Over the years, I have come across instances where issues have arisen, such as the filters blinding prematurely.  With testing, this has ultimately been identified as leaving the tank open in a paper mill, and an investigation of the elements highlighted this, along with the high particle counts. 

There have been other root causes, such as mineral oil being added to a phosphate ester oil on an electro-hydraulic control system, or, in another case, the oil supplier putting engine oil in drums intended for turbine oil.  In the latter case, within less than an hour of topping up the turbine tank with just one of the mislabelled drums, the filters were showing as blocked, and the turbine was out of service for six months.

Within less than an hour of topping up the turbine tank with just one mislabelled drum, the filters were blocked, and the turbine was out of service for six months.

A more confusing scenario was a switch in supplier for a bearing oil at a paper mill.  The end-user was assured of compatibility, but it transpired that a difference in the additive package, combined with water ingress (it was a paper mill after all), led to deposits on the filter.  This could so easily have been checked by a filter-compatibility test from the new oil supplier.  Filter companies often offer this service as well.

Consequently, I tend to use the following checklist when clients experience sudden, premature filter blockages in a previously stable system.

In the first instance, however, it is always useful to ask what the last maintenance action was, as this is often the cause or at least a clue to the possible cause. 

While a number of these were major incidents involving high costs, I still frequently encounter the “oil is just oil” issue, and top-ups on smaller machines have been made with the wrong oil.

I still frequently encounter the “oil is just oil” issue, and top-ups on smaller machines have been made with the wrong oil.

Typically, I might get a phone call along the lines of “Is it possible to see if the wrong oil has been used for a top-up?”  To which my answer is always, “Let me guess, you found the wrong container next to the asset?”  Invariably, the answer is always yes. 

Field Checks Before the Lab

So, when it comes to testing for the wrong oils used as top-ups, before even considering a laboratory test, there are a few basics to consider first.

What the Lab Results Reveal

When it comes to laboratory testing, ideally, two samples need to be sent: a sample of the correct oil from a container in the store, along with the suspect sample from the asset.  Using a sample of the correct oil, fresh from a container, a reasonable baseline for inorganic additive levels can be established and used for comparison with the suspect oil.

In terms of testing, however, apart from the obvious chemical and physical properties, measured wear rates may be affected by incorrect oil, which will elevate the measured wear metals. 

Ultimately, though, several lessons spring to mind that we would do well to remember:

1. Training and raising awareness of the need to avoid cross-mixing oils
2. The use of a color code system for lubricants, with the color code visible on the new containers in stores, on handling equipment, and on assets.
3. Guarantees backed up by insurance coverage from the suppliers when switching lubricant brands, but ideally, with technical testing.
4. Certificates of conformity for all new batches of lubricants supplied.
5. Random sampling of new oils, particularly for the high-cost assets.

What’s the Right Number of Lubricants for Your Plant?

Over the years, I have been to sites with either too many or too few lubricant types.

Both scenarios are potentially costly.

On the one hand, too many types of lubricant are costly in terms of purchase price and ultimately risk downtime due to the wrong lubricant being used.

On the other hand, too few lubricant types are costing the company due to overzealous consolidation, leading to a possible substandard lubricant specification in use.

Why Do Lubricant Inventories Get Out of Hand?

Generally, I find that where too many lubricant types exist, usually differing brands, is the result of procurement blindly following the Original Equipment Manufacturer (OEM) insistence on a brand for “Warranty reasons”.  Legally, the OEM should provide a recommended lubricant specification and include a list of brands.  However, if a non-recommended brand can be shown to meet or exceed the required specification, the warranty issue is no longer a concern, especially if the OEM is contacted and obtains written approval. 

I have been through this process on several occasions, especially on new builds, where various electric motor and pump suppliers will try to enforce a particular brand, sometimes for commercial rather than technical reasons.

Where too many lubricant types exist, usually differing brands, is the result of procurement blindly following the OEM insistence on a brand for warranty reasons.

Another possibility is that the procurement team is shopping around for the best pricing, resulting in numerous brands in the storeroom.  This has happened in both small, family-run businesses and in larger operations where a procurement contractor is responsible and is shopping for the best deal. 

What Makes Lubricant Consolidation Worth the Effort?

Primarily, the main reason is cost-benefit.

Purchasing fewer lubricant types means each remaining type in use is purchased in greater volumes, thereby realizing potential cost savings through negotiated discounts for higher volumes. 

This goes further: particularly with oils, these can be bought in larger container sizes, further reducing the purchase price, as typically the larger the container, the cheaper the unit cost.  However, while handling small pails is cheap, handling drums is more complex. Still, with the installation of a “best practice” bulk storage system, the oil can be purchased in drums but handled and transferred via smaller, more easily managed, sealable, and refillable containers that also meet “best practice” guidelines.

A secondary cost reason is the reduced risk of using the wrong lubricant and the resulting damage from cross-contamination.

This latter issue, however, is also the result of a lack of “best practice” with no tagging of the machines and no internal company policy of colour-coding the lubricants, either, allied to poorly written work orders that lack detail.

Is There a Business Case for Consolidation?

Yes…and no.

Be careful of being penny-wise and pound-foolish, as we say in the UK, or should that be cents-wise and dollars-foolish?

Let’s clarify.  In the late 1990s, working with BP, they stated that the average customer will spend less than 1% of their annual maintenance budget buying lubricants, but will spend more than 40% of it dealing with the outcomes of poor lubrication practices on site.

To put that into context, with a $10 million annual maintenance budget, less than $100,000 is spent on lubricants, while $4 million is spent on repairs, rebuilds, and other downtime costs associated with poor lubrication management.

So, would you rather chase a $20,000 savings or deal with an internal issue costing $4 million and recover at least $1 million of that?

The average customer will spend less than 1% of their annual maintenance budget buying lubricants, but will spend more than 40% of it dealing with the outcomes of poor lubrication practices.

In my opinion, the cost-benefit of a lubricant consolidation exercise will also depend on the industry type.  In some instances, certain industries, such as Food & Beverage and Pharma, have limited lubricant ranges, with consolidation already underway, particularly for NSF-approved Food-Grade lubricants, and limited asset types. 

On the other hand, Oil & Gas, mining, Pulp & Paper, for example, not only have a larger range of lubricants to suit a wide variety of asset types, but these industries will also utilise greater quantities, especially in fluid power systems, engines, transmissions, and turbine trains for compressors or power generation.

The Right Way to Consolidate Your Lubricant Program

Lubricant consolidation, in my opinion, is again an essential first step in implementing a world-class lubrication management programme.  Apart from getting a handle on all the lubricants on site, it will help identify obsolete stock, address issues arising from product name changes, and create a plan for the discontinued and hard-to-obtain products still on the list.

Ideally, using internal or sub-contracted, independent expertise, a list of the lubricants in use should be compiled at the beginning.  This is a useful exercise, as I often find multiple duplicates in Enterprise Resource Planning systems (SAP, Maximo, etc.) for lubricant accounting codes.  While each container size of a lubricant type should have its own accounting code, there are often instances where procurement has inadvertently added another, but under a slightly different term, for example, as 15-40 instead of the original 15W-40.

Once the duplicates have been removed, the list should be tabulated in a spreadsheet with columns denoting the brand, product, and then further itemized by column headings not only for the base oil type, thickener type, and intended application, but also relevant to the lubricant type, showing the physical, chemical, and performance properties.

 I would then prioritise the lubricants, with the highest priority given to those used in critical assets or specialised equipment that must remain, and the lowest to those in general applications and low-criticality assets.

However, be aware that, for greases. At the same time, it is tempting to use a multi-purpose grease for the motors; the base oil’s viscosity may be too high compared to a specialist electric motor bearing grease, which can increase power consumption.

In addition, gearboxes and transmissions need investigation, as Sulphur-Phosphorus-based Extreme Pressure oils may not suit all designs. In fact, apart from the chemical issue with the S_P EP oils, which require a solid-suspension type physical EP oil, some gears may only need an Anti-Wear oil.

Rather than dumbing down to the cheapest level, take the opportunity to raise the bar to the highest level.

A final comment here is that rather than dumbing down to the cheapest level, take the opportunity to raise the bar to the highest level.  For example, switching from mineral to synthetic base oils may seem counterintuitive in terms of cost; however, there are several benefits.  The higher VI of the synthetic base oils may help consolidate into different Viscosity Grade oils, while potential cost benefits include longer oil change intervals and reduced energy consumption.

What Comes After Consolidation?

While the consolidation may be your only objective, the cost-benefit of such a process will be limited and, in fact, incur additional costs due to downtime resulting from uncertainty about the new lubricant range and cross-contamination. 

In addition, it is simply not possible to start topping up with a revised oil grade, such as an ISO VG 22 synthetic oil, on a gearbox currently using an ISO VG 320 mineral oil. Hence, the likelihood is that the consolidation won’t happen.

Further, even if consolidation reduces the number of lubricant types in use, it may still result in a variety of container sizes or require purchasing smaller containers at a higher unit cost unless steps are taken to address processing with larger containers in the lubricant store.

