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For maintenance and reliability professionals, a deep understanding of machine wear and its underlying causes is essential for making pre-emptive informed decisions. Recognizing whether wear is driven by mechanical stress, contamination, or lubricant breakdown enables engineers and technicians to identify issues early, and before they escalate into major failures. Oil analysis plays a crucial role in this process by providing detailed insights into both lubricant and machinery conditions, supporting a proactive maintenance approach that significantly reduces downtime and extends equipment life.

Causes of Wear in Machines

Mechanical Stress

Mechanical stress is the primary driver of machine wear. Continuous cyclic loads, vibration, or shock can induce microstructural changes that eventually lead to fatigue, causing small cracks or even complete material failure. Whether stemming from misalignment, overloading, or regular operation, understanding these stress factors allows engineers to design components that are more resilient to such forces.

Contamination

Contaminants may be classified as solid, liquid, or gas. Common solid contaminants include dirt and metal shavings, while water is a frequent liquid contaminant, and process gases often represent gaseous contaminants, particularly in compressor systems. When these particles enter a machine’s lubricating system, they can act as abrasives—scratching and wearing down surfaces. Additionally, liquid and gas contaminants can alter lubricant viscosity, reducing fluid film thickness and increasing friction. This can lead to accelerated wear and even corrosion, which degrades machine components and shortens their service life. Stringent filtration and regular maintenance are essential to mitigating these risks.

Lubricant Breakdown

Lubricants reduce friction and dissipate heat between moving parts, but over time they can degrade due to oxidation, thermal stress, or contamination. As the lubricant’s protective properties diminish, equipment friction increases which accelerates wear and increases mechanical stress. Monitoring you in-service lubricant’s condition through scheduled oil analysis ensures that any degradation is identified early, preventing further damage.

Common Wear Mechanisms

Abrasive Wear (Two-Body and Three-Body)

• Two-Body Abrasion Wear Mechanism

Two surfaces slide directly against each other without intermediary particles. Inadequate lubrication, whether a result of low oil viscosity, an insufficient lubricant film, high contact stresses, misalignment, or rough surface finishes, can cause two-body abrasion. Preventative measures include (1) using the correct lubricant at the proper viscosity, (2) maintaining precise alignment, and (3) ensuring high-quality surface finishes. Regular oil analysis can detect early wear signs and confirming whether the lubrication system is performing optimally.

• Three-Body Abrasion Wear Mechanism

When loose particles such as dust, dirt, or wear debris become trapped between sliding surfaces, they act as a third body that intensifies abrasive effects. Proper filtration, maintaining a clean operating environment, and deliberately productive lubrication practices are critical in preventing three-body abrasion. Routine oil analysis can detect elevated particulate levels, allowing maintenance teams to intervene before significant damage occurs.

Surface Fatigue (Contact Fatigue)

Surface fatigue develops from repeated cyclic stresses that initiate micro-cracks on a material’s surface, leading to material loss and spalling. High contact stress from heavy loads, increased vibration, shock loads, and elevated temperatures all accelerate this process. Inadequate lubrication, misalignment, and contaminants further contribute to uneven load distribution and friction. Regular oil analysis helps detect fatigue early so that maintenance can be performed before severe failures develop.

Adhesive Wear

Adhesive wear is commonly observed in components subjected to frequent metal-to-metal contact under high pressures and sliding conditions, such as gear teeth and sliding surfaces. Under high pressure, microscopic asperities on contacting surfaces may fuse and then break apart as the surfaces slide, removing small material fragments. If the oil viscosity is too low for the required application, the lubricant may not maintain an adequate protective film, increasing the risk of adhesive wear. Maintaining the recommended optimal viscosity and if needed, the use of extreme pressure (EP) additives help sustain a robust lubricating film. Oil analysis measures viscosity and EP additive levels, ensuring the right oil is in use and detecting degradation before significant damage occurs.

Corrosive Wear

Corrosive wear occurs due to chemical or electrochemical reactions between machinery materials and their environment, leading to surface degradation. Prolonged exposure to moisture, acidic or alkaline contaminants, high temperatures, or corrosive chemicals can accelerate this process. Additionally, the breakdown of oil additives and protective coatings reduces the oil's ability to neutralize harmful substances. Preventative measures include using oils with robust corrosion inhibitors, controlling exposure to corrosive elements, and maintaining regular cleaning and maintenance routines. Regular oil analysis monitors chemical properties and additive levels, allowing early detection and intervention.

Cavitation Wear

Cavitation wear occurs when vapor bubbles form within a lubricant and collapse rapidly near a surface, creating shockwaves that erode the material. Factors that contribute to cavitation include high fluid velocities, rapid pressure fluctuations, elevated temperatures, and inadequate lubrication. In pump systems, insufficient fluid input or leaks can create low-pressure zones that promote bubble formation. Preventive measures include using oils designed to resist cavitation, ensuring a stable fluid supply, and optimizing system design to avoid pressure drops. Regular oil analysis identifies early changes in oil properties that may indicate the onset of cavitation.

Introduction

Customers often ask us to test for antioxidant strength in refrigeration oils. We explain that antioxidants are not typically used in lubricants for refrigeration systems, but why? In this blog, we will explore the reason for this and discuss the general role of antioxidants in lubricants.

Common Antioxidants

While antioxidants are not often formulated into refrigeration system lubricants, they are widely used in other lubrication applications. Antioxidants prevent oxidation, which can lead to sludge formation, acidity buildup, and degradation of oil properties. The most common types of antioxidants found in industrial lubricants include:

1. Aromatic Amines

Aromatic amines, such as diphenylamine, are highly effective antioxidants often used in high-temperature applications. Examples of aromatic amines are shown in Figures 1 and 2. They extend oil life by reacting with and neutralizing free radicals, which propagate oxidation.

·        Radical Scavenging: Aromatic amines donate hydrogen atoms to free radicals, interrupting the chain reaction of oxidation.

·        High-Temperature Stability: They perform well even at elevated temperatures, making them ideal for engines and turbines.

·        Long-Lasting Protection: Provide durable protection under sustained elevated temperatures and heavy loads.

Figure 1

Figure 2

2.     Phenolic antioxidants

Phenolic antioxidants interrupt an oxidation chain reaction at an early stage. They are effective in environments where oil is exposed to air at moderate temperatures. Sterically hindered phenols, like butylated hydroxytoluene (BHT), are a class of antioxidants characterized by bulky substituents around the phenolic group. Figure 3 shows the chemical structure of BHT. This steric hindrance protects the reactive hydroxyl group from undergoing unwanted reactions, especially from interacting with other chemicals prematurely. These antioxidants donate hydrogen atoms to free radicals, stabilizing them, and preventing further oxidation reactions. Oil oxidation can lead to the formation of acids, sludge, and varnish, which degrade the lubricant's performance. The bulky structure of sterically hindered phenols helps prevent oxidation without significantly reacting with other components in the lubricant, ensuring long-term stability and protection against oxidation.

Figure 3

3.     Zinc dialkyldithiophosphates (ZDDPs)

ZDDPs are multifunctional additives that function as antioxidants and anti-wear agents. The structure of ZDDP is shown in Figure 4. They protect oil in more severe conditions, but their use in refrigeration systems is limited due to potential interactions with refrigerants. ZDDP will decompose hydroperoxides and protect metal surfaces from catalyzing further oxidation. Their multifunctional nature not only extends the life of lubricants but also enhances the protection of mechanical components.

Figure 4

Why are antioxidants not used in refrigeration systems?

Low temperatures: Refrigeration oils operate at low temperatures. The rate of oxidation increases with increasing temperature. The Arrhenius equation states that oxidation doubles for every 10⁰ Celsius or 18⁰ Fahrenheit. Therefore, oxidation is reduced to a slow crawl under low temperatures.

Closed system: Refrigeration systems are sealed environments, which minimizes exposure to air and oxygen. Oxidation is required for oxidation to occur so the closed nature of these systems limits the conditions under which oxidation can occur, reducing or eliminating the need for antioxidants.

Potential interactions with refrigerants: Some antioxidants could negatively react with the actual refrigerant in the system. These interactions may produce byproducts and reduce system cooling efficiency.

Let us look at a specific example where an additive can react with the refrigerant in ammonia-based refrigeration compressors, ammonia (a base) can react with phenolic antioxidants (slightly acidic) to form salts. This acid-base reaction can create deposits and system performance issues.

Summary

Antioxidants are not typically used in refrigeration lubricants because operating conditions that necessitate their use, elevated temperatures and exposure to oxygen, are absent in refrigeration systems. The low operating temperatures and sealed environments minimize oxidation, reducing the need for antioxidants. Additionally, potential negative interactions between antioxidants and refrigerants, such as ammonia, can produce undesirable byproducts that compromise system efficiency and longevity. By understanding the specific requirements and conditions of refrigeration systems, we can appreciate why antioxidants, while valuable in other applications, are not suitable here. Refrigeration oils are formulated to perform optimally under the unique conditions of these systems without the need for additional antioxidant additives.

Each type of mechanical rotating equipment can have different lubrication regimes, lubricant requirements, and wear modes. Analyzing used oil analysis is common preventive maintenance worldwide, although interpreting oil analysis results can often be confusing without training. How do trained analysts at commercial oil analysis laboratories decide which test results warrant further monitoring, additional (exception) testing, inspection, or corrective action?

There are several methods of determining which test results indicate a potential problem, statistical comparison, rate of change, or a lock-step approach. A statistical comparison is the most widely employed methodology. Monitoring the rate of change (RoC) is employed when there is not a well-behaved normal (Gaussian) distribution of the data over time. The lock-step approach is useful for determining cause and effect.

Statistical Methodology

A statistical approach works well when the data follows a standard bell curve, as seen in Figure 1 below. Viscosity measurements are a great example of a symmetrical (two-sided) curve. Viscosity can be low due to fuel dilution, process contamination, viscosity index (VI) improver shearing, or mixture with a lower viscosity lubricant. The viscosity may increase due to oxidation, fuel soot, or mixture of a higher viscosity lubricant.

In a Gaussian distribution, density, on the y-axis, tells us how likely are the different test results. Imagine a bell-shaped curve. The top of the curve is where the most common values are, and as you move away from the top, the values become less common. Density helps us understand where most of the values in a dataset are concentrated and how they spread out around the average.

Figure 1

Data may be skewed to the right or left. Figure 2 is a graph of iron values, which is skewed to the right. This is an example of data where we are primarily concerned when the data exceeds a specified limit.

Figure 2

Statistical limits, although they have limitations, are a useful tool for setting alarm limits in oil analysis testing. These limits can be modified based on feedback from plant personnel. OEMs often require oil analysis and provide guidelines for limits on fluid condition, wear, and contamination. It is important that the OEM guidelines are followed, especially if the equipment is within the warranty period.

While statistical methods provide valuable insights, they should be complemented with expert judgment, qualitative analysis, and real-time monitoring to ensure a comprehensive understanding of machinery reliability and oil condition. Combining statistical analysis with a holistic approach helps address the limitations and improve overall predictive maintenance strategies.

Cumulative Trends and Rate of Change (RoC)

In a splash lubrication gearbox without oil circulation or filtration there can be a steady increase in particles or wear metals over time. Figure 3 below, shows a steady increase in iron concentration (measured in ppm) in a 12-month period. This increase occurs because there is no filtration system in place to remove wear particles from the oil.

Figure 3

At first glance the increase in iron debris per month looks steady, although the rate of change from month 11 to month 12 is substantial and should be flagged abnormal. Let’s look at the same data plotting the iron (ppm)/month (Fig. 4). Viewing the data in this format makes it obvious that the increase is about 3x that of the previous samples during this final recorded period.

Figure 4

"What is the cause of this increase?" Utilizing lock-step trending can assist the investigation.

Lock Step Trending

We investigate other changes that might be trending upward along with the iron. In this particular case, silicon and aluminum are also increasing.

Figure 5

A graph of the data (Figure 5). Reveals that increases in the three elements appear to positively correlate. Increasing silicon can be dirt contamination, but also anti-foaming additives, coolant leak, leaching of silicon sealants and gaskets or manufacturing residue. Dirt often has a silicon-to-aluminum ratio around 4:1. In this oil analysis case the ratio of silicon to aluminum is consistent and both metals are increasing over time. Therefore, abrasive dirt contamination is a defensible cause of the accelerated iron contamination which warrants further near-term investigation.

Taking this a step further, if Chromium is also present and increasing, this would lead us to conclude that bearing wear is occurring since chromium is commonly found in steel alloys used for bearings. Microscopic analysis of this sample is ideal in this situation. Dirt is easy to see under the microscope and abrasive debris should be prevalent and quickly identifiable in this case. 

Investing in contamination prevention measures is not just a smart choice—it’s a necessity for any operation aiming to maximize efficiency and longevity. By ensuring that your lubricants remain clean and free from contaminants, you significantly reduce the risk of costly machinery breakdowns and unscheduled downtime. The cost of implementing proactive strategies is a fraction of the expense associated with reactive maintenance and repairs. Consider the long-term benefits: extended equipment life, improved reliability, and sustained productivity. These advantages translate into substantial cost savings and a stronger bottom line. Proactive contamination control measures not only enhance the performance and lifespan of your machinery but also contribute to a safer working environment by minimizing the risk of equipment failure. Budget a portion, or all of these items:

Proper Storage: Store lubricants in a clean, dry environment away from direct sunlight and temperature extremes. Use dedicated storage containers and avoid open containers that can allow contaminants to enter.

Regular Inspection: Conduct regular inspections of lubricant storage areas and machinery. Look for signs of contamination such as changes in oil color, the presence of particles, or unusual odors.

Inspection of Seals and Gaskets: Ensure that all seals and gaskets on machinery and storage containers are in good condition and properly fitted to prevent contaminants from entering.

Clean Transfer Equipment: Always use clean transfer equipment such as pumps, hoses, and containers when moving lubricants. Contaminated equipment can introduce dirt and other particulates into the oil.

Proper Handling Practices: Train personnel in proper handling and dispensing practices. Avoid opening containers unnecessarily, and always clean the area around the fill port before adding oil to machinery.

Condition Monitoring: Implement a condition monitoring program that includes regular sampling and analysis of lubricants. This will help detect any early signs of contamination and allow for timely corrective action.

Filtration Systems: Utilize inline filtration systems to continuously remove contaminants from the oil while it is in use. This can help maintain oil cleanliness and extend the life of both the lubricant and the machinery.

Cleanliness Standards: Establish and enforce cleanliness standards for lubricant storage and handling areas. Implementing a “clean as you go” policy can help prevent contamination from occurring.

Dedicated Tools and Equipment: Use dedicated tools and equipment for different types of lubricants to avoid cross-contamination. For instance, use separate funnels and pumps for synthetic and mineral oils. Cross contamination occurs when one lubricant inadvertently mixes with another. For example, mixing an oil containing a detergent additive with an R&O fluid can destroy the R&O fluid’s water separability. Proper labeling and dedicated containers are essential. One solution is the use of “right-size containers,” which are used once and, if there is unused oil remaining, the oil is disposed of.

Implementing these strategies involves an initial investment in proper equipment, training, and regular maintenance. However, this investment is quickly offset by the reduction in emergency repairs, replacement parts, and labor costs. Choosing to prevent contamination is choosing to protect your investment and ensure the smooth, efficient operation of your machinery. It’s about making a commitment to quality, reliability, and optimal performance. This proactive approach fosters a culture of care and attention to detail that permeates all aspects of your operations, ultimately driving success and profitability.

To take your contamination control strategy to the next level, contact MRT Laboratories. Our team of ICML and STLE certified professionals can assist you in establishing or improving your current oil analysis program, selecting the right tests, and determining the appropriate testing frequencies. Together, we can enhance your machinery’s performance, extend its lifespan, and significantly reduce your maintenance costs.

Do you know anyone that works at an oil analysis laboratory that fails to lubricate the end plate bearings and spring on their overhead garage door? Well, you do now!

The cover image is one of the two roller bearings which had received no periodic lubrication maintenance over the past two years, and this was after the garage door mechanic professional advised that this easy quarterly maintenance was critical to avoid a catastrophic bearing or spring failure.

A new bearing end plate looks like this.

Fortunately, the replacement part is readily available, but the service is a meaningful expense that could easily have been avoided. Our garage door repair company recommends lubricating with WD-40, four times per year. I could not resist asking whether he thought WD-40 was actually a lubricant, but that question is better asked by someone already properly executing a preventive maintenance plan.

Please spray lubricate your garage door end bearings and spring on a regular basis if not already doing so!

Performing regularly scheduled oil analysis is the best methodology to monitor wear and oil condition. Even under normal operating conditions, wear particles and oil degradation by-products are generated. If abnormal lubricating conditions exist, wear and degradation can occur at an accelerated rate. This makes regularly scheduled oil analysis even more important.

Routine analysis can detect problems such as wear, oxidation, and acidity. However, more advanced testing is needed to detect deterioration in a lubricant’s performance properties such as water separability, foaming management, and varnish prevention.

Wear particles circulating through a lubricant system can be abrasive, generating more wear particles as they rip through a lubrication regime. Left unchecked, elevated concentrations of abrasive debris this will lead to accelerated wear, reduced component life, and increased maintenance. Wounded lubricant properties can adversely affect lubricant performance and, ultimately, your equipment’s performance.

Excessive entrained air causes extreme heat on metal surfaces and will reduce hydraulic performance, cause micro-dieseling, pump cavitation, and other problems. A lubricant’s ability to release entrained air has become increasingly important as newer machines' oil capacity has become smaller, resulting in decreased reservoir dwell time in a circulating lube system.

Water separability is critically important, especially for applications prone to water ingression, such as steam turbines. Prolonged periods of water saturation lead to corrosion and accelerated lubricant degradation. A typical lubricant’s water separability declines as oil degradation occurs. Stand-alone routine oil analysis will not measure whether a fluid’s water separability remains adequate for the application.

Varnish accumulation in a lubricating system has received much attention in recent years due to problems such as filter plugging, increased bearing temperature, valve stiction, and increased scrap rates in plastic injection molding machines. Often a vanishing issue originates from an accumulation of spent oil additives that attract to lubricated metal surfaces once an in-service fluid is no longer able to dissolve an their concentration. Here are some actions you can take to mitigate varnish:

·       Targeted Filtration Technology: Use special filters to remove varnish. Electrostatic, resin, and cellulose depth filters (CDF) are the main filters used, and they should be put in place using the correct technology to combat the specific issue in a system. Resin filters work well on R&O oils but are not typically used with AW hydraulic oil due to the potential of removing the ZDDP additive. Electrostatic filters don’t work well with R&O oils but are a viable choice for hydraulic oils. Electrostatic filters were first developed for AW hydraulic oils in plastic injection machines.

·       Solubilizers and Re-additization: These may be viable, chemical enhancement alternatives to re-charging the solubility of a used fluid so it can re-dissolve an accumulation of spent additives. Several companies offer these products and provide support regarding which option best fits your requirements.

·       Prevention: Consider using varnish-resistant lubricants. If you prefer to change the fluid rather than employ varnish mitigation technology, several lubricant manufacturers provide varnish-resistant fluids.

As the service life of the fluid increases, the antioxidants, which are sacrificial, are gradually depleted. Low levels of antioxidants leave the fluid susceptible to degradation. Monitoring the active antioxidant protection remaining in a used fluid can be performed with the RULER™ test, which uses the linear sweep voltammetry technology to assess remaining active protection of the antioxidant package of a certain lubricant. Changing or partially replenishing the oil can improve the additive level. Re-additization can be an option to changing the oil under the right circumstances.

