Tagged: contamination

How Do We Prevent Contamination?

Contamination exists all around us, but we must prevent its intrusion into our lubrication systems to help keep our machines alive for a longer period. Some simple steps can be performed to help reduce levels of contamination. Also, lab tests can identify the presence of contaminants.

Storage & Handling

Unfortunately, this is the area in which many of the contaminants enter the lubricant. There is no discrimination in this area because all solids, liquids and gases can easily contaminate the lubricant.

Some best practices to follow are to first ensure that all lubricants are properly labeled and that everyone on the team knows the different uses for each lubricant. While this may seem simple, some people think that “oil is oil,” and any oil can work. Educating them on the differences and their effects of being mixed is critical to ensuring that they don’t get mixed up (or used as a contaminant to another lubricant).

Typically, with construction equipment, a lot of smaller sumps do not require a full pail of oil or may require an odd volume of oil. This often means that new unused oil either remains in the original packaging or is transferred to a holding container. If the new oil remains in the original packaging the user should ensure that the packaging remains sealed after use; is airtight (not to allow any other particles in); and stored in a cool, dry place.

If it is decanted into another container, this container needs to be:

Clean (not previously used for another oil, not “cleaned” using fuel or some other substance)
Properly capped (to prevent any contaminants from entering)
Kept in a cool, dry place

Filtration

While this may seem trivial, lots of users assume that their new lubricants meet the required cleanliness standards for their machines. This is not true. New lubricants can be dirty and should be filtered before use. The filtration specification will vary depending on the cleanliness required for your machine.

For instance, the cleanliness specification for a hydraulic machine will be different from that of the engine oil specifications because hydraulics have closer clearances. Although many machines contain system filters which will also catch some of the contaminants, it is always a best practice to filter all lubricants before placing them in your system.

Oil Analysis

Oil analysis is not a likely method to prevent contamination, but it can inform end users of the presence of contaminants. Because of this benefit, it should be used to monitor the level of contaminants in a lubricant and trend their increase or decrease over time. This can spot whether a leak in the system, if a correlation between wear and contaminants exists or an anomaly is present in the system.

The tests that should be used to identify the presence of contaminants include:

Viscosity (to determine if there is change in this value)
Fourier transform infrared spectroscopy
Elemental (to identify wear metals, additives and contaminants)
Karl Fischer or crackle for the presence of water or fuel

Elemental analysis can easily help identify the presence of wear metals or contaminants, but it can also identify the presence of additives that are not representative of the oil in use. This is a good way of identifying the presence of an incorrect lubricant or solution that may have been used during a top up for that component.

Example

A mixed fleet operator began noticing that the jobs allocated to the excavation crew were taking twice as long as usual, and the costs associated with those jobs for materials also increased. He decided to tag along with the site manager for one of these projects to understand the escalation of the hours and costs.

At the site, the project began smoothly and ran as it should for the first two weeks. Afterwards, he noticed that the equipment began experiencing some downtime on the site. Typically, this occurred on the day after the site maintenance crew carried out their lubricant top ups.

The lubricants were being stored in the elements close to a makeshift shed that held some other necessary tools. The maintenance crew did not have smaller containers to decant the oils for the hydraulic equipment, so they used their disposed soda bottles to “help.” Any lubricant that remained in the bottle was left open to the atmosphere, and then this was topped up by the new lubricant.

Unknowingly, these users were contaminating their oil before placing it in the machines. This led to the unplanned downtime and extra resources, such as more oil, filters and hours for the mechanic. Immediately, proper storage and decanting containers were purchased. The onsite staff was trained in using these containers, which were also color coded to avoid the mixing of different lubricants.

The allocated time for these jobs returned to normal. In addition, the costs associated with the materials decreased because they no longer had to purchase extra oil to make those oil changes when the equipment shutdown.

Contamination can have a significant impact on the downtime of your equipment but can be easily prevented by using proper storage and handling techniques and monitoring the presence/absence of particles through oil analysis.

References

SKF, (June 6, 2024). Solutions for Contamination. Retrieved from SKF: https://www.skf.com/group/industries/mining-mineral-processing-cement/insights/solutions-for-contamination.

Find out more in the article in Equipment Today Magazine.

Storage & Handling of Lubricants

Is Oil Contamination Affecting the Performance of Your Equipment?