Simply put, the real benefit comes from a structured process of improvement across the whole lubrication management strategy.

Should You Let Your Supplier Run the Consolidation?

It is, of course, possible, and increasingly, lubricant vendors are going down this road with their clients.  A strong supplier with your best interests as the end user at heart is the ideal approach.  Unfortunately, I have seen too many instances of a cursory review of the lubricants resulting in over-consolidation to the detriment of the machinery.

One outcome of creating a spreadsheet, as mentioned earlier, is the generation of an internal lubricant specification document.  With actual product names removed, the folder of specifications for each lubricant can be shared with all suppliers as part of a single-source procurement process.  This means that, without the current product name, the lubricant supplier must review the specification document in detail, note its properties and performance criteria, and recommend a suitable lubricant.

What Are the Benefits of a Single Lubricant Supplier?

Just as there is a cost-benefit to lubricant consolidation, rationalising the supplier base can also realise cost savings.  Buying all the lubricants from one source will also help push for discounts beloved of bulk purchasing.

There are other benefits to single sourcing, too.  When evaluating responses to the tendering process, a single-source supplier is more likely to support the process once in place.  Naturally, this depends on the volume of business, but a single-source supplier is more likely to commit to your process of improving the lubrication management strategy.

With actual product names removed, the folder of specifications for each lubricant can be shared with all suppliers as part of a single-source procurement process.

Of course, a single-source supplier may not be able to cover all lubricants, so some allowance will need to be made for specialist lubricants.

What’s the Big Picture Here?

While a cost-benefit, the desire for lubricant consolidation should not be driven by procurement looking to maximise short-term savings, especially by avoiding the temptation to err on the side of cheaper, lower-performing products. 

Lubricant consolidation should be driven by reliability professionals looking to improve the overall lubrication strategy, in which knowledge of future improvements in storage and handling will enable more effective consolidation decisions, maximising the cost-benefit.

I had a laboratory manager, over twenty years ago, complain to me that he wished I would stop pushing particle counting, as he was getting annoyed by clients asking for it after my courses.  In his view, particle counting was necessary primarily for hydraulic oils and gas turbine oils. He stressed that PQ readings (ferrous density analysis) were far better than particle counting.  Nothing that I could say would ever change his mind.

Admittedly, having been heavily involved in all forms and techniques of particle counting in the past, I may be biased. Still, particle counting plays a role in all forms of machinery for used oil analysis.

So, the question is: how can we ensure the two are used correctly and complement each other?

Predictive or Proactive?

The term Predictive Condition Monitoring is used a lot on LinkedIn to the extent that I begin to wonder whether people really understand that whilst predicting failure is a cost-benefit, preventing failure is essential to achieving reliability and sustainability in a safe and green plant.

A proactive approach considers the root cause of failure rather than simply predicting failure. Solid particles are among the leading causes of failure in most applications and industries. Indeed, this can vary across industries and machine types, where moisture is a significant root cause of contamination.

Understanding Wear Debris Generation

Before we can get into the issue of particle counting versus ferrous density testing, let’s revisit the issue of wear debris generation.

In normal rubbing wear, debris is generally small and low in number.

However, as the wear rate increases, the amount of material generated increases, but more importantly, so does the size of the debris.

Particle Counting for a Proactive Approach

Simply put, monitoring particle counts helps identify what’s happening.  It’s not quite that simple, however.  We need to determine whether the observed trends reflect increased particle ingestion or increased normal wear material.

In the early 1980s, when the ISO 4406 cleanliness code was developed, the idea was that particles larger than 5µm were considered silt, while particles larger than 15µm were considered chips.  Silt is generally considered dust particles ingested with normal wear debris.  Chips are typically the result of abnormal wear. 

Consequently, a rise in silt is likely due to either increased levels of ingested external solid particulate or increased normal wear, the latter indicating an issue.  Either way, both are an alert to a problem.

However, a rise in chips is definitely of concern as that indicates the onset of abnormal wear.

The Limitations of Particle Counting

The reason many commercial laboratories avoid particle counting for machinery other than hydraulics is simple.  Most rely on the light obscuration or light scattering particle counters for various reasons, namely:

1. Light blockage/light scattering units comply with ISO 11500:2022 – Hydraulic fluid power — Determination of the particulate contamination level of a liquid sample by automatic particle counting using the light-extinction principle” and thus tie in with other compliance requirements.
2. They require a small sample volume, typically less than 15mL.
3. Bench units are typically automated for high-volume use.

However, the downside is that anything other than relatively clean, dry oil will cause an issue, namely:

1. The flow through the sensor is restricted, so large debris could block the device and hold up the testing of samples as it is cleared.
2. Water droplets and air bubbles are counted as solids.
3. Dark fluids can be difficult for the light to penetrate.
4. Soot in engine oils, while technically not counted as per ISO 4406, owing to their tiny size, will cause issues with blinding the sensor.

While the above can be addressed by properly preparing a sample to eliminate air and water, this is time-consuming for a high-turnover laboratory.

Indeed, recent advances in light-blocking technology have reduced the occurrence of water droplets and air bubbles, but this still poses a problem with gear oils in particular, owing to the often-present issue of large debris, even if the water issue has been, or can be, addressed.  Note that many industrial gear oils have higher viscosity grades, which would hamper flow through the sensor.

It is easy to see why commercial laboratories would shy away from using gear oils for particle counting, and the same applies to high-soot-load engine oils and to water in the case of steam turbine and paper machine oils.

Hydraulics are perhaps the most sensitive to particle ingress, and, fortuitously, these are typically of lower viscosity grade, are clean and dry, and have significantly less wear debris, which is typically much smaller.

Ferrous Density Analysis Techniques for a Predictive Approach

As the name implies, ferrous density analysis measures the concentration of iron in the oil sample.  Unlike spectrographic oil analysis at the elemental or atomic level, it is not limited by debris size.  With elemental analysis utilising inductively coupled plasma or arc-spark technology, wear debris particles exceeding 8µm create a blinding spot. 

Simply put, the concentration of the atoms on the surface of the debris is detected, but the atoms of the inner body of the larger wear debris are not detected.  This has been addressed using X-ray Fluorescence Technology, which is more accurate in this context, but it is not widely used in many laboratories.

In ferrous density analysis, various approaches rely on magnetism or the Hall Effect to determine the result.  The three primary techniques are:

1. Particle Quantifier – The ANALEXpql was initially developed by the late Dr. Mervyn Jones of the Swansea Tribology Centre and is now a product in the Parker Hannifin range of instrumentation. Based on Hall Effect measurements, it reports a value on a 0–200 scale, with higher values indicating greater ferrous material in the sample. 
2. Direct Reading Ferrograph – The Trico DR-7 Direct Reading Ferrograph unit uses a magnetic gradient to trap ferrous debris and measure the amount of small (<5µm) and large (>5µm) debris to provide a Wear Particle Concentration, as well as a Percentage of Large Particles.
3. Coil measuring technology – The Spectro-Scientific FerroCheck 2000 utilises a pair of precision, rounded coils that, when powered, generate magnetic fields. When a small amount of in-service oil is introduced into one of the coils, ferrous particles interact with the magnetic field, inducing current changes in the coil. The amount of current change is proportional to the amount of Ferrous particles in the oil and can output a result in parts per million (ppm) as per ASTM D8120-17 Standard Test Method for Ferrous Debris Quantification
4. Another approach is that users of portable particle counters have been able to use a strong magnet to separate the Ferrous material from a sample following a particle count, and then repeat the count minus the Ferrous material to see how significant the percentage is. In addition, the trapped Ferrous material is analyzed using a microscope.
5. A simple magnetic sump plug or “mag-plug” is a fundamental form of Ferrous density trending; however, a photograph should be taken during inspection to assist with trending the amount of material trapped at each inspection.

In most commercial laboratories, my experience is that the PQ unit is more common outside North America, while the DR unit is more popular in North America.

For more details on the ANALEXpql and FerroCheck 2000, I suggest you also read the excellent article by Bryan Debshaw and David Swanson in Precision Lubrication, “Assessing Spectroscopic Methods to Analyze Particles: PQ vs. FerroQ” – Assessing Spectroscopic Methods to Analyze Particles: PQ vs. FerroQ.

The Limitations of Ferrous Density Testing

By the very nature of relying on magnetism to trap the Ferrous material or measure it via the Hall Effect, then clearly the focus is on Ferrous debris.  Moreover, the magnet is more likely to attract the larger material, too.

Consequently, while this approach works well on gearboxes that by their nature generate more wear debris, typically of a Ferrous nature, it is less successful on other machines where the amount generated is significantly less and more varied, with the focus needing to be on the non-Ferrous material.

Unlike the Direct Reading Ferrograph unit, the ANALEXpql cannot differentiate between small and large debris, either. However, there are ways around this by shaking the sample and observing how the PQ reading rate changes.  A slow increase in small debris, a rapid increase in larger debris.  The actual oil volume and the sample bottle size may also affect the result, so consistency is required to avoid erroneous results.

