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FLUITEC INTERNATIONAL | www.fluitec.com

Turbine Oil Oxidation Research

Test  Start of 

Test Value 

End of 

Test Value 

Comments 

Viscosity (cSt @ 40C) ASTM D‐445M 

31.7  32.1  Insignificant. Within Test Reproducibility. 

Acid Number (mg KOH/g)  ASTM D‐664M 

0.10  0.11  Insignificant. Within Test Reproducibility. 

RPVOT (mins) ASTM D‐2272 

945   900  Insignificant. Within Test Reproducibility. 

Membrane Patch Colorimetry  Draft ASTM Standard 

2  57  Very Significant. Indicates high varnish potential. 

RULER™ – Amines (% of new) 

ASTM D‐6971 

100%  91%  Significant. Close relationship to RPVOT values. 

RULER™ – Phenols (% of new) 

ASTM D‐6971 

100%  17%  Significant. MPC increases as Phenols deplete. 

0102030405060708090100

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1 2 3 4 5 6 7 8

ViscosityANRPVOTMPCAminesPhenols

Summary of Oxidation Experiment

The results of the experiment show that Viscosity, Acid Number

and RPVOT show little change over the course of the 8-week

experiment. However, there is a clear change in looking at the

RULER results which measures the amine and phenol

antioxidants. There is also a significant rise in the Membrane

Patch Colorimetry test, which is measuring the accumulation of

oil oxidation products. The summary of the experiment

demonstrate the effectiveness in monitoring individual

antioxidants in aged turbine oils and some of the challenges in

using RPVOT and other testing methodologies. The experiment

also illustrates the value in running RULER™ testing along with

MPC testing.

MPC Patch at End of Test

RPVOT: 1850

Very high varnish potential.

MPC Patch at End of Test

RPVOT: 217

Very low varnish potential.

Understanding How Turbine Oils Degrade

Oil analysis has been the primary tool to detect incipient lubricant

failure for the last half century. The first step however in

determining an appropriate test slate for turbine oil is

understanding its mode of failure. Fluitec personnel were part of

a research project during which five turbine oils were circulated in

immersion heated baths at 120oC for 8 weeks (ASTM Paper

JAI100465). A wide range of analytical tests were performed in

order to better understand which specific testing methodologies

would provide the highest value for detecting early signs of

turbine oil degradation and the associated by-products which

negatively impact lubrication systems. Below is a summary of

results averaged from all 5 samples over the 8 week test.

MPC, Amines & Phenols are plotted on the right hand axis.

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