Often, the particles we don’t see are the ones that affect us most. For instance, we can’t see bacteria or germs but those can easily get into our body and make us sick. Something similar occurs with our equipment and the lubricants which are used to help them work more efficiently. SKF notes that contamination and ineffective lubrication are responsible for 51% of bearing, coupling, chain and other machine component failures in equipment.

Logically, if we control the amount of contamination, we can control the number of failures and all the resulting consequences, such as unscheduled downtime and rush expenses (for called out or specialized labor and parts). In this column, we explore how contamination can impact the performance of your equipment, ways to combat contamination and some examples.

Is Oil Contamination Affecting the Performance of Your Equipment

What Is Contamination?

Contamination is anything that is foreign to the environment. For machinery lubricants, these are usually classified in three main groups: Gases, liquids and solids. When speaking about gases, this can be air or other gases (such as ammonia or methane) that encounter the lubricant. For liquids, this includes water, fuel or any other liquid that can enter the lubricant, particularly other lubricants or liquids that can be added knowingly or unknowingly. Lastly, solids can mean dirt (from outside the process), metals (from inside the machine) or any other solid particle in the lubricant.

Gases

Gases are the most unsuspected forms of contamination since many people believe that a gas will not affect the lubricant or by extension the machine. However, if air gets trapped in a closed loop system, this can lead to foaming (if the oil makes its way to the surface) or to microdieseling if it remains entrained in the oil.

With foaming, this typically occurs in gearboxes or equipment that are subjected to high churn rates of oil. Foam can settle at the top of the oil and cause the lubricant to not form a full film to separate the contacting surfaces. As such, this can lead to wear of the equipment.

On the other hand, microdieseling or the entrainment of air in the system can also prove to be dangerous because the trapped air bubbles can give rise to temperatures in excess of 1,000°C if they move between different pressure zones. This will lead to oil degradation, often producing some coke or tar insoluble as final deposits. Additionally, this trapped air/gas can also advance to cavitation inside the equipment.

Additionally, if the gas trapped is not air but a catalyst to a chemical reaction, this can incite further or more rapid degradation of the oil making it no longer able to protect the equipment. Therefore, identifying the presence of unwanted gases in your lube oil systems or preventing their entry in the first place is important.

Liquids

Liquids are trickier than gases because they somehow seem to enter the lubricant more easily or get mixed in unknowingly. When a liquid enters a lubricant, it can directly impact the viscosity of the lubricant, either increasing it or decreasing it. In either of these cases, this can be detrimental to the equipment.

If the lubricant’s viscosity increases above the essential value, then the machine will demand more energy to execute its required functions. This will directly impact its efficiency and energy consumption. On the other hand, if the lubricant’s viscosity decreases outside of the essential value, then the lubricant may not be able to adequately protect the contacting surfaces. Therefore, this increases the amount of wear that may occur on the inside of the machine.

Typically, water and fuel are the most common culprits of liquid contamination. These can easily get into your lubricants through poor storage and handling practices. Water can increase the viscosity of your lubricant and cause some additives to drop out of it, reducing its level of protection. Fuel will decrease the viscosity and possibly add to the fire risk of the system. Both can severely damage your equipment.

Another common culprit is the mixing of different types of oil. On an average day, things are busy, and people can get confused and pick up the wrong oil to perform a top up on a system. If we add gear oil or hydraulic oil to an engine oil system, we can have a catastrophe! These oils would have different viscosities, and their additive packages (or even base oils) may not be compatible. This can cause the equipment to stop working, leading to unplanned downtime and then exorbitant resources to get the machine operating again.

Solids

Solids can easily get into our equipment either from the outside or the inside. If there are openings to allow solids to enter then they will. However, sometimes solids enter our lubrication systems without us knowing. This can happen through poor storage and handling practices.

Once solids enter the system, they can:

Increase the viscosity of the oil
Increase the amount of wear occurring inside the equipment
Act as a catalyst (depending on their nature)
Block smaller clearances causing unwanted downtime in the equipment

Typically, solids are usually dirt, which can enter from outside the equipment. However, these hard particles can cause some metal to be damaged on the inside the equipment which can then lead to the metal being a catalyst for another degradation mode.

