Dirt Contamination in Lubrication Systems
by David Doyle, CLS, OMA I, OMA II
Vice President, Americas

Contamination is the number one cause of component failure in lubricating systems. Dirt is a main source of contamination and one of the most destructive contaminants, thus a primary culprit in compromising equipment reliability. Dirt contamination affects all types of equipment designs; gears, engines, hydrostatic system, power generation. This contaminant promotes a variety of problems within a lubricating system and equipment health;

  • Accelerated wear
  • Ties up additive compounding
  • Stabilize foam when it is created
  • Accelerate the formation of additional abrasive contaminants, which can also act as catalyst for oxidation
  • Loss of power when clearance tolerances are eroded

Dirt contamination originates for several sources

  • Airborne from surrounding work environment
  • Surface of machine and reservoirs
  • Lubricant storage and transfer practices

Equipment design and maintenance practice will also promote entry of dirt contamination

  • Poorly functioning seals
  • Poorly operating breathers
  • Poorly functioning or dirty fill caps
  • Insufficient flushing after maintenance
  • Poor reservoir maintenance and house keeping

Dirt contamination and its effects on equipment reliability does not discriminate. Synthetics are not immune. A contaminated synthetic lubricant will not function any better than a conventional mineral oil based lubricant. Dirt contamination can also affect ancillary systems which will compromise lubricant integrity. Air cooled systems are susceptible to dirt film within the area of air entry. This will compromise the cooler’s ability to properly protect lubricating systems from excessive heat.

When using fluid analysis to compliment maintenance and equipment reliability practices dirt can be recognized by an increase in the combination of silicon aluminum and sodium, especially if accompanied by an increase in wear metals. An increase in particle count can indicate the presence of dirt contamination, though particle count alone will not identify the source or nature of the particulate. Dirt contamination can also be confirmed by a microscopic filter patch analysis which directly looks at particulate material in an oil sample.

Management of contaminants in general, especially in “clean systems” is best achieved by establishing root cause thresholds that prevent problems from arising in the first place. ALS testing services can partner with our clients to optimize data reporting and data management for in-service lubricants to help establish and achieve goals for equipment reliability. Maximum thresholds for test results that represent dirt contamination, directly or indirectly, such as silicon, aluminium, sodium, and/or particle count, associated with increases in wear patterns, can be established to meet system reliability requirements.  Do not wait until dirt contamination and associated wear becomes evident before taking action. Catching a problem before failure is much less expensive than catching a problem after failure.



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