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ensayospredictivos

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Reply with quote  #1 

Hello friends!

It is a combustion air blower of a boiler with 1X of 1784 cpm.
The values of 1X radial direction with 4 mm/seg-rms in ODE and 6 mm/seg-rms in DE, but in the axial sense the 1X is 17 mm/seg-rms. There are no harmonics or BPF present in the graphics.
What could be producing this high 1X in axial?

Further information is needed and can be supplied.
Thank you for your valuable comments.
Regards,

Raul Rios

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jpeg Vent 4.jpg (23.61 KB, 12 views)

 
Attached Files
pdf Blower.pdf (850.84 KB, 47 views)


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Noknroll

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Reply with quote  #2 
Bent shaft? Impellor cocked on shaft,impellor warped
John from PA

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Reply with quote  #3 
What is the width to diameter ratio?  When this type fan exhibits axial vibration, they can often benefit from a 2-plane static couple balance correction.

For everything you wanted to know about fans, and then some, go to http://www.vibration.org/Presentation/Overhung%20Fans.pdf.  I think the type of fan you have and its discussion begins on slide 54.

For a discussion of static couple balancing see http://www.maintenance.org/topic/balancing-of-overhung-rotors or do a Google search.  LOts of stuff out there.
Ralph Stewart

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Reply with quote  #4 
ensayospredictivos,

Is this something that has gradually came about or is it a sudden increase for no apparent reason or is this the only history you have on the fan?

Thanks and Have a Great Day,
Ralph

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ensayospredictivos

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Reply with quote  #5 
Dear Ralp.
Appeared after the maintenance work.



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Walt Strong

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Reply with quote  #6 
"Appeared after the maintenance work."

What work was done on the fan?

If the fan is sitting on vibration isolators, then check their condition.

Check the fan wheel for excessive axial run-out or wobble; either visually or with indicator/scale.

Conduct impact test for natural frequency in axial direction.

Walt
ensayospredictivos

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Reply with quote  #7 
Hi Walt!
1.- Change motors bearing.
2.- It is not vibrations isolator.
3.- In the next week we will do a impact test.

reagards,


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electricpete

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Reply with quote  #8 

If the fan is mounted directly on the motor shaft, then you had to remove the fan wheel to replace the motor bearings.  It can result in fan wheel cocked upon motor shaft (possibly loose or damaged seating surface) which can create couple unbalance which is the scenario discussed by others.   

 

Also where are you measuring the axial vibration.

ensayospredictivos

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Reply with quote  #9 
Hi electricpete!
Thank a lot for you input.


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Noknroll

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Reply with quote  #10 
check with maintainer what type bearings went in to the motor.
its out there, but NU style bearings at both ends of motor will offer no axial locating capability
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