Filter Types by Circuit Position
Where a filter is installed in the hydraulic circuit determines what it protects and how it is sized. Eaton offers filters for every position.
Pressure Filters
Pressure filters are installed on the high-pressure side of a hydraulic circuit, typically downstream of the pump and upstream of components that require protection from fine particulate contamination.
Because of their location in the circuit, pressure filter housings must be selected for the operating pressure, anticipated pressure peaks, flow rate, fluid viscosity, connection type, and required filtration performance of the system.
Eaton offers pressure filters in several configurations, including:
- In-line pressure filters
- Flange-mounted filters
- Manifold-mounted filters
- Stainless steel pressure filters
- Simplex pressure filters
- Duplex pressure filters
The HPX Series, for example, is a high-pressure filtration option rated for working pressures up to 4,568 PSI, 315 bar. Eaton also offers multiple additional pressure filter families to accommodate different mounting arrangements, pressure requirements, flow rates, and system designs.
Return-Line Filters
Return-line filters are installed on the return side of the hydraulic circuit to capture contamination before fluid re-enters the reservoir.
This position allows the filter to capture particles generated by pumps, valves, cylinders, motors, and other system components during operation. Because return-line filtration typically occurs at lower pressure than pressure-side filtration, these filters can be configured around the return flow, allowable pressure drop, required cleanliness level, and available installation space.
Eaton return-line filter options include the TEF, DTEF, TEFB, and TRW Series, along with the TRS and TNRS Series return-line filters with suction connections.
Suction Filters and Strainers
Suction filters and strainers are installed on the pump inlet side of the system to help prevent larger contaminants from reaching the pump.
Filtration on the suction side requires careful sizing because excessive restriction can negatively affect pump inlet conditions. Suction filters are therefore generally selected to provide the required pump protection while maintaining an appropriately low pressure drop for the application.
Eaton's tank-mounted suction filter families include the AS, TS, and TSW Series, with ASF Series suction strainers also available for applications requiring coarse contamination protection.
Tank Breathers
Hydraulic reservoirs exchange air with the surrounding environment as fluid levels change during normal system operation. Without effective breather filtration, airborne particles can enter the reservoir and become a continuing source of fluid contamination.
Eaton tank breathers filter incoming air before it enters the reservoir, helping reduce environmental contamination at one of its potential entry points.
Available Eaton breather families include the NBF, EBF, TBF, BFD, and BF-WP Series.
Simplex vs. Duplex Configurations
The required filter configuration also depends on whether the system can be stopped for filter element replacement.
Simplex filters use a single filter housing and element. When the element requires replacement, filtration through that housing must be interrupted. Simplex configurations are appropriate for equipment where planned maintenance shutdowns are acceptable.
Duplex or changeover filters use two filter chambers connected through a changeover arrangement. Flow can be directed from one chamber to the other, allowing an element to be serviced while filtration continues through the second housing.
Duplex filtration is particularly useful for equipment and processes where continuous operation is required, including:
- Power generation and turbine lubrication
- Continuous manufacturing processes
- Marine hydraulic and lubrication systems
- Industrial equipment where shutdowns are difficult or costly
Eaton offers both simplex and duplex versions across pressure, return-line, and suction filter positions.
Eaton Hydraulic Filter Elements
Eaton offers an extensive range of replacement filter elements covering its hydraulic and lubrication filter product families. Elements are available in different media types, micron ratings, sizes, and configurations to meet different fluid cleanliness and operating requirements.
Filter Media
Common Eaton filter media options include:
- Glass fiber fleece, VG: High-efficiency media designed for fine filtration and high dirt-holding capacity in demanding hydraulic and lubrication applications.
- Paper, P: An economical filtration media used in applications where extremely fine filtration is not required.
- Stainless steel wire mesh, G: Durable, cleanable media commonly used for coarser filtration and applications where reusable elements are preferred.
Selecting the appropriate media depends on the fluid, contamination type, target cleanliness level, operating conditions, and filtration requirements of the equipment being protected.
