Oil analysis is the core but not the limit of condition monitoring.

Oil Analysis: 10 Core Tests

While there are dozens of basic fluid analysis tests and many advanced tests, the following are the 10 core fluid analysis tests. 

• Viscosity: This measures a lubricant’s resistance to flow at a specific temperature. An oil’s viscosity is considered its most important property and is the best indicator for measuring oil serviceability.
• Elemental Spectroscopy: This determines the concentration of wear metals, contaminant metals and additive metals in a lubricant. However, spectroscopy cannot measure particles larger than roughly 7 microns; there are other tests for that. 
• Karl Fischer Water Test: This method analyzes water in the microgram or part-per-million range. This test is very accurate to 0.001%. Low levels of water (less than 2%) are typically the result of condensation. Higher levels can indicate a source of water ingress. 
• Fourier Transform Infrared Spectrometry (FTIR): Molecular analysis of lubricants and hydraulic fluids by FTIR spectroscopy produces direct information on molecular species of interest, including additives, fluid breakdown products and external contamination. 
• Acid Number: This is useful in monitoring acid buildup in oils due to depletion of antioxidants. High acid levels can indicate excessive oil oxidation or depletion of the oil additives and can lead to corrosion of the internal components. 
• Base Number: Base number testing is very similar to acid number testing, except that the properties are reversed. The sample is titrated with an acidic solution to measure the oil’s alkaline reserve. Measuring the base number (BN) can help ensure that the oil is able to protect the component from corrosion due to acid. As with viscosity, both acid number and base number are serviceability measures. 
• Particle Count:  This measures the size and quantity of particles in the oil sample. It is a way to monitor the level of solid contamination in an oil. Particulate contamination is an indication of the effectiveness of filtration and can indicate excessive external contamination.
• Ferrous Wear Concentration: In components such as gearboxes, ferrous wear may be more important than overall particle count and is therefore a good substitute. It measures ferrous wear debris in all types of oil—from gearbox lubricants to hydraulic oil. It also measures ferrous wear debris in grease. 
• Analytical Ferrography: This gives analysts the ability to visually examine wear particles present in a sample by separating solid contamination and wear debris for microscopic evaluation. It can identify wear particles, their composition and their origin. 
• Fuel Dilution: This test takes a portion of used engine oil and uses a gas chromatograph to measure the amount of fuel contained in the sample by comparing carbon chain length. A high amount of fuel in the oil causes degradation and a loss of viscosity.

The latest breakthroughs in oil analysis involve the integration of artificial intelligence and machine learning to interpret data more effectively. 

Complements to Oil Analysis

Oil analysis is a valuable condition monitoring tool, particularly for machinery and engines, but it is not always sufficient on its own. It primarily detects issues related to lubrication and wear particles, but it may not identify problems related to other factors such as electrical malfunctions. Three excellent complements to oil analysis that create a system of checks and balances are thermography, vibration analysis and acoustic monitoring.

Thermography, vibration analysis and acoustic monitoring are reactive and, more importantly, are useful predictive maintenance tools. Because of the predictive nature of these tests, unplanned downtime for heavily used equipment can be reduced or eliminated, allowing repairs to be scheduled during planned downtime. 

Thermography. Thermography pairs well with oil analysis. In medical terms, oil analysis is comparable to the bloodwork of the asset, while thermography is comparable to checking the temperature. An asset can look fine, but the thermal camera can see the “fever” that may be affecting the oil. This high temperature can cause the oil to burn off. High oil burn-off can then lead to internal destruction and may cause the asset’s power source to fail. Key industries where vibration analysis is most beneficial include the following:

• Manufacturing: To monitor and maintain machinery, electrical systems and production lines.
• Power generation and utilities: For inspecting electrical switchgear, transformers and other critical components.
• Oil and gas: To ensure the proper functioning of machinery and equipment in harsh environments.
• Facilities management: To maintain HVAC equipment, electrical panels and other building infrastructure.
• Mining: For monitoring heavy machinery, conveyor systems and electrical systems.

The main objective of thermography is to confirm that the machinery is running at a healthy temperature and to detect abnormal heat patterns that would indicate inefficiency and/or defects. 

Vibration Analysis. Vibration analysis can be used on many types of rotating components including bearings, gears, shafts, rotors, electric motors, turbines, fans, drivetrains, gearboxes, pumps, piston engines and compressors. 

Vibration analysis supplies important information for most industrial or manufacturing facilities—anywhere machinery and equipment play a critical role in operations. Primary sectors include the following:

• Manufacturing: Factories with heavy machinery such as motors, pumps, compressors and conveyors.
• Energy: Power plants, wind turbines and other energy-producing facilities.
• Automotive: Companies involved in the production and maintenance of vehicles.
• Aerospace: Aircraft manufacturing and maintenance facilities.
• Oil and gas: Refineries, drilling rigs and pipelines.
• Mining: Equipment such as crushers, mills and conveyors.
• Marine: Ships and offshore platforms.
• Building maintenance: HVAC systems and other mechanical infrastructure in large buildings.

In addition to determining critical speed and flagging imbalances and bearing failures, vibration analysis is capable of identifying such issues as misalignments and mechanical looseness, electrical motor faults, bent shafts, gearbox failures, and empty space or cavitation in pumps. For example, vibration analysis can help to detect misalignment in a pump or determine if a bearing is beginning to wear.

Acoustic Monitoring. The benefits of acoustic monitoring extend across many industries including aviation, manufacturing and energy production—anywhere air and gas systems play a critical role. Acoustic imaging is particularly beneficial for railway and mining applications. 

In the railway industry, acoustic monitoring can be used to detect leaks in brake systems by analyzing the sounds produced by faulty brakes. With mining, acoustic monitoring can be used to detect malfunctions and pending failures in critical equipment. 

While these systems are designed to operate reliably and safely, they can be prone to leaks and malfunctions that lead to costly downtime, loss in equipment efficiency, increased costs, decreased reliability and increased safety hazards. Early detection of air and gas leaks saves on energy costs, improving equipment performance and preventing potentially hazardous safety risks.

Other Complementary Condition Monitoring Technologies

Depending on the application, other condition monitoring tests to consider may be ultrasonic analysis, which detects high-frequency noise from friction, impact or electrical discharges; and acoustic emission analysis, which detects stress waves produced by crack formation and other critical structural changes.

Together with oil analysis, these technologies refine predictive models, resulting in more accurate and efficient condition monitoring. Ultimately, maintenance teams get a holistic view of equipment condition, leading to better maintenance decisions and improved reliability.  

Mary Messuti is the president of Eurofins TestOil, Inc. located in Strongsville, Ohio.  Her lab offers a full line of lubrication testing as well as fuel, coolant, grease and associated tribology services.  Mary enjoys over 25 years of experience in both laboratory management as well as heavy industrial and aerospace manufacturing environments.

Al Yates is the vice president of sales and marketing for Eurofins TestOil. He is responsible for leading the industrial and transportation sales team. With valuable experience in robotics and automation, he creates workflow automations that lead to company-wide efficiency. 

Camron Cunningham is the field service business unit supervisor for Eurofins TestOil and is Thermographer CAT Certified. He is responsible for all reliability services rendered in the field, and for all field service personnel. Camron has worked in the reliability field and reliability-related field for more than 16 years.