Step 7:
Contamination Control & Protection
Once a lubricant is applied to your equipment, the job isn’t over. Controlling contamination is essential to maintain oil cleanliness and ensure the long-term reliability of components like bearings, gears and hydraulics. In this step, we cover how contamination enters a system, the damage it causes, and how to prevent and remove it effectively.
Why is contamination control so important?
Even the highest quality lubricant is only as good as the cleanliness it maintains in operation. Contaminated oil can cause:
Common saying in reliability engineering
What types of contamination should I watch out for?
Contamination can take many forms, but most problems fall into three main categories:
Contamination removal is achieved using:
Each application should be evaluated for cost-effectiveness. Importantly, achieving target cleanliness does not always require the most expensive filter. In many cases, a lower-cost filter used correctly delivers the desired results.
To validate effectiveness, take oil samples before and after the filter and compare the results. See more about oil sampling in step 8.
The cleanliness of oil is typically measured using the ISO 4406 cleanliness code. This code classifies the number of particles of various sizes in the oil. A high particle count can be a warning sign of abnormal wear or poor contamination control.
Best practice:
Take oil samples at multiple points - stored oil, oil in the system, and after filtration - to compare and identify issues early.
To gain an accurate understanding of contamination levels:
Test new oil before use
Sample oil in bulk tanks or containers
Measure contamination inside the equipment
Compare pre- and post-filtration results
Monitoring at multiple points ensures that contaminants are detected and addressed—wherever they enter the system.
How contaminants enter the system
Contamination doesn't just happen externally. Internal wear generates particles too. Common entry points and causes include:
Open vents or missing/damaged breathers
Worn or faulty seals
Ingress during maintenance or component replacement
Internal wear (gears, bearings, seals)
Once inside, contaminants cause abrasive wear, which leads to a damaging cycle of particle generation that accelerates equipment failure unless stopped by proper filtration.
Worn seals
Internal wear gears
Contamination prevention steps:
Use high-quality breathers and sealed storage containers
Maintain and inspect seals and gaskets regularly
Ensure all replacement parts and new oil are clean
Use clean tools and containers during maintenance
Minimise exposure to open environments during servicing
In this animated video, discover how the Air Sentry® Guardian Breather defends your critical equipment against moisture and airborne contaminants. Through clear and engaging visuals, you’ll see how the breather’s advanced desiccant and filtration system works to prevent condensation, corrosion, and particle ingress - extending the life of systems like transformers, hydraulic units, and gearboxes.
Key features highlighted in the video:
Whether you're maintaining industrial machinery or sensitive systems, this video shows why the Guardian Breather is a vital component in any contamination control strategy.
Lubretec helps you implement proactive contamination control measures that improve reliability, reduce wear, and extend equipment life.
Contact our specialists today for a contamination control assessment