Increased acidity can lead to corrosion and deposits forming in the system. Phosphate esters are prone to hydrolysis (cleavage by water), producing degradation by-products that are very acidic. Phosphate esters are more expensive than typical hydrocarbon lubricants. Resin filters are utilized to reduce acidity. It's very important to measure for a reduction in a phosphate ester’s resistivity over time, and to understand the condemning limit for call to action. Reduced resistivity (increased conductivity) may lead to electro-corrosion of servo valves.

These are some of the advanced tests commonly performed on industrial oils to monitor internal contamination and fluid condition. Proper implementation promotes much longer fluid life to minimize equipment downtime.

In the world of industrial machinery, clean lubricants are the lifeblood that ensures optimal performance and longevity. Contaminants such as water and dirt are silent enemies, leading to accelerated abrasive wear and corrosion. Industrial process and fuel contamination also pose significant threats to a lubricant’s viscosity and overall lubricating properties, resulting in increased machine downtime and maintenance costs.

Routine oil analysis can detect contaminants, enabling corrective actions to be taken. However, prevention is always better than cure. Preventing contamination before it reaches the machines is a proactive approach that pays dividends in the long run. Studies have shown that preventing contamination is significantly more cost-effective than reacting to an alarm triggered by an oil analysis report. This proactive approach not only saves money but also extends the life of both the lubricants and the machinery they protect. Seventy percent of alarms on oil analysis reports are caused by sample contamination. If left unchecked, contamination accelerates lubricant degradation and increases the wear and corrosion of machine components.

How do we prevent contamination from occurring in the first place? In this blog, we will explore key measures that can be taken to ensure that your lubricants remain clean and effective. By adopting these proactive strategies, you can enhance machine reliability, reduce maintenance costs, and maximize runtime (MRT).

Contamination can be divided into three broad categories: built-in contamination from manufacturing and storage before the machine is put into service, external contamination, and internally generated contamination such as wear particles and lubrication degradation by-products. We will focus on external and internally generated contamination in this blog. Let’s start with proactive strategies to prevent external contamination.

Proactive Strategies

Pre-filtered Oil: The first step to ensuring that a machine is charged with clean oil is using pre-filtered oil. Most oil distributors offer pre-filtered oils and may package the oil into smaller containers. Consult with your lube supplier about the available service options to ensure you receive clean, ready-to-use oil.

Checking New Oil Deliveries: Oil deliveries need to be sampled and sent to the lab to verify cleanliness, check oil quality, and ensure the oil meets the necessary specifications for the application. This crucial step helps address any issues before the oil is used in machinery.

Bulk Tank Inspection: Periodically sample bulk tanks to ensure that the quality of the lubricant remains within cleanliness specifications.

Filter Cart Filtration: Filter carts are essential for keeping the oil clean during transfer from bulk tanks or totes to machines. The oil may need to be transferred from the tote to intermediary containers before reaching the machine. Transferring oil with filter carts ensures it remains uncontaminated. We recommend reading 10 Applications for Filter Carts, by Noria Corporation, for more information on maximizing the use of this important equipment.

Desiccant Breathers Moisture Prevention: Desiccant breathers prevent moisture contamination from entering the lube reservoir. Use a sizing chart to select the correct size breather. Some desiccant breathers are equipped with check valves, extending the life of the desiccant by exposing it to the atmosphere only when necessary. This type of breather is ideal for standby equipment and storage tanks. Service representatives often recommend breathers with check valves for all equipment along the Gulf Coast region due to the high humidity.

Proper Sealing and Ventilation: Ensure that all machinery and storage containers are properly sealed and ventilated to prevent contaminants from entering. Use high-quality seals and gaskets and inspect them regularly for wear and tear.

Routine Maintenance: Implement a routine maintenance schedule that includes regular checks, servicing, and routine analysis of in-service lubricants. This helps in early detection and correction of any potential contamination sources as well as other issues.

Training and Awareness: Educate and train staff on the importance of contamination control, proper handling of lubricants, and best practices for maintaining clean oil. Awareness and adherence to these practices are key to preventing contamination.

By implementing these proactive strategies, you can ensure that your machines are filled with clean oil and that the oil remains clean throughout its use. These measures will help you avoid the pitfalls of contamination, leading to better machine performance, extended lubricant life, and significant cost savings.

While both vibration analysis and used oil analysis play integral roles in predictive maintenance, each method offers distinct advantages and capabilities.

Vibration analysis excels in identifying mechanical and operational issues associated with rotating machinery, such as misalignment, unbalance, and bearing faults. Its nonintrusive nature allows for real-time monitoring and early detection of potential problems, enabling timely maintenance interventions to prevent costly downtime.

On the other hand, used oil analysis offers unique insights into wear, contamination, and the overall condition of lubrication systems. By analyzing the physical and chemical properties of lubricating oil, used oil analysis can detect subtle changes indicative of impending issues, providing an early warning system for potential failures. The table below summarizes the strengths and weaknesses of each one.

When combined, these two methods provide a comprehensive approach to equipment health monitoring. Vibration analysis primarily focuses on the mechanical aspects of machinery, while used oil analysis provides insights into lubrication system health and internal component wear. By integrating these techniques, organizations can leverage the strengths of each method to enhance predictive maintenance efforts, minimize downtime, and optimize equipment reliability.

Implementing an Enhanced Reliability Program

Adopting an integrated approach to reliability that combines both vibration analysis and used oil analysis can significantly enhance the predictive maintenance strategies of any organization. Here are key steps to effectively implement an enhanced reliability program:

1. Assessment of Current Practices

Start by conducting a thorough assessment of your existing maintenance and reliability practices. Identify what methods are currently in use, the frequency of these activities, and their effectiveness. This review should also include interviews with maintenance personnel to understand their experiences and insights, which can reveal hidden challenges or opportunities for improvement.

2. Training and Skill Development

Ensure that your maintenance team is professionally trained in both vibration analysis and used oil analysis. This might involve sending staff to specialized training courses, inviting experts to conduct workshops, or subscribing to online courses. It is crucial that the team not only understands how to perform the analyses but also how to interpret the data and make informed decisions.

3. Integration of Technologies

Integrate vibration and oil analysis technologies by setting up the necessary equipment and software systems. Choose tools that can interface with each other to allow for easier data correlation and analysis. For instance, software that can compile data from both vibration sensors and oil analysis reports into a single dashboard will provide a more comprehensive view of machine health.

4. Establish Routine Monitoring

Develop a routine monitoring schedule that includes regular checks using both vibration analysis and used oil analysis. The frequency of these checks can vary based on the criticality of the equipment and past maintenance records. Critical machinery might need more frequent monitoring, while less critical systems may require less frequent checks.

5. Data Analysis and Reporting

Implement robust data analysis procedures to ensure that the data collected is used effectively. Develop standardized reports that highlight key metrics and trends. Use predictive analytics to forecast potential failures before they occur, allowing for proactive maintenance and repairs.

6. Continuous Improvement

Adopt a continuous improvement approach by regularly reviewing the effectiveness of the maintenance program. Update your practices based on new insights and advancements in predictive maintenance technologies. Encourage feedback from the maintenance team, as their firsthand experience can provide valuable insights into the practical aspects of the program.

7. Stakeholder Engagement

Keep all stakeholders informed about the changes and benefits of the enhanced reliability program. Regular updates, whether through internal reports, meetings, or newsletters, will help maintain alignment and support for the initiative. Highlight successes and learnings from the program to promote its value and encourage continuous support.

8. Compliance and Safety Standards

Ensure that all practices comply with industry safety and quality standards. Regular audits and compliance checks should be part of the program to maintain high standards and avoid potential legal or operational risks.

Conclusion

By effectively implementing an enhanced reliability program that synergizes vibration analysis and used oil analysis, organizations can expect a significant improvement in equipment uptime, reduced maintenance costs, and overall enhanced operational efficiency. The key to success lies in careful planning, skilled execution, and ongoing management of the program to adapt to new challenges and technologies.

Introduction

Predictive Maintenance is an advanced reliability and maintenance that maximizes machine uptime and reduces unexpected downtime. Predictive maintenance reduces maintenance costs over preventative maintenance since maintenance tasks are performed only when warranted.

Vibration and oil analysis should not be thought of as an “either or” scenario since both have distinct strengths that will enhance your condition monitoring program.

In this blog we will explore how adding or expanding an oil analysis program can enhance overall equipment reliability alongside vibration analysis. Next, we will briefly describe vibration analysis for those who are unfamiliar with the technology.

Understanding Vibration Analysis

Vibration analysis is a cornerstone of predictive maintenance, offering valuable insight into the health of rotating machinery. By measuring and analyzing vibrations, maintenance professionals can detect early signs of mechanical issues, allowing for timely intervention and preventing costly downtime.

At its core, vibration analysis involves monitoring the vibrations produced by rotating machinery. These vibrations are indicative of various mechanical and operational conditions within the equipment. By capturing and analyzing vibration data over time, maintenance teams can identify trends and anomalies that may signal potential problems.

One of the key advantages of vibration analysis is its nonintrusive nature. Unlike some other diagnostic techniques, such as dismantling machinery for inspection, vibration analysis can be performed while the equipment is in operation. This not only saves time and labor but also eliminates the risk of introducing contamination into the machinery.

Vibration frequencies are typically measured in cycles per second, or Hertz (Hz). The frequency spectrum ranges from low to high frequencies, typically spanning from 2 to 10,000 Hz. Low-frequency vibrations are often associated with issues such as misalignment, unbalance, and looseness, while high-frequency vibrations may indicate problems like bearing faults, gear damage, or cavitation.

By understanding the vibration signatures associated with diverse types of machinery and operating conditions, maintenance professionals can effectively diagnose issues and plan appropriate corrective actions. Furthermore, vibration analysis software and tools have become increasingly sophisticated, enabling advanced analytics and predictive modeling to forecast equipment health and anticipate potential failures before they occur.

Exploring Used Oil Analysis

Used oil analysis encompasses a variety of tests and techniques aimed at assessing the physical and chemical properties of lubricating oil, contamination, and wear. Spectroscopic analysis, for instance, involves analyzing the elemental composition of the oil, detecting trace elements that may indicate wear, contamination from external sources and oil additives. Particle counting, on the other hand, quantifies the concentration and size distribution of particles suspended in the oil, helping identify abrasive wear and the presence of contaminants such as dirt or metal fragments.

Additionally, viscosity measurement plays a crucial role in used oil analysis, as changes in viscosity can signify contamination, fluid commingling or degradation of the oil due to thermal or oxidative degradation. Other common tests include acid number, water content wear, contaminant and additive metals, particle counting (ISO code), ferrous wear and acid number. There are many more tests that can provide additional information about the remaining life of the lubricant, type and severity of the wear occurring. These tests are typically when a problem is suspected or on a less frequent basis than the routine tests. Your oil lab can provide insights into what testing may be warranted.

One of the key advantages of used oil analysis is its ability to detect internal wear, contamination, and degradation within your machinery, even before visible (or vibrational) symptoms manifest. By monitoring trends in oil properties over time, maintenance professionals can identify subtle changes indicative of impending issues, allowing for proactive maintenance interventions, and minimizing the risk of catastrophic failures.

Moreover, used oil analysis serves as a valuable tool for assessing the effectiveness of maintenance practices and the performance of lubricants. By tracking parameters such as oxidation levels, additive depletion, and contamination levels, organizations can optimize their lubrication practices, extend equipment life, and reduce overall maintenance costs.

Used oil analysis is a powerful tool for keeping your equipment running smoothly and avoiding costly breakdowns. But what happens when the results you get seem contradictory? This can be especially puzzling when readings from different analysis methods, like ICP (Inductively Coupled Plasma) and FDM (Ferrous Density Meter), tell different stories.

The Case of the Curious Iron:

Let us imagine a scenario where your oil analysis shows a low iron value in parts per million by ICP but a high iron reading in parts per million by FDM. This might seem like a contradiction, but it is not uncommon, and it can actually reveal valuable insights into your equipment's health.

Understanding the Discrepancy:

Here are why these readings might differ:

•             ICP: This method measures the total elemental iron present in the oil. ICP detects magnetic and nonmagnetic iron oxides (rust) and has a size limitation of about 5 microns. In other words, the instrument can detected total iron in a sample in parts per million for particles that are great than or equal to 5 microns in size

•             FDM (ferrous density meter): FDM works by using a magnetic field. This device directly detects ferrous wear debris that is magnetic. FDM does not have the same size limitation as ICP. The debris that this instrument can detect must be magnetic. For example, much of rust is not magnetic. Tin, also a common wear metal that is found in oil samples, is not magnetic so an FDM will not detect that metal.

What Does It Mean if the ICP and the FDM generate materially different results for iron in ppm in an oil sample? How is that information useful?

This discrepancy in test results for iron in ppm can point to several possibilities:

•             Specific wear mechanisms: The high FDM reading could indicate wear concentrated on components like gears or bearings, releasing larger ferrous debris. Meanwhile, the low ICP iron might suggest wear of other components generating smaller, non-ferrous particles.

•             Iron oxide formation: If iron is present as oxides, the particles will be detected by ICP. However, the FDM directly detects magnetic ferrous particles, potentially explaining the higher reading.

•             Measurement limitations: Both methods have their limitations, and factors like oil viscosity or particle size distribution can influence the readings.

Going Deeper: The Power of the Full Ferrogram

To unravel the mystery behind these discrepancies, a full analytical ferrogram can be your next step. A Ferrogram, or ferrographic analysis, determines the concentration, general size ranges, shape, and several of the metal types of wear particles through microscopic examination with the goal of heading off the accelerated wear that tends to precede equipment failure. This visual analysis of microscopic particles in an oil sample provides invaluable insights:

•             Particle size and morphology: It reveals the size and shape of iron particles, helping differentiate between normal wear debris and abnormal wear modes.

•             Composition analysis: It identifies the specific elements present in the particles, pinpointing potential contamination sources.

•             Wear trend monitoring: Comparing ferrograms over time can track the progression of wear and identify early signs of trouble.

When to Consider a Ferrographic Analysis (Ferrogram):

A ferrogram is especially beneficial when:

•             You have unexplained high iron readings by FDM (ferrous debris density test).

•             You are dealing with critical equipment where early wear detection is crucial.

•             You are experiencing unusual performance changes or noise vibrations.

•             You want to establish a baseline for wear monitoring.

Do not Let Contradictions Confuse You:

Remember, contradictory readings in oil analysis are often opportunities for deeper understanding. By combining different methods like ICP and FDM, and leveraging the power of a full analytical ferrogram, you can gain comprehensive insights into your equipment's health and make informed maintenance decisions.

Contact us today at MRT Laboratories to discuss your specific needs and how our advanced oil analysis services can help you optimize equipment performance and prevent costly breakdowns.

Happy New Year, MRT blog readers!

I'm kicking off the new year emphasizing how much effort we put into providing the most accurate test results as possible. At the top of the list of importance is oil viscosity. In Q3 2021 we validated and began using one of our favorite lab instruments, the Cannon CAV 4.1 Kinematic viscometer.

Automated Viscometers and Rheometers | Accurate Viscosity Measurements | CANNON Instrument

In our opinion it is the Formula 1 race car of automatic viscometers - a finely tuned machine supported by an excellent pit crew of Cannon service technicians. We look forward to purchasing more of these. The instrument is extremely consistent, and last week a customer pointed this out by analyzing their MRT viscosity results on a certain gearbox lubricant over the past several years.

I'm referring to the attached image of the viscosity results of an ISO VG 320 gear lubricant since January 2019. Notice that all of these viscosity results are less than 10% above or below the rated viscosity of 320 Centistokes for this oil; therefore, all of the results are NORMAL viscosity readings. This is great news, but notice the spread of the results to the left of the dotted red line compared to the right of the dotted red line. Why is there so much more variation in the results before Q3 2021? This was the question from our customer. My first reaction was that this customer probably had a seal leak issue in the past that was fixed in late 2021, and there was no longer a process contamination issue in the gearbox. But then I looked more closely at the small range on the y-axis of the graph. All of these results are very normal throughout the period, but after Q3 2021 the range is significantly tighter with results that are much more consistent on a month-by-month basis. A process contamination issue typically would create a much wider range of viscosity results over time. Also, it's more likely that all of the viscosity results would have been less than 320 cSt due to contamination, and not above and below 320 cSt.

We looked back to when the Cannon CAV 4.1 viscosity was put into service and realized that because of this instrument and our uniform application of our laboratory procedure, these results became much more consistent and accurate. It's great to have normal oil analysis test results, but we take pride in always improving our instrumentation and our procedures.

Karl Fischer (KF) titration is a widely used analytical technique for determining the water content of various materials, including pharmaceuticals, chemicals, food products, and used oil. It is based on a chemical reaction between water and a Karl Fischer reagent, which consumes iodine in proportion to the amount of water present. Water reacts with iodine and sulfur dioxide to form sulfur trioxide and hydrogen iodide. An endpoint is reached when all the water is consumed. The basic Karl Fischer chemical reaction is I₂ + SO₂ + H₂O → 2HI + SO₃. A Karl Fischer reagent in a titrating vessel contains iodine and sulfur dioxide that will react with the water contaminating a sample of lubricant of fuel. The endpoint of the titration is detected by monitoring the change in electrical conductivity. A titrating vessel contains a large volume of reagent solution so a large volume of samples can be tested during the day. In a titrating vessel, once all the iodine is transformed to hydrogen iodide the reagent solution must be replaced with fresh fluid.

Volumetric Karl Fischer Titration

In volumetric Karl Fischer titration, a pre-prepared Karl Fischer reagent is used to titrate the sample. The titrant is added from a burette until the endpoint is reached. The amount of titrant used is then calculated to determine the water content of the sample. Volumetric KF titration is suitable for determining water contents ranging from 0.1% to 100%. Volumetric KF titration has been largely replaced by Coulometric Karl Fisher titration in used oil analysis.

Coulometric Karl Fischer Titration

In coulometric Karl Fischer titration, the iodine is separated electrochemically within the titration cell, so it can be free to react with sulfur dioxide. This eliminates the need for a pre-prepared titrant and makes the method more accurate and precise, especially for low water content samples. Coulometric KF titration is suitable for determining water contents ranging from 1 ppm to 100%.

KF titration is a versatile and powerful technique for water content determination, offering accurate and precise results.

ASTM D6304 (Method A) Direct Method: A specific mass of lubricant, measured by weight, is injected into the reagent that contains iodine, base, sulfur dioxide, and a solvent to create the reaction of transforming iodine to hydrogen iodide. The concentration of water is quantified once all the water in an oil sample that’s introduced to the titration vessel is consumed. The chemical reaction takes longer if the oil sample is more saturated.

 ASTM D6304 (Method B) Indirect Method: This second method involves heating the sample until water vapor is produced by distillation. The water vapor is introduced into the Karl Fischer reagent using a dry air stream. This method minimizes contamination and side reactions since only the distilled water is introduced into the vessel and not reactive additives or chemicals.  

 Certain lubricant samples are not suitable for the direct method of sample injection into the Karl Fischer solution vessel. Calcium and boron additives, commonly found in engine oil samples, interfere with the Karl Fischer chemical reaction. In addition, heavily contaminated oil samples are not best quantified using the direct method. At MRT Laboratories, we identify all engine oil samples, all samples that are found to be super contaminated through visual inspection, and certain viscous gear oil samples for quantifying water contamination through ASTM D6304 Method B instead of Method A.

