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RickP330

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Reply with quote  #1 
Hi Guys,
I have two dozen of these Helium compressors.  It's a mixture of Ball Bearings AND hydraulic (Journal) bearings.  Where to start - Accelerometers or proximity sensors....

RickP

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Danny Harvey

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Reply with quote  #2 
I'm thinking maybe both. Looking further, I'm not sure how you would mount prox probes. Are you talking about permanent mounting?

What speed?  I've never encountered a helium compressor but other than the bearing arrangement it doesn't look like there's really anything that unusual about it.

Have you asked Howden if they have a standard?
RickP330

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Reply with quote  #3 
Danny,
The only difference which makes it a He compressor are the clearances set at the factory and rebuild.  Otherwise it is no different.  But the mix of Ball and journal bearings has me stumped.

Ask Howden?  What a novel idea.  Embarrassing I didn't think of it.  I'll inquire and get back to you.  But for now any ideas would be much appreciated!

Regards,
Rick
Danny Harvey

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Reply with quote  #4 
I'd do it with accels, collecting accel twf's and velocity spectra along with demod or PeakVue or whatever.  

I don't guess it's running too fast but you have to remember the normal limits on your sensor mounting.
John from PA

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Reply with quote  #5 
Quote:
Originally Posted by RickP330
But the mix of Ball and journal bearings has me stumped.


The rolling element bearings provide thrust capability that is lacking in the fluid film bearings.  See the marked up areas of the attached photograph.  You can also go to http://www.screwcompressorsspecialist.com/howdencompressoroverhaul/compressormodels/howdenwrv321compressoroverhaul.html and scroll down and examine the pictures of a unit prior to overhaul. 

This type machine is discussed in great detail in API 619 although that specification may not necessarily apply to the machine you purchased.  You would have to check the original purchase details to see what if any specifications have been invoked. 


HE Compressor thrust arrangement.JPG

Vibe-Rater

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Reply with quote  #6 
Hi Rick,

I would make a great start with accellerometers. Setting up my machine points order normalised to each shaft. Sometimes the second shaft may be higher speed 6:4 or something like that. Input speed US 4 pole? 1800 rpm?  So dominant synchronous stuff to both shafts. From there anything non synchronous is almost always bearing. rgds
Vibe-Rater

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Reply with quote  #7 
And prox probes very expensive to properly install. Best to start with accelerometers then you can step up according to your budget. rgds

Noknroll

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Reply with quote  #8 
What Danny & vibe said re: accelerometers, plus i would do some oil sampling.
OLi

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Reply with quote  #9 
I would go for absolute bearing monitoring not only it is cheaper but it gives you the chance to monitor the antifriction bearings that would be the main wear part maybe.
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Shoveldr

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Reply with quote  #10 
Installing displacement probes on that would not be something I would want to undertake in the field.  The rolling element bearings on the outboard end will let you know what is going on with the rotors.

I would take horizontal readings on the right and left sides of the compressor with a vertical and add an axial to the outboard.
RustyCas

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Reply with quote  #11 
I do a lot of large Centac air compressors with sleeve bearings on each of the high speed 'stage' impellers and a rolling-element-bearing on the bull gear. There is a prox probe built in for each stage impeller and I monitor the bullgear with an accel. Monitoring 18 compressors over 15 years, I've never seen a bad bullgear bearing, and only once a 1X vibration on the prox probes that "trended" up. All of the problems have been motor issues.

Also do a lot of ammonia compressors, and a compressor issue is very rare - it's always the motors.

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Ron Brook

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Reply with quote  #12 
This isn't Brookhaven is it? Monitored those babies for 25 years.
Ron Brook
RickP330

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Reply with quote  #13 
Ron,
I send you a private message.
Regards,
Rick
RRS_Dave

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Reply with quote  #14 

It's a Howden compressor. Use accels and collect as Danny said above. I do several Howden NH3 compressors and you can see the sleeves when they get worn. I have good luck trending the g's and spike energy on most screw compressors.

D

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