For most high-volume commercial laboratories, the ANALEXpql and FerroCheck 2000 are better suited in terms of test time and ease of sample preparation.

Particle Counting and Ferrous Density Testing?

Running both particle count and ferrous density tests together will ensure that the full range of particle sizes can be detected and that changes at any size are captured.  While elemental analysis is an indicator of the presence of smaller material, it reports only concentration, not the number of particles or their size.

While several laboratories will simply not accommodate that request for both techniques, the use of a portable particle counter, such as the Pall PCM500 unit that uses mesh blockage, as this, while not conforming to the ISO 11500, does not suffer from the problems of dark, high viscosity oils contaminated with larger wear debris or water. 

Similarly, these units are not affected by high soot loading on engine oils.  The Pall instrument is ideally suited to on-site use; however, most laboratories do not use this method because it is technically classified as a trending device rather than a counting device per ISO, and it requires a sample volume of over 200mL.

In the last decade, the Laser Net Fines unit has proven effective, offering both particle counting and a breakdown of wear debris by wear mechanism, while also differentiating water and air in the sample. It complies with ASTM D7596 – Standard Test Method for Automatic Particle Counting and Particle Shape Classification of Oils Using a Direct Imaging Integrated Tester.

In Summary

Whichever way you choose to approach this, remember that particle counting provides insight into what is happening within the machine based on the size and number of solids, and enables proactive intervention to prevent failure.  Wear debris is the result of a root cause issue, whether that be looseness, misalignment, imbalance, or a lubricant-related cause.

Ferrous density testing is a reliable indicator of increasing ferrous material levels. Sadly, for most end-users, and given how their oil analysis programmes are set up and managed, the data is often seen too late. The problem results in downtime and machine intervention rather than a proactive correction during machinery uptime.

As with many things in lubrication, sometimes too much is as bad as too little.

This is certainly the case with filtration. 

How Fine Is Too Fine for Your Oil Filter?

To answer that, we need to look at several factors.

First, let’s dispel a few myths about fine filtration and the perceived problems it can create.

“My oil analysis report showed a huge drop in additive elements after fitting finer filters.”

The perception here, of course, is that fitting the fine filters has removed much of the additive package.  This is not the case.  Before fitting the fine filters, a large quantity of solid material, including wear metals and depleted additives, would cling to these particulates.  The spectral analysis will still detect these elements even though the additive is no longer of use. 

After fitting the finer filters, much of this material is removed and no longer detected in the oil sample, allowing the proper level of fresh, available additive to be more clearly shown.

All of that said, there are several instances where caution is required regarding additive separation from barrier filtration.  The following three additives are of most concern. In order of decreasing concern:

• Solid suspension EP additives such as Molybdenum Disulphide or graphite that can be up to 40µm in size. This is usually only applicable to gear oils, and in these instances, it is unlikely that filtration is even applied. More to the point, the lubricant supplier will usually provide warnings in this regard with these oils in the product data sheet.
• Defoamants work in various forms, but Silicon in its supersaturated state, as microscopic globules, can be up to 10µm in size. This is a concern with hydraulic systems, where there is a tendency to want the finest filter possible.
• Viscosity Index Improvers swell when subject to the oil warming and, as such, can potentially be caught in the filter. However, being soft in nature, they do typically make their way through.

Generally, additives are much more at risk from decomposition driven by water, heat, oxygen, and reactive solids such as wear metals, or from poor storage in extreme ambient temperatures over longer periods.

“Fitting finer filters will simply result in shorter element life, and the cost will be significantly higher.”

The assumption here is that the finer filter will be working harder, which is true initially. However, after the cleanup period, the removal of the previous high levels of particulate will reduce the wear rate, resulting in less work for the finer filter.  Additionally, better quality system filters with a finer rating typically use synthetic fibres, which often have a higher dirt holding capacity than cheaper elements of a coarser rating.

Indeed, though, there is no point in fitting better filtration without first taking steps to prevent the ingress of solids, such as uprating the breather, seals, and gaskets, and improving the transfer and storage practices.  Remember, it is easier to keep dirt out of the oil than to remove it from the oil.

“Surely fitting finer filters will impact the pressure delivery to the machine.”

Obviously, assessing the pressure drop across the filter is essential. Indeed, it may be necessary to increase the filter housing dimensions or to put two filters in parallel to maintain the correct differential pressure.  However, as mentioned above, better quality system filter elements with synthetic fibres smaller than those in cheaper elements will have less restriction to the oil flow. Thus, the pressure drop is less affected.

Key Factors That Define When a Filter Is Too Fine

Target cleanliness levels to achieve the desired reliability.

This means we need to look at the following issues:

• Machine type – what clearances are we dealing with, and how susceptible is the machine to solid particle damage?
• Ambient conditions – how dusty is the environment, including not just from the process, but also geographically and with respect to the weather and winds.
• Lubricant type – particularly with respect to the additive package restrictions.

Machine Type Considerations

In order of cleanliness needs, gearboxes are the least concern since with their hardened surfaces and the typically higher viscosity oils, they are reasonably tolerant of particulate and therefore, while they do undoubtedly benefit from cleaner oil, the need for extreme fine filtration is unlikely and consequently, something like a ß₁₀ > 1,000 is often sufficient.

While engines will benefit from cleaner oils than gearboxes, there is the added pressure of the soot loading.  Although correctly dispersed, soot is unlikely to trouble the filter because it is well under 1µm in size. However, experience has shown that high levels, especially with dispersancy package failure, can lead to premature filter failure. 

In these scenarios, ß₁₅ > 1,000 is potentially the lower limit, although the quality of the fuel and lubricant may allow tighter levels.  In addition, the use of by-pass filtration may allow for even finer protection, as it involves a small percentage of flow via the relief valve and diverts directly back to the sump without concern for the pressure drop.

Bearing oils need to be as clean as possible to avoid abrasive wear and fatigue, especially in rolling element bearings with oil films as thin as 1µm.  However, in most cases, basic bearing oils are not highly complex in terms of additive formulations. Consequently, very fine filtration is possible with due care regarding the defoamant if it is used. 

On turbines with plain bearings, then a ß₇ > 1,000 is probably in order.  However, in the case of turbine oil systems, the filtration is generally in the pressure line, so attention needs to be paid to the differential pressure.  Therefore, it makes sense to consider off-line filtration, as it offers the benefit of a lower flow rate with minimal vibration, and the system does not need to be shut down for a filter change. 

In these instances, the off-line skid unit may also incorporate water removal.

Hydraulics are probably the most complex in terms of cleanliness requirements, and it is in these fluid power systems that I often encounter enthusiastic engineers overindulging in filtration.  Whilst hydraulics are usually the most susceptible thanks to their pumps and very fine clearances on the valves, the oils are also often formulated with defoamants, too.

Depending on the complexity, it may be a simple return line filter, but more complex ones will also have, or instead of, a pressure line filter.  Generally, the limit on hydraulic oil filtration is around ß₅ > 1,000.

Is Micron Size Alone Enough to Specify a Filter?

What irks me most is when people talk about filtration and discuss the micron rating without stating the Beta Ratio or Capture Efficiency. The observant amongst you will have noted that my guidance on the filter sizes stated above was with a Beta Ratio (ß) of 1,000 or a Capture Efficiency of 99.9%.  This is three times better than a Capture Efficiency of 90% or a ß of 10.

Consequently, in my experience, a ß₃ > 10 is no more harmful than a ß₅ > 1,000.   Just looking at the graphic below, we have three filters capable of stopping particles of 10µm, yet with widely different levels of performance.  Therefore, it is important to be specific about the performance as well as the micron rating. 

In summary, there is no absolute limit as there are a number of factors involved, not least the cost and ensuring that the return on investment is reached, which in itself will depend on the type and criticality of the system, so no, there is no easy answer to what the finest filter can use.

Over the years, the one thing that has always struck me is how few reliability teams work with their counterparts in the Health and Safety and Environmental departments.

Linking Lubrication to ESG and Sustainability Goals

To quote the guru, Ron Moore, in his article, “A Reliable Plant – Good for Personal and Process Safety”:

Compelling data from operating plants has been provided to demonstrate that “a reliable plant is a safe plant, is a cost-effective plant, is an environmentally friendly plant.” The reverse was also shown, that is, an unreliable plant is less safe, more costly, and less environmentally friendly.

This is something that I trot out in every training session, whether it be an awareness class or a certification preparation class.  Yet I sense there is still a “them and us” attitude between reliability engineers and their colleagues on the other side, and vice versa.

I want to focus on the environmental benefits in this article as they are fundamental to sustainability.  A quick trawl of LinkedIn and, of course, a rapid scan of most corporate mission statements, one is bound to see Sustainability mentioned.  Just how serious are we about this, or is it simply paying lip service to a perceived wish from the public at large?

I believe that the majority of the general public is concerned about the environment and the impact that it may have, and hence the proliferation of electric cars.  I believe companies are also concerned, perhaps more so as a result of the penalty to comply and the cost in terms of environmental damage and the punitive costs that result.