Critical machinery are the backbone of industrial operations. The efficiency, longevity, and reliability of these systems heavily depends on the quality and condition of the lubricants used. As such, used oil analysis emerges as a crucial aspect of ensuring optimal machine performance. Over the next month we will write describe different tests in our industrial slate of laboratory oil analysis. This discussion will break the testing into three broad categories, routine, advanced and exception.

Routine Testing

Routine testing of an in-service lubricant has a laboratory test package that is performed on a predetermined time interval typically at every one to three months. These tests monitor for equipment wear, oil contamination, and oil condition. MRT Laboratories' STLE and ICML certified professionals can help you determine the optimal testing to fit the needs of your unique equipment and operations. In this blog we discuss automatic particle counting to measure fluid cleanliness, since we receive the most customer questions about this portion of the industrial testing slate. Thank you, CiNRG for providing a photo of their CINRG CS-APC-22M particle counting system, which is our primary particle counting instrument (https://www.cinrg.com/).

Automatic Particle Counting (APC) is a widely used technique for measuring the number and size distribution of particles in a fluid. It is a common test used in used oil analysis to monitor the condition of the oil and to identify potential problems with the equipment in which it is used. Automatic particle counting methods can be categorized into two main types: optical and non-optical.

Optical Particle Counting

Optical particle counting utilizes light to detect and count particles suspended in a fluid. A sample of the fluid is passed through a light beam, and the light scattered by the particles is detected by a sensor. The size of the particles is determined by the angle at which the light is scattered.

Particle Counting by Pore Blockage

Particle counting by pore blockage, also known as the pore blockage method, is a technique for measuring the number and size distribution of particles in a fluid. It is a widely used method for determining the cleanliness of fluids, particularly in hydraulic and lubrication systems.

The pore blockage method involves passing a known volume of fluid through a calibrated filter membrane with a defined pore size. Particles larger than the pore size are trapped on the membrane, while smaller particles pass through. The pressure drop across the membrane is measured as a function of time. As more particles are trapped on the membrane, the pressure drop increases. The pressure drop data is then used to calculate the number and size distribution of particles in the fluid using a mathematical model that relates the pressure drop to the particle size and concentration.

Particle Dilution to Reduce Interference

To reduce interference and improve the accuracy of particle count measurements, particle dilution is often employed. This involves diluting the fluid sample with a clean solvent, which will dissolve bubbles and also microscopic spent additive material that typically cannot be filtered from the oil with a traditional filtration capture method.

Conclusion

APC is a valuable technique for assessing fluid cleanliness and monitoring equipment health. Optical and non-optical methods, including particle counting by pore blockage, each offer unique advantages and limitations, making them suitable for different applications. Precisely applied sample dilution can effectively reduce interference and enhance the accuracy of particle count measurements by conditioning the fluid for an optimal view of the sample stream by the optical laser.

Thank you to everyone in research and development that innovates the lubrication industry! Let’s take a high-level view of several areas of advancement in oil additives.

Nanoparticles

Nanoparticles are increasingly being used as additives in lubricants to improve their performance and properties. Some examples of nanoparticles that are used as lubricant additives include:

•             Graphene: Graphene is a single layer of carbon atoms arranged in a hexagonal lattice. It is one of the strongest and lightest materials known to man. Graphene can be used as a lubricant additive to reduce friction and wear, improve heat dissipation, and extend the life of lubricants.

•             Molybdenum disulfide (MoS₂): MoS₂ is a layered material with a strong lamellar structure. It has excellent lubricating properties and can be used to reduce friction and wear under a wide range of conditions. MoS2 is also a good thermal conductor, which helps to dissipate heat away from lubricated surfaces.

•             Carbon nanotubes (CNTs): CNTs are cylindrical structures made up of rolled-up graphene sheets. They have excellent strength, stiffness, and thermal conductivity. CNTs can be used as lubricant additives to reduce friction and wear, improve heat dissipation, and extend the life of lubricants.

•             Metal oxides: Metal oxides, such as titanium dioxide (TiO₂) and zinc oxide (ZnO), can be used as lubricant additives to reduce friction and wear, improve heat dissipation, and protect surfaces from corrosion.

•             Ceramic nanoparticles: Ceramic nanoparticles, such as boron nitride (BN) and silicon nitride (Si3N4), can be used as lubricant additives to reduce friction and wear under extreme conditions.

However, there are also some challenges associated with the use of nanoparticles as lubricant additives. One challenge is that nanoparticles can be expensive to produce. Another challenge is that nanoparticles can agglomerate, which can reduce their performance.

Overall, nanoparticles offer a number of promising advantages such as lubricant additives. As technology continues to develop and the cost of producing nanoparticles decreases, we can expect to see them being used in an even wider range of lubricant applications in the future.

Biodegradable Additives

A biodegradable additive is a substance that can be broken down by microorganisms into natural substances, such as water, carbon dioxide, and biomass. Biodegradable additives are used in a variety of products, including lubricants, plastics, and detergents.

In the context of lubricants, biodegradable additives can be used to improve the biodegradability of the lubricant itself, or to enhance the performance of the lubricant in other ways, such as reducing friction and wear.

Some examples of biodegradable lubricant additives include:

•             Plant-based oils, such as soybean oil and rapeseed oil. This oil can be used for a VI improver additive.

•             Esters, which are used as additives to increase solubility with other additives.

•             Polyalkylene glycols (PAGs), as a VI improver additive and they also have very good lubricity

•             Nanoparticles, such as graphene and molybdenum disulfide

Biodegradable lubricant additives offer a number of advantages over traditional additives, including:

•             Reduced environmental impact: Biodegradable lubricant additives can help to reduce the environmental impact of lubricants by making them more biodegradable and non-toxic.

•             Improved performance: Biodegradable lubricant additives can help to improve the performance of lubricants in terms of friction reduction, wear protection, and heat dissipation.

•             Extended service life: Biodegradable lubricant additives can help to extend the service life of lubricants by reducing their degradation and preventing the formation of deposits.

Biodegradable lubricant additives are expected to become more widely used in the near future, due to a combination of environmental regulations, consumer awareness, and technological advancements. Here are some specific examples of how biodegradable lubricant additives are being used today:

•             In the industrial sector, biodegradable lubricant additives are being used to develop lubricants for machinery and equipment that operates in sensitive environments, such as food processing plants and water treatment facilities.

•             In the aerospace industry, biodegradable lubricant additives are being used to develop lubricants for aircraft and spacecraft that operate under extreme conditions.

•             In the automotive industry, biodegradable lubricant additives are being used to develop more environmentally friendly engine oils and transmission fluids.

Overall, biodegradable lubricant additives offer promising advantages over traditional additives. As technology continues to develop and the cost of producing biodegradable additives decreases, we can expect to see them being used in an even wider range of lubricant applications in the future.

Smart Additives

Smart additives are a new generation of lubricant additives that can respond to changes in operating conditions and adapt their performance accordingly. This can help to improve the performance and efficiency of lubricants, while also extending their service life.

Smart additives are typically made up of nanoparticles or other materials that can change their properties in response to stimuli such as temperature, pressure, or shear stress. For example, some smart additives can become more viscous at elevated temperatures, which can help to improve lubrication under extreme conditions. Other smart additives can release anti-wear agents when needed, which can help to reduce wear and tear on machine components.

Smart additives are still in their early stages of development, but they have the potential to revolutionize the way that lubricants are used. Here are some of the potential benefits of using smart additives in lubricants:

•             Improved performance: Smart additives can help to improve the performance of lubricants in terms of friction reduction, wear protection, and heat dissipation.

•             Extended service life: Smart additives can help to extend the service life of lubricants by reducing their degradation and preventing the formation of deposits.

•             Reduced environmental impact: Smart additives can help to reduce the environmental impact of lubricants by making them more biodegradable and non-toxic.

•             Reduced maintenance costs: Smart additives can help to reduce maintenance costs by extending the service life of lubricants and reducing the need for repairs.

Smart additives are currently being developed and tested for a variety of applications, including:

•             Automotive: Smart additives are being developed to improve the performance and efficiency of engine oils, transmission fluids, and other automotive lubricants.

•             Industrial: Smart additives are being developed to improve the performance and durability of lubricants for machinery and equipment in a variety of industries, including manufacturing, mining, and energy.

•             Aerospace: Smart additives are being developed to improve the performance and reliability of lubricants for aircraft and spacecraft.

Smart additives have the potential to offer a number of significant advantages over traditional lubricant additives. As technology continues to develop and the cost of producing smart additives decreases, we can expect to see them being used in an even wider range of lubricant applications in the future.

Many MRT customers are the operators of multi-million-dollar mechanical equipment that runs without interruption for months or even years. We also assist certain lubricant manufactures that will ask us to test new formulations throughout the process of adding and blending additives into their base oils.

Formulating lubricants with additives is a complex process that requires careful consideration of a number of factors, including the type of base oil, the operating conditions of the lubricant, and the specific challenges that need to be addressed.

Here are some specific examples of challenges that formulators face when working with additives:

·        Balancing multiple additive functions: Formulators need to balance the performance of different additives to ensure that the lubricant meets the needs of the specific application. For example, a lubricant for a high-temperature application may need to contain additives that reduce friction and protect against wear at elevated temperatures. However, these additives may interact with each other in a way that reduces their performance. Formulators need to carefully select and balance different additives to ensure that they work together effectively to meet the needs of the application.

·        Compatibility with other additives and base oils: Formulators need to ensure that the additives they select are compatible with each other and with the base oil. If additives are not compatible, they can interact with each other or with the base oil in a way that reduces their performance or even causes problems, such as sludge formation.

·        Environmental and regulatory considerations: Many countries and regions have regulations that restrict the use of certain additives. Additionally, formulators need to be aware of the environmental impact of the additives they use. For example, some additives may be toxic or persistent in the environment. Formulators need to select additives that are environmentally friendly and compliant with all applicable regulations.

ZDDP and detergents can interact with each other in a way that reduces their performance. Detergents can remove the ZDDP layer from metal surfaces, which can reduce the anti-wear protection of the lubricant. This interaction can be particularly problematic in high-temperature applications, where the ZDDP layer is more likely to be removed by detergents. Formulators can overcome this challenge by selecting detergents that are less likely to interact with ZDDP. Additionally, they can increase the amount of ZDDP in the lubricant to compensate for the loss of anti-wear protection.

Another approach is to use a different type of anti-wear additive, such as a molybdenum disulfide (MoS2) additive. MoS2 additives are not as susceptible to interaction with detergents as ZDDP additives. Overall, the interaction of ZDDP and detergents is an important consideration for formulators when developing lubricants. By carefully selecting and balancing different additives, formulators can create lubricants that provide excellent performance, protection, and durability.

The additives in a lubricant ensure that machinery operates smoothly, with minimal wear and tear to optimize reliability and machine life. Engine oils typically have the highest percentage of additives in a lubricant, reaching up to 30% of its volume. In contrast, phosphate ester hydraulic fluids typically have the lowest percentage of additives or even no additives. Additives perform three general functions:

1.      Enhance desirable properties of a lubricant. For example, viscosity index improvers enhance the ability of an oil to maintain its viscosity over a wide range of temperatures.

2.      Suppress undesirable properties of a lubricant. For example, antioxidants slow down and suppress future oxidation of an oil which leads to the formation of sludge and deposits.

3.      Add a new property to a lubricant. For example, extreme pressure additives add protection against wear under high-pressure conditions.

Whether you are a seasoned engineer, a maintenance professional, or simply curious about the world of industrial lubricants, this blog aims to shed light on the unsung hero of the lubrication world – additives. Join us as we delve deeper into the intricacies of these compounds, their classifications, and their transformative impact on tribology.

Industrial Lubricant Additives

Lubricants are more than just slick agents; they are composed of intricate chemical formulations tailored to specific functions. In the vast world of industrial machinery each moving part may have its own unique needs. Understanding the roles of different additives can be crucial.

Rust & Oxidation (R&O) Inhibitors:

Role: These protect lubricated machinery parts against rust and oxidation. By preventing the oxidation of the oil, they prolong the lifespan of the lubricant and help in maintaining its viscosity over time.

Examples: Sterically hindered phenols and aromatic amines.

Corrosion Inhibitors:

Role: While R&O inhibitors protect the oil, corrosion inhibitors safeguard the machine parts, especially metal components, from corrosive elements present either in the lubricant or the operating environment. Corrosion inhibitors are typically specific to specific metals.

Examples: Tolyltriazole is commonly used in lubricants to protect copper and bronze components from corrosion.

Anti-wear Additives

Role: As the name suggests, these additives are designed to prevent wear in situations where moving parts come into close contact. They form a protective layer on surfaces, preventing direct metal-to-metal contact.

Examples: Zinc dialkyldithiophosphate (ZDDP) is an anti-wear agent typically found in hydraulic oil. ZDDP serves a dual purpose as it also acts as an antioxidant. Tricresyl phosphate (TCP) is a frequently used AW agent, especially in aviation turbine oils.

Extreme Pressure (EP) Additives:

Role: EP additives are for conditions where immense pressure might cause lubricants to break down. They create a protective film on machine parts, ensuring that they do not weld together under high-stress situations.

Examples: Phosphorus-sulfur derivatives, molybdenum disulfide, graphite, sulfurized olefins and dialkyldithiocarbamate complexes.

De-emulsifiers:

Role: These additives help separate water from the oil, ensuring that any moisture that enters the system can be easily removed, thus preventing issues like corrosion or reduced lubrication performance.

Emulsifiers:

Role: Opposite of de-emulsifiers, emulsifiers help oil and water mix, which can be essential in specific applications where water contamination may be unavoidable or metalworking fluids where a stable emulsion can aid in cooling and chip removal.

Friction Modifiers:

Role: Friction modifiers reduce the frictional properties of a lubricant reducing friction as needed, which can be especially important in transmissions or certain types of bearings.

Examples: sulfured compounds, chlorinated compounds and phosphorus-sulfur derivatives

Viscosity Index Improvers:

Role: These additives ensure that a lubricant maintains its viscosity across a broad temperature range, ensuring consistent performance whether in the cold of winter or the heat of summer.

Examples: Polymethacrylates are used to help the oil maintain its viscosity across varying temperatures.

Neutralizers:

Role: Neutralize acidic components that may form during oil degradation or due to external contaminants, ensuring the acidic compounds do not harm the machinery.

Examples: Calcium or magnesium sulfonates and phenates serve as detergent additives, helping to neutralize acidic components and clean internal parts of engines.

Dispersants:

Role: Dispersants keep contaminants suspended in the oil, preventing them from clumping together and forming sludge or varnish, which can impair machine function.

Example: Succinimides, derived from polyisobutylene, help keep contaminants suspended in the oil, preventing sludge formation.

Detergents:

Role: Not to be confused with household detergents, these additives play a role in keeping machinery clean by neutralizing acidic compounds and helping to remove internal deposits.

Examples: Calcium or magnesium sulfonates, calcium or magnesium phenates.

Each of these additives plays a critical role in the formulation of lubricants, ensuring that they perform optimally under various conditions and in various applications. By recognizing the specific chemicals used for each function, professionals can better understand the chemistry behind the lubricants they use and optimize their choices accordingly. In continuation, new trends in oil additive formulation.

Elasto-hydrodynamic lubrication (EHL) is a specialized lubrication regime that combines hydrodynamic lubrication principles with the elastic deformation of contacting surfaces. It is utilized in applications with high loads, high speeds, and tight clearances, requiring a lubricant capable of withstanding extreme operating conditions.

Key characteristics of elasto-hydrodynamic lubrication include the elastic deformation of surfaces under the pressure generated by the lubricant film, high contact pressures leading to localized elevated temperatures within the film, and the viscoelastic behavior of the lubricant, exhibiting both viscous and elastic properties. In the contact zone the pressure on the lubricant film layer causes the lubricant viscosity to increase significantly where it can be almost solid, which causes elastic surface deformation of the lubricated surface. Elastic deformation, by definition, indicates that the microscopic change in shape in the contact zone is temporary and the lubricated component resumes is original shape once pressure is reduced.

Is elastic deformation of the surface a good thing? Yes, it is. Elasto-hydrodynamic lubrication operates through several mechanisms to reduce friction and wear. The deformation and load support mechanism involves elastic deformation of surfaces as the lubricant film thickness decreases, resulting in a larger contact area and increased load-carrying capacity. Shear-thinning and film generation occur as the lubricant experiences decreased viscosity under high shear rates, allowing for the formation of a thinner yet robust lubricating film. The elastic deformation of surfaces dissipates energy, reducing frictional losses and heat generation.

Several factors influence the effectiveness of elasto-hydrodynamic lubrication. Higher loads and pressures promote greater deformation of surfaces, enhancing load support. Surface roughness and finish affect the contact area and the lubricant's ability to form and maintain an effective elasto-hydrodynamic film. The viscosity and additives of the lubricant play a crucial role in film formation and stability, particularly under extreme operating conditions.

In elasto-hydrodynamic lubrication, the lubricant film formation and deformation progress through stages, starting with initial contact and deformation as the surfaces come into contact and creating a larger contact area. This process leads to full-film formation, where the lubricant film reaches its maximum thickness and separates the surfaces completely as they continue to move.

Elasto-hydrodynamic lubrication finds applications in various high-load and high-speed systems, including automotive engines (e.g., camshafts, crankshafts, and connecting rods) and rolling element bearings (e.g., ball and roller bearings).

Advantages of elasto-hydrodynamic lubrication include its high load-carrying capacity due to surface elastic deformation and its ability to minimize friction and wear compared to other lubrication regimes. However, it is sensitive to surface finish, lubricant properties, and critical operating conditions, requiring appropriate lubricant film thickness and specific load and speed ranges to be effective.

Understanding elasto-hydrodynamic lubrication is crucial for selecting lubricants with suitable viscosity and additives, optimizing surface finishes, and designing systems capable of withstanding high loads and speeds.

We photographed sulfuric acid reacting with the mineral oil that’s contaminating a customer’s sample of phosphate ester. Notice the cloudy swirl reaction in the photo, which will eventually settle as a top layer that we can measure into percent contamination of the sample. This sample happens to be 2% contaminated with mineral oil which is a MONITOR. 3% is ABNORMAL, and 4% is the condemning limit. The sulfuric acid reacts with the mineral oil and ultimately rests at the bottom of the graduated cylinder in its own layer, while the mineral oil rises to the top above the fire-resistant hydraulic fluid. 

This is a very useful test. In a large petrochemical facility, it is not difficult to mistakenly contaminate a fire-resistant phosphate ester hydraulic fluid with one of the many mineral oil lubricants used in the plant. Don’t do it! It will accelerate EHC fluid degradation, reduce the fluid’s fire-resistance, and in certain cases soften seals if they are specifically engineered to work exclusively with phosphate ester fluids. We recommend this test on an annual basis for all phosphate ester fluids.

Common catalysts in the petrochemical industry are Triethylaluminium Al₂(C₂H₅)₆, also called TeAl, and Trimethylaluminium Al₂(CH₃)₆, also called TMA. These products are often used in the production of detergents and polyolefins, respectively. We help our petrochemical customers look for process contamination in compressor and gearbox lubricants. TeAl and TMA typically leave behind very elevated levels of aluminum in a contaminated lubricant. They also contribute to lowering the oil viscosity and the flash point of the oil in a lube system. Changes in these test results correlate roughly to the level of contamination in a lube system and the urgency to take action to reduce contamination to avoid negative effects.

