Hydraulic System Filtration Guide: Types, Buyer’s Guide, and Maintenance Tips
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Hydraulic System Filtration Guide: Types, Buyer’s Guide, and Maintenance Tips


As you know, maintaining your hydraulic filter ensures all impurities and contaminants are cleaned out for a longer-lasting system. With increased tolerances and pressure loads, contaminated hydraulic fluid can have increasingly harmful effects on equipment, making your maintenance all the more essential.

With the right hydraulic oil filters and filtration equipment, your system can run smoothly and last longer. When choosing the correct filters, and properly maintaining them, you can avoid the impact of contaminants on your system, avoiding damage to a well-running machine.

To better care for and maintain your hydraulic fluid filter and boost the longevity of your system, we are breaking down all you need to know about a hydraulic filtration system and how to maintain it. Let’s dive in!

What Is a Hydraulic Filter and What Are the Common Types?

filter hydraulic

Hydraulic filters are used in hydraulic systems to keep contaminants from the fluid. To do so, the filtration system works by continuously removing the contaminants, ensuring the fluid remains clean for a well-running hydraulic tank filter and system.

To purify and filter hydraulic fluid, different types of filters in hydraulic system units are used, ensuring each system is running well and clean. Some of the most common types of filters include:

  • Suction filters: Placed before the pump, suction filters work to prevent large dirt particles from entering the system and damaging the pump;
  • Pressure filters: Placed after the pump, pressure filters ensure the fluid is clean before entering the circuit from the pump;
  • Return line filters: This is a low-pressure filter that purifies fluid before it returns to the reservoir, filtering out dirt that has accumulated from the pump and actuators;
  • Off-line filters: A small independent filtration sub-system that includes a pump, filter, motor, and hardware connections. This filter operates when the machine isn’t active, ensuring the fluid keeps a constant contamination level;
  • Air filters: Also referred to as air breathers, this filter focuses on the air entering the system. An air filter is essential to avoiding contamination of the fluid.

Function of a Hydraulic Filtration System

hydraulic oil filters

A hydraulic filter is essential to ensuring a hydraulic system runs at optimal functioning capacity. With this in mind, there are a few different reasons hydraulic oil filters are implemented in a hydraulic system, including:

  • Removing foreign particles: As noted before, foreign particles, including elements like copper and iron, can have incredibly damaging effects on a hydraulic system when contaminating the hydraulic fluid. Thankfully, with a filter system, this harm can be removed, eliminating contaminants with proper filtration;
  • Improved efficiency: When contaminants enter the system, they can greatly reduce productivity and efficiency. With the right filtration, you can keep your system running properly;
  • Reduced maintenance costs: Without a proper hydraulic filtration system, a hydraulic system is likely to break down. With this, the cost of maintenance will increase as opposed to when a hydraulic oil return filter is in place;
  • Longevity of the hydraulic system: With effective filtration, the lifespan of a hydraulic system increases. This not only helps reduce expenses but improves the ROI.

How Do Contaminants Affect Your System’s Performance?

hydraulic tank filter

There are many ways contamination can impact the hydraulic fluid and ultimately the overall system. With the build-up of contamination, complications can get worse, leading to catastrophic impacts on your hydraulics. Some of the resulting damage includes:

  • Corrosion: As a result of fluid degradation, corrosion of any component the fluid passes occurs throughout the system;
  • Leakage: With dirt in the system, leakage within the system can occur, which directly impacts the performance of the pumps, motors, cylinders, and valves;
  • Sticking parts: Contamination can lead to the sticking of components in a system. When this happens, the spool can no longer change positions, reducing performance and efficiency.

How Hydraulic Fluid Gets Contaminated

A hydraulic filter is designed to remove contaminants from the system, but how do they get in there in the first place? Contaminants may enter the hydraulic system for various reasons, including:

  • Environmental: Contaminants can accumulate during the manufacturing process of the hydraulic system itself. This can include substances like rubber particles, paint chips, and metal shavings. To remove this, an air hose can quickly blow them away, but some smaller contaminants must be filtered out. In addition, when adding new fluid, contaminants can enter the system, making a good filtration practice essential when integrating new fluid;
  • System-generated: Some internal parts of the system, such as pumps and piston rods, can create contaminants during their routine functioning. Thankfully, return-line filters are good at collecting this kind of contaminant;
  • External: On occasion, air can get into the system through the breather caps, imperfect seals, or other openings. As a result, the air condenses on the system’s walls, causing rust. To avoid this, it’s a must that you maintain clean breather caps.

How to Choose a Hydraulic Filtration System

hydraulic fluid filter

Whether you need a hydraulic in-line filter or a hydraulic pump filter, there are some filtration options to choose from, each with a unique offering.

Each hydraulic filter component is designed for specific placement in the system. With this in mind, the filter you choose will depend on the positioning you need, in addition to a few other factors, including:

  • Type of hydraulic fluid;
  • Operating pressure;
  • Operating temperature;
  • Fluid flow per cycle;
  • Required resistance of filter;
  • Allowed system pressure drop;
  • Ease of element maintenance.

With the right hydraulic filter selection, you can aptly reduce the amount of dirt in your system, ensuring the system runs smoothly and efficiently.

Top Tips for Hydraulic Filtration Maintenance

hydraulic in-line filter

Wondering if you need hydraulic pressure filters or hydraulic oil filters? Ensuring you have the right hydraulic filtration system is the first step to maintaining your system, but after that, it’s all about maintenance.

Once you have the right filtration system in place, ensure you follow the necessary maintenance steps, including:

  • Begin with clean fluid: A well-operating system starts with clean fluid. A filtration system is not designed to restore fluid that already exhibits a large number of contaminants, and will quickly clog without a clean fluid. To avoid this, start with fresh hydraulic fluid;
  • Change and clean filters: As particles and contaminants become trapped in the filtration system, the volume of fluid that can pass will decrease over time. As a result, the pressures in your system will increase, leading to further problems in performance, as well as pump damage. Thankfully, newer filters have an indicator letting you know when it’s time to clean or change your system. When it’s time to clean or change your filter, follow the manufacturer's instructions to avoid clogged filters;
  • Keep records: No matter what machinery you choose and your maintenance needs, be sure you keep accurate notes, especially when it comes to your hydraulic fluid filtration system. This will help you keep track of your maintenance, avoiding only noticing a problem once it’s too far along, and, instead getting ahead with regular, efficient maintenance.


A hydraulic filtration system is essential to a properly running hydraulic system, and with the right choice of filter and proper maintenance, you can avoid any unnecessary damage and replacement of your system, ensuring everything runs as it should. By getting ahead and promoting the longevity of your filters in a hydraulic system, you can not only ensure everything runs smoothly but reduce long-term maintenance and replacement costs.

Whether you have questions about the proper hydraulic filter for you or need a hydraulic cylinder repair company, our team at Cylinders, Inc. is here to help. To begin, request our service online today.

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