bearing condition unit (bcu)

hi dear

is there any one have information about  alarm and danger value  of  bearing condition  unit (bcu ) for different power and speed of machine  . this parameter use in schenck portable analyzer .

 

best regards

Original Post
John from PA posted:

There are numerous ISO specifications that have suggestions based on machine type, power, speeds etc.  Google "iso vibration standards" (without the quotes) and you'll get some examples.

dear john

i read iso10816.but for this parameter that related to acceleration sensor with (g) value for amplitude i cant find any reference . because iso standard mention only overall vibration limits.

Aziz58,

I have not seen any standardized limits for BCU, but you can keep searching. Here are some links:

Google: bearing condition unit (bcu) limits

 "BCU is not used industry-wide or within international standards. You need to contact Schenck or search their Website." 6/16/10 by Strong
Pasted from <http://www.maintenance.org/top...on-units-bcu-schenck>

Bearing Condition Unit (BCU)
Pasted from <http://www.schenck-usa.com/pro...stems/vibro/VT60.php>

Typical condition monitoring scalar measurement techniques include the BCU (Bearing Condition Unit) or the BCUp (Bearing Condition Unit Peak).
Pasted from <http://www.bkvibro.com/en/moni...lement-bearings.html>

http://inplantservices.com/pdf...bration-analysis.pdf

 http://bruel.hu/doksik/vc1100e.pdf

There are a number of high frequency "bearing units", so it is best to rely on instrument manufacturer for initial settings and then make your own changes. SPM units differ from Schenck and other companies.

Walt

thanks for all

before i post this topic i had read those articles . but unfortunately couldn't find useful things. as i know    bcu measured the peak amplitude in (500-5khz) frequency rang.

when usually  we measure the overall vibration in (1-1000HZ) rang. how should i correlated this values?

beat regards 

Aziz,

http://www.cdnova.com/Portals/...ation%20Analysis.pdf

From what i've seen on page 35 it is very similar to enveloping process. 

BCU : Band pass filter - Rectify - RMS 

BCU= Final RMS / Initial RMS

So they are measuring BCU at the initial stage with everything is in good condition and then trending it. Back to original question, " is there an alarm limit or danger point for BCU? " I guess it all depends on the band pass filter they are using and that, we don't know.

But if you are regularly measuring narrow band filtered vibration (enveloping) you may have something to compare with. As an example lets say you are measuring 5kHz - 20 kHz band on a motor bearing regularly. You have a spectrum and RMS value of that spectrum that can be trended. When you have a bad bearing check your RMS value and compare it with brand new installation RMS. That ratio should be your BCU limit for that application and for that frequency range.

These are what i think and of course not solid informations and needs confirmations. 

Serdar posted:

Aziz,

http://www.cdnova.com/Portals/...ation%20Analysis.pdf

From what i've seen on page 35 it is very similar to enveloping process. 

BCU : Band pass filter - Rectify - RMS 

BCU= Final RMS / Initial RMS

So they are measuring BCU at the initial stage with everything is in good condition and then trending it. Back to original question, " is there an alarm limit or danger point for BCU? " I guess it all depends on the band pass filter they are using and that, we don't know.

But if you are regularly measuring narrow band filtered vibration (enveloping) you may have something to compare with. As an example lets say you are measuring 5kHz - 20 kHz band on a motor bearing regularly. You have a spectrum and RMS value of that spectrum that can be trended. When you have a bad bearing check your RMS value and compare it with brand new installation RMS. That ratio should be your BCU limit for that application and for that frequency range.

These are what i think and of course not solid informations and needs confirmations. 

thanks so much for reply and useful manual .

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