Not only does this type of contamination lower oil viscosity but it also reacts with the amine and phenol antioxidants in the oil and degrades the lubricant’s antioxidant protection at an accelerated rate. Remember to test the active antioxidant levels on at least a six-month basis on units that experience this type of contamination. We recommend the Ruler test, ASTM D6971, for most applications.

In addition, TeAl and TMA can leave behind a gel or residue that clogs lube oil filters. Consider an annual or semi-annual laboratory inspection of the lube oil filter from the contaminated system. The residue left behind on the filter will typically consist of thousands of ppm of aluminum. Lastly, the residue can build up in bearing locations, almost like a varnish, and shrink a bearing clearance which causes elevated temperature issues. Elevated oil temperature also accelerates oil oxidation.

Sample with frequency. We recommend near term action when contamination levels are elevated. Monitor antioxidant levels in contaminated oil, monitor filter dP, and check bearing temperatures on a regular basis.

Full-Film, Hydrodynamic Lubrication

A hydrodynamic lubrication regime occurs when a full fluid film is formed between two surfaces in relative motion, effectively separating them and reducing friction and wear. In this regime, the lubricant's primary function is to create and maintain a pressurized fluid film that supports the load and prevents direct contact between the surfaces.

Characteristics of Hydrodynamic Lubrication:

1.    Fluid film formation: Hydrodynamic lubrication relies on the formation of a thick fluid film between the surfaces, which provides complete separation and minimizes contact.

2.    Pressure generation: As the surfaces move relative to each other, the lubricant gets squeezed between them, generating pressure that supports the load and maintains the fluid film.

3.    High-speed operation: Hydrodynamic lubrication is particularly effective at higher speeds where the relative motion of the surfaces generates sufficient hydrodynamic pressure to sustain the fluid film.

Mechanisms of Hydrodynamic Lubrication:

1.    A wedge effect: The converging shape of the lubricant film due to the surfaces' geometry creates a wedge-like action, generating pressure and lifting the load, effectively separating the surfaces.

2.    Fluid shear: The relative motion between the surfaces causes shear forces within the lubricant, creating a hydrodynamic pressure that further supports the load and maintains the fluid film.

Factors Influencing Hydrodynamic Lubrication:

1.    Operating conditions: Hydrodynamic lubrication is more pronounced at higher speeds and loads where the hydrodynamic pressure generated is sufficient to sustain the fluid film.

2.    Viscosity: The viscosity of the lubricant is crucial in hydrodynamic lubrication, as it affects the film thickness and the ability to generate and maintain the necessary fluid pressure.

3.    Surface geometry: The shape and design of the surfaces, including clearances and surface roughness, influence the fluid film formation and the hydrodynamic pressure developed.

The stages to create full film, hydrodynamic lubrication:

1.    Initial contact: Initially, the surfaces are in contact and the lubricant is squeezed out from the clearance between them.

2.    Inlet zone: As the surfaces continue to move, the lubricant enters the inlet zone, where the fluid film starts forming.

3.    Full film zone: Further into the motion, the fluid film thickness increases, reaching its maximum in the full film zone, fully separating the surfaces.

Hydrodynamic lubrication is commonly employed in journal bearings used in engines, turbines, and other rotating machinery to minimize friction and support heavy loads. It’s also ideal for sliding surfaces, such as sliding guides, machine tool slides, and hydraulic cylinders, which benefit from hydrodynamic lubrication to reduce wear and friction.

Hydrodynamic lubrication offers several advantages:

1.    Excellent load-bearing capacity: The thick fluid film generated in hydrodynamic lubrication can support high loads and reduce friction effectively.

2.    Lower friction and wear: Hydrodynamic lubrication minimizes direct contact between the surfaces, resulting in reduced friction and wear.

However, hydrodynamic lubrication also has limitations:

1.    Dependence on speed: Hydrodynamic lubrication is more effective at higher speeds where sufficient hydrodynamic pressure can be generated. At low speeds, the fluid film may be less developed, leading to increased contact and higher friction.

2.    Start-up and shutdown: Hydrodynamic lubrication may take time to establish at start-up and may not be fully effective during shutdown, which can lead to increased wear during these transient operating conditions.

To compensate for the lack of full film lubrication at start up, a hydrostatic lift is used. Hydrostatic lift offers a vital solution for addressing start-up and transient challenges. This mechanism involves pressurized fluids that create a fluid cushion between surfaces, preventing direct contact and reducing wear. During start-up, when immediate hydrodynamic lubrication can be difficult, hydrostatic lift proves its effectiveness. By introducing pressurized fluid externally, a thin fluid film rapidly forms even at low speeds, preventing initial friction and wear.

External pumps and compressors will deliver fluid through dedicated channels in bearing surfaces. Turbines and centrifugal compressors commonly require hydrostatic lift since they commonly experience frequent start-stop cycles. A properly maintained hydrostatic lift system will significantly extend machinery lifespan.

Understanding hydrodynamic lubrication is crucial for selecting appropriate lubricants, optimizing clearances and surface design, and operating machinery at optimal speeds and loads. In the next section, we will explore elastohydrodynamic lubrication (EHL), which combines aspects of hydrodynamic lubrication with elastic deformation of the surfaces. 

Introduction

A lubrication regime is the type of lubrication layer between two metal surfaces that can come in direct contact with one another. A lubrication regime can be either boundary, mixed, or full-film lubrication. Deciding the proper lubricant for an application requires determining which lubrication regime or regimes occur during equipment operation. Understanding these regimes is essential to minimize damage from metal-to-metal contact, selecting the right lubricant and additives to optimize the performance, reliability, and longevity of mechanical systems.

Different machinery types operate under varying lubricating conditions. For example, journal bearings in electric motors rely on full-film hydrodynamic lubrication, where a fluid film separates the metal surfaces and there is no metal-to-metal contact during running operation. On the other hand, gears, especially under heavy loads, can experience physical contact between the interacting gear teeth while in boundary and mixed lubrication regimes.

By understanding the characteristics and mechanisms of these lubrication regimes, we can make informed decisions when choosing lubricants and additives. We will explore each regime's unique features, mechanisms, and applications.

Boundary Lubrication

Boundary lubrication is a lubrication regime that occurs when there is direct contact between two surfaces (at times >90% metal-to-metal surface contact¹), and a thin film of lubricant is unable to separate the metal surfaces from rubbing against each other. Boundary Lubrication has by far the highest coefficient of friction amongst the regime types. In this regime, the primary function of the lubricant is to minimize friction and wear by forming a protective boundary film on the surface.

Characteristics of Boundary Lubrication:

1.    Thin lubricant film: The lubricant film in boundary lubrication is extremely thin, often in the range of just a few molecular layers. This thin film is not sufficient to provide complete separation between the surfaces.

2.    Direct surface-to-surface contact: The surfaces in contact experience significant load and can come into direct contact with each other, leading to higher friction and wear.

Mechanisms of Lubrication

Boundary lubrication relies on several mechanisms to reduce friction and wear:

1.    Boundary film formation: The lubricant forms a protective film composed of additives, such as anti-wear and extreme pressure agents, which adhere to the metal surfaces. We will discuss additives in more detail in a future blog post. This boundary film acts as a barrier, preventing direct contact between the surfaces.

2.    Adsorption and chemical reaction: The lubricant molecules adsorb onto the surface, creating a monolayer that reduces friction and wear. Chemical reactions between the lubricant additives and surface materials can further enhance the protective effects.

3.    Tribochemical reactions: Under high pressure and temperature, the lubricant can undergo chemical reactions with the surface, forming a solid film that reduces friction and wear.

Factors Influencing Boundary Lubrication

Several factors influence the effectiveness of boundary lubrication:

1.    Load and pressure: Higher loads and pressures increase the likelihood of direct surface contact, leading to a greater reliance on boundary lubrication.

2.    Surface roughness: rougher surfaces provide more contact points, making it challenging to maintain a continuous lubricant film and promoting boundary lubrication.

3.    Lubricant properties: The chemical composition and additives of the lubricant play a crucial role in boundary lubrication. Anti-wear and extreme pressure additives enhance the formation of the protective film.

Applications and Examples

Boundary lubrication is commonly encountered in various applications, including:

1.    Metal forming processes: When metals are shaped through processes like stamping, drawing, or extrusion, boundary lubrication is essential in reducing friction between the metal and the forming tools.

2.    High-pressure gears and bearings: In applications with heavy loads and intermittent high contact pressures, such as gearboxes and heavy machinery, boundary lubrication helps protect the surfaces from excessive wear.

3.    Automotive engines: Boundary lubrication occurs in the piston-cylinder interface, where the lubricant film is frequently breached due to elevated temperatures and pressures.

Limitations of Boundary Lubrication

Boundary lubrication offers certain advantages, such as its ability to provide protection under extreme conditions where other regimes may fail. However, it also has limitations:

1.    Limited load-bearing capacity: Boundary lubrication cannot support high loads as the lubricant film is thin and easily breached.

2.    Increased friction and wear: While boundary lubrication reduces wear compared to dry surfaces, it still exhibits higher friction and wear compared to other lubrication regimes.

3.    Sensitivity to operating conditions: Boundary lubrication's effectiveness depends on factors such as temperature, speed, and surface roughness, making it more sensitive to variations in operating conditions.

Understanding boundary lubrication is crucial for selecting appropriate lubricants and additives, optimizing surface finishes, and implementing maintenance strategies to minimize wear and friction.

Mixed Lubrication

The mixed lubrication regime that occurs when both a fluid film layer lubrication and boundary lubrication mechanisms are simultaneously present between two surfaces in relative motion. It serves as a transitional regime between boundary and full-film lubrication. In mixed lubrication, the lubricant film thickness is not sufficient to separate all surfaces, resulting in intermittent contact and partial fluid film formation. Mixed lubrication most commonly occurs at start-up or shutdown.

The characteristics of mixed lubrication include moments of direct contact between the surfaces, as well as partial separation due to the presence of a thin fluid film. Therefore, it has the 2^nd highest coefficient of friction amongst the regime types. It combines aspects of both boundary lubrication and full-film lubrication, with the lubricant film thickness being neither fully developed nor completely absent. The lubrication regime can vary along the contacting surfaces, with some regions exhibiting more boundary lubrication and others displaying characteristics of full-film lubrication.

Mixed lubrication relies on a combination of mechanisms to reduce friction and wear. In areas of direct contact, boundary lubrication mechanisms come into play, where additives in the lubricant form a protective film on the surface, minimizing friction and wear. In regions where the lubricant film is thicker, full-film hydrodynamic lubrication mechanisms contribute to load support and reduced friction, although not to the extent of a fully developed fluid film. Does your equipment experience mixed lubrication? Selecting lubricants with the proper additive chemistry protect equipment during these expected periods.

Several factors influence the occurrence and effectiveness of mixed lubrication. Operating conditions, such as moderate speeds and loads, play a role as the fluid film thickness is insufficient for complete separation. Surface roughness also influences the extent of boundary lubrication, with rougher surfaces promoting boundary lubrication in those areas. Additionally, the viscosity, additives, and film-forming characteristics of the lubricant impact the transition between boundary and full-film lubrication within the mixed regime.

Mixed lubrication finds applications in various systems. For example, in automotive engines, the camshaft and lifter interface often experience mixed lubrication due to high contact pressures and the intermittent nature of the motion. Rolling element bearings, specifically the contact between the rolling elements and the raceways, can also exhibit mixed lubrication.

Mixed lubrication offers advantages such as moderate load-carrying capacity due to the combined effect of fluid film and boundary lubrication mechanisms. It also provides improved wear resistance compared to pure boundary lubrication due to the presence of a partial fluid film. However, it has limitations, including increased friction compared to full-film hydrodynamic lubrication due to intermittent contact and sensitivity to operating conditions such as speed, load, and surface roughness.

Caution must be exercised when incorporating additives into lubrication systems, especially in cases where the metallurgy of components involves sensitive materials such as copper-based alloys. While additives can enhance lubrication performance, certain formulations, like sulfur-based extreme pressure additives, can react adversely with these alloys.Top of Form

Understanding mixed lubrication is crucial for optimizing lubricant selection, surface finishes, and operating conditions. By minimizing direct contact and enhancing fluid film formation, the detrimental effects of boundary lubrication can be minimized. In the next section, we will explore full-film hydrodynamic and elastohydrodynamic lubrication (EHL).

Much more regularly we measure particle contamination of machine fluids with ASTM D7647. We find the method superior to testing undiluted fluids with a laser optical instrument as well as a pore blockage instrument. By incorporating accurate and consistent dilution we can clear up almost every sample for laser optical particle counting to quantify insoluble debris that can be extracted from a fluid with traditional filtration. ASTM D7647 provides superior sample preparation and a significant reduction in interference from water or entrained gas. Our new CINRG autosampler instrument does a wonderful job. Why didn’t we buy this five years ago?

Selecting the right base oil for a particular application is crucial to achieving optimal lubrication and extending the life of the equipment. Some of the factors to consider when selecting a base oil include: Compatibility with Equipment, Operating Conditions, Environmental Considerations, the Cost, and Regulatory Requirements.

Application of Base Oils

Base oils are used in a wide range of applications, including:

Industrial Lubricants:

Base oils are used in industrial lubricants such as hydraulic fluids, compressor oils, and metalworking fluids. In these applications, the base oils provide essential lubrication and cooling properties to the equipment, extending its useful life and improving its efficiency.

Hydraulic Fluids:

Base oils are used in hydraulic fluids to transmit power and lubricate the hydraulic system. In these applications, the base oils must have good viscosity properties to ensure the system functions correctly.

Compressor Oils:

Base oils are used in compressor oils to provide essential lubrication and cooling properties to the compressor. The base oils must be carefully selected to ensure compatibility with the compressor and its seals.

Metalworking Fluids:

Base oils are used in metalworking fluids to provide lubrication and cooling properties during the cutting and shaping of metals. In these applications, the base oils must be carefully selected to ensure compatibility with the metals being worked and to prevent corrosion.

Automotive Lubricants:

Base oils are the main component in engine oils, transmission fluids, and gear oils used in vehicles. High-performance base oils are necessary to ensure maximum engine protection and fuel efficiency.

In each of these applications, the selection of the appropriate base oil is crucial to achieving optimal lubrication and equipment protection. The physical and chemical properties of the base oil must be matched to the specific application to ensure that it can provide adequate lubrication, cooling, and protection against wear, oxidation, and corrosion.

Choosing the right base oil for a particular application involves careful consideration of several factors, including:

Equipment Compatibility:

The base oil must be compatible with the equipment being used to avoid issues such as seal leakage, corrosion, and wear. Manufacturers' recommendations should be followed when selecting a base oil for a particular application.

Operating Conditions:

The operating conditions of the equipment, including temperature, pressure, and load, must be considered when selecting a base oil. The base oil must be able to withstand the operating conditions and provide optimal lubrication and protection. Aviation hydraulic systems are a good example of an application that requires a lubricant to function under extreme temperature ranges as well as being fire resistant. In such systems, the hydraulic fluid must provide effective lubrication and transfer of power under extreme temperature fluctuations. They also require strict fire-resistant hydraulic fluid requirements for aircraft hydraulic systems. Phosphate esters have good low-temperature fluidity, high-temperature stability, and excellent lubricity properties, making them suitable for use in aviation hydraulic systems that operate under extreme conditions. However, it is important to note that phosphate esters have limited compatibility with some elastomers and plastics, and they can be more expensive than other types of base oils. Therefore, proper selection and compatibility testing with aircraft and component manufacturers are critical when choosing a phosphate ester-based hydraulic fluid for aviation hydraulic systems.

Environmental Considerations:

Environmental concerns, such as biodegradability and toxicity, must be considered when selecting a base oil. If the equipment is used in environmentally sensitive areas, biodegradable oil may be preferred. One example application where a biodegradable lubricant would be needed is in marine environments. Biodegradable lubricants are necessary to protect marine life and prevent contamination of the water. For example, hydraulic systems used in ships, boats, or offshore platforms require lubricants that can perform in the harsh marine environment without causing harm to marine ecosystems. Biodegradable lubricants can provide lubrication and protection while also breaking down naturally in the event of a spill or leak, reducing the risk of environmental damage. Oil analysis can be a valuable tool in maintaining the performance and environmental benefits of biodegradable lubricants, by providing insights into lubricant condition and performance and helping to optimize lubricant use.

The Cost:

The cost of the base oil should also be considered when selecting the lubricant. More expensive synthetic base oils may provide better performance, but they may not be necessary for every application. A cost-benefit analysis should be conducted to determine the most appropriate base oil for a particular application.

Regulatory Requirements:

Regulatory requirements, such as industry standards or environmental regulations, must be considered when selecting a base oil. The Environmental Protection Agency (EPA) has regulations in place to limit the amount of sulfur in base oils used in certain applications. In addition to these factors, the API base oil classification system can also be used to select the appropriate base oil for a particular application. The API system categorizes base oils based on their properties and performance characteristics, allowing for easier selection of the appropriate base oil. Selecting the right base oil is crucial to achieving optimal lubrication and equipment protection. A thorough analysis of equipment compatibility, operating conditions, environmental considerations, cost, regulatory requirements, and the API base oil classification system can help ensure the selection of the most appropriate base oil for a particular application.

Conclusion

Base oils are a fundamental component of lubricants, providing essential lubrication, cooling, and protection against wear, oxidation, and corrosion. There are several types of base oils available, including mineral, synthetic, vegetable, and biodegradable oils, each with its own set of properties and characteristics. The selection of the appropriate base oil for a particular application involves careful consideration of several factors, including equipment compatibility, operating conditions, environmental considerations, cost, and regulatory requirements. The API base oil classification system can also be used to aid in the selection of the appropriate base oil. In conclusion, selecting the right base oil is crucial to achieving optimal lubrication and equipment protection. Proper selection can help extend the life of the equipment, improve its efficiency, and reduce maintenance costs. Therefore, it is important to consider all the factors involved and choose the most appropriate base oil for a specific application.

In our next blog, we will be discussing oil additives, which are important components that enhance the performance of base oils. While selecting the right base oil is crucial for a lubricant's performance, oil additives play a significant role in improving wear protection, oxidation resistance, and viscosity stability. By understanding the advantages and disadvantages of different API base oil groups, we can select a base oil that provides the necessary performance characteristics for a particular application.

This newer instrument at MRT Laboratories works very well for the membrane patch colorimetry varnish potential test. Thank you, Azzota Scientific. See video of their Vacuum Filtration 6-Branch Manifold System. We run six MPC tests at a time. High quality lab instrument fabrication and a quality vacuum pump.

See video: https://youtu.be/FXJ3G1cOQCI

Lubrication is a vital aspect of the proper functioning and longevity of machinery, whether in the automotive, industrial, or other sectors. At the heart of every lubricant is a base oil, which makes up to 80% of any engine lubricant and 90% of any industrial lubricant. A base oil provides the fundamental lubricating properties needed to reduce friction, wear, and heat between moving parts. Base oils can be derived from various sources, including mineral, synthetic, vegetable, and biodegradable oils. They also possess a range of physical and chemical properties that must be considered when selecting the appropriate base oil for a particular application. In this article, we will explore the different types of base oils and their properties. In the future part two of this segment, we will cover proper base oil applications and the factors that should be considered when choosing the right base oil for optimal lubrication.

