Lower Maintenance Costs Through Better Hydraulic Oil Filtration
Wiki Article
More than 70% of hydraulic system failures are related to oil contamination. Choosing the right filtration method is often more important than simply selecting a finer filter element.
The two most common solutions are Online Filtration and Offline Filtration Units (Kidney Loop Systems). They are not competitors—but tools for different purposes.
This article compares them from a practical, field-focused perspective.
TYA Series Vacuum Hydraulic Oil Filtration System
How They Work: The Key Difference
Online Filtration
Installed directly in the main hydraulic circuit
Oil is filtered only when the system is running
Flow rate and filtration efficiency depend on system conditions
Offline Filtration Unit
Independent filtration loop with its own pump
Operates regardless of machine operation
Circulates oil continuously at a controlled flow rate
Online filtration follows the system.
Offline filtration focuses on oil cleanliness.
Filtration Performance & System Impact
Factor | Online Filtration | Offline Filtration |
Filtration stability | Affected by flow & pressure changes | Stable and consistent |
Fine particle removal | Limited at high flow | Excellent (≤5 μm) |
Water removal | Minimal | Optional dehydration |
Pressure drop impact | Yes | None |
Maintenance risk | Higher during operation | Safe, independent |
High flow rates reduce real filtration efficiency. Offline units use low flow + high-efficiency media, which removes contaminants more effectively.
Maintenance & Long-Term Cost
Online Filtration
Frequent filter replacement
Increasing pressure drop over time
Limited ability to recover heavily contaminated oil
Offline Filtration
Extends life of online filters
Reduces oil replacement frequency
Protects pumps, valves, and servo components
In practice, offline filtration saves oil first, then saves equipment.
Best Application Scenarios
Online Filtration Is Suitable When:
Systems are small and simple
Cleanliness requirements are moderate
Space and budget are limited
Offline Filtration Is Ideal When:
Equipment is high-value or mission-critical
Machines run continuously or cannot stop easily
Oil cleanliness levels (ISO 4406) must be controlled
Long oil and component life is a priority
Best Practice in Industry
Online + Offline filtration used together
Online filtration = immediate system protection
Offline filtration = long-term oil health management
Quick Decision Checklist
Consider an offline filtration unit if two or more apply:
High maintenance or downtime costs
Short oil change intervals
Repeated valve sticking or pump wear
Unstable oil cleanliness test results
Conclusion
Online filtration is essential—but not sufficient.
If your goal is not just to keep machines running, but to run them longer, cleaner, and more cost-effectively, offline filtration is often the smarter investment.