Hello All 

my case is an atlas copco compressor GA132w-10 fitted with 3000 RPm Motor ABB 

number of male element and female element is not known but i suspect something will show you in the spectrum 

thsbladepass frequency

the sharp frequency is 6XTS i think its related to blade pass frequency the the time diffrence between the impacts in the waveform =0.003418 second 

so related to frequency =(1/0.003418)hz=17554.12 cpm if we check which order is this frequency we found that 17554.12/3000 = about 6XTS which related to vane frequency the family of compressors all have this frequency but this is the highest value. any ideas dears.



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741.CP114 - Compressor # 5 (05-Jan-16)
M1H 2.463 mm/Sec
M1P 1.980 G-s
M1V 3.871 mm/Sec
M1A 3.530 mm/Sec
M2H 2.111 mm/Sec
M2P .893 G-s
M2V 5.044 mm/Sec
M2A 4.309 mm/Sec
C1H 3.863 mm/Sec
C1P .251 G-s
C1V 3.834 mm/Sec
C1A 4.898 mm/Sec
C2H 7.221 mm/Sec
C2P .117 G-s
C2V 7.263 mm/Sec
C2A 8.093 mm/Sec

One reading at one location is difficult to asses a machines health. You do not state what is your symptom? Hi oil temp, poor performance, noise....

Your trend is stable on your one plot you posted, yes air compressors have vane pass/all of them, you have 32 g's pk=pk on your plot, has this value been stable or is it increasing overt time?

Was the compressor loaded at the time you took data? Vane pass typically increases and decreases when the compressor is loaded or unloaded, dirty/plugged air inlet can be one cause of why vane pass increases

Has this same pattern shown up before, look at multiple spectrums to verify

Would suggest, if you have not done so already, take data with fmax of 5000Hz or 300,000cpm with 3200 or 6400 lines of resolution 4 svgs 50% overlap in horizontal directions of your machine points

I assume that M*P or C*P are peakvue readings? If so, these values are quite small, have the trends for peakvue changed? Any specific frequency activity present in peakvue?


thank you for your attention 

firstly the pk-pk value is stable for months 

2)no complain came from this compressor but the vibration values was concerning comparing to the other compressors as the values is way smaller than this one

3)the compressor measurements conducted while loading the compressor 

4) the atlas copco used to performing their schedueled maintenance each period to change filters..etc.

5)C*p and M*P peakvue values yes and they are stable at the trend over 2 years


These type of compressors are always running like this, I monitor a few and yours look no different by terms of amplitude from this, the levels are high compared to say a fan but you guys really need to stop living by ISO tables, adjust alarming according to the past trends and then worry if something starts to increase noticeably. I use ISO for first 3-4 readings til I get a good trend then adjust alarms thereafter, use envelope or band alarms where possible.

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