Base Oil Types

There are several types of base oils available in the market, each with its own set of characteristics and properties. The main types of base oils include:

Mineral Base Oils:

Mineral base oils are derived from crude oil through a refining process. They are widely used in lubricants due to their excellent lubrication properties, high availability, and low cost. Mineral base oils are suitable for many applications.

Synthetic Base Oils:

Synthetic base oils are chemically synthesized to achieve specific properties such as high-temperature stability, low volatility, and excellent oxidation resistance. These base oils can be customized to meet specific requirements and are often used in high-performance applications such as aerospace, racing, and extreme temperature conditions.

Vegetable Base Oils:

Vegetable base oils are derived from various plant sources, such as rapeseed, sunflower, and soybean oil. These oils are environmentally friendly, biodegradable, and non-toxic, making them a popular choice for applications where environmental concerns are important, such as in the food industry and maritime industries and as biodegradable lubricants.

Biodegradable Base Oils:

Biodegradable base oils are designed to break down naturally and do not harm the environment. These base oils can be derived from mineral, synthetic, or vegetable sources, and are suitable for applications where environmental considerations are a high priority, such as in marine and forestry applications.

Each type of base oil has its own advantages and disadvantages, and the selection of the appropriate base oil for a particular application depends on several factors such as the operating conditions, equipment type, and environmental considerations. There was significant variability in the quality and performance of base oils. This made it difficult for lubricant blenders and end users to know exactly what they were getting and how it would perform in different applications. The industry needed a way of categorizing the different base oils. We will look at one of the most used base oil classification systems.

The American Petroleum Institute (API) has developed a classification system for base oils, known as the API Base Oil Classification System. This system categorizes base oils into five groups, based on their properties and characteristics, with each group representing a different level of performance and quality. Understanding the advantages and disadvantages of each API base oil group can help in selecting the most appropriate base oil for a specific application. The following table provides a summary of the advantages and disadvantages of each API base oil group, including their availability, cost, lubricity, and performance at high and low temperatures. It is important to note that the selection of a base oil should be based on the specific requirements of the application, including equipment compatibility, operating conditions, and environmental considerations.

API Base Oil Classes

* Group I base oils used in the USA and Europe have declined significantly due to the availability of Group II and Group III base oils and increased environmental requirements. Group I base oils are still used in Russia, areas of Asia, and many Middle Eastern countries.

Properties of Base Oils

The properties of a base oil play a critical role in determining its suitability for a particular application. Some of the key properties of base oils include:

Viscosity:

Viscosity refers to the oil's resistance to flow and is considered the most important physical property of a lubricant. Viscosity is typically measured at two temperatures, 40°C and 100°C, and two of the most widely used classification systems are ISO (International Standards) and SAE (Society of Automotive Engineers). The results are typically reported as cSt (centistokes). The correct viscosity grade must be selected to ensure that the oil flows freely and provides adequate lubrication.

Oxidation stability:

Oxidation stability refers to the ability of the oil to resist breakdown due to exposure to air and high temperatures. An oil with good oxidation stability will resist the formation of harmful sludge and varnish deposits, which can lead to engine or equipment failure. The importance of oxidative stability in turbine oils cannot be overstated, as the oil is continuously exposed to extreme temperatures, pressures, and oxygen-rich environments. When exposed to these conditions, the oil can begin to oxidize, leading to the formation of harmful deposits, sludge, and varnish. This degradation can cause increased wear and tear on turbine components, reduced system efficiency, and increased maintenance costs. To ensure maximum equipment protection, performance, and lifespan, turbine oils must have exceptional oxidative stability to resist oxidation and maintain their performance over extended periods. Therefore, it is crucial to choose a turbine oil with high oxidative stability and implement regular oil analysis and proper fluid maintenance practices to ensure optimal turbine performance, avoid costly maintenance and downtime, and extend the service life of the oil.

Volatility:

Volatility refers to the oil's tendency to evaporate at high temperatures. Base oils with high volatility can lead to oil consumption and contribute to air pollution. High-performance applications require base oils with low volatility to ensure the oil remains in the system and continues to provide adequate lubrication.

Pour point:

Pour point refers to the temperature at which the oil becomes too viscous to flow. A low pour point is essential for oils used in cold environments, as it ensures the oil remains fluid and can flow through the system.

Additive solubility:

Additive solubility refers to the ability of the oil to dissolve additives such as detergents, dispersants, and anti-wear agents. A base oil with good additive solubility will ensure that the additives remain suspended in the oil, providing maximum protection to the system.

The properties of a base oil can be improved through the addition of specialized additives, which can enhance its performance and extend its useful life. However, it is essential to select a base oil that possesses the necessary properties for a particular application to ensure optimal lubrication and equipment protection. The combination of the correct group of base oil and its properties determine its useful application, which we will discuss in Part II of this segment!

Selecting the best location for a sample

“Maximize the data density” of a sample by ensuring we collect the sample with the best procedure and at the optimal location. For example, taking the sample downstream of the filter would result in missing critical wear or contaminant particles that would have been removed from by the filter. Samples should be taken upstream of filters and downstream of machinery components.

Collecting samples of oil that is circulating

In any circulating system we want to collect a lubricant sample in turbulent flow and downstream of critical lubricated equipment. This ensures that the sample is well mixed and has the best chance of capturing wear debris from the critical lubricated components of the system.

Collecting a sample from oil that is stagnant or flowing in a straight line (laminar) is not as representative as turbulent flow. Laminar flow refers to parallel fluid layers adjacent to each other without mixing. Wear or contaminant particles flow along with the fluid. If we take a sample under these conditions, some of the particles will “fly-by” our sampling point. We will miss important information about the particles that are circulating in the system. We should take samples at locations where there is turbulent flow when possible. Piping elbows are perfect turbulent flow locations. Mixing of the layers occurs at these points.

The best place to take samples is at an elbow on a return line, downstream of machine components but upstream of filters. In a reservoir the fluid will rest and can lose concentration of any wear metal debris. Although the second-best sampling location is on the supply side of a circulating system, the oil flows through a filter is still before the oil flows through a filter. Much of any active wear debris will remain suspended in the oil even as it rests for the minutes that it would circulate through a reservoir before being pumped back through the system.

Collecting samples of oil that is NOT circulating

Oil reservoir, gearbox sump, or from any drain location is where oil is considered non-circulating. Since these locations may not be capturing oil in turbulent flow, they can miss out on capturing fresh wear material from lubricated components. When faced with having to sample non-circulating oil we can still capture the best samples available.

Drain Port Sampling: Particles and water will settle to the bottom of the sump, resulting in a bad (non-representative) sample. Drain off and discard a sufficient volume of oil before taking the sample to be sent to your laboratory for used oil analysis. This will remove as much stagnant debris and water from the sample which does not represent the oil that’s actively lubricating critical components. A preferable way to take a drain sample is to use a pitot tube, which extends into the fluid so that the sample will be more representative. The tube should drop down to the midpoint depth of the fluid level in the reservoir.

Handheld Vacuum Pump and Tubing: Collect a sample from the fill port of a reservoir or gearbox sump with a handheld vacuum pump and polyethylene tubing. This technique allows the technician to collect oil that is not resting near a drain, therefore it’s an improvement from a drain sample.

This method has several drawbacks. Inserting the tube to the correct depth of reservoir oil and using a consistent technique can be difficult. Soft tubing will bend and curl up at the fluid line and it can be difficult to get the right angle of the tubing to enter the fluid. Fill port screens may also be time consuming to remove to prepare for collection. Lastly, the tip of the tubing can scrape metal surfaces and contaminate the sample.

Installing the right equipment to facilitate sampling

Hydraulic Oil Adapter Kit

Image from Trico Corporation.

Minimess Oil Sampling Port: A minimess oil sampling port is a type of sampling valve that is commonly used for taking oil samples from hydraulic and lubrication systems. It is a compact, self-sealing valve that can be installed directly into the system for easy and convenient collection. Here are some of the advantages and disadvantages of using a minimess oil sampling port:

Advantages of a minimess port:

1.    Easy to install: Minimess oil sampling ports are designed to be easy to install, with a threaded body that can be screwed directly into the system.

2.    Easy to use: The self-sealing valve design of the minimess port makes it easy to take oil samples quickly and cleanly.

3.    Minimal system downtime: Because the minimess port can be installed without draining the system, there is minimal downtime required for installation.

4.    Clean: The minimess port helps prevent contamination of the oil sample, as it is designed to seal tightly when not in use.

5.    Compatible with different types of oil: Minimess ports can be used with a variety of different types of oils and fluids, making them a versatile choice for oil sampling.

Disadvantages of a minimess port:

1.    Cost: Minimess oil sampling ports can be more expensive than other types of sampling valves, which may be a consideration for some applications.

2.    Maintenance: Like any type of valve or sampling device, minimess ports require regular maintenance to ensure proper operation and prevent leaks.

3.    Limited flow rate: The flow rate through a minimess port is limited, which may be a consideration for larger hydraulic or lubrication systems.

4.    Limited pressure rating: Minimess ports typically have a limited pressure rating, which may make them unsuitable for use in high-pressure systems.

Overall, minimess oil sampling ports are a convenient and reliable option for taking oil samples from hydraulic and lubrication systems. They are easy to install and use and help prevent contamination of the oil sample. However, their higher cost and limitations in flow rate and pressure rating may be a consideration for some applications.

Additional alternative – the Portable Filter Cart: Portable filter carts will typically have at least one oil sample location on them. Filter carts can be equipped with a bypass valve so that oil can be circulated without flowing through the filters. Circulating the oil for a few minutes allows us to take a representative oil sample. After the sample is taken, switch the valve to filter the oil. This method lets you take a representative before and after any external filtration work.

Sample Methods Summary

Accurate analysis and diagnosis of an oil system depend on obtaining a representative sample, free from contaminants. Regardless of the sampling method used, it is crucial to follow proper procedures and guidelines to ensure the sample collected accurately reflects the oil's condition.

To ensure that the oil sample is representative, the sampling location should be flushed before collecting the sample. Clean and properly labeled sample containers should be used to avoid contamination. It is also essential to prevent any contact between the sample and surfaces or materials that may introduce contaminants.

Consistency in sampling is crucial to accurately assess the oil system's condition over time. The best way to ensure consistent sampling is to have a written procedure that outlines the steps to be followed, including the frequency of sampling, the type of container to be used, and any flushing or cleaning procedures necessary.

When developing a sampling procedure, consider the specific needs of your oil system, the equipment to be used, and the type of analysis required. Consult industry standards and guidelines and involve key stakeholders in the process. It is also essential to review and update the procedure regularly to ensure it remains current and effective.

Sending the Sample to the Laboratory

When submitting a used oil sample for analysis, it is important to provide certain information to ensure that the laboratory can perform an accurate and meaningful analysis. This information includes equipment information, sampling date, service hours/mileage, operating conditions, and any additional relevant information such as recent maintenance, repairs or any unusual observations. These observations may be unusual equipment noise, vibration, or operating temperature. By providing this information, the laboratory can better determine the condition of the oil and machine to make more accurate recommendations for maintenance and equipment performance.  Sometimes you may not have all of the above information so just include as much information as possible.

Conclusion of the Blog Information

Overall, oil sampling is an essential tool for maintaining the reliability and performance of machinery and equipment. By using appropriate sampling methods and following proper procedures, maintenance professionals can ensure that oil samples are accurate, representative, and useful for making informed maintenance decisions. Good sampling technique will go a long way to improving your reliability program and reducing unexpected downtime and lost revenue.

At MRT Laboratories, we are here to help optimize sample collection and quality. Whether you need guidance on sampling technique or have questions about our services, our team of STLE/ICML certified professionals is always available to assist you. Please don't hesitate to reach out to us. We value your input and are committed to providing the highest level of support and expertise. You can email us at info@mrtlaboratories.com or call us at 713-944-8381

Oil sampling is a critical aspect of predictive maintenance for lubricated machinery and equipment. By regularly monitoring the condition of lubricating oil, maintenance professionals will: (1) detect issues at an early stage and minimize unanticipated catastrophic failure events, and (2) make informed decisions about when to perform maintenance or replace components.

Draw the most representative sample in any circulating or non-circulating lubrication system. A representative sample provides very useful information about machine condition, oil condition, and the nature of fluid contamination, which are the three main categories of information contained within a used oil analysis report. An improperly drawn oil sample may lead to taking unnecessary corrective action or, perhaps even worse, not taking corrective to prevent unexpected downtime and loss of production and revenue. Gathering the most representative oil sample starts with using high quality sample bottles with exceptional cleanliness.

Always use super clean sample bottles

Sample bottles need to be super clean. If new sample bottles are not free of contaminants, the bottle contaminants may be misinterpreted as coming from the equipment. “Noise” refers to contamination material that is present in a new sample bottle before the oil is collected. “Signal” is the term for the contaminants in an oil sample from fluid degradation, lube system contamination such as debris and water, and microscopic equipment wear particles. We only want to analyze the “signal” and we do not need interference from the “noise” of a dirty sample bottle. In other words, we need to ensure that we have a high signal to noise ratio.

The International Standards Organization (ISO) has established standards for bottle cleanliness. The ISO standard is ISO 3722. Below is the ISO table for sample bottle cleanliness.

 ISO 3722 Bottle Cleanliness Levels Bottle Cleanliness

Specification

Clean Has less than 100 particles greater than 10 microns per ml of fluid.

Super Clean Has less than 10 particles greater than 10 microns per ml of fluid.

Ultra Clean Has less than 1 particles greater than 10 microns per ml of fluid.

Consider not only sample bottle cleanliness, but also sample bottle material. The primary alternatives for oil sample bottles are high density polyethylene (HDPE), polyethylene terephthalate (PET), polypropylene (PP), aluminum, and glass. HDPE containers are the most durable under high temperatures but are typically either translucent or opaque in appearance. PET are transparent, so it’s easy to see through the bottle wall at the sample appearance, but the material has a lower heat tolerance. PP has a good balance between a semi-transparent appearance and acceptable heat tolerance. Aluminum samples bottles are best for heat transfer oils for maximum heat tolerance. Glass sample bottles are an excellent, all-around alternative for holding samples but are often not practical since they are fragile for shipping and collection in the field. Glass samples are available up to ultra-clean whereas the plastic bottles are only available up to super-clean. Fluid samples that are hygroscopic are ideal candidates for using glass sample bottles since glass provides more protection from atmospheric moisture than plastic bottles, which “breath.” The most common oil sample bottle material is polypropylene. Continuing next week with proper sampling locations.

Gene Wagenseller, CLS, OMA II, MLT II, MLA III, MLE

MRT Laboratories

Thank you, Harvard Filters for letting us test whether we could lower the MPC Delta E of an in-service hydraulic oil in a 24-hour filtering lab simulation. The filter did an excellent job, significantly lowering the MPC Delta E value of this sample. Let's try another one! (Oil Filters and Oil Filtration Systems | Harvard Corporation).

The dry bath oxidation tester by Tannas. Why own only one when you can own two? We'd love to have five, and maybe we will. This a such a reliable instrument for RPVOT ASTM D2272. One of my favorite purchases since being at MRT Laboratories. It helps us do our jobs better.

https://www.tannasking.com/laboratory-instruments-accessories/quantum-oxidation-tester/

MRT is enjoying our new Karl Fischer oven, the Metrohm 885 (see photo). Eighteen samples on the autosampler tray and ideal for our needs when customers require the most accurate measurement of water contamination in parts per million of heavily additized lubricants. Our main of use of this instrument is for testing engine oils. At MRT we also administer the Crackle test, but it simply isn’t as accurate, and this new instrument is perfect for us. We should have purchased this a long time ago! 

We are adding ASTM D6304, Procedure B to our testing capabilities when previously we offered only Procedure A. With this new KF oven we can now run Procedure B for superior accuracy of measuring water contamination in fluids whose additive chemistry interferes with the direct sample injection Karl Fischer titration process. Engine oils commonly contain higher concentrations of either calcium or boron. Both elements will interfere with direct KF titration. As a reminder, the KF titration generates iodine from iodide and water in a sample is titrated by reacting with the iodine in the titration solution and the concentration of water is measured by correlating the current required to generate iodine from iodide. Certain heavily additized lubricants increase iodine consumption in the titration which creates a higher testing result for H2O in a sample. ASTM D6304 Procedure B, or the indirect procedure, titrates water vapor being distilled from the oil sample, so iodine consumption is unaffected by oil additives.

Thank you to Metrohm for this great instrument!

By Michael D. Holloway, 5th Order Industry and Ben Hartman, MRT Laboratories

Entry level chemistry students learn Entropy – how every system is always trying to achieve its most comfortable state of existence. That concept holds true for societies, companies, families, animals, and even molecules and atoms. All things are in a constant state of change. All things are working towards their ‘Enthalpic Goal’. Metal is no different. Metals can be pure elemental (Iron, Aluminum, Copper, etc.…) or combinations forming alloys (Brass, Bronze, Stainless Steel, etc.,,,). Metal is normally present in a stable oxidized form as ore. These metal ores tend to react with water or oxygen to form corresponding metal oxides. This process leads to deterioration known as corrosion. While the metal achieves a ‘comfortable state’ it no longer has certain physical characteristics we find useful such as strength, durability, ductility, and even conductivity. The metal has experienced corrosion.

In a 2016 study conducted by the NACE (formerly known as the National Association of Corrosion Engineers) and outlined in their publication “The International Measures of Prevention, Application and Economics of Corrosion Technology (IMPACT),” corrosion is responsible for a global cost of $2.5 trillion dollars. This figure represents roughly 3.4 percent of the global Gross Domestic Product (GDP).

Corrosion can be further defined as being Dry or Wet. Dry Corrosion occurs when oxygen reacts with the metal without the liquid. While dry corrosion is not as harmful as wet corrosion, it is temperature sensitive. Exposing a clean piece of metal to an open flame will quickly form an oxide layer. The formation in certain metals may lead to the reduction of the rate of corrosion. This layer acts as a barrier for further oxidation. This is known as Passivation. This is common in many alloys and certain metals. Copper and aluminum form a protective oxide layer or scale. This will slow down oxidation and ultimately corrosion. Stainless steel has chromium which helps form a protective layer that prevents further corrosion. Unfortunately, not all oxide layers form a protective layer. If the oxide layer is not continuous, it will not be able to reduce the amount of oxygen reaching the metal surface.

Wet corrosion is also known as Galvanic Corrosion. This form of corrosion (also known as bimetallic corrosion) is more dangerous than the dry type. Here, an electrochemical cell is produced consisting of an Anode (negative charged metal), a Cathode (positive charged metal), and an Electrolyte solution that allows for electron transference. Ground water or sea water is a common electrolyte and is responsible for the majority of metal corrosion. The movement of electrons from the anode to the cathode starts an oxidation reaction at the anode that causes it to degrade. This type of corrosion is affected by the magnitude of electric potential created. To determine the severity of the potential corrosion, you would have to look at the metal’s potential in a galvanic series table. This is where corrosion engineers will determine the rate of corrosion at the metal surface. One metal experiences corrosion (loses electrons), while the other will not normally corrode when in proximity. This doesn’t mean that it will not corrode because often it will, just not at the same rate, conditions or mechanisms. Cathodic metals (positive charged metals) corrode when in proximity to anodic metals (negative changed).

