Which is best param. to identify oxidation???

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Dear All,
Upon opening due to high bearing temp., excessive varnish formation was observed on the 3rd stage journal and lower pads of a 3 stage (rpm 39000 - turbine+ bull gear driven) Ingersol-Rand plant air compressor.
It is understood that varnish formation is a consequent effect of oxidation due to high oil temp. Oil used is Mobil DTE lite. Oil inlet temp. is <35deg. Bearing Clearances set as per manufacturer's spec.
A permanent solution to this is changing to synthetic oil, and the idea is on the anvil. Well, TAN and viscosity being the primary parameters for highly oxidised oil, lab analysis results does not show any significant changes from the base level. No bad odour and excessive discolouration is also observed !!
Since all these 'thumb rules' failed, I wish to know which is the best parameter to identify oxidation? Although we don't have test facility, I am curious to learn how helpful is RBOT and FTIR data? How's FTIR values interpreted?
Voltametry test???- is this test performed in manufacturing level, or can be adopted for investigation in such a case???
Your valuable suggestions solicited.
Kind Regards,
Sajeev

2/16/052:51 AM

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nnkmenonMember

RPVOT and FTIR will give best results in your case.The TAN is also a significant test to confirm the oxidation.A 0.20 mgKOH/gm increase from the basic TAN would be a matter of concern.
Expect more experts to react.

3/19/051:08 AM

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dcandersonMember

If you have a Centac air compressor, Mobil DTE Light is no longer approved for use. The problem you are seeing is why. Need to change to Techrol Gold Synthetic Lubricant.

3/20/0512:17 AM

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roboMember

Dear Sajeev,

Although the suggestion dcanderson proposes,change that to a different oil, might be right, it does not at all tell you the root cause of the temp rise and varnish you encountered.

Next to the acid nr you should also have the ambient temperature at nominal and max load to think about. Next to that a check on the used filter should be performed.
Acid nr tells you something anout the degradation (loss of properties)
Ambient temperature defines to wether this type of oil and viscosity is good enough for this conditions.
A check on the particles found in used breather and oil filters can sometimes tell you more about the fenomena you encounter.
Some oils, although looking and smelling good, fail due to getting "crunched" so breaking the molecules. Also some... oils do not have enough sticky aditives and therefor will not adher well enough to the gears and bearings.

Keep a good track record on analysis (minimum 1-2 times a year)ormore depending on the nr of working hours.

And if you still not have found the answer send me a mail.

quote:
Originally posted by Sajeev:
Dear All,
Upon opening due to high bearing temp., excessive varnish formation was observed on the 3rd stage journal and lower pads of a 3 stage (rpm 39000 - turbine+ bull gear driven) Ingersol-Rand plant air compressor.
It is understood that varnish formation is a consequent effect of oxidation due to high oil temp. Oil used is Mobil DTE lite. Oil inlet temp. is <35deg. Bearing Clearances set as per manufacturer's spec.
A permanent solution to this is changing to synthetic oil, and the idea is on the anvil. Well, TAN and viscosity being the primary parameters for highly oxidised oil, lab analysis results does not show any significant changes from the base level. No bad odour and excessive discolouration is also observed !!
Since all these 'thumb rules' failed, I wish to know which is the best parameter to identify oxidation? Although we don't have test facility, I am curious to learn how helpful is RBOT and FTIR data? How's FTIR values interpreted?
Voltametry test???- is this test performed in manufacturing level, or can be adopted for investigation in such a case???
Your valuable suggestions solicited.
Kind Regards,
Sajeev

3/21/0510:36 AM

❤️ 0