run out vertical pump shaft.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[pradeep4u]

I am asking whether run-out should be checked in a vertical pump shaft or not?

 

[Artisi]

You asked 2 question's without any real data for a sensible answer

1, should the shaft/s be check for straightness
2.what tolerance.
For 1, probably if you have doubt regarding manufacture etc.
For 2. Depends on length, bearing spacing, speed etc.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[handleman]

You should certainly check if you have run out of shafts. Otherwise you won't be able to complete the job. Perhaps a database to track your inventory of shafts? When your inventory runs low, just buy some more. Then you will avoid running out of shafts.

 

[BrianE22]

I'm not familiar with tower pumps but I'm guessing they use long slender shafts. If so, they can have some runout without causing problems. Typically runout will produce excess bearing loads and/or excess vibration. You need to know how much bearing load and vibration you can allow and then look at the stiffnesses of the shaft and structure to estimate the bearing loads and vibration.

 

[Tmoose]

yes the runout/shaft straightness/machining accuracy should be measured at several locations and recorded.

the support at each end should be the feature that locates the shaft in service, not machining centers in the shaft end.

==============

"We are making new CT pump assembly in workshop"
Making a brand new pump, or rebuilding and assembling a used pump?
As others said, the manufacturer has the specifications you need for shaft runout and MANY other features of the pump components.

 

[JJPellin]

When we overhaul a cooling tower pump of a vertical turbine design, we would check the run-out on the shaft just above the packing gland or mechanical seal. We would do this as a final check after the assembly of the rigid coupling to verify we have no major coupling assembly issues. We would allow no more than 0.003 inch TIR at that location. Those rigid couplings can be tricky. If the run-out is excessive, the coupling is usually the problem. If the run-out is allowed to be higher than this specification, it can shorten packing or mechanical seal life or even impact the reliability of the lower motor bearing.

Johnny Pellin

 

[pradeep4u]

I attached photo of cooling tower pump assembly drawing. 3 shafts in series joined by coupler. Length of each shaft is 1.4m and diameter of shaft is 50mm.

 

[Artisi]

Is this a rebuild with new or existing parts or are you manufacturing a new pump?


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[pradeep4u]

We are making pump with new spare parts.
Regards

 

[Artisi]

I would check the shafts. especially the intermediate unsupported shaft for straightness and ensure all shaft ends are machined square and flat (no burrs etc) - you also need to ensure the shaft ends butt together on assembly, therefore trial assemble all shaft ends and shaft couplings.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)