When two dissimilar metals are put in proximity of each other, it is essential that we contemplate their anodic index. The anodic index is a measure of the electrochemical voltage that will be developed between the metals. When two metals are in proximity and an electrolyte provides separation, a voltage potential is created. This is how the first batteries were developed. To find the relative voltage of a pair of metals we subtract their anodic indices. By doing so, one can calculate the voltage potential that can be generated. This also provides insight into the galvanic corrosion response. The greater the generated potential, the greater the galvanic corrosion. Consider the following table of metals and their Voltage Index (V):

Ref: Handbook of Corrosion Engineering, Pierre R. Roberge, McGraw-Hill; 2000

According to the Handbook of Corrosion Engineering, to reduce galvanic corrosion for metals stored in normal environments such as storage in warehouses or non-temperature and humidity-controlled environments, there should not be more than 0.25 V difference in the anodic index of the two metals in contact. For controlled environments in which temperature and humidity are controlled, 0.50 V can be tolerated. For harsh environments such as outdoors, high humidity, and salty environments, there should be not more than 0.15 V difference in the anodic index. For example: gold and silver have a difference of 0.15 V, therefore the two metals will not experience significant corrosion even in harsh conditions.

If dissimilar metals must come in contact due to design, the difference in anodic index is often managed by finishes and plating. The finishing and plating selected allow the dissimilar materials to be in contact, while protecting the cathodic metals from corrosion by the anodic metal. The metal with the most negative anodic index will corrode. A real-world example would be why sterling silver and stainless-steel tableware should never be put in a dishwasher at the same time. The steel items will corrode. The soap and water provide an electrolyte solution that will increase the galvanic corrosion of the metals.

Thank you so much for reading!! In our next installment, we will explore the several different types of corrosion that can occur in a lubricated system.  

By Michael D. Holloway, 5th Order Industry and Ben Hartman, MRT Laboratories

The major contributor for component failure is external contamination in the form of sand or soil (dirt). A leading cause for failure is surface wear from abrasive materials. Abrasive materials find their way into a lubricated system through several ways, including contaminated lubricants, unclean application methods, exposed reservoirs, and compromised seals. Abrasive particles wear surfaces by inserting into the space tolerance between two sliding, lubricated surfaces or as an erosive agent in a highly turbulent system. Abrasive particles are typically hard metallic contaminants.

Metallic elemental analysis can help in understanding the physical nature and chemical structure of contaminants and proven valuable in oil and equipment condition monitoring. Understanding the particle shape and size, as well as the chemical signature can help determine the source and root cause of wear. Dirt and sand are major sources of wear. Sand is Silicon Dioxide (SiO₂) with distinctive particles between 10µm to 2mm in diameter. Dirt is composed of minerals, water, gases (air, CO₂, Methane), organic matter, and microorganisms. The mineral, air, and water concentrations vary from 2% to 50% each, depending upon origin. Organic matter from decayed animals and plant can make up to 25% and microorganisms can be found up to 5% by volume. All five components of dirt can contribute to failure opportunities in equipment with minerals offering the largest contribution.

Minerals have distinct elemental signatures defined as naturally occurring homogeneous elements or inorganic compounds with a chemical composition and characteristic geometric molecular shape. There are two fundamental types of minerals: Primary and Secondary.

Primary Minerals formed from the crystallization of molten magma. This type of mineral has persisted with little change in composition since they were extruded in molten lava such as Quartz (SiO₂), Feldspar (KAlSi₃O₈), Biotite (KMg₃AlSi₃O₁₀), Albite (NaAlSi₃O₈), Muscovite (KAL₃Si₃O₁₀) to name a few. Primary minerals are most prominent in sand and silt fractions. Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz with particles typically between 2µm to 30µm in diameter.

Secondary Minerals are formed on the Earth’s surface by the weathering of Primary Minerals. These minerals are composed of silicate clays and iron oxides and have been formed by the breakdown and weathering of less resistant minerals. Common examples of these minerals would be Goethite (Fe₃O(OH)), Hemacite (Fe₂O₃), Calcite (CaCO₃), Gypsum (CaSO₄), Dolomite (CaMgCO₃), and Clay composed of Aluminum Silicates with particles <4µm in diameter.

Understanding what makes up minerals, as well as their concentration ratios, help to determine the origin of the metals. Elemental oil analysis through Inductive Coupled Plasma (ICP) or Rotrode Emission Spectroscopy (RDE) will only provide information of the concentration in parts per million of various metals without providing the molecular signature. Unless a sample is digested with hydrofluoric acid, particles greater than 7µm will not have enough residence time in the instrument to provide a completely accurate concentration. Using X-ray diffraction will provide molecular information without particle size restriction, yet reference standards are required. If a sample contains iron, the ICP will indicate ppm of Fe whereas the X-Ray Diff can discern between molecular structures such as wear debris or external contamination.

Metals not only represent the source and result of wear, but they also contribute to the formation of acids (Fig. 1). Acid generation in lubricated systems will lead to the development of sludge, varnish, and lacquer due to the free-radical generation, followed by the propagation of larger molecules, and terminating with highly crosslinked polymers. The synthesis route for sludge is a coordination free-radical polymerization. This form of polymerization is also a common process to manufacture useful plastics. Metallocene catalysts that assist in plastics production are similar in functionality to the metal ions that are typically found in used oil. Understanding and eventually controlling metallic concentration in the lube system will lead to increased reliability through reduced failure. 

Figure 1. The Catalytic Effect of Metals and Water in the Formation of Acids

Ref: Lubricant Deterioration in Service, E. Abner, Vol 1, pg. 518 CRC Handbook of Lubrication

Metals have a significant contribution to the demise of an asset. Water contamination plays a synergistic role when combined with metals. The next submission will examine how water jeopardizes the function of a lubrication system. 

Formulas for lubricating oils can be complex often using several reactive chemicals to achieve various performance goals. The balance and concentration require knowledge of organic and inorganic chemical reactions as well as surface chemistry and metallurgy. The formula for a gear oil is very different compared to a hydraulic fluid. While compressor and turbine oils rely on the performance of the base oil primarily with a low concentration of additives, engine and universal hydraulic fluids are the most additized products in comparison.  The required functions of a finished lubricant dictate the use of performance additives. The additives impart functionality through component surface activity, contamination activity, or oil condition activity. The following table lists the additive characteristics:

Several of the additives are molecules which contain a metallic element called organometallics. Organometallics, with their metal–carbon bonds, lie at the interface between classical organic and inorganic chemistry establishing interactions between metal surfaces and carbon-based molecules. The organometallic compounds used in lubricant additives are composed not only of typical metals, but also of metalloids such as boron, silicon, phosphorus, with ongoing research into other metals. Applied organometallic chemistry is among the most actively researched areas in organic, inorganic, biochemical, and catalytic chemistry. Lubricant formulators use various organometallic compounds for various reasons. Common additives include:

•            Zinc - Anti-wear, Extreme Pressure, Antioxidant  

•            Calcium – Detergent, Antioxidant

•            Magnesium - Detergent

•            Silicon – Anti-foam

•            Phosphorus - Anti-wear, Extreme Pressure, Antioxidant  

•            Boron – Detergent, Anti-wear 

•            Molybdenum disulfide - Friction Modifier  

Organometallic compounds have been known and studied for over 250 years. Many of these early compounds were prepared directly from metals by the oxidative addition of alkyl halides. Organometallic compounds are used in lubricant additive applications because they provide a source of nucleophilic carbon atoms which can react with electrophilic carbon atoms to form a new carbon-carbon bond. The metals used in organometallic compounds resist electron loss (low reduction potential), and this structure lends to improved stability and reactivity. Many additives are polar being either cationic (positive charged or acidic) or anionic (negativity charged or basic). 

The physical and chemical properties of organometallic compounds vary greatly. Most are solids, particularly those whose hydrocarbon groups are ring-shaped or aromatic. Their heat and oxidation stability vary widely. Some are very stable while others are not. Some can work well when in contact with water and others breakdown. For an example, the common anti-wear compound Zinc Dialkyldithiophosphate (ZnDTP) has three common molecular structures; primary, secondary, and Aryl that produce different responses in oxidative inhabitation and wear protection functions as well as thermal and hydrolytic stability properties (fig. 1). 

Ref: Oxidative Degradation and Stabilization of Mineral Oil-Based Lubricants G. Aguilar, G. Mazzamar and M. Rasb, Chemistry and Technology of Lubricants, 3rd ed.

Fig. 1 – Function and Property Responses of Various ZDTP Structures

Oil samples contain information that can be used to understand the asset as well as the environment the equipment performs in. The metals found in an oil sample may very well be intentional. MRT Laboratories can help identify the source of the metallic compounds to help drive reliably. Find out how MRT Laboratories has helped improve equipment effectiveness through an oil and equipment condition monitoring program.

Next Submission:

Contamination is responsible for the majority of equipment failures. Many contaminants contain metal which can be identified. Let’s explore the different sources of metals as contaminants in the next installment.  

Where is the wear from?

by Michael D. Holloway of 5th Order Industry and Ben Hartman of MRT Laboratories

There are millions of different machines and countless components that make up these machines. The material fabricating these components are mostly made of metal and the metal is rarely from just one element. The metals are alloys. The alloys are combinations of various metallic elements that provide performance properties either for increased wear resistance, increased corrosion resistance, improved ductility or flexibility, and even hardness. When a machine runs, the components such as bearings, gears, and pumps may experience wear of two surfaces rubbing due to lack of lubrication or exceptional load. When this occurs, metal debris can be found in an oil sample. The metal provides a signature for its source. An understanding of the elements that make up the metal will provide insight into the component that is wearing out. An understanding of the metallic make-up is critical for pinpointing the wear source to take proper action avoiding a catastrophic failure.

The prevailing metal that makes up the majority of the alloys used in machines is iron.  Metals can readily form alloys with iron because their atoms are a similar size. The atoms of other metals simply replace atoms of iron in the metal lattice. Pure iron is too soft and reactive to be used for components therefore it is mixed with other elements such as carbon to make it stronger. This alloy is commonly referred to as steel. There are thousands of different kinds of steel, all containing slightly different amounts of other alloying elements. Steel alloys contain other elements, such as carbon, chromium, copper, manganese, nickel, silicon, or vanadium. 

Carbon is considered to be the most important alloying element in steel with concentrations up to 4% (although most welded steels have less than 0.5%). Increased amounts of carbon increase hardness and tensile strength, as well as response to heat treatment. Chromium is a popular alloying element used to make steel. It strongly increases the hardness and improves the corrosion resistance of the metal. While it is rarely used by itself in a moving component because of its raw brittle properties, it is alloyed with iron (up to 20%) to make stainless steel. Steels usually contain at least 0.30% assisting in the deoxidation of the steel. This prevents the formation of iron sulfide and inclusions which act as a weak site for possible fractures to occur. Manganese promotes greater strength by increasing the hardenability of the steel with concentrations of up to 1.5% in carbon steels. Nickel improves the toughness and ductility of the steel. It is also used to improve toughness for low temperature applications. Silicon is used in steel castings of up to 1% to strengthen it. Weld metal usually contains silicon as a deoxidizer. When these filler metals are used for welding on clean surfaces, the resulting weld metal strength will be markedly increased however the resulting decrease in ductility may increase cracking if stressed. Vanadium is used in small amounts in steel alloys. The addition of vanadium will result in an increase in the hardenability of a steel. In amounts more than 0.05%, steel can become embrittle during temperature cycling.

While iron is the most popular choice for the base metal, copper offers unique advantages as a base metal for alloys.  The performance of copper alloy is useful in many applications. Copper exhibits good electrical and thermal conductivity, strength, ductility and excellent corrosion resistance.  There are over 500 different types of copper alloys. Brass is a copper zinc alloy with properties such as improved strength, machinability, ductility, wear-resistance, hardness, electrical and thermal conductivity, and corrosion-resistance.  Bronze alloys are made from copper and tin and are lower in electrical conductivity compared to pure copper. The most widely used is phosphor bronze used for electrical applications. The combination of high yield strength and good corrosion resistance make this bronze ideal for a wide range of small electrical connectors, switches, current carrying springs and rotor bars.

Aluminum bronze is an alloy of copper with 5-12% aluminum with the inclusion of iron, nickel, manganese and silicon. Aluminum bronze is stronger than brass or other bronzes with better corrosion resistance due to the protective surface coat of alumina film. The major use for aluminum bronzes is in seawater applications, such as fasteners, pumps and valve components, pipe fittings, heat exchangers, and bearings. Of the aluminum bronze alloys, the nickel aluminum bronze group is the most widely used having high strength, corrosion and wear resistance applications including gears and bearings.

There are also aluminum copper alloys with copper concentrations ranging from 0.7 to 7%.  These alloys are high strength and performance that are often used for aerospace and aircraft applications.  Other aluminum alloys incorporate manganese, silicon, or magnesium.  The aluminum zinc alloys with zinc concentrations ranging from 0.5 to 12.0% account for the highest strength aluminum alloys.

Under operation, components wear. The product of wear is microscopic (and sometimes visible) metal particles. The following is a very general overview of the types of metallic elements that can be found in various assets. Keep in mind, these elements are most typically going to be alloyed in various combinations and percentages:

Engines

•         Iron (Fe) - Cylinder, Blocks, Gears, Bearings, Crankshaft, Wrist pins, Rings (Cast), Camshaft, Valve train, Oil pump., Liners

•         Aluminum (Al) – Pistons, Bearings, Bushings, Blocks (Some), Housings, Oil pump bushings, Blowers, Thrust bearings

•         Chrome (Cr) – Rings, Roller taper, Bearings (Some), Liners, Exhaust valves

•         Copper (Cu) - Wrist pin bushings, Valve train, Bushings, Cam bushings, Babbitt Bearings (Near failure), Oil cooler, Thrust washers, Governor, Oil pump

Hydraulics

•         Iron (Fe) - Pump/motor vanes, Gears, Pistons, Cylinder bores & rods, Bearings, Valves, Pump housing

•         Aluminum (Al) - Pump / motor Housing, Cylinder (Some)

•         Chrome (Cr) – Rods, Spools, Roller/taper, Bearings (Some)

•         Copper (Cu) - Pump thrust Plates, Pump pistons, Cylinder, Guides, Bushings. Oil coolers (Some)

Gears and Transmissions

•         Iron (Fe) – Gears, Thrust washers, Bearings

•         Aluminum (Al) – Oil pump housings, Thrust washers, Bushings,

•         Chrome (Cr) – Roller taper bearings

•         Copper (Cu) – Gears, Bushings, Cages, Thrust washers, Backstops   

MRT Laboratories can help identify the source of the metal debris before the onset of a catastrophic event occurs.   Find out how MRT Laboratories has helped improve equipment effectiveness through an oil and equipment condition monitoring program.

Next Submission: Metals from surface wear were explored, the next submission shall focus on metals from other sources; is it additive chemistry?  Is it contamination?  Let’s find out…

MRT Laboratories and the Value of Oil Analysis

By Michael D. Holloway of 5^th Order Industry and Ben Hartman of MRT Laboratories

Many companies use oil analysis unfortunately not all companies take full advantage of what oil analysis can provide. The successful oil analysis program considers several aspects – goal, training, sampling, data interpretation, and action. Establishing the goal for an oil analysis program can be the most difficult. Before goals are set, it is important to understand what oil analysis can provide. Simply put, an oil analysis program can help establish fluid management, predictive maintenance, strategic sourcing, operational effectiveness, and even research and development. 

How Oil Analysis Contributes to Fluid Management

Oil analysis provides data on the serviceability of the fluid forming insight into the performance of the lubricant in the components which has a direct influence on the spend profile.  Dissolved or emulsified water can be identified which provides information on how well the oil will shed water.  Oil analysis data can help in optimizing change intervals.

Predictive Maintenance

Abnormal machine wear behavior is identified which helps with maintenance planning which leads to the elimination of repetitive problems towards driving increased reliability. Using this data helps with root cause analysis and equipment lifetime projections.

Strategic Sourcing

Making a decision on which oil to buy through oil analysis has been a tool employed from the onset. Yet only recently have companies begun using oil analysis data to audit procurement of not only their lubricants but also the various components and filters. Premature wear is identified through the elemental analysis. 

Operational Effectiveness

The proper operation and uptime of an asset has a direct influence on the quality of the end product. If the hydraulics experience cavitation or sluggish behavior due to an oil issue, the end product may suffer. Oil analysis has a direct influence on the quality control due to the fact that the lubricant influences the operation of the asset. Using oil analysis supports a continuous improvement initiative. Complying with or administering a warranty will often require empirical evidence. Oil analysis has been used by end-users and OEMs alike for warranty programs. 

Research & Development

Often a lubricant, component, or equipment manufacturer will test their products in a simulated environment in order to produce data for formulation or part enhancement.  When an end-user practices oil analysis, that data can become very useful in order to understand how well a formula, part, or machine is performing in a real application. 

Getting Started

Practicing oil analysis requires proper sampling. The task must be repeatable, no matter who collects the sample.  The process must remain the same with emphasis on reducing as much opportunity for outside contamination as possible.  The goals must be established for a specific purpose and Key Performance Indicators put in place.  Oil analysis provides valuable data concerning wear debris, contaminants, organic matter, and the oil condition. The process must be accurate so that it may reflect the current lubricant and machine condition. Over a period of time, a strategic wear pattern can be developed leading to a more accurate prediction model. Basic requirements for optimizing an oil analysis program will include synchronizing the oil analysis data along with maintenance records, establishing limits for wear, contaminants, oil life, and performance of the oil. This will help in targeting optimizing drain intervals. In the submissions that follow, there will be an examination of the tests run as well as the data interpretation of results for:

·         Wear Metals

·         Viscosity / Flow

·         Contamination

·         Performance Chemistry

Oil analysis has become an integral tool for many organizations. Find out how MRT Laboratories has helped improve equipment effectiveness through an oil and equipment condition monitoring program.

Next Submission:

Are metals in an oil sample coming from mechanical wear via surface contact? Is it corrosive wear? Is it additive chemistry? Is it contamination? Let’s find out!…

Nice work!, Airgas for a super professional installation of a new argon tank for our ICP. Also, thank you, AG Welding for the fence installation that looks great behind our building. Both companies help make MRT better!

Understand why and how we analyze machine fluid samples from critical equipment, with this short and informative video.

MRT Microscopic Analysis Video

https://youtu.be/LWmTnUCMROg

Ben Hartman

A long-time chemical company client in Waggaman, Louisiana shared a spreadsheet copy of their oil sampling equipment list that features very useful detail that I rarely see. The data includes the quality of sampling location and the quality of the most recent sample. I recommend that all of our customers track this level of detail on their oil sampling equipment lists.

Include a sample location grade as well as a most recent sample quality grade.

On this customer‘s list they include typical descriptions of each critical piece of equipment, i.e. UNIT, AREA, TAG NUMBER, DESCRIPTION, NAME OF FLUID, GRADE OF FLUID. In addition they note the actual sampling location on the unit with a pull down list of options such as, Fill Line, Supply Line, Return Line, Filter Housing, Cooler Drain, and they also rank the quality of the sampling location on a 1 to 5 scale. For example, if a lube oil circulating system has a Return Line location with a 5 rank for location, this indicates an optimal sampling location is already in use. The optimal location is downstream of rotating equipment and upstream of filtration. A Drain Line location receives the lowest score of 1 for sampling location. Adjacent to the sample location score, our client notes any plans to improve the sampling location in the future.