So, if companies are serious about sustainability, how can lubrication assist in the challenge for a more sustainable operation?

Why Reliability and Lubrication Are Sustainability Cornerstones

Let’s start with the issue of reliability.  Lubrication is, call it what you will, a cornerstone, a foundation block, or a core element of reliability.  Without a successful lubrication strategy based on best practice, reliability is doomed to mediocrity at best.

• When equipment runs smoothly, without unnecessary stops and breakdowns, then the emissions are lessened, and this also avoids the energy spikes that a start-up generates.
• With longer-lasting components and machines resulting from improved reliability, fewer emissions are created by re-manufacturing and shipping of the replacement parts and units.
• With longer lubricant life, there is less risk of spillages and leakages, and reduced deliveries to the site.
• With all the above, the strain on natural resources is diminished.

That, in a nutshell, is lubrication-focused sustainability.

Essentially, any business seeking to be more sustainable needs to put an effective lubrication strategy in place as part of its reliability drive.

However, that isn’t all of it. What else can be done to achieve greater levels of sustainability that also aid in the reduction of costs?

Reduction of costs? Surely sustainability costs?  For once, we have a win-win scenario!

Let’s start by looking at some of the simpler aspects.

Simple Lubrication Changes That Deliver Big Sustainability Gains

The first option is to switch from spin-on oil filters to simply replacing the elements.  A spin-on filter requires an element, as well as a core support tube and a housing, the latter two typically being of metal.  On disposal, this is a larger, heavier unit needing specialised disposal owing to the oil contamination.

However, going back to the traditional idea of a removable housing, with the core support tube as part of the filter head, then we have only the element to dispose.  This is something that the automotive industry has returned to, with all new cars now typically just needing the element replaced.  Here’s the win-win: less damage to the environment and cheaper element replacements.

Labyrinth or non-contact seals versus the elastomer lip seal are another opportunity, particularly with process pumps with significantly higher shaft speeds.  In addition to providing better sealing and reducing contamination ingress, the elastomer lip’s rubbing contacts cause less damage to the shaft, resulting in reduced friction and wasted power. 

However, work by Heinz Bloch showed that while the superior seals are more expensive, the life-cycle cost was still significantly less than that of the simple elastomer lip seal—another win-win scenario for the environment and the profits.

Reducing Waste and Costs Through Smarter Lubricant Handling

Buying lubricants in larger volume containers is a further opportunity for win-win. 

Going back to the mid-1990s, I recall many companies transitioning from buying lubricants in the 208L drums to buying in smaller 20L and 25L pails.  Similarly, grease transitioned from the 20kg and 25kg kegs to the 400g plastic tubes.  Understandably, this was partly a move to safer handling by having smaller packaging without the need for the handling equipment that heavy (more than 180kg) oil drums required, whilst 400g tubes of grease meant there was no longer the need to hand pack grease guns.

So why transition back to the older, less safe ways?  Again, sustainability, yet with a win-win situation.

In researching pricing, it is often the case that for a container of fifty times the quantity of grease, the cost is only ten times more than that of the 400g tube.  With oil, the proportionate volume differential from 20L to 208L to 1000L (ten times and 50 times, respectively) is eight times and thirty-six times, respectively.  In my experience, buyers are always looking for the lowest price on lubricants! 

Apart from the costs, think of the disposal issues associated with fifty plastic tubes compared to one metal pail. A further issue I find with the 20L and 25L pails, and even the smaller 400g tubes of grease, is the amount of waste.  Volumes of 1L or more of new oil are often disposed of as the pail is near empty, and some remaining new grease is often discarded in the 400g tubes, which, over time and a reasonable throughput of these small containers, adds up to a considerable cost and impact on the environment.

Balancing Bulk Purchasing With Safe Handling Practices

But what about the handling issues?  For many sites, such volumes are deemed unnecessary due to the numerous small-volume sumps. The volume of grease used is considered so low that it is not worth the larger volumes, especially given the health and safety risks associated with manual packing of grease guns, as well as the added contamination.

There’s an easy solution to these problems that addresses the issue of both safety and the environment, albeit at a small price of an investment.  Frankly, though, these would be part of any best practice strategy in any case, but it is useful to justify the installation by linking the safety and sustainability aspects to the reliability needs.

For the oils, the automated tank units allow for oil to be purchased in the 208L drums with dispensing into the smaller sealable and refillable containers.  This will require the use of appropriate handling equipment for the movement of the drums.

Images from Enluse/OilSafe

For the grease, the cleanest way to fill the grease, with caution, is to use a drum pump.  Most large containers of grease get left open and become contaminated, whereas using this method eliminates that problem.  Fit a grease nipple to the gun in place of the vent, and then backfill the gun via a pump fitted to the larger 20/25kg pail.

Do not over-pressurize while filling!

Just from some of the examples above, it can be seen that aspects of lubrication can contribute significantly to reducing waste as well as cost.  However, let’s keep in mind that irrespective of these, a reliable plant is a sustainable plant.  Any company pushing its sustainability agenda should start with reliability.

Solid Particle Cleanliness

In my previous articles, I have discussed how to achieve cleanliness within gearboxes and pumps, examining the entire aspect of solid particulate contamination ingress.

However, I was recently asked by an engineer following the above articles what a good target for cleanliness in these systems would be.

Cart Before the Horse

I probably should have written this article first, since the standard approach to improving reliability in terms of contamination control is as follows:

1. Set targets for the contamination levels within the system.
2. Undertake the steps to achieve the targets.
3. Measure to ensure the targets are met.

Many programs initially focus on the 3rd step, believing that simply performing oil analysis will prevent failure.  However, as I mentioned earlier in previous articles, this is akin to standing on the bathroom scales each morning and wondering why the hoped-for weight loss is not occurring.  The simple act of measuring is not going to achieve the desired reliability, and as with weight watching, the oil analysis reflects the lubrication lifestyle of the plant.

How Much Should I Weigh?

As with any proactive lifestyle change, we need a target weight.  Many years of medical research have shown that for a given height and gender, there are appropriate target weights.  Though the effort put in now will not be apparent until later in life, and more to the point, it is not a simple matter of the more weight we lose, the longer we will live.  Add variables to account for body shape and structure, etc., and it is not a simple calculation to set a target weight.

So What’s Involved in Setting a Target Cleanliness Level?

Probably the first aspect is the asset type, followed by the operating parameters, and finally, in my humble opinion, the desire to achieve the desired level of reliability.

Machine Type Influences

If we were to put the list of machine types in order from most to least tolerant of the solid particulate, then it would be:

Note that I have provided a generalized guide to the targets above. For those familiar with the ISO 4406:1999 Cleanliness Coding system for solid particles, hydraulics typically require a cleanliness level of around eight times cleaner than gearboxes.

There is a reason for this, and that is that when examining the clearances between components, complex hydraulic systems often feature valving with clearances of less than 5µm. In many cases, the high pressure and flow rate can lead to significant damage from solid particulates.

With gearboxes, however, gear teeth are generally hardened, and along with higher viscosity grades of lubricant, the solid particulate has a less significant impact on the wear rate.

Is a Cleanliness Target Necessary for a Gearbox?

Of course, it will still benefit from a reduction in wear rate and hence an increase in service life.  That said, though, the implementation, or Step 2, must not come at a price greater than the financial gains incurred by the cleanliness control.

As with any reliability initiative, there must be a financial incentive to justify any technical improvements.

But Surely the OEM Will Advise What This Should Be?

Indeed, the Original Equipment Manufacturer may well give a guideline value.  As mentioned, a reader contacted me, and he had approached several OEMs for clarification or had looked up the value in their documentation, which ranged from “not stated” to -/20/15 to 20/18/15 (ISO 4406:1999 solid particle reporting).

In my experience, OEM values are sufficient to avoid short-term and mid-term issues, but are inadequate concerning long-term reliability.  The cynical may suggest that the OEM wants the user to replace parts, regardless.  That said, there is a balance as an OEM does not want a reputation for poor reliability, either. 

More specifically, a value stated in the OEM documentation may not account for the worst-case scenarios in terms of environmental conditions and operating conditions, either geographically or in terms of the business’s nature.

What About the Nature of the Business Or the Environment?

Let’s consider the geography; some locations will be more prone to dust ingress, such as those in or near desert environments. Conversely, the issue is less prevalent in damp environments, such as at sea.  Concerning the industry, cement plants and mining/quarrying will again have higher levels of solid particulate than other industries.

Are There Other Factors to Consider When Adjusting the Target Cleanliness Level?

The cost justification has to be addressed, and therefore, other financial impacts include:

1. Capital cost
2. Repair costs
3. Downtime costs
4. Health and Safety risks
5. Potential energy loss costs

The greater these are, the cleaner the oil needs to be. 

Of course, to undertake a cost-benefit analysis, one must consider the additional costs of improved contamination control to achieve the target cleanliness levels, as well as the costs associated with monitoring these levels.  Once that is known, we can then verify it against the potential savings. Worked from the above expenses.

