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Oil Quality Monitoring and the Advances in Real Time Oil Analysis

Oil Analysis Need Not Be Like Finding A Needle In A Haystack

Oil sampling analysis through oil condition monitoring systems has been the backbone of all oil reliability programs for the past century.

The foremost goal of an oil analysis strategy is the early detection of oil degradation, oil contamination, increased operating temperature and mechanical wear of the lubricating oil in an oil circuit. This early detection can bring about several important benefits including the prevention of a potential catastrophic failure.

Typical practice was/is to analyse oil samples in accredited oil labs and whilst oil samples provide a significant amount of information of an oil's condition and the presence of contaminants, it is a slow and costly process that can be akin to finding a “needle in a haystack”.

Whilst not trying to duplicate laboratory derived results, by providing real time analysis whilst the equipment is still operational, online oil sensors will continuously monitor wear debris generation.

With the advent of sensors, these were typically simple single point dielectric, conductivity or permittivity measurement devices detecting the rough oxidation level of the oil with little sensitivity to other key parameters.

More recent sensor advancements are now capable of detailed data analysis including detecting degradation of not only overall quality, but estimating percent soot, total base number, relative humidity, additive depletion, oil temperature, viscosity etc, all via remote monitoring whilst the equipment and asset is still in operation – no downtime periods.

Miniotec offers two (2) complimenting sensors for oil analysis which have proven to be an effective tool for determining failure modes for both equipment and the lubricant.

The wear debris sensor provides very early detection of mechanical failure within an asset. The sensor can detect and categorise ferrous and non-ferrous particles as small as 40μm thus offering ‘best in class’ sensitivity. Competing technologies are typically only able to detect 120 – 150 μm particle sizes. This is insufficient to identify important failure modes in gearboxes, particularly within wind turbine applications.

The online oil quality sensor is the worlds most advanced sensor of its service and is the only real-time oil quality sensor for monitoring the health state of lubricating oils / fluids and capable of replacing most periodic (preventative) oil sampling.

The sensors can provide real time monitoring and continuous insight to oil health, promoting condition-based maintenance practices such as optimised fluid drain intervals and reduced dependence on offline analysis. This solution uses Electrochemical Impedance Spectroscopy (EIS), a sensing method based upon analysing the fluid’s electrical properties to determine its condition. EIS is used across a range of frequencies to track changes in the impedance over time. The benefits of EIS include:

  • Different frequencies correlate more closely with the various actual condition indicators.

  • The EIS solution utilised in the Oil Sensor is superior to competition sensors which only perform single frequency analysis

These sensors within the online monitoring system delivers real time data that can detect most, if not all, key oil events and project remaining useful life of the oil while the asset is in operation.

While these sensors cannot exactly duplicate lab analysis results, they can provide the necessary insight to make maintenance decisions well before damage occurs remotely, in harsh conditions and hazardous environments.

Beware of Optical Particle Counter Technology

Optical particle counters are an inferior solution for online oil analysis. While they can provide ISO particle counts, they rely on visual inspection of lubricant colour to determine oil quality, ignoring other crucial indicators required for fluid condition monitoring. Multi-frequency dielectric measurements, on the other hand, offer a more comprehensive analysis.

It is important to note that colour changes are not always reliable indicators of oil quality and optical particle counters therefore may not detect potential issues within an oil circuit until it is too late. As a result, relying solely on optical particle counters for online oil analysis is not recommended.

In Summary

Adopting online oil quality sensors to monitor a lubrication system is a key enabler to shifting the oil sampling paradigm from periodic to true ‘real-time’ condition-based monitoring whilst the equipment is still online and operational. Best in class reliability programs have found a step change in asset longevity and performance by implementing online fluid sensor in their oil monitoring programs.

Let us know your thoughts?

We are keen to work with you on your Digital Maintenance Strategy.



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