Lastly, the most recent sample from each sampling location receives a 0 to 4 ranking for sample Clarity and a 0 to 4 ranking for Contamination level. A 0 indicates a perfect is a perfect score for both Clarity or Contamination and a 4 is the worst. Before any oil sample arrives at MRT for analysis, this customer’s reliability team can already quantify whether the most recent sample from each unit is clear or cloudy and whether it is visibly contaminated with particle debris using the 0 to 4 scale. We strongly encourage sharing this sample quality score across the facility and throughout the team. If a bad sample is being shipped to the lab, the team can already expect an abnormal test result before the lab report is completed.

Please consider adding all of this this useful information to your equipment list and call us with any questions.

Varnish occurs when a lubricant degrades and produces by-products, which accumulate in the lube system. These degradation by-products are dissolved in the lubricant until it becomes saturated. Once the lubricant is saturated, these by-products can agglomerate and then adhere on metal surfaces to form varnish. Varnish formation is dependent on factors such as temperature, pressure, flow properties, fluid solvency, and base oil chemistry.

What causes varnish?

The three most common causes of varnish are:

1. Oxidation: chemical breakdown of the oil that occurs in the presence of oxygen. Oxidation occurs gradually under normal, mild operating conditions after the antioxidant additives are depleted. However, the rate of oxidation accelerates as temperatures increase. Typically for every 10°C (18°F) increase in operating temperature, the rate of oxidation doubles (Arrhenius Rate Rule).
2. Thermal degradation: a similar process that occurs without the presence of oxygen. Thermal degradation occurs because of adiabatic compression from entrained bubbles or when the oil encounters hot surfaces greater than 200°C (400°F). Adiabatic compression occurs when air bubbles rapidly implode due traveling from low pressure to high pressure. The implosion increases the oil’s temperature to greater than 1,000°F, which is sufficient to thermally degrade the oil.
3. Foreign contaminants: Contamination in the oil can be a primary constituent of varnish, or it can be present as inclusions in existing soft contaminant formations.

These degradation processes are accelerated by:

• Heat
• Water
• Oxygen
• Metal catalysts such as copper, zinc, and iron
• Organic acids

The processes that lead to varnish formation.

Why is varnish a problem?

Varnish can impact equipment operation in many ways:

• Increases the rate at which the oil degrades, which reduces the oil’s service life. Varnish degrades a lubricant by an autocatalytic reaction which accelerates degradation as free radicals and temperatures increase.
• Decreases the oil’s ability to dissipate heat. Varnish can form an insulating layer on heat exchangers and reservoir walls which prevent them from properly transferring heat. This can increase the temperature of the oil and lead to further degradation. It can also reduce heat transfer from critical components such as bearings, which can lead to premature failure.
• Reduces clearances in critical components, such as, spools, bearings, servo valves, and last-chance filters (LCFs). The solvency of varnish in turbine oil is temperature dependent. When temperatures fall below certain thresholds in the hydraulic control section of turbines, the formation of deposits can occur on the control valves. This can lead to sticking and malfunctioning of tight clearance moving parts.
• Interferes with proper lubrication, which promotes wear. Varnish can impede the flow of critical oil pathways which can cause metal to metal contact. Varnish also attracts abrasive dirt and solid particles which can increase wear.

As mentioned before, base fluid chemistry has a significant impact on the propensity of a fluid to form varnish. Certain Group V (synthetic) formulations utilize glycols or esters for the base fluid, which can have radically different varnish-forming properties than traditional mineral oils. Some of these base oil formulations may even claim to be varnish-free. However, it is important to note that varnish formation is a complex process, with interplays between temperature, pressure, moisture content, flow properties, and many other parameters. We would recommend that you do not take it for granted that your oil cannot varnish!

Soft contaminant levels (varnish), compared to fluid appearance.

Varnish CANNOT always be detected by routine lubricant analysis tests, such as appearance, color, acid number, viscosity, and particle count.

How to detect varnish proactively?

• Determine the Remaining Antioxidant Levels (RULER): Remaining Useful Life Evaluation Routine (RULER) determines the levels of antioxidants remaining in the oil. Antioxidants control the rate of oxidative degradation. Oxidation is the primary degradation route for turbine oils. When antioxidants are depleted, rapid degradation can occur.
• Measure Varnishing Potential of the lubricant (MPC): Membrane Patch Colorimetry (MPC) determines the concentration level of compounds in a lubricant that are precursors to soluble and insoluble varnishes. This test is effective at detecting the varnish potential before problems occur.
• Ultra-Centrifuge (UC) to look for sub-micron insoluble particles: Insoluble contaminants can be high in concentration in a used lubricant, although undetected through routine particle counting techniques. The UC creates an elevated angular velocity of a lubricant sample that causes sub-micron insoluble contaminants to accumulate for measurement.

MRT Laboratories has the capability to perform the above tests, and much more. If you'd like to learn more about Advanced Testing, please check out this link.

How often to test for varnish?

Testing frequency depends on:

• Unit criticality: critical systems should be tested more often.
• Unit age: new units should be tested more frequently during break‐in (first 6 months).
• Fluid age: fluids should be tested more frequently when they begin to approach the end of their service life.

Testing should be done within 1 month after varnish mitigation to validate a successful removal.

Typical testing intervals are every 3 to 6 months. This should be determined by the severity of the system after the first round of testing.

Analytical ferrography (microscopic analysis of a fluid sample) is an invaluable part in the oil analysis toolkit. By analyzing metallic particles present in used oil samples, under a microscope, you can often determine important information on the system such as wear severity, mode, and lubricated component location. Ferrography also allows the analyst to potentially identify contaminants in the oil such as dirt, fibers, or corrosion particles.

When preparing a sample of oil for ferrography, the analyst must deposit the wear particles, and other foreign materials, onto a substrate to then view them using a microscope.

The choice of substrate for the oil sample has a significant impact on the type of information that can be derived from the analysis.

Two main options exist for substrates: glass slides and filter patches.

Glass Slide

An example of a glass slide used in the preparation of ferrograms.

A glass substrate is a transparent, rectangular glass slide, with a U-shaped, oil-resistant barrier. The presence of the barrier allows for smooth flow of the oil sample down the slide and into a waste container. Prior to applying the oil sample, the slide is placed onto a ferrogram maker, which has a strong magnet underneath the slide aperture.

This magnet collects ferrous particles along its magnetic field lines, that separate ferrous vs. non-ferrous particulates. The presence of a slight slope on the slide aperture also allows for sorting of particles by size, with larger particles collecting near the mouth of the slide, and smaller particles near the end.

Filter Patch

An example of a filter patch membrane.

The filter patch consists of a very fine membrane, often with pores as small as 0.45 microns (10^-6 m) in size. This oil sample is mixed with a filtered solvent, such as heptane or petroleum spirits, and then poured through the filter membrane. The fine pores of the filter allow solvent and oil to pass but collect all particulates.

Glass Slide Microscopic Analysis

An example of a micrograph performed using a glass slide.

Advantages of using a glass substrate slide for microscopic analysis:

The glass slide is transparent

• The glass slide is transparent by nature, which assists in differentiating translucent/transparent particulates from those that are opaque. The presence of translucent, granular material is often an indicator of dirt contamination.

Heat resistance

• The heat resistant glass slide allows the use of a hot plate, most often set at 625F, to determine wear particulate metallurgy. Low alloy steel turns blue at this temperature, medium alloy steel turns bronze, while high alloy steel typically does not change color. Also, certain non-ferrous metals slightly melt at this temperature (Babbitt).

Separates particles by magnetism

• The magnet present on the ferrogram maker forces ferromagnetic particles (steel, dark oxides) to collect along magnetic field lines. This allows the analyst to easily differentiate between magnetic white metal particles and non-magnetic white metal particles (aluminum and some Babbitt materials).

Chemically resistant

• The chemical resistance of the glass slide can be extremely useful, as it allows the careful addition of alkaline or acidic mixtures onto the slide. This can assist in determination of metallurgy, or providing additional information on foreign materials present in the oil. For example, aluminum is a white metal, which does not change color after heating. This can make it difficult to differentiate between aluminum and high alloy steel, as high alloy steel often shows weak response to magnetic fields. However, aluminum reacts readily with potassium hydroxide (KOH), a common laboratory chemical, while high alloy steel does not.

Disadvantages of using the glass slide rather than the filter patch for analysis 

Slower

• The preparation of the glass slide can take longer than a filter patch, due to setup, time for careful pipetting, and the wait for the solvent to dry. Devices exist to help automate these procedures, which helps to offset this inefficiency.

Non-magnetic particle loss

• Non-ferrous metals, dirt, and other non-magnetic particulates can be inadvertently rinsed off the slide, if the slide preparer is not cautious. This can lead to a lack of detection of these materials in the analysis stage.

Filter Patch Microscopic Analysis

An example of a micrograph performed using a filter patch.

Advantages of using a filter patch

Speed

• A filter patch can be prepared very quickly, as the main setup involves the preparation of the sample mixture. Often, a vacuum is used to quickly pull the sample mixture through the filter patch.

Retains non-magnetic particles

• Whereas the glass slide preparer must exercise caution to retain non-magnetic particulates, the filter patch collects all materials greater in size than the pore diameter.

Disadvantages of the filter patch

Not heat resistant

• The filter patch is often constructed from nitrocellulose or nylon, which are not tolerant of heat up the temperatures required to cause color changes in metal alloys. This means that the ferrographer can not easily determine wear particulate metallurgy.

No separation of particles by magnetic properties or size

• Because there is no magnet involved in the filter patch preparation, all particulates are deposited in random orientations. This makes it more difficult for the analyst to differentiate between metals such as steel and aluminum.

Opaque

• As the filter patch is made from an opaque material, it is not easy to determine if the visible particles are transparent/translucent. This makes it more difficult to identify debris such as red oxides or dirt.

As you can see, both options have merits.

Here at MRT, we generally prefer the use of a glass slide, but the filter patch technique is excellent in certain situations, such as when the primary focus of the analysis is on confirming the presence of non-magnetic particulates.

However, we feel that the ability to determine wear particle metallurgy, as well as the composition of certain foreign materials, are invaluable tools that help provide the maximum amount of information to our customers.

Please reach out to us if you have any additional questions regarding analytical ferrography, or other testing employed in oil analysis. 

Ferrography is the best way to identify early-stage wear in your rotating equipment, but you must also pay attention to key fluid properties such as viscosity, flash point, and antioxidant health. Check out our test catalog for more info.

An experienced oil analysis professional is ready to help you get started testing.

We’ve already started our investigation on whether MRT customers that pull oil samples from the ideal locations receive fewer abnormal alarms on oil analysis reports. We aim to report our findings at the end of the year, and here is our Scientific Method for this research.

Step 1-Question: Do MRT customers that collect samples from downstream of equipment and upstream of filters receive the fewest number of abnormal oil analysis alarms?

Step 2-Research: We are recording the sample port locations on lube oil circulating systems for all participating MRT customers. We already analyze their oil samples.

Step 3-Hypothesis: Large industrial clients with optimal sampling locations have the fewest equipment or lubricant condition issues that can be detected by oil analysis testing.

Step 4-Experiment: For the MRT family of customers, we will determine a correlation between having a high percentage of optimal oil sampling locations at a facility and a low number of abnormal alarms on oil analysis reports.

Step 5-Observations: In December we will correlate the data to see how it compares to the hypothesis.

Step 6-Conclusions: We aim to conclude our study by the end of 2020.

Step 7-Communicate and Replicate: If a positive correlation exists between having optimal sampling locations and receiving few oil analysis alarms, then we will communicate the benefit of our findings to existing and perspective customers.

To MRT customers, expect an email about this very soon if we haven’t reached out to you yet.

Last week an MRT customer lost a critical compressor due to unexpected bearing failure. The customer diligently mails in lube oil samples for routine analysis on a monthly or bi-monthly basis. Why didn’t the oil analysis detect early stage abnormal bearing wear in advance of this unexpected failure? Isn’t that what oil analysis is for, to catch abnormal wear issues at the earliest stage?

It’s an understatement to say that it’s frustrating when this happens. Together let’s review recent oil analysis results as the unit approaches failure in late September. See an abbreviated set of data from the five most recent lube oil samples and a filter sample completed after the failure.

Relevant Observations of each sample’s test results

Sample 1 from April 2020 has visible debris particles that are >40 microns in size. Oil condition is normal. There’s 2 ppm of iron, but no ferrous magnetic debris detected and no other wear metals or contaminant metals detected. No indication of abnormal equipment wear according to these oil analysis tests. Continue use of oil. Filter the oil to remove the visible debris and re-sample in one month to monitor for an improvement in cleanliness.

Sample 2 from July 2020 has an elevated ISO 4406 particle count result, but that is actually an improvement in cleanliness compared to the sample from April since there’s no visible debris to the naked eye. Only 1ppm of iron and no other wear metal elements detected. No indication of abnormal equipment wear. Oil condition is normal. Continue use of oil and continue to filter the oil. Re-sample in one month to monitor for an improvement in cleanliness.

Sample 3 from August 2020. Noticeable improvement in oil cleanliness! Looking good – the oil is cleaning up and all other test results are normal. No wear metals and no ferrous debris detected. No indication of abnormal equipment wear. Continue use of oil and continue to filter the oil. Re-sample in one to two months.

Sample 4 from September 2020 is similar in condition and cleanliness to Sample 3. The particle count has leveled off. The ISO 4406 remains moderately elevated. The oil could be cleaner, but there’s still no indication of an abnormal wear issue THAT IS ALREADY OCCURING!

Unfortunately, the active abnormal wear condition remains undetected by oil analysis. Why?

Sample 5 from October 1, 2020 is a postmortem / post bearing failure oil sample taken from the filter housing. Severe concentrations of various wear metal elements in the oil. Over 20,000 ppm of magnetic debris in the oil sample taken from the filter housing location. The uncirculated oil in this housing is dark in color from the extreme level of debris present. See one microscopic image of wear debris in the sample.

The sample contains large ferrous abrasive and fatigue wear particles (100+ microns in size). These particles were likely generated during, or immediately prior to, equipment failure. Many ferrous rubbing wear and large (60+ micron) ferrous fatigue wear particles were present, which appeared oxidized and/or corroded. These particles were likely generated prior to equipment failure.

Sample 6 from October 1, 2020 is a postmortem filter analysis. The filter is loaded with wear debris. See the metal coated to the filter media.

What happened? Why didn’t the oil analysis catch this earlier, by detecting microscopic wear particles ripping and rubbing off a bearing? By the way, not until one or two days before the failure did the unit begin to vibrate aggressively. Vibration readings did not detect this issue either, nor were there elevated bearing temperature readings.

Unfortunately, this is an extreme example of the danger of sampling a circulating oil at a location that is downstream of the filter. All the oil samples taken prior to the bearing failure are from a location after the filter (an example of sampling bias). This issue would have been detected by the oil analysis if the sample port was located downstream of the bearings and upstream of the filter. The filter analysis confirms this, since a meaningful percentage of the wear debris is darkened from oxidation – meaning it was ripped and rubbed from the bearing some time ago.

Please use this case study as motivation to survey your plant to list all the critical lube system sampling locations that are downstream of filters. We highly recommend scheduling the work to optimize the sample ports locations to avoid this issue happening to you. In the short term if a sample location cannot be changed then we recommend an annual filter analysis on each critical lube system.

The end-result of any laboratory analysis is data.

Sometimes our customers will come to us with questions about their data. It can feel like they are being inundated with esoteric test names, values, and trends, and it isn’t clear what is important to focus on, and what is not.

Ultimately, it is up to the data analyst (one of our Certified Lubrication Specialists) to derive meaning from these results and communicate this information to the customer. However, gaining further understanding of the testing process, what these tests output, and what these data represent, will always serve to enrich, and empower, our clients’ oil condition monitoring programs.

What Is Data?

Although this question may seem philosophical, the differences between the concepts of ‘data’ and ‘information’ are important to your understanding of oil analysis results.

Strictly speaking, data is the raw, unorganized representation of measurements captured of an item of interest, usually compared to some standard.

The width of the desk that I am sitting at is an example of data, and its value varies depending on the standard of measure (e.g., the desk is 5 feet wide, 60 inches wide, and 1524 millimeters wide, depending on your choice).

If you run your hydraulic oil on laser particle count (ISO 4406) a single time, that represents a data point.

A data point, on its own, rarely provides information. Information is typically contrasted from data in that it provides understanding to its recipient. This is one reason that we always stress to our clients to pay close attention to the trend of the data, rather than isolated data points.

If you know you are filtering your hydraulic oil, but your ISO particle count is not diminishing, this gives you information that lets you know there is something potentially wrong with the filtration process. This realization is typically referred to, variably, as insight or knowledge.

It is very possible for a single, off-trend result to creep into your data set. If you immediately act on this data point, you could potentially engage in unnecessary, and costly, maintenance on your equipment. To avoid situations like these, we typically recommend our customers to resample any abnormal, off-trend result to confirm conditions.

Good analysis lies in the ability to separate the wheat from the chaff, providing the final link in the data -> information -> insight chain.

Accuracy, Precision, and Bias

When performing laboratory analysis, the goal is to be as accurate and precise as possible.

What is the difference, you ask?

As you can see from the picture above, if the center of the bullseye is the target value, the accuracy (or trueness) of a measurement would be how close that measurement is to the center.

Meanwhile, precision describes the level of variance seen in the results. High variance means that there is, on average, a large magnitude of difference between each individual result, relative to each other. 

In the picture above, each bell curve is centered around the ‘true’ value. However, the level of precision represented by each curve differs wildly, with the red curve showing a relatively high level of precision, and the blue curve showing lower precision.

The average of the sum of the squared differences of each individual result from the mean (quite a mouthful) is the variance.

The standard deviation of a sample set is simply the square root of the variance. One thing that is nice about standard deviation is that it is expressed in the same units as the measurements, themselves.

Since we are still using the same units, we can say things like, “This measurement is 0.8 standard deviations from the mean”. 

Why does this matter? Well, if we assume that our data set has a Gaussian (or normal) distribution, we can use the 68-95-99.7 rule to gain a quick, intuitive grasp on the likelihood that an individual measurement is valid.

Simply put, the 68-95-99.7 rule states that:

·        68% of a data set’s values will fall within 1 standard deviation from the mean.

·        95% of a data set’s values will fall within 2 standard deviations from the mean.

·        99.7% of a data set’s values will fall within 3 standard deviations from the mean.

What this indicates is that, if you get a result that falls outside of 2 standard deviations from the mean, then this result only has, at most, a 5% likelihood of being valid. If your result falls outside of 3 standard deviations from the mean, then it has, at most, a 0.3% chance of being valid (actually, you can usually say it has a 0.15% chance of being true, since that 0.3% is split on either side of the mean. This logic also applies to statement made regarding data points outside 2 standard deviations).

The data analysts at MRT are always on the lookout for these statistical irregularities, and we recheck any suspect data to confirm its accuracy.

So, what happens when your recordings are precise, but they are not accurate? This phenomenon is typically seen as an example of bias.

Sources of bias are many, but it is commonly caused by:

·        Unrepresentative data sampling

·        Systematic error in instrument measurements

·        Faulty assumptions

The first example is also known as sampling bias. It is very easy for this form of bias to creep into your data.

Here is one practical way it could happen: if you always sample your oil from a port located behind a filter, where the filter lies in between the sample port and the rotating equipment, this can mask the detectable effects of machinery wear and therefore bias your results.

Likewise, sampling fluid that has been sitting near the bottom of the sump, near the drain, can significantly (and negatively) impact the cleanliness of the sampled fluid. The sampled oil is not actively lubricating the equipment, so it is not a representation of the true health of the system.