To establish the possible savings, however, it is essential to look at the existing history and any recorded “Mean Time Between Repairs/Rebuilds/Failures”.  Based on the research, we can then determine the potential life extension and calculate the resulting savings.

As with medical research, the Life Extension Tables serve as a useful guide to conservatively estimate potential gains.  In the image below, for every 1 Range Number improvement in the ISO 4406:1999, we have an incremental increase in life.  For gearboxes, this is not as great as with engines and hydraulics, but from around the 5 Range Numbers improvement (32 times cleaner), we start to see a significant gain.

Is It Worth It?

In my experience with gearboxes, few laboratories ever measure the solid particulate levels, with some suggesting that Ferrous Density is a better guide.  There are various reasons for this, not least the risk of choking the Automatic Particle Counter with large gear wear debris. 

Add in the fact that gear oil samples are often “wet,” leading to counting errors due to the thicker oil, and it is easy to see why most labs shy away.  However, Ferrous Density analysis, such as PQ (Particle Quantifier) or WPC (Wear Particle Concentration), does not offer a predictive view of potential failure, as Ferrous Debris is the end result of the wear process, not the cause.

Consequently, using particle-trending techniques such as a mesh obscuration instrument or a microscope to establish the level will reveal that gearboxes are often significantly dirty.  I have regularly seen ISO 26/23/21 on gear oils in some plants using mesh obscuration trending tools.  Yet, with little effort, this has been reduced to as low as ISO 14/11/9.

That would result in a 12-range number gain, putting the potential life extension factor at around 7 times.

Even being conservative, a more than 6 Range Number improvement is more than double the life currently experienced.

In summary, a Cost-Benefit Analysis is essential to setting a target.  Once the target is set, implement the improvements in contamination control and continually monitor to ensure the targets are being achieved.

• Determine the additional costs of filtration & Contamination Control
• Determine the Savings relating to the Life Extension
• Implement the 5-Year Cost-Benefit Analysis
• Seek Approvals

Targets must be optimized, feasible, and justifiable.

Achieving proactive maintenance involves three key steps: setting cleanliness targets, implementing specific actions to meet those targets, and frequently measuring contaminant levels. This article focuses on the second step—specifically, how to choose the most effective filter location to support contamination control.

Once the target cleanliness level is established, engineers face the challenge of optimizing filter placement, often involving multiple locations. Selecting the right filter location is crucial for achieving a balance between contaminant ingress and removal while maintaining accessibility, system performance, and cost-effectiveness.

To ensure effective solid particle ingression balance, the engineer must consider various elements such as:

• whether the filter will be for protection or for maintaining contamination control,
• ease of access for maintenance,
• and the performance of the unit being considered to meet the challenges of the target cleanliness levels set.

Protection-Focused Filtration Strategies

The first decision to be made is whether the system is a complex unit requiring the protection of sensitive components. The main hydraulic units operating with sensitive servo valves would be typical of such a requirement, where clearances are <5µm. In this case, it is advisable to consider a protection filter to minimize damage to components, particularly those with minimal working clearances between components.

Protection filters considerations:

• Located upstream of sensitive components, typically protecting from particles entering the circuit from the tank or pump wear debris.
• Typically located downstream of the pump, it is mounted in a high-pressure zone. This will necessitate a stronger element and housing, thereby increasing costs.
• Because of the role of protection, the units are typically not fitted with a bypass option. This means the system will shut down if a sudden rise in ingression occurs, which will prematurely block the element.

Protection filters are not intended to balance system ingression; they are merely protection devices. Given the high cost of these elements, their use as contaminant control filters is not advised.

Filtration for Maintaining Cleanliness Targets

Filtration for the purpose of contamination control becomes more complex in certain locations.

The first stage in the location selection process for contamination control is to map the solid particle ingression across the asset to determine the required balance. The aim is to optimize a filter specification that balances ingression and a location that optimizes this process.

Consider the following ingression points in the system:

1. Ingression from manufacturing and service work, which is usually dealt with by flushing following installation or outages.
2. Ingested contamination from the environment via the
   1. Breathers or vents
   2. Hatches or filler ports
   3. Seals or gaskets
3. Generated contaminants from the working surfaces or the lubricant itself.

Therefore, if we consider that the filter must achieve a balance, then the particle removal rate is as follows:

Removal Rate > Sum of Contaminants Ingested and Generated

High-performance filters are expensive. To optimize the cost of filter maintenance, it is necessary to explore ways of reducing the cost of performance to an acceptable level. Therefore, it is imperative to consider possible alternatives, such as offline filtration, to reduce the ingress level, thereby minimizing the performance and cost of the filtration required to balance this.

Firstly, the ingression associated with manufacturing can be controlled by specifying agreed standards of cleanliness with the manufacturer, which can be tackled through flushing before commissioning. Service ingression can also be controlled to some extent by applying clean working procedures and using portable filtration or fixed inlet/filler filter units to ensure the delivery of clean fluid to the system.

This would ensure that the specified filter is not over-engineered for the task merely to meet the challenge of intermittent contaminant ingress due to oil top-ups and changes.

The cost of preventing dirt from entering the system is a fraction of what it costs to remove it

Therefore, the focus of filtration for maintaining cleanliness levels should be on dealing with ingested and generated debris. Considering wear debris, the generation of contaminants from within the machinery, an active root-cause-focused condition monitoring program with frequent inspections would ensure that this aspect is minimized.

Tasks such as regular alignment and balancing, tightening of fasteners, and regular machinery inspections would help limit the risk.

Regarding the ingestion of solid particle contaminants again, depending on the quality of the components at the ingestion point, this will further reduce overall ingression and minimize wear debris generation. Therefore, the emphasis of expenditure should not be solely on filtration, but also on upgrading the breather, vents, seals, and fill points.

To highlight this, the cost of preventing dirt from entering the system is a small fraction of what it will cost to remove it from the system. This enables funding to be applied more proactively across the system, thereby minimizing expenditure and time spent on maintaining the filtration.

Considering these issues, the next step is to evaluate the system itself. The complexity and type of the system will determine the ease with which a location is selected.

1. Suction Line
2. Pressure Line
3. Return Line
4. Offline
5. Bypass

Each of the locations will be discussed.

Suction Line Filtration

• All units should be fitted with a strainer, typically of 100µm rating, to minimize the risks of large foreign objects entering the system and potentially causing catastrophic damage. These must be accessible for regular inspection and cleaning if necessary.
• It is not generally recommended except as a strainer device to avoid large debris that may have accidentally entered the tank.
• Generally, it is an inexpensive option.
• There is a risk of cavitation to the pump if too fine a filter is fitted or if the strainer becomes choked with sludge, heavy sedimentation, or foreign objects such as rags.
• There is no protection of sensitive components beyond the pump.
• The filter must be large to avoid excessive pressure drop and avoid compromising on coarse filtration rather than fitting a bigger element.
• Access can prove challenging for replacement or monitoring inside the tank.
• Always consult the pump manufacturer before fitting any device upstream of the pump.

Typical Applications

Pick-up strainers are usually used where an oil pump is in operation. However, actual suction line filters are typically on hydraulic systems and should be in addition to the main filtration in the pressure or return lines.

Pressure Line Filtration

• Provides effective control over system fluid cleanliness levels
• Provides effective protection to sensitive components and sub-systems.
• Protects systems from pump failure.
• The filter must be able to withstand full system pressure.
• Pressure drop across filters is less of an issue than on return or offline filters.
• Potential harm from vibration or transient pressure and flow peaks.
• The system must be stopped for element change unless duplex filter housings or service bypass valves are fitted.
• The filter must withstand any cyclic pulses produced by pump or system pressure variations.
• Has a perceived high unit cost.

Typical Applications

• Turbines
• Compressors
• Engines
• Hydraulic systems

Return Line Devices

• Provides effective control over system fluid cleanliness levels.
• Prevents ingested or generated debris from reaching the reservoir.
• The filter may be subjected to high flow surges when the system is operating.
• The system must be interrupted for maintenance unless duplex filters or service bypass valves are employed.
• Return line filters may be mounted on the reservoir or fitted in-line.
• Generally, less expensive, less complex design.
• No direct protection of sensitive components.
• Care should be taken to avoid excessive back pressure against upstream components.

Typical Applications

Hydraulic systems only because, in most cases, there is sufficient pressure in the return line to use on a hydraulic unit, and the most likely point of dust particulate entering the system is usually at the “machine” or, in the case of hydraulics, a cylinder ram. In the case of turbines, it is typically a gravity drain to the tank, so return line filtration should be avoided as the filter may cause flooding of the bearing housings.

Offline, Side Stream, or Kidney Loop Devices

There is the option of fitting a permanent offline filtration unit as supplemental/additional filtration or using a filter cart or filter skid as a temporary offline filter.

• Provides effective control over system fluid cleanliness levels when permanently mounted with no concern about pressure drop.
• Filtration is still possible when the system is in shutdown mode.
• The filter is not subjected to system conditions of flow/pressure peaks or vibration.
• The filter can be positioned for ease of access.
• Does not require system interruption for element replacement.
• The offline circuit can be utilized for system refills or top-ups.
• This introduces a higher cost of setup owing to the extra pump, piping, and valves.
• Not suitable for in-line protection of sensitive components.
• Does not alone filter 100% of the fluid in the system.

