Hydraulic filters play a key role in hydraulic systems and are the line of defense to ensure cleanliness, stable operation and extend the life of equipment. Their failures will affect system efficiency, increase wear and even cause system paralysis. It is particularly important for maintenance personnel to understand their common faults, causes and treatment methods.

1. Filter blockage

Fault manifestations:

• System pressure rises abnormally, hydraulic pump load increases;

• Warning light turns on or pressure switch sends alarm signal;

• Oil temperature rises, flow rate drops significantly;

• The actuator moves slowly or fails.

Possible causes:

• The filter element has not been replaced for an extended period, causing the absorbed contaminants to become saturated;

• Poor quality of hydraulic oil, contains too much impurities, water or oxides;

• Filter element filtration accuracy is too fine, resulting in easy clogging;

• The system is seriously polluted, and impurities are generated quickly.

Solutions:

• Develop and implement a maintenance plan for regular replacement of filter elements;

• Use branded high-quality hydraulic oil and strictly control cleanliness;

• Reasonably select filtration accuracy (such as 10μm, 25μm, etc.) according to system flow and pollution level;

• Thoroughly clean the system and improve the overall sealing performance.

2. Filter element damage

Fault manifestations:

• The filter element exhibits obvious deformation, such as cracks, breakage, or mesh damage;

• A large number of metal particles or impurities appear in the oil;

• Actuators experience rapid wear, leading to a significant reduction in their lifespan.

Possible reasons:

• The filter element material is not strong enough to withstand the high pressure of the system;

• The oil is seriously contaminated, resulting in excessive load on the filter element;

• Improper installation or impact by external force;

• Use inferior non-standard filter elements.

Solutions:

• Replace high-pressure durable filter elements to ensure that their pressure resistance matches system requirements;

• Increase pre-stage coarse filtration to reduce the load on the main filter;

• Strictly implement filter element installation standards and use genuine filter elements that meet ISO standards;

• Using double-layer or composite filter elements is recommended to enhance durability and resistance to damage.

3. Bypass valve failure

Fault manifestation:

• The filter element is blocked but the system is still running, and no warning appears;

• The oil is not fully filtered, resulting in continuous wear of the equipment;

• The absence of a proper bypass path compromises system safety.

Possible reasons:

• Bypass valve stuck, spring failure or poor sealing;

• Long-term lack of maintenance, valve body scaling or rust;

• Irrational design pressure setting, opening and closing failure.

Solutions:

• Regularly check whether the opening and closing pressure of the bypass valve is within the set range;

• Replace or clean failed parts to ensure sensitive valve response;

• For critical equipment, installing a dual filter system is recommended to enable uninterrupted filtration through seamless switching.

4. Decreased filtering effect

Fault manifestations:

• The filter element is not blocked but the oil is still turbid and contains many impurities;

• The actuator is unstable and faults occur frequently;

• The system's cleanliness does not meet the standard for a long time.

Possible reasons:

• The filter element is of poor quality or aging, and the filtering efficiency is