Some solids are formed inside the equipment as deposits. These deposits can occur if another contaminant (liquid, gas or another solid) enters the system and reacts with the oil to produce them. As such, these deposits may clog injectors, other valves or tight clearances causing the equipment to malfunction.

Find out more information in the article in the Equipment Today Magazine.

Lubricant Degradation

The Six Forms of Lubricant Degradation

Oxidation

The most common form of degradation is oxidation. While this is the most recurrent form of degradation, the term is often misused to describe all forms of degradation. During Oxidation, a free radical is formed, which is highly reactive. Its primary purpose is to create other free radicals which can attack the base oil.

However, lubricants have been formulated with antioxidants. These knights in shining armor react with the free radicals to neutralize them and protect the base oil. As such, during the oxidation process, one will notice a decline in the concentration of antioxidants typically evaluated using the RULER® (Remaining Useful Life Evaluation Routine) test.

Eventually, the antioxidants become depleted, and the free radicals begin attacking the base oil. During this stage, polymerization can occur, which leads to the formation of deposits within the lubricant. Not every deposit is chemically similar.

The deposit will gain its characteristics from its environment and the products present during the chemical reaction. When these deposits occur, they can get lodged in the smaller clearances (particularly servo valves), which leads to possible malfunctioning of the equipment. Due to the nature of lube oil varnish, it can act as an insulating layer that increases the temperature throughout the equipment.

Thermal Degradation

Another form of degradation is called thermal degradation. As its name suggests, heat is one of the environmental conditions required for this degradation mechanism. During thermal degradation, the oil can experience temperatures over 200°C.

The Arrhenius equation is one of the industry’s rules of thumb whereby for every 10°C rise over 60°C, the life of the oil is essentially halved. At 200°C, the oil is cooked and produces carbon-based deposits, which is this mechanism’s characteristic type of deposit. The FTIR (Fourier Transform Infrared) test is instrumental in identifying the presence of these deposits.

Microdieseling

One can argue that microdieseling is a form of thermal degradation and should be classed as such. However, during microdieseling, air becomes entrained in the oil and moves from a low-pressure zone to a high-pressure zone.

If the oil does not have good air release properties, then the entrained air will not make its way to be dissipated at the surface. This entrained bubble in the oil can cause temperatures to rise to 1,000°C.

The bubble interface usually experiences some carbon accumulation and then implodes. This can be through a high implosion pressure which results in soot, tars, or sludge, or through a low implosion pressure which can form carbon insolubles such as coke, tars, or resins.

Electrostatic Spark Discharge

Electrostatic spark discharge may be classified under thermal degradation as it involves temperatures over 10,000°C. During this mechanism, oil builds up static electricity at a molecular level when the dry oil passes through tight clearances in the equipment.

Eventually, the static will build to a point where it produces a spark, and free radicals are formed. This can lead to uncontrolled polymerization producing varnish, sludge, or other insoluble materials. One of the tell-tale signs of this mechanism is the presence of burnt patches of membranes on the filters.

Additive Depletion

Additive depletion is often a form of degradation which gets left behind. As stated earlier, additives are sacrificial and will be depleted over time. Their purpose is to protect the lubricant and the machine, but they can be significantly depleted in some instances, leaving them vulnerable.

This type of degradation can produce two types of deposits, organic or inorganic. During degradation, rust and oxidation additives can become reacted with other components. These types of reacted additives can form organic deposits.

Alternatively, inorganic deposits such as ZDDP (Zinc dithiophosphate) can deplete and form a tenacious layer. The Depletion of ZDDP will impact the wear rate as this is the antiwear additive.

Contamination

Often, the most unrecognized form of degradation is contamination. Some may argue that this is not a form of degradation. On the contrary, this degradation mode can be the initiator for other mechanisms such as oxidation, thermal degradation, or even microdieseling.

Essentially, contamination occurs when foreign material is present in the lubricant. Often, this foreign material can become a catalyst for one of the other forms of degradation. Therefore, it must be acknowledged separately, as only the degradation mode can be eliminated by removing the contaminant.

Want to read the entire article? Find it here on Precision Lubrication Magazine!

Industrial / Strategic Tips

ISO 4406 rating

Is the ISO 4406 rating important?

Yes, it is very important!

The ISO 4406 rating tells us the cleanliness level of our lubricant. It tells us the number of particles that can pass through a 4, 6 and 14 micron rating.