Filter Carts – Use Them For

• Periodic clean-up
• Flushing
• Pre-filtering new oil
• Filling tanks and machines

Typical Applications

• Gearboxes without OEM filtration
• Storage tanks
• Hydraulic system tanks
• Turbine tanks

Bypass Filtration Devices

• Generally recommended on engines as 5% of the flow returns direct to the sump, so the level of filtration is not a concern to the flow rate.
• The bypass filter can be a finer rating than the full flow filter.
• Generally, an inexpensive option
• Always consult the engine manufacturer before fitting any device upstream of the pump.

Typical Applications

Typically used on engines.

Other Contaminants and Multiple Locations

Multiple objectives may lead to the consideration of several possible locations. For example, in extreme environmental conditions, an offline circuit may prove invaluable to the pressure or return line setup.

Filtration is not merely limited to solid particles. Other contaminants, such as water, may ingress into the system. One consideration may be connecting vacuum dehydration units on an offline circuit to remove incidental water ingress.

Filtration isn’t just about particles—water, varnish, and oxidized oils demand equal attention.

In addition, it is becoming more common to incorporate oxidized oil molecule removal units on the offline circuit, particularly on hydraulic machinery that has experienced varnishing problems in the past.

On crankcase units, bypass filtration is also an option to support pressure line filtration and enhance filtration performance. The benefit is that it allows finer filtration without affecting the flow or pressure delivered to the working components.

Key Takeaways for Smart Filter Placement

The goal of the solid particle filter is to balance the system’s ingression rate. To minimize costs, the issues of built-in debris and generated particles should be controlled through proactive maintenance strategies. This would reduce the ingression rate and maximize the filter’s life and required location.

The right location and choice of housing can further minimize the impact of filter maintenance on production. Above all, ensure that the housing is easily accessible for regular inspection, includes a pressure differential monitoring device to look for the onset of filter blockage, and considers the ease of servicing and element replacement.

At any given point, the overall contamination in a gearbox is BIG!

Remember that contamination ingression is the overall amount of contaminant in the oil with:

B – Built-in contamination from the unit’s manufacture.

I – Ingested is the “sucked in” contamination during operation, whether as the unit cools or other activity such as top-ups and oil changes.

G – Generated during operation, or in other words, wear and fatigue creating debris, whether from the lubricant, ingested contamination, or other root causes.

Simply put:

Ingression = Built-in Contaminants + Ingested Contaminants + Generated Debris

 Generated debris (or wear) is the result of several root causes, namely;

1. Tightness – fasteners torqued correctly to eliminate vibration from movement
2. Rotating set-up – alignment and balance set-up to avoid overload on the bearings and teeth
3. Lubricant quality means the right specification and the right oil used during lubrication tasks
4. Lubricant contamination levels
5. Other root causes

Based on the Pareto Principle or the 80:20 Rule, the other root causes are the 80% causing 20% of the problems, while the first four listed are the 20% of the root causes creating 80% of the problems.

Because tightness, rotating set-up, and lubricant quality are in control, contamination levels or ingested contaminant levels are left. 

Sadly, contamination control is overlooked on gearboxes, so the ingested levels are usually high, resulting in day-to-day damage. 

Identifying the Sources of Contamination – Built-in and Ingested

Having made sure that the right lubricant is in use on the gearbox to meet the demand of the application and that any overloading or operational abuse has been dealt with, the final stage in a proactive gearbox focus should be to deal with the ingression points of the contamination. 

But, first, it is essential to identify contamination as it can be in one of many forms.  

Contamination is any matter or body that enters the system and causes physical or chemical harm to either the lubricant or the machine, which reduces the effectiveness and life of the lubricant or the asset and potentially impacts the effectiveness of the operation.

Such examples include:

• hard particles from external sources or generated within (wear),
• water, or moisture, from rain or wash-down sprays,
• high temperature from overloading or poor heat transfer,
• aeration from incorrect levels of oil or poor specification in terms of the defoamant,
• UV radiation
• or process matter (chemical or physical) from the environment.

There are several easily identifiable ingression points on a gearbox, namely:

• the seals,
• damaged gaskets,
• the breathers,
• contaminated new oil
• other maintenance activity, such as top-ups from contaminated handling units, or complete drain and refill of the unit not following best practices.

These all allow the introduction of contaminants. Bear in mind that the rate at which these enter the unit will depend to some extent on ambient conditions and, depending on the contaminant type, will be subject to such issues as whether the equipment is located inside or outside, whether it is raining, or whether it is windy. 

For example, in wet conditions, the likelihood of moisture ingress significantly increases; however, the ingress of hard dust particulates from the environment is reduced accordingly. 

On the other hand, given a hot, dry, and windy day, while the risk of moisture ingress is minimized, the risk of ingesting hard atmospheric silica-based particulates is greatly increased.  Of course, depending on the nature of the organization, some contaminants may be unique, such as coal dust or iron ore dust. 

Process chemicals in a nylon spinning or paper mill environment.  Another aspect of increased risks of contamination is nearby activity, for example, the risk of cement dust when construction work is taking place, and again, the risk will be greater in windy or dry conditions.

Of course, the above is a controllable situation on-site and can be dealt with accordingly.  What must be dealt with is the manufacturing debris in the gearbox during commissioning. 

This requires that either the OEM or the installer take the appropriate actions to ensure a clean unit before start-up; otherwise, this debris will immediately impact the system’s reliability.

Dealing With the Contamination

 Rectifying the situation involves upgrading existing fittings and implementing some new components to bring the necessary improvements. 

 However, as a gearbox manufacturer customer, you have two choices.  How you move forward will depend on your Original Equipment Manufacturer’s (OEM) cooperation in these matters.

Unfortunately, owing to certain design criteria, as an end-user, it is difficult to walk away from an uncooperative OEM since they may be the sole source of gearboxes to meet the design constraints of the machine train. 

 It is necessary to discuss your contamination control program with your OEM and have them implement your requirements at the build phase. It is also necessary to ensure compliance through a regular supplier audit. Remember, it is always much cheaper in the long term to pay more upfront at the supply stage than to retrofit the better-quality hardware later.

 A further aspect is to ensure the supplier follows best practices for storing the new or rebuilt units before shipping to the site.

 Whether you choose to implement yourself or set up an ongoing improvement program, you will need to consider the following:

 Seals

 Standard lip seals are a low-cost item but require frequent replacement, and their performance at sealing against oil leakage and contaminant ingress is poor compared to labyrinth seals. 

 Although labyrinth seals are at a greater cost initially, their superior performance will ensure minimal risk from water or dirt ingress and minimize lubricant loss and potential process/environmental problems. 

 In addition, many of the gearboxes I see fitted with labyrinth seals also have a greasing point, as fresh grease should regularly be applied to aid the sealing action yet are often overlooked. 

 Of course, training the maintenance staff to avoid using high-pressure wash-down sprays directly on the seals is a must, although, in food and beverage-related environments, this cannot always be avoided.  In this instance, a seal guard can prove beneficial.

 Breathers

 In many cases, older units still have an open tube for breathing, although newer units now incorporate a vent plug into the fill plug.  When stopping large bodies from falling into the gearbox, these serve their purpose but are ineffective at stopping a destructive smaller than 20µm particle. 

 Essentially, upgrading the breather should minimize or eradicate the ingestion of hard particulates and moisture.  There are several ways to achieve this.  The first would be to fit a good quality breather, such as a 1µm rated unit that will remove as much airborne particulate as possible. 

A standard ß10>200 spin-on filter will perform up to ten times more effectively in air than oil, making these possible in a dusty but dry location. 

 If in a moist environment, then the use of desiccating breathers is advisable.  Please beware of the desiccant in some industries; ensure that the appropriate handling guidelines are adhered to and that they comply with food and other related industries. 

 Also, remember to set them up to minimize damage, so provide a protective housing such as in the photo example of a desiccant breather used on a crusher gearbox where rocks may fall over the side.  Consider mounting the breather away from the unit in a wet environment to avoid wash-down sprays or process water falling on it directly.

However, on splash-lubricated gearboxes, there is little actual need for breathers. Generally, they are there to allow for changes in volume because of top-ups, leakages, and temperature-related volume changes. 

For applications with minimal volume changes, the ideal form of breather is a bladder type.  This effectively seals the internal of the gearbox from the atmosphere, but a small bladder allows for expansion and contraction of the air within because of temperature changes. 

These are especially ideal where high levels of particulate or moisture occur in the environment. In addition, creating a vacuum as levels fall may also reduce leakages.

Breathers/Fillers/Samplers

 It is helpful to combine the functions where regular sampling or using a filter cart occurs, particularly where cost and space constraints dictate. 

 When filling or topping up, it is imperative to ensure that the oil is delivered clean to the gearbox.  This may mean dispensing through a filter cart or using the sealable oil canisters that have become the norm in the industry.