Sampling bias is the likely cause of a significant number of the abnormal sample reports we distribute.

Repeatability and Reproducibility

ASTM, ISO, and other standardization organizations typically list two measures of precision with their test methods: repeatability and reproducibility.

After getting an initial result, these two measurements provide a maximum range that subsequent results should conform to be considered valid.

Repeatability and reproducibility differ in how strict they are regarding the subsequent measurements.

Measurements taken by the same analyst, using the same equipment, under the same testing conditions, and on identical sample material, are subject to repeatability.

Measurements taken by a different analyst, using different equipment, under different testing conditions, or using non-identical sample material, are subject to reproducibility.

Essentially, repeatability represents within-run precision, while reproducibility represents between-run precision.

As you might expect, the repeatability threshold is often much narrower than the reproducibility threshold.

These values can significantly differ between tests, or even within the same test. The relative magnitude of the repeatability/reproducibility threshold reflects the overall level of precision possible when running that test.

For example, ASTM D6595 (Elemental Spectroscopy by RDE-OES) states the following reproducibility limits for zinc and phosphorus:

This table states that, if one laboratory runs a sample and receives 700 ppm for zinc and phosphorus, another laboratory could run that same fluid and receive a result that is 700 ± 176 ppm for zinc, and 700 ± 216 ppm for phosphorus. As far as ASTM D6595 is concerned, interlaboratory results for zinc of 700 and 870 ppm are identical.

The level of variance demonstrated here for phosphorus content is great enough that it could actually knock a passenger car engine oil out of API compliance when its formulation is perfectly conformant (we may have heard of this happening before from an anonymous lubricant manufacturer).

As demonstrated, knowledge of expected repeatability/reproducibility criteria are critical in laboratory operations. Recurring non-repeatable results may indicate instrument malfunction, improper training of personnel, or issues with testing standards. 

Our Quality Process

As an ISO 17025 accredited laboratory, MRT has built a robust system for QA/QC.

All accredited methods are performed with NIST-traceable standards. Technicians are thoroughly trained to look out for many of the statistical irregularities we have discussed in this article.

All our equipment is strictly maintained with regular preventive maintenance and re-calibrations provided by qualified personnel.

Any non-repeatable results immediately trigger a quality assurance check, where the technician performs the analysis again with an appropriate standardized material.

The reference value of the standard should, optimally, be close to the expected value of the unknown material. Failing to adhere to this credo can lead to unfortunate consequences.

For example, if you suspect you have received an invalid result for an oil with a 320 cSt viscosity, it isn’t much good to confirm that your instrument is reading correctly at 22 cSt! It is entirely possible for the instrument to be inside calibration at one measurement range, and outside calibration at another.

Any non-repeatable results are immediately communicated to Lab Management, where a root cause analysis of the discrepancy is performed. Any instruments that are found to be outside of acceptable performance are taken out of commission until they can be repaired.

These systems help to ensure that our end-product, the sample report, can be relied on to provide accurate and actionable information to the client.

Conclusion

We hope that this summary of some of the numerical methodologies used in oil analysis has given you a fresh perspective on your results. Using these techniques, we can glean meaningful trends and forecast equipment condition into the future.

This allows our customers to employ predictive, rather than reactive, maintenance, which can make a huge difference on their bottom line by improving efficiency, preventing failures, and maximizing run-time.

Please feel free to reach out to us if you have questions.

In our oil analysis laboratory we tested the effect of gasoline contamination on the viscosity and flash point of a new lubricant and found repeatable results that can be helpful for refining industry clients. We injected gasoline at 0.5%, 1.0%, 2.0%, and 3.0% by weight into new lubricant samples to track the effect on oil viscosity at 40 degrees C (using ASTM D7279) and on flash point (using ASTM D6450, which is closed cup). By using this information our refining customers can estimate the level of gasoline contamination in used lubricants with spot testing of viscosity in-house.

Summary of Findings:

The oil analysis testing was performed on the same ISO VG 100 Group IV PAO, new and uncontaminated.

At 0.5% gasoline contamination the oil viscosity reduced by less than 5%, but the closed cup flash point of the lubricant sample reduced by more than 50%. At 1% gasoline contamination the reduction in viscosity was still less than 10%, which does not trigger a contamination alarm on most oil analysis lab reports. Although with only 1% contamination the flash point of oil reduced by 67%. At 2% gasoline contamination the viscosity reduced by approximately 20% which would be flagged as abnormally low by most oil analysis laboratories. And at 3% gasoline contamination the viscosity reduced by more than 50% and the flash point was lowered by 80% to approximately room temperature. It would require a cold room to track flash point accurately at greater than 3% gasoline contamination.

A few interesting take-aways: lubricant viscosity begins the very steep decline after 2% gasoline contamination. Closed cup flash point begins a steep decline at only 0.5% contamination. At >3% contamination the flash point approaches room temperature and can no longer correlate to the level of gasoline contamination unless testing is performed at well below room temperature.

August 13, 2020

For our refining and petrochemical clients, we highly recommend regularly scheduled analysis of your industrial glycol-based coolants. Moving to a semi-annual testing schedule is the goal, which we recommend after confirming that coolant of correct formulation flows through every critical system and that the system is free of corrosive build up.

Case Study: Ten years ago, a major US refiner began coolant analysis at MRT. They were already sending routine oil samples to the lab but had been noticing that their large reciprocating compressor trains could not adequately cool and nothing more could be improved on the lube oil side.

The client found deposits in heat exchanger tubes and in their valve mechanisms. In MRT’s baseline comparative analysis between OEM glycol specification and used coolant formulation the lab determined the refiner was using an automotive antifreeze rather than the proper inhibited glycol with a more modest additive package. The silicone in the automotive package was responsible for the unwanted deposits and severe system under-performance. Flush and replacement was required on several systems.

After several months of frequent sampling, MRT and the client agreed that coolant condition and equipment condition were optimized, and the client moved to semi-annual lab testing.

Unexpected situations like these can quickly arise in the field, therefore it is crucial to maintain a keen eye on the health of your glycol-based coolants.

We are able to provide an extensive suite of coolant testing, with an emphasis on speed, affordability, and dependability. Please refer to this link for a thorough description of our coolant testing program.

If you are looking for a concise, accurate, and insightful description of the basics of lubrication – you’re at the right place.

In this article, I want to describe the mechanics of wear, the different types of lubrication regimes, and the steps you need to take to ensure your fluid does its job.

Recent estimates state that equipment wear could cost the US economy as much as $300B per year! This should provide plenty of justification for every operator to pay close attention to their equipment through oil condition monitoring.

Any time two metal surfaces move against each other, there will be friction. Friction is primarily caused by microscopic irregularities present on the two surfaces, which are called asperities.

Without effective lubrication, these asperities will contact each other, causing mechanical wear as well as decreasing the efficiency of the rotating equipment by energy loss.

This metal-to-metal contact can be avoided by using proper lubrication.

There are four different lubrication regimes:

1.      Boundary Lubrication (BL) – This regime is characterized by an insufficiently thick lubricating film between the two moving surfaces, causing metal-to-metal contact via the asperities. This metal-to-metal contact causes high friction, which leads to energy loss and wear. BL is most common during start-up, shut-down, low speeds, and high loads. Anti-wear additives often play a critical role during these scenarios, as they can coat the metal surfaces and prevent welding and tearing of asperities. However, even with anti-wear additives, this lubrication regime is to be avoided as much as possible. One technique to avoid metal-to-metal contact during start-up is via hydrostatic lubrication, where a bearing may be supported by oil pressure supplied by a hydraulic pump. After the bearing has come up to speed, the external pressure can be removed, and full film lubrication will continue due to rotational forces.

2.      Mixed Film Lubrication (MFL) – This is an intermediate condition between boundary lubrication and full film lubricating conditions. In MFL, a large amount of the load still rests on the asperities, causing significant metal-to-metal contact. The goal of the lubrication engineer is to successfully transition from MFL to a full fluid film.

3.      Hydrodynamic Lubrication (HDL) – This regime occurs when there is a full oil film keeping the asperities of the two metal surfaces from contacting each other. This type of lubrication is typically achieved after the rotating equipment has come up to its operating speed. During HDL, direct metal-to-metal contact is entirely avoided, and friction/wear is at a minimum.

4.      Elastohydrodynamic Lubrication (EHD) – This is a unique kind of lubrication that typically occurs in rolling-element bearings. During operation, the raceway and rolling element will elastically deform from the force of the oil wedge between them, creating a very fine point of contact. This very fine point results in high pressure, which increases the viscosity and load carrying capability of the oil. EHD is typically considered a form of full fluid film, where metal-to-metal contact is avoided and, therefore, most friction/wear is eliminated.

Now you’re probably wondering how you can ensure that you are achieving full film lubrication, and avoiding boundary conditions, as much as possible.

Well, other than avoiding unnecessary instances start-up and shutdown (where boundary conditions are certain to occur), you need check on the health of your fluid.

Lubricating oils don’t just prevent wear - they also help to clean, cool, and protect the equipment from corrosion.

To do these jobs effectively, lubricating oils need to have:

1.      The Right Viscosity – The measure of a fluid’s tendency to flow is referred to as viscosity. Viscosity is typically considered to be the most important of the key fluid properties typically measured with oil condition monitoring. If the viscosity is too low, the fluid will not be able to support the load, and metal-to-metal contact will occur via the asperities. If the viscosity is too high, energy loss will increase due to fluid drag, decreasing equipment efficiency. However, most experts agree that if the machine operator is forced to choose between a fluid with an excessively high viscosity, or an excessively low viscosity, they should always go with the higher viscosity. Typically, applications with high speeds and low loads (such as turbines) will use a lower viscosity oil, while applications with low speeds and high loads (such as gearboxes) will use a higher viscosity oil. Viscosity can be measured using a viscometer, and we typically recommend most reliability specialists, with normal equipment conditions, to check their fluid viscosity every 3 months.

2.      Low Water Content – The moisture content of a lubricating oil can be easily checked via Karl Fischer Titration (ASTM D6304). Although it depends on the base oil type, you are typically looking to have less than 100 ppm of water (with certain synthetic oils being more tolerant). Excessive water contamination harms equipment by preventing the oil from forming a full lubricating film, by promoting rust and corrosion, and by damaging or destroying the additives. Without Karl Fischer titration, water can be easily estimated by visual inspection, with any haziness or cloudiness in the oil typically representing abnormal water levels. Another test that can be extremely useful is ASTM D1401 Water Separability, which checks the fluid’s ability to readily shed entrained water.

3.      Functioning Additives – Most modern lubricating oils contain additives (chemical compounds designed to improve fluid performance). In the case of engine oils, additives can make up as much as 25% of the total fluid. These chemical compounds can fulfill a variety of roles, such as protecting the equipment from wear, maintaining viscosity with temperature, and preventing oil oxidation. It is very common and effective to check the antioxidant health of the oil. The best way to measure oxidative resistance is through RULER, which allows direct measurement of the antioxidants in the fluid. Other test methods exist to check on the anti-wear capabilities of the additive, such as Nuclear Magnetic Resonance (NMR).

4.      Minimal Contamination by Particulates - The majority of serious equipment damage occurs through abrasive wear, where foreign material such as dirt or metal debris (particulates) causes scratches and scars in the associated metal surfaces. Abrasive wear can be divided into two categories, two-body abrasion and three-body abrasion. In two-body abrasive wear, one surface rubs against another, with the harder of the two surfaces often scraping or scratching the softer surface. In three-body abrasive wear, hard particulates such as sand or hardened steel become trapped between two surfaces, causing gouges to one or both surfaces. The most dangerous particulate is one that is close to the clearance size of the two surfaces. Fluid cleanliness is commonly measured using ISO 4406 Particle Count. The test result is reported in the form of an ISO Code, which appears something like this: 17/16/14. Each number corresponds to the number of particles counted at a certain size range (>4 microns/ >6 microns/ >14 microns). Particle Count has quickly become one of the most important tests in oil analysis, for good reason – a recent study found that for each increase of a fluid’s ISO Code, the equipment life is halved!

5.      Limited Oxidation/Degradation – It is inevitable for lubricating oils to “spoil” over time, this process is referred to as oxidation or degradation. It is most common for mineral oils to oxidize, while many synthetic oils will oxidize and/or degrade, depending on the base oil. As lubricants oxidize or degrade, they tend to lose key fluid properties such as viscosity. Also, mineral oils and certain synthetic oils can produce harmful organic acids as they degrade, which can greatly contribute to corrosion on metal surfaces. These organic acids can be detected through testing the Acid Number (ASTM D974) of the fluid. Of particular note, in today’s day and age, is the problem of varnish. Varnish is created from the byproducts of oil degradation. These varnish particles can eventually agglomerate and attach themselves to metal surfaces, where they can cause a laundry list of equipment problems. One of the best ways to detect these varnish particles (soft contaminants) is through Membrane Patch Colorimetry (ASTM D7843). We typically recommend our customers to run an MPC every 6 months, even when there are no obvious signs of varnishing. MPC can be paired with RULER to provide a truly predictive assessment of fluid health.

With these five properties satisfied, equipment operators can rest assured that their lubricating oil will perform its desired functions: cleaning, cooling, and protecting the equipment from wear. Those who take the time to set up a quality oil condition monitoring program can feel confident that they have maximized their fluid life and equipment run-time.

That concludes this brief summary of the fundamentals of lubrication. Thanks for sticking all the way through.

Please feel free to reach out to MRT at any time if you have further questions. We’re real oil nerds and we love to get into the nitty gritty of this material.

Contact us by phone at 713-944-8381, or by email at info@mrtlaboratories.com.

We hope to hear from you!

While many businesses have been able to successfully transition to remote work during COVID-19, for many personnel in critical industries such as power generation, transportation, and manufacturing, this is not a practicable option.

For these operators, the need to maintain equipment up-time is as real as ever.

MRT has been fortunate to, so far, have zero employees affected by COVID-19.

We are playing our part to help curb this illness by incorporating proper social distancing, mandatory masks, daily temperature checks, and other measures to ensure the safety of both our employees and customers.

Please be informed that we are ready for all your lubricating oil, fuel, coolant, refrigerant, and advanced testing needs during these unusual and difficult times, with no significant impact to our working availability or turn-around time. Same-Day Service is also available.

We continue to offer fast, accurate results to help you maximize your productivity.

Feel free to reach out to us at any time for quotes or consultation at 713-944-8381, or by email at info@mrtlaboratories.com.

Thank you very much. Stay safe and sound!

The three phases of water in a lubricant are dissolved water, emulsion, and free water. 

In every lubricant the goal is for water to be dissolved. It is abnormal for any lubricant’s appearance to be cloudy (emulsion) or for there to be water drops or a water layer (free water) in the oil. The only exception to this rule is an engine oil that can have a black and translucent appearance but still be suitable for continued use.

We are commonly asked; in any lubricant how much water is too much? What threshold setting should I use to determine normal and abnormal levels of water contamination?

Here’s a very worthwhile exercise that we recommend to every customer. Create a spreadsheet list of every lubricant in the plant and list the alarm levels for (1) viscosity, (2) water contamination, (3) acid number, and (4) ISO 4406 Cleanliness Code (Particle Count). 

What is in spec and what is out of spec for each fluid? Your third-party oil analysis laboratory might already provide this information on each report. If not, then they should be able to provide when asked.

Compare this data with alarm levels provided by each lubricant’s OEM. A knowledgeable sales representative should be able to provide the information.

This spreadsheet should be on one page of paper and available to anyone who utilizes oil analysis reports to make equipment reliability maintenance decisions. We recommend updating the list once per year. 

There will likely be one or two lubricants for which you are uncertain of the water contamination alarm levels. If a lubricant has Anti-Wear or Extreme Pressure additives it will likely hold more water in a dissolved state, due to the polar nature of the additives. In contrast, a typical turbine oil will lack those additives, therefore water contamination should be less than 100 ppm if possible, and less than 200 ppm for certain.

Measuring contamination by an oil’s appearance is the cheapest and quickest way to determine whether a lubricant has an abnormally high amount of water in it. 

Is the sample transparent? Can you see through it in a clear sample bottle, regardless of the color?

If you can then the water is dissolved, the sample is not saturated, and this is normal.

Once the sample is at the oil analysis laboratory, the ISO 4406 by laser particle counter will confirm whether water is dissolved and below any saturation threshold. The water bubbles in a saturated oil sample will be counted as particles by a laser particle and create an excessively high ISO 4406. This indicates abnormal water contamination and can assist in setting a limit on whether the amount of water in a sample is excessive.

Watch for follow up articles on this subject in the near future, and we encourage any questions or comments.

The oil sample in the photo is a from an outboard turbine bearing and the poor appearance raises a red flag. What specifically is the issue? What does the company need to do? What questions should they ask? Is a catastrophic failure imminent? Shutting down the unit is not an option.

By the way, it’s difficult to obtain a good oil sample from this unit. The unit holds very little oil that lubricates a critical bearing. Pulling a sample from the drain is the only option and shutting down the unit is not an option. You can argue that the lubrication design is flawed, but that won’t help you get a good sample in the immediate term.

What do we do to analyze the severity of the issue? Here is MRT’s recommended order of operations.

1. Check for abnormal vibration and elevated bearing temperature.
2. Review the maintenance activity on this unit from recent history – was there a recent, oil change, or bearing change.
3. Review the oil analysis report for signs of possible equipment failure.

• Even though the sample is severely contaminated, often you can still determine whether contamination is due to abnormal equipment wear
• Check for elevated wear metals in the sample using emission spectroscopy.
• Also check for elevated magnetic debris using one or more of the following tests, Direct Read Ferrography, Ferrous Debris Meter, or PQ Index.

1. Check for water contamination, and if elevated, look for any possible contaminant metals that can also be detected by emission spectroscopy.
2. If possible, examine the visible debris in the oil sample under the microscope. But you need to be trained for the analysis to be useful. Depending on the results of the other tests, often a microscopic analysis is not necessary.

We found the following results with this sample:

• Abnormal vibration? NO
• Elevated temperature? NO
• Summarize the recent maintenance on the unit:  The complete bearing housing was replaced three months ago, and the repair was urgent. There is a high likelihood that a proper system flush was not completed.
• Is there an elevated concentration of copper, lead, iron, or any other common wear metal? SLIGHT, not severe by any means.
• Did any other magnetic material test find an elevated concentration of ferrous debris? NO
• Is there water contamination? YES. There are visible water bubbles and Karl Fischer titration confirmed that the oil is saturated.
• Are there contaminant metals being detected in the sample? NO
• Microscopic evaluation? Not available, but probably not necessary. The debris looks like chips of rubber or paint and there are small particles that almost look like sand.

But again, no contaminant metals including silicon are being detected, so probably not sand.

What do we do?

Fortunately, there is no indication of abnormal wear. Drain off more stagnant oil from the reservoir, then pull another sample for analysis. In fact, tomorrow I am driving over to the client to do this with them.

There is stagnant debris and water in the reservoir, likely due to break in and since it’s unlikely that the new bearing housing was properly flushed, we need to get all of the break in debris out of there ASAP.

Unfortunately, there is little oil in this circulating system, therefore we will likely have to install an external kidney loop filtration to remove the debris. Simply draining off more oil is unlikely to solve the problem and it could trigger a low-level lubricant alarm quickly. 

More to come, after pulling a sample tomorrow.