Contamination is a leading cause of machinery damage and reduction in the oil’s ability to properly perform. By controlling contamination, the life of the lubricant and machine can be extended greatly.  Like any good maintenance practice, the earlier a problem is detected, the cheaper it is going to be to correct. After implementing a few good maintenance practices to control contamination, the rewards can be seen almost instantaneously.

There are many possibly sources of contamination with any oil reservoir. New oil is one of the most important areas to consider as a source of potential contamination. When we think of something as being new, we typically think of it as being fresh and clean.  Although new oil has not normally been considered as a likely source of contamination, new lubes are often contaminated.

Contamination of new lubricants can happen in a variety of ways.  The oil itself may be dirty upon receipt from the supplier.  The oil may be dirty as it leaves the refinery or contamination can be introduced during the transportation process. Most end-users do not ask their vendors what type of cleanliness levels they will be receiving and most vendors do not automatically provide this information.

Storage of the oil on-site also can be a source of contamination. Many times the containers of new oil are stored in an area and manner that can introduce contamination.  Exposing the new oil to extreme weather conditions or unclean environments can easily introduce water contamination or airborne dust and debris.  Transporting the fluid from the storage area to the equipment also may introduce a variety of contaminants.

The equipment itself can contribute to sources of contamination.  Vents, breathers, filters and seals all offer an avenue of contamination. Vents that are open provide a passage for airborne particles or water.  Breathers and filters that are not effectively controlling particles or moisture allow them to enter the system.  Similarly, seals that are damaged or not working properly also allow particles or water to enter units. 

Likewise, the environment also can be a contributing factor for introduction of contamination.  Whenever it rains or if the equipment is washed down during a cleaning process, the opportunity for water to be introduced into the equipment increases. 

Additionally, units that contain fuel, glycol or coolant all have the potential to be contaminated with these products.  Improper or defective equipment can cause these products to enter systems.  Furthermore, systems with poor combustion may also introduce excessive soot levels.

Contamination of any kind can have an adverse effect once it enters a system.  Contamination can affect the equipment itself in addition to the oil that is lubricating the equipment.

Particles can increase the rate of wear and oxidation and reduce the effectiveness of the additives in the oil.

Water increases wear, promotes rust and oxidation, and weakens the lubricant’s ability to perform. 

Fuel contamination causes lubricants to thin, dilutes additives, increases wear, and creates a fire hazard. 

Glycol contamination increases wear, corrosion, and oxidation.

Soot increases viscosity, reduces the additive’s ability to perform and promotes varnish and sludge.

After identifying sources of potential contamination, procedures can be implemented that help avoid the risk of the contamination. Controlling the risk of contamination will help extend the life of the equipment and lubricant.

It may be that the lubricant arriving from the supplier does not meet your cleanliness requirements.  This can be corrected by requiring the supplier to provide you with cleaner oil or by filtering the oil before it is introduced into the equipment.

On-site storage facilities may need to be re-evaluated.  All new oil should be stored in a clean, controlled environment.  Additionally, all storage containers should be clearly marked.  Containers used to transport the oil to the equipment should be clean and used for only one lubricant.

Vents, breathers, filters and seals should all be checked for their effectiveness in keeping contaminants out of the equipment.  Equipment that does not have breathers and filters should be evaluated.  Breathers can be installed in place of the vents and installation of filters can add extra protection.

Oil analysis can assist in evaluating your current maintenance practices for effectiveness.  There are numerous tests available that can detect particles, water, fuel, glycol, and soot. Oil analysis can be used to check the cleanliness levels of new lubricants. Obtaining an oil sample before and after the filter also can evaluate the effectiveness of the filter.

Spectrometric Analysis is the technology most used to trend the accumulation of small wear metals, elemental constituents of additives, and identification of the possible introduction of contaminants.

Viscosity is a measurement of resistance to flow at a specific temperature in relation to time.  A decrease in viscosity may indicate contamination with a solvent, fuel, or lower grade viscosity oil.  An increase may indicate lube oxidation or contamination with a higher grade lubricant.

Solids Content will determine soot, sludge, varnish, and gross particulate contamination.  Upward changes in the levels of solids may indicate environmental or wear debris.  It is especially useful in systems with poor or unsophisticated filtration.

Water Content will determine the presence of water in the sample.  Increasing water concentrations indicate possible condensation, coolant leaks, or process leaks around seals.

Particle Counting will track all ranges of particles that are found within the sample.  However, particle counting will not differentiate the composition of material present.  All particles are counted and reported over a particle size range.

Infrared Analysis monitors the chemical composition of the oil in certain key wavelengths.  Contaminants such as glycol, fuel and water can be detected.  Lubricant degradation products such as oxidation and nitration are monitored and trended.

Flash Point measures the temperature at which the lubricant is heated and produces a flash when an open flame is passed over it.  A decrease in the flash point value can be a good indication that the lubricant is contaminated with fuel or a solvent.

Glycol Based Antifreeze Test detects presence of glycol based antifreeze in used lubricating oils.

Analytical Ferrography is a technology that utilizes microscopic analysis to identify the composition of the material present.  This test method evaluates the particle type, size, concentration, distribution, and morphology.

By reducing contamination from its originating source, the life of the equipment and the lubricant will be extended.  The use of contamination control will enable you to obtain better equipment reliability and reduce costs associated with lubricants and disposal fees.

Using oil analysis will help identify existing problems with lubricants and equipment.  Regular inspections of vents, breathers, filters, and seals for effectiveness will aid in decreasing the risk of introducing contamination to a machine.  Implementing a routine oil analysis program can provide early detection of abnormal conditions.  

Contamination control starts by keeping the contaminants out of the equipment initially.  The costs associated with keeping the contamination out to begin with are much less than cleaning up a system once it has been contaminated.  Once the contamination is introduced in the lubricant, the lubricant can start to degrade and internal components can deteriorate pre-maturely.  Implementing a few good maintenance practices can provide the reliability needed to keep your equipment running in optimum condition.

as seen in:
Maintenance Technology Resource Guide
January 2000