However, the value on the ISO rating does not represent the number of particles. On the contrary, it represents the range in which the number of particles can lie.

One key point to remember is that the rating will always change from the time that the sample was taken to the date that the results were processed.

Therefore, it is a good idea to use the sample result as a guide as estimate a bit higher for the real value of your lubricant.

Check out our article which goes into more detail about ISO 4406.

Matt Spurlock CLS, CMRP, MLE explains further about redefining the ISO code in his article entitled; "A Twist on Particle Evaluation: Redefining the ISO Cleanliness Code".

Industrial / Strategic Tips

Filter rating

Is the filter rating important?

Yes! It is very important.

Usually, the OEM of the equipment specifies the filter rating (and even the filter material in some cases). These ratings help us to keep out particles of larger sizes that may cause damage to the equipment either through wear or clogging of fine clearances.

Some filters allow us to monitor the differential pressure. This is the pressure between the outside of the filters and inside and as this approaches the warning limits, we know that a filter change is needed in the near future.

However, there are times when there is no warning and the filter goes into bypass. When a filter goes into bypass, this means that the filter is no longer keeping back the larger particles. This can be catastrophic for the equipment as a higher concentration of contaminants can now enter the system and damage it.

It is common practice to change the oil filter when the oil is being changed. In some instance, (especially depending on the environment), OEMs recommend changing the oil filters twice or more before the actual oil change.

Always consult with your owner’s manual about the maintenance practices before adopting your own.

Lubricant Degradation / Storage & Handling of Lubricants

Conditions that affect lubricants

What conditions affect lubricants?

How are your lubricants currently stored?

Are you storing lubricants under the correct conditions?

These questions have come up a dozen times during audits and countless warehouse meetings!

To answer these questions, there are five main conditions that can affect lubricants. We have detailed them along with the effects of these conditions on the lubricant.

Temperature – if incorrect can lead to oxidation. For every 10C rise in temperature above 40C the life of the lubricant is halved.
Light – too much can lead to oxidation especially for light sensitive lubricants such as transformer oils. Hence the reason that most packaging is opaque.
Water – this usually works with additives to cause their depletion or contamination of the product. Water in any lubricant is bad (especially for transformer oils as they are involved in the conduction of electricity.
Particulate contamination – contamination can occur by air borne particles if packaging is left open or if dirty containers/vessels are used to transfer the lubricant from its packaging to the component.
Atmospheric contamination – this affects viscosity and promotes oxidation and can occur if packaging is left open. For instance, if a drum is not properly resealed or capped after usage or the most common practice of leaving the drum open with the drum pump on the inside.

Different types of lubricant degradation

Why is it important to know the types of lubricant degradation?

It’s important since it helps us to figure out why or in some instance how, the lubricant degraded! Usually degradation is the change that occurs when the lubricant can no longer execute its five main functions:

the reduction of friction
minimization of wear
distribution of heat
removal of contaminants and
improvement of efficiency.

Types of lubricant Degradation Mechanisms

There are 6 main types of Lubricant Degradation as detailed below. Each type produces various by products which can enable us to understand the reason for the degradation and eliminate that / those reasons.

Here are the 6 main types of Lubricant Degradation:

1. Oxidation
2. Thermal Breakdown
3. Microdieseling
4. Additive Depletion
5. Electrostatic Spark Discharge
6. Contamination

As discussed, each mechanism produces distinct results which help us in their identification! Check out our article on why lubricants fail for more info!

Used Oil Analysis

ISO 4406

A lot of people get confused when reading the ISO 4406 rating. The rating specifies a range of the number of particles of certain sizes that can pass through 3 particular sized filters namely; 4micron, 6 micron and 14 micron filters respectively.

For instance; a rating of 13/11/8 indicates:

13 represents 40-80 particles over the size of 4um
11 represents a range of 10-20 particles over the size of 6um and
8 represents a range of 1.3-2.5 particles over the size of 14um.

These values are actually the number of particles per milliliter. It does not mean that you have 13, 11 or 18 particles only in your oil, it's much more than that!

There are different ratings for different levels of cleanliness.

If your numbers are really high (25/22/19) then there’s definitely a high level of contamination! (the full chart goes up to 28 and all the way down to 0).

