Lub Oil Varnish

[NCTHAI]

Team,

I am new to this forum. At our powerplant we are looking for various methods for varnish controls and has installed two different system.

In order to evaluate oil conditioning system for varnish removal, have taken sample before and after systems were in place.

Can you please let me know if there is any standard method for measuring varnish in lubricating oils used in power plant equipments?

Thanks,

 

[Murec]

We use a test called RPVOT ( Rotating Pressure Vessel Oxidization Test )

 

[unclesyd]

These sites gives you the basic information on the QSA test for measuring the potential to form varnish (VPR) in your oils.

http://www.machinerylubrication.com/Read/761/varnish-test-lubricant

http://www.analystsinc.com/pages/3365/QSA®_FAQ.htm

 

[electricpete]

Interesting. The QSA sounds interesting. But there is no ASTM standard yet, and that is a reason for caution imo. There is abundance of ASTM tests which have been carefully studied and documented. A lab comes up with a new test and says "look... we've got the best thing since sliced bread"... well it could be, or it could be marketing hype to get you to switch to that oil lab because no-one else offers that test. If it really is that good it will eventually become an ASTM standard test, and then it'll be worth looking at imo.

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(2B)+(2B)' ?

 

[unclesyd]

electricpete,
Regardless of the fact it isn't an ASTM it is about the only game in town as far as prediction (VPR) of a lube oil to form a varnish. As you are probably aware there are many test conducted on different materials that are not covered under ASTM or any standard.
One item of note, directly from the horses mouth is that the suppliers of lube oils don't particularly care for the test unless their lubricant has a very low VPR, which can be used as a selling point.

 

[electricpete]

As you are probably aware there are many test conducted on different materials that are not covered under ASTM or any standard.

In the lube oil world, all of the "standard" tests are described by an ASTM standard: water by Karl Fisher, viscosity, particles by ICP or RDE or RFS, ISO cleanliness code, RPVOT. Even color has an ASTM standard. Also TOST although that's not a routine test.

If you open the door to proprietary tests, there will be a lot more. What about "ruler". What do these proprietary tests really mean.... how repeatable are they... what are their limitations? There is only one entity that can tell you and that is the lab that invented the test. Are they going to give you an objective opinion on the value of proprietary test? Don't think so.

Maybe it is just my excuse for being lazy and waiting for new technology to be accepted by the mainstream community. We don't have the time or energy to be the guinea pigs and do research for items that are not core business at our plant. Could we be missing out on a valuable tool for a few years? Sure could. Could we be saving time on other tools that would be a waste of time.. sure could.

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(2B)+(2B)' ?

 

[electricpete]

I guess what I am saying is a matter of strategy and opinion... nothing to do with the merits of the test itself.

Each person/company can decide such things for themselves. Since you have brought new info for the original poster to consider, that is certainly valuable contribution.

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(2B)+(2B)' ?

 

[25362]

Try reading ASTM D943 and D2893 to see whether these standards satisfy your requirements.

 

[NCTHAI]

Thanks to all for your responses and information provided.

Here is few items from experience. Have find out two different tests to determine varnish level
Method 1: Membrane Patch Colorimetry (MPC) This method is in accordance with ASTM Draft standard. This draft standard - not approved yet. In this method, 50 ml of oil is mixed with 50 ml of petroleum eather. This mixture is filtered under vaccum of 71 kPa. After removing vacuum, filter membrane is dried by heating and they colour is determined of this membrane patch. Each colour is given index number.

Method 2: VPI. This method is same at above with difference that petroleum eather is not mixed - pure oil is used and no vacuum is used while filtering. Filter membrane color is determined and index number is assinged.

Need to know which method is better??? One of the opinion expressed is all varnish present in oil is dissolved in petroleum eather and hence Method 1 is not accurate and reliable.

Please share any other opinion and experince on the subject.

Regards,

NC

 

[drwebb]

ASTM standards are administered by technical experts who are VOLUNTEERS (supported by their employers). I mention this because of the statement "We don't have the time or energy to be the guinea pigs and do research for items that are not core business at our plant."