Micron Rating & Filtration Efficiency
The appropriate micron rating should be selected based on the cleanliness requirements of the system and the components being protected. Systems incorporating contamination-sensitive components such as servo or proportional valves may require finer filtration than general-purpose hydraulic equipment.
Micron rating alone, however, does not provide a complete picture of filter performance. Filtration efficiency should also be considered when comparing elements.
Understanding Beta Ratings
Beta ratios measured according to ISO 16889 provide a standardized method for evaluating a hydraulic filter element's particle removal efficiency at a specified particle size.
For example, a Beta ratio of 1,000 corresponds to a filtration efficiency of approximately 99.9% at the specified particle size.
When evaluating replacement elements or specifying filtration for a new system, consider the Beta rating together with the micron size, dirt-holding capacity, pressure drop, flow rate, and target system cleanliness.
How to Select the Right Filter and Element
Choosing the correct filter requires more than matching a connection size or micron rating.
| Selection Factor | What to Consider |
|---|---|
| Circuit position | Is filtration required on the pressure, return, suction, reservoir breather, or another portion of the system? |
| Operating pressure | The filter housing must be rated for the maximum system pressure plus anticipated pressure spikes at that location. |
| Flow rate | The filter must handle the maximum flow rate at that point in the circuit without excessive pressure drop. |
| Fluid and viscosity | What hydraulic fluid, lubricant, gear oil, or other fluid will be filtered, and at what operating temperature? |
| Target cleanliness | What ISO 4406 cleanliness level is required by the equipment or critical components? |
| Filtration efficiency | What micron rating and Beta efficiency are required to achieve the target cleanliness level? |
| Continuous operation | Can the equipment be stopped for element changes, or is a duplex/changeover configuration needed? |
| Mounting configuration | Does the application require in-line, flange-mounted, manifold-mounted, or tank-mounted filtration? |
| Pressure drop | What differential pressure can the system tolerate across the filter and element? |
| Element replacement | How frequently will elements need to be changed? Glass fiber elements last longer but cost more; cellulose is more economical for frequent changes. |
For replacement applications, the existing Eaton filter housing model or filter element part number is often the best starting point. For new systems, CFS can help identify an appropriate filter configuration based on system pressure, flow, fluid, filtration requirements, and installation conditions.
Clogging Indicators and Filter Condition
Filter elements collect contamination over time, increasing differential pressure across the element as it loads.
Eaton offers visual and electronic clogging indicators that can help identify when an element has reached its recommended service point. Available indicator families include multiple configurations designed for different Eaton filter housings and operating requirements.
Using a clogging indicator or differential pressure measurement can help maintenance teams base element replacement on actual filter condition rather than relying only on fixed replacement intervals.
Applications
Eaton hydraulic and lubrication filters are used across a wide range of industries and equipment types, including:
- Industrial hydraulic presses and machine tools
- Gearbox and turbine lubrication systems
- Wind turbine hydraulic and lubrication systems
- Mobile construction, mining, and agricultural equipment
- Power generation
- Marine hydraulic systems
- High-speed rail
- Steel and metals processing
- Plastic injection molding
- Tunnel boring machines
- Paper and printing equipment
Eaton's hydraulic filtration range also includes specialized configurations for applications involving abrasive fluids, cooling lubricants, water-based fluids, high-pressure hydraulic circuits, and continuous-duty lubrication systems.
Complete Hydraulic Contamination Control
Inline hydraulic and lubrication filters address contamination at specific points within the fluid circuit, but they can also be used as part of a broader contamination control program.
Offline filtration systems can provide independent kidney-loop filtration and fluid conditioning outside the primary circuit.
Contamination monitoring equipment can provide information about fluid cleanliness and help determine whether filtration is maintaining the required ISO cleanliness level.
Together, inline filtration, offline filtration, reservoir protection, and contamination monitoring provide multiple points of control for maintaining hydraulic and lubrication fluid cleanliness.
CFS carries all three product categories from Eaton and can help you build a system-level contamination control program.
Need help selecting an Eaton hydraulic or lubrication filter? Call (855) 236-0467 or submit a quote request for filter selection, replacement element identification, cross-references, pricing, and availability.