Different components have different ISO cleanliness ratings. For instance, a roller bearing has a higher cleanliness target than a Variable Vane pump.

Understanding the ISO 4406 codes are crucial for determining the steps needed in “cleaning up” your system lubricants.

However, when we test for the cleanliness of an oil, there are a couple things that we need to consider:

When testing, we have exposed the oil to the elements (highly dependent on the method of sampling)
Results are not instantaneous (even with an onsite lab, there will be a timeframe between collecting the sample and processing it)

Since there are lag times involved, the value that is reported for the ISO4406 rating is never really truly representative of the oil. As such, when analysing the results of this test, it is important to consider that the actual value may potentially be higher than reported.

Matt Spurlock CLS, CMRP, MLE explains further about redefining the ISO code in his article entitled; "A Twist on Particle Evaluation: Redefining the ISO Cleanliness Code".

Lubricant Degradation / Used Oil Analysis

How can a lubricant fail?

This question has caused many sleepless nights and initiated countless discussions within the industrial and even transportation sectors. Before examining the causes for lubrication failure, one must first consider the definition of lubricant failure.

The composition of a liquid lubricant can be described as a combination of base oil and additives (Menezes, Reeves and Lovell 2013, 295). These two components work in tandem to define particular characteristics of the lubricant to perform its functions. According to Menezes, Reeves and Lovell (2013, 296) the five functions of a lubricant include;

the reduction of friction
minimization of wear
distribution of heat
removal of contaminants and
improvement of efficiency.

As such, lubrication failure can then be described as the failure of a lubricant to adequately perform any or a combination of its five functions as a result of the degradation of any of its two components; namely the base oil or additive package. Thus, it can be deduced that lubrication failure is as a result of lubricant degradation.

Now that we understand that a lubricant fails when it undergoes degradation which by extension results in the lubricant not being able to perform any of its functions properly, we need to explore further on the types of degradation that exist. Only then can we really answer the question of how a lubricant can fail.

Barnes (2003, 1536) focuses on three main mechanisms of lubricant degradation namely;

Thermal Degradation
Oxidation and
Compressive Heating (Microdieseling).

One may argue that these three types form the basis of all mechanisms of lubricant degradation.

However, Livingstone, Wooton and Thompson (2007, 36) identify six main mechanisms of degradation namely;

Oxidation
Thermal Breakdown
Microdieseling
Additive Depletion
Electrostatic Spark Discharge and
Contamination.

In this instance, the six identified mechanisms all produce varying identifiable characteristics which lend to these six forming the foundation of identification of lubricant degradation mechanisms. With these six in mind, one would need to be able to determine which degradation mechanism is at work in their facility. Afterwards, methods to treat with these mechanisms must be administered. Firstly, let’s understand each mechanism.

Oxidation

This mechanism involves the reaction of oxygen with the lubricant. According to Livingstone, Wooton and Thompson (2007, 36) oxidation can result in the formation of varnish, sludge, increase in viscosity, base oil breakdown, additive depletion and loss in antifoaming properties of the lubricant.

Barnes (2003, 1536) refers to this phenomenon as the addition of oxygen to the base oil to form:

Aldehydes
Ketones
Hydroperoxides and
Carboxylic Acids.

On the other hand, Wooton (2007, 32) explains that there are three main stages of oxidation namely initiation, propagation and termination. Fitch (2015, 41) explains that:

Initiation entails the production of a free radical via the lubricant and a catalyst.
Propagation involves the production of more free radicals via additional reactions.
Finally, termination entails either the continuation of the oxidation process after the antioxidants have been depleted or the antioxidant stopping the oxidation process.

Microdieseling

Livingstone, Wooton and Thompson (2007, 36) have characterized Microdieseling as a form of pressure induced thermal degradation. They describe it as the transition of entrained air from a low pressure to a high pressure zone which results in the adiabatic compression.

This type of compression results in localized temperatures almost on excess of 1000°C.As such, the lubricant undergoes dramatic degradation. Wright (2012, 14) explains that because of these high temperatures, the bubble interface becomes carbonized. As such, carbon by products are produced and the oil undergoes oxidation.