Apart from the supply of clean, new oil, the fill port must be clean before use, so any type of protection that can be added to the fill area is beneficial, mainly where process debris could fall into the fill port when in use. 

Using quick connectors is ideal as, like sampling ports, they minimize the risk of ingested contamination. My preference is to use the sealable type containers with a hand or battery-operated pump piped direct to a quick or snap-on connector on the gearbox to ensure clean delivery of the oil and to minimize any risk of spillage, while also minimizing any longer-term injury resulting from lifting and pouring from heavy containers.

Portable Off-line Filtration

 While some gear units may incorporate a small pump and perhaps even a filter, many gearboxes are not equipped with a pump for circulating the oil, nor are they filtered. This can be easily overcome, and a filter cart can make significant gains quickly. 

 Sometimes, it is impossible to make the necessary upgrades or modifications without a major shut-down, so as mentioned, always specify these upgrades as part of the new order or during the gearbox rebuild. However, filter carts can be applied by quickly changing the fill and drain plugs.

Portable Off-line Filtration

 While some gear units may incorporate a small pump and perhaps even a filter, many gearboxes are not equipped with a pump for circulating the oil, nor are they filtered. This can be easily overcome, and a filter cart can make significant gains quickly. 

 Sometimes, it is impossible to make the necessary upgrades or modifications without a major shut-down, so as mentioned, always specify these upgrades as part of the new order or during the gearbox rebuild. However, filter carts can be applied by quickly changing the fill and drain plugs.

Permanent Off-line Filtration

 A permanent off-line circuit could be employed on larger units, particularly where large volumes of oil and high cleanliness levels must be maintained. The benefit of the permanent mount is that it can continue to operate while the gearbox is not in use. However, the optimum filtering time is during the higher operating temperatures. 

 If high running temperatures are an issue, a cooling circuit could be designed with the offline circuit to reduce the oil temperature and increase the oil life and performance.

 In addition, with a permanent offline filtration loop on a gearbox, the circuit can be started separately before starting the gearbox, particularly for vertical shaft gearboxes; this can be beneficial in ensuring a “wet start” with oil flowing to the components before start-up.

 The choice between a portable unit and a permanent mount unit will come down to criticality of production (i.e., the need for reliability), safety, severity/penalty of failure, and if none of the above are important, then the need to achieve a reasonable life extension within a limited budget on contamination improvement.

Absolute cleanliness levels should not be quoted as individual units within the same site may have differing needs, imposing higher or slacker cleanliness limits.  However, in the majority of cases, there are areas for significant improvement from the typical ISO 4406 25/23/20 often seen. 

It is also safe to say that the stringent cleanliness levels required by complex hydraulics are not necessary with gearboxes unless circumstances are exceptional. However, aiming at a cleanliness target of ISO 4406 18/16/13 or better is not unreasonable.  With improvements to that level, life extensions over 3 times are realistic.

Built-in Filtration

As dealt with earlier, the cleanliness of units at the commissioning stage is crucial to ensuring successful infant reliability and increased unit life.  It is common to find manufacturing debris (casting sand, machining swarf, etc) present in a new gearbox. 

At least one OEM told me this is normal and that it will be an extra cost if the client wishes to remove it! This is unacceptable, and as a client, vote with your order book.  Unfortunately, reality sometimes means staying with the supplier, but at least ensure that the best quality breather and seals are fitted as standard when specifying new units. 

Storage

In terms of the gearboxes in storage, ensure that any openings in the castings, etc, are plugged, the shafts and gears are covered with a protective film of grease or oil, and this is thoroughly removed before use. 

Use the portable filter cart to flush the gearbox through before it is turned during installation.  The best way is to use a low-viscosity oil of the specified gear oil that can splash through the box, ensuring that all the dead zones are cleaned and that any debris is dislodged and trapped by the filter cart. 

If you request the OEM to do this before delivery, ensure they flush according to the appropriate standards and show certification or proof of achieving your required levels. 

While all these additional specifications add to the initial purchase cost, the savings incurred in the increased reliability and life of the unit far outweigh the penalty.

Other Opportunities?

 Where several identical gearboxes are in close proximity, a possible upgrade that assists with contamination control is to put in a circulating “dry sump” setup as in the diagram below. Having the tank as central to the lubrication minimizes effort because of:

• The oil is maintained in the ideal state, so it will last much longer and reduce the need for individual oil changes on each gearbox.
• The oil is always being filtered and cooled again, adding to the oil life and reducing the gearbox wear.
• The circuit can be started before the start-up of the gearboxes so “dry starts” are avoided.
• A single oil analysis sample is all that is required on the common return to monitor for oil health, contamination, and wear debris, albeit if wear debris levels change, trouble-shooting samples will need to be taken on each gearbox drain.

What Causes Wear?

 Contamination has frequently been identified as one of the major causes of premature wear on rotating machines. If all other root causes, such as the alignment, balance, and mounting integrity, have been checked, then the other major influences are solid particulate and moisture. 

Contamination control is critical—solids under 10µm are often the most destructive to rotating machines.

The pumped product itself may be the cause in pumping systems, but solids of less than 10µm are generally deemed the most destructive.  Other root causes of premature wear also come into play, such as topping up with the wrong lubricant or using inadequately specified oils and greases.

Dealing with the Sources of Contamination

Attitude

The biggest hurdle to improving systems is to change the culture.  An active discipline of good housekeeping goes a long way towards this, but ultimately, all maintenance and operations personnel need to understand why contamination control is critical. 

Create a Color-coded Tagging System

Create a color and shape-coded chart to identify each lubricant.  Ensure that all the units are tagged with the appropriate color code for the oil or grease in use, along with the frequency and number of shots applied on greased systems.

Apply the color coding to the new lubricant packaging and the funnels and tools used for dispensing when it arrives on-site.

New Equipment Commissioning

The cleanliness of units at the commissioning stage is crucial to ensuring infant reliability and increased operating life. It is common to find manufacturing debris present in a new unit. Ensure that when specifying new units, the best quality breather and seals are chosen as standard.

The cleanliness of units at commissioning sets the stage for infant reliability and longer operating life.

Ensure that any openings in the castings, etc., are plugged, the shafts and gears are covered with a protective film of grease or oil while in storage, and that this is thoroughly removed before use. Use the portable filter cart to flush the unit through before it is turned.

The best way is to use a low-viscosity fluid that can splash through the box, ensuring that all the dead zones are cleaned and any debris is dislodged and trapped by the filter cart. If you request the OEM to do this before delivery, ensure they flush according to the appropriate standards and show proof of achieving your required levels. 

Storage and Handling

Ensure a clean, dry environment for the storage of the oils.  Pre-filter drums of new oil before use to bring them to a standard of cleanliness suitable for the machine. 

Use color-coded, sealable containers to dispense the oil.  Avoid leaving open containers and funnels lying by the machinery, but make provisions for storing the sealable top-up containers in a cupboard nearby, and ensure these are taken away when empty to be cleaned and refilled.

Use a small dispensing bottle for constant-level oiler bottles to minimize waste and spills, and ensure this is also sealed when not in use. For grease guns, use a dedicated gun for each grease type and use the cartridges to minimize contamination where possible.

Only use the larger 20/25kg pails of grease with a proper dispensing pump, and keep the unit sealed at all times.  Identify the grease guns and pumps using color electrical cable ties in line with the grease color coding structure.

Set-up for Dispensing

Avoid using funnels and instead use hand pumps and snap-on connectors to ensure the oil is not contaminated during the dispensing. Ensure the fill ports and grease fittings are clean before use, and use color-coded dust caps on these. 

Set-up for Inspection

Many units will have simple check plugs, port-hole level gauges, or dipstick. This can be improved by fitting a combination sight glass and drain that will allow inspection of the oil right down to the lower level where water may be sitting. If using an external sight tube gauge, ensure this is vented to the breather via a tee-piece to minimize contaminant ingression. 

Alternatively, bottom sediment and water inspection bowls can be fitted at the unit’s base to check for water, sludge, or sediment levels. 

Combine these fittings with oil sampling ports with an internal extended tube arrangement to avoid drawing sediments and sludge from the base.  This will allow sampling on the run rather than stopping and inserting a tube into the unit. 

Seals

Standard lip seals are a low-cost item but require frequent replacement, and their performance deteriorates over time as they cause wear on the shaft where they rub. 

Mechanical and magnetic seals cost more initially but minimize dirt ingress and shaft wear, saving costs long-term.

Although mechanical and magnetic-type seals initially cost more, their superior performance will ensure minimal water or dirt ingress risk and minimize shaft wear, lubricant loss, and potential process/environmental problems.

Training the cleaning staff to avoid using high-pressure wash-down sprays directly on the seals is a must, although this cannot always be avoided in food and drug-related environments.  In this instance, a seal guard can prove beneficial.

Breathers

Vent plugs serve their purpose but will not stop destructive 10µm particles. The upgrade to the breather should minimize the ingestion of hard particulate and moisture. A good quality breather, such as a 1µm-rated spin-on filter canister, will remove as much airborne particulate as possible. 

