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Does it make any sense to do RPVOT test on Turbine oil that is used in an ID fan (induce draft fan at a power station)? It is not better just to do this kind of test in oil that is used in a turbine?

I asked because I have an ID fan oil (Premium R & O 100 turbine oil) that has a very low RPVOT value of 38 (in 2005 was 450) and we are debating if we should change it or no. The oil is pretty clean, viscosity is good, there is not water and the TAN is just 0.17. Maybe, it does not make sense to do RPVOT test on this application. Please advice.
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Dear Octavio,

RPVOT test measures the level of antioxidant in turbine oils. RPVOT value of 38 mins, means that you have low presence of inhibitors and the life of the oil is finishing. The degradation of the oil is measured with TAN test. Your result (0.17) is good, but the rate of increasing of TAN with the time, will be higher than before, because the RPVOT is low. For this, I will recommend that you run the TAN test more often, and when you arrive to TAN = 0.25, you should change the oil.

For monitoring fan oils, I would recommend TAN, ISO Code, Color, Metals, Water Content, Viscosity. As you comment RPVOT doesn't make sense on this application. When you fin a high TAN, you program a change of oil.

In the case of Turbine Oils, it is necessary to run RPVOT, because, you could be able to detect problems with a degradation of the oil, before of having increasing of TAN.

Best Regards,
Dear Octavio,

I agree with Cristian, the TAN is a really good indicator of your oil's condition. How often do you have a sample taken on your ID fan? This is a critical piece of equipment you probably will take a derate or a forced outage if this fan is not in service. I sample critical pieces of equipment on a monthly route. Getting back to the RPVOT test it is my understanding it is designed for turbine oils with the R&O additives. I have heard a mixed view when it comes to the test. Some like and some think that the RULER (remaining useful life) test is a better represenitive of your oil. With all that bieng said the TAN is just as good of an indication especially if you have consistent results. If you Viscosity is good and moisture is low and TAN is low then you should have good oil and adequate protection of your equipment.

Paul Lair
Dynegy Kendall Generation
Minooka, Illinois
815.521.1000 52
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