Electrostatic Spark Discharge

Livingstone, Wooton and Thompson (2007, 36) describe this phenomenon as the generation of static electricity at a molecular level when dry oil passes through tight clearances. It is believed that the static electricity can build up to a point whereby it produces a spark. This spark can induce localized temperatures in excess of 10,000°C which can significantly degrade the lubricant at an accelerated rate.

Van Rensselar (2016, 30) also advocates that Electrostatic Discharge contributes to the formation of free radicals in the lubricant which subsequently results in uncontrolled polymerization. This polymerization of the lubricant gives rise to the formation of varnish and sludge which may deposit on the surface of the equipment or remain in solution. Van Rensselar (2016, 32) indicates that the most common result of Electrostatic Discharge is an elevated rate of fluid degradation and the presence of insoluble materials.

Thermal Breakdown

This mechanism is largely dependent on temperature as one of its contributory factors even though dissipation of heat was highlighted above as one of the functions of a lubricant. However, during the operation of machinery particular components tend to develop increasing temperatures.

As described by Livingstone, Wooton and Thompson (2007, 36) once this temperature exceeds the thermal stability point of a lubricant, the consequences can include shearing of the molecules. This phenomenon is also called the thermal cracking of the lubricant which can result in the production of unwanted by products, polymerization and decrease in viscosity.

Subsequently, Barnes (2003, 1536) explains that thermal degradation usually occurs when the lubricant experiences temperatures in excess of 200°C. He also states that the by-products of thermal degradation differ from that of oxidation.

Wooton and Livingstone (2013) state that there are two main actions that can occur once a lubricant is thermally degraded.

Either the small molecules will become cleaved off and volatize from the lubricant. This does not leave any deposit in the lubricant.
On the other hand, there is the condensation of the remainder of the molecule in the absence of air thus dehydrogenation also occurs. Consequently, coke is formed as the final deposit with numerous types of deposits forming between the start of the condensation to its final deposit of coke.

The main contributing factor for thermal degradation can therefore be linked to dramatic increases in temperature or constant high temperatures.

Additive Depletion

Wooton and Livingstone (2013) indicate that additive depletion can result in either organic or inorganic deposits. The nature of the deposit is dependent on the type of additive that has been depleted and its reaction with other components in the oil.

For instance, if the rust and oxidation additives drop out of the oil, they typically react to form primary antioxidant species thus producing organic deposits. However, as Wooton and Livingstone (2013) explain, inorganic deposits can also be formed from additives that have dropped out of the oil but did not react with anything. This unresponsive reaction is typical of ZDDP (Zinc dithiophosphate) which is an additive that assists with reducing wear in the lubricant.

In cases of additive depletion, the FTIR test seeks to identify spectra relating to the reacted or unreacted additive packages for the lubricant in use (Wooton and Livingstone, 2013).

Contamination

This mechanism of degradation can include foreign material entering the lubricant and being used as catalysts for degradation mechanisms listed above. Contaminants can include a variety of foreign material, however Livingstone, Wooton and Thompson (2007, 36) have narrowed the list to metals, water and air. These main contaminants can significantly contribute to the degradation of the lubricant by oxidation, thermal degradation or compressive heating.

From the above, we can summarize these lubricant degradation mechanisms into the following table:

From this summary, we can now assess the methods in which a lubricant can fail. While this article may serve as a guide in determining various lubricant degradation mechanisms, each mechanism must be treated differently depending on the conditions (environmental and operational) that exist during the lubricant failure. A proper root cause analysis should always be done when investigating any type of failure.

References

1 Livingstone, Greg, Dave Wooton, and Brian Thompson. 2007. “Finding the Root Causes of Oil Degradation.” Practicing Oil Analysis, Jan – Feb.

2 Barnes, M. 2003. “The Lowdown on Oil Breakdown.” Practicing Oil Analysis Magazine, May-June.

3 Livingstone, Greg and David Oakton. 2010. “The Emerging Problem of Lubricant Varnish.” Maintenance & Asset Management, Jul/Aug.

4 Wooton, Dave and Greg Livingstone. 2013. “Lubricant Deposit Characterization.” Paper presented at OilDoc Conference and Exhibition Lubricants Maintenance Tribology, OilDoc Academy, Brannenburg, Rosenheim, Germany, United Kingdom, January 22-24, 2013.

5 Van Rensselar, Jeanna. 2016. “The unvarnished truth about varnish”. Tribology & Lubrication Technology, November 11.