If in a moist environment, then the use of desiccating breathers is advisable. However, on pumps, there is little actual need for breathers. Generally, they allow for volume changes due to top-ups, leakages, and temperature-related air pressure changes. The ideal breather form for applications with minimal volume changes is a bladder-type sealed unit.

This effectively seals the internal of the unit from the atmosphere, but a small bladder allows for expansion and contraction of the air within due to temperature changes.  These are especially ideal where high levels of particulate or moisture occur in the environment.

Portable Offline Filtration

Generally, oil-lubricated pumps can benefit from the use of a filter cart.  Filter carts can be applied by replacing the fill and drain plugs with snap-on quick connectors.  The use of periodic portable filtration will then deal more effectively with contaminant ingression, minimizing the need for frequent oil changes, assuming the oil is not contaminated by the pumped fluid. 

Periodic portable filtration combats contaminant ingress effectively, reducing the need for frequent oil changes.

The filter carts should be selected for easy maneuverability and allow for a selection of filter ratings (including small amounts of water removal) within the design constraints of the pump on the cart.  If you are operating a sampling and analysis program, collect the samples before filtering. 

Remember that these filter carts are non-intrusive and best used while the unit operates at higher temperatures. However, ensure that there is not too much level of loss when engaging the cart, which may be detrimental to the asset.  At least 5 to 7 times the volume of the oil in the system should be passed through the filter cart to ensure adequate cleanup.

Mist Lubrication

That is mist, not missed, lubrication.  In pure mist designs, the bearings are lubricated by a ‘total loss’ mist of oil droplets.  This eliminates the potential for damage from oils with moisture and solids and the risk of bearing damage from oil contaminated by the pumped fluids leaking into the housing.  The mist also generates a positive pressure within the bearing housing, reducing the risk of moisture and solid ingestion from the atmosphere.

Benefiting from the Changes 

If spread over three years, the above changes are not onerous and are easily adapted to the pumps. Those companies that have made the changes often state that the lubrication technician’s job is now easier and safer. They also have better control over the lubrication tasks and keep better records of how much oil is being used, while wastage from leakages and spillages is minimized.

To truly measure the success of your lubrication program, you need to look beyond consumption and focus on key lubrication metrics.

Is Lubricant Consumption All I Need to Measure Success?

Of course, but like most statistics, there are lies, damned lies and statistics. Figures can be fudged. Take the example of a maintenance manager telling me he had ordered additional lubricants on this year’s budget so that next year would show a decrease.

Or how about simply reducing the frequencies of greasing and extending oil drain intervals? The program has succeeded by that measure, but has reliability been achieved?

Naturally, any lubrication-focused reliability program should see a reduction in lubricant consumption, but do not be disheartened to find this is not the case, particularly in the first few years of the strategy, as more flushing activity is undertaken to deal with past mismanagement.

If employing condition-based lubrication using ultra-sound, the increased greasing activity may also see a rise in throughput.

Consumption should be reduced in the longer term, especially by addressing leakage and waste issues. However, this metric or Key Performance Indicator (KPI) needs to be managed correctly, and the trend will only show a true reflection in the longer term as the program settles in.

Aren’t There Other Ways to Measure the Success of a Program?

Certainly. The target of the program is to improve reliability. Lubrication success is just part of the overall success, but monitoring issues like:

• Improvements in the Mean Time Between Rebuilds (MTBR) of assets such as the gearboxes, pumps and electric motors
• Improvements in the Mean Time Between Failure (MTBF) of lubricated components such as bearings

As stated, lubrication, while a significant root cause, is only part of the overall reliability strategy. Therefore, it could be argued, particularly with rotating equipment, that some benefits may come from alignment, balance, and fastener tightness improvements. That said, these are all still valuable KPIs in an overall reliability strategy rather than for measuring the success of lubrication.

What Do Bathroom Scales and Oil Analysis Have in Common?

Bathroom scales are simply a reflection of a lifestyle. A reflection of the effort one puts into a proactive lifestyle is dietary and exercise regimes.

In that sense, an oil analysis program reflects a company’s lubrication lifestyle.

Implementing an oil analysis or condition monitoring program will not magically increase reliability. Reliability will stem from changes made in maintenance practices, and any condition monitoring program is simply an effective tool for measuring progress in controlling the root causes of poor reliability.

Can Oil Analysis Be Used to Measure the Success of a Lubrication Improvement Plan?

Yes, simply by monitoring the overall results and seeing if the overall trends are heading in the right direction. Let’s look a little closer at how this can work:

The Oil Health Trend

How many times are the reports recommending oil be changed?

How often do the oil health values exceed the caution and critical alarms?

If lubrication best practices are in place and successful, oil life will benefit. Oil will last longer, and consequently, fewer alarms will be triggered.

Set a goal for the various lubricant types regarding anticipated life and the desired targeted life extension. Trend how often the limits are exceeded for the oil health reports, aiming for a yearly reduction.

The Contaminants Trend

How often do the measured contamination levels exceed the caution and critical alarms?

If contamination control has been implemented in all its forms (storage, handling and transfer, and machine protection) as part of the lubrication improvement plan, then this should start to show in the oil analysis data, with reducing levels overall. The cleaner the oil, the greater the chance of success.

Set Target Cleanliness Levels (TCL) for each asset based on the desired life extension and other factors, such as criticality, and ensure these are met. Trend the number of times the oil analysis reports show caution (typically three consecutive readings over the TCL) or critical (one reading over the TCL) alarms.

The Wear Debris Trends

How often do the measured wear levels exceed the caution and critical alarms?

Wear results from various root causes, including lubrication, oil health, and, more likely, contamination levels. Therefore, one can expect to see wear debris levels reduce as the program rollout continues. However, remember that other root causes exist beyond lubrication, so some of the gains in this area are potentially, as said earlier, from alignment, balance, and fastener tightness improvements.

So, Oil Analysis Reflects the Lubrication Lifestyle, But Are There Any Other Metrics Or KPIs We Need To Consider?

Definitely. Just as an athlete has a program that must be maintained, so must the lubrication activity. Lubrication activities are implemented for a reason: to create reliable operation.

Therefore, the biggest KPI or metric in this case would be achieving 100% completion on the lubrication tasks. If this action is undertaken, success will be assured.

Add in KPIs for monitoring the rollout, such as completion of aspects of the implementation like:

• Tagging the machines with the relevant information
• Upgrading the machines for contamination control

We should remember that education is also crucial to implementation and success. Without the awareness and knowledge to support the program, business as usual will result, with staff reverting to old ways.

Therefore, another key metric is the rollout of training. Set a KPI for getting personnel trained to the appropriate levels that their roles require, be that awareness training or achieving the required levels of certification by an independent body.

But Is There a Way To Compare Our Performance Against An Industry Average?

Be very careful about comparing yourself to average! The average is just that. You can pat yourselves on your collective bacs because you may be better than average. Is that enough in today’s world of global economic challenges?

What About a Global Standard For Lubrication?

Just as the ISO 55000 series of standards were introduced for asset management, there is a standard for lubrication. Introduced by the International Council for Machinery Lubrication, the ICML 55™ is a series of standards for lubricated assets.

There are three sub-standards under the ICML 55™ that assist in the process of making ISO 55000 “Asset Management” concepts directly applicable to lubrication programs.

ICML 55™ is an enabling standard in strategic and operational alignment with the broader ISO 55000:

• ICML 55.0 “Overview”
• ICML 55.1 “Requirements”
• ICML 55.2 “Guideline”

Jointly authored by an international team of forty-five subject matter experts, this standard offers a detailed, practical consensus on lubrication management systems and processes for effectively managing lubricated physical assets.

The adoption of ICML 55.1 requirements, as augmented by ICML 55.2 guidelines, will enable an organization to achieve its objectives of effectively and efficiently managing its physical lubrication and lubricant asset policies, strategies, and plans.

ICML 55.1 identifies and defines requirements rather than explaining how to do it, which allows for customizing to suit specific needs rather than trying to force-fit a process.

It should be noted that while intended to align with ISO 55001, the ICML 55.1 standard is the work product and exclusive intellectual property of ICML. It is neither explicitly nor implicitly endorsed by the International Organization for Standardization (ISO) or any other standards body.

How Does Implementing ICML 55™ Help My Organization In Terms Of Measuring Our Lubrication Program Success?

If there is any doubt as to whether any stones are left unturned regarding lubrication, the ICML 55™ covers all aspects. If implemented correctly, then success will follow. It is successful not just in terms of reliability but also in terms of health, safety, and sustainability through environmentally aware lubrication.

More to the point, with the forthcoming ICML 55.3 – “Assessors’ Conformance Guideline,” annual lubrication program reviews and audits will ensure the business remains on track to achieve the end goal.

What Else Should We Consider?

Never be afraid to publish your success! Consider writing monthly for the company newsletter. Initially, lay out the new program’s strategy and goals, and then follow up with the trends from the KPIs and any short-term success stories.

Also, consider putting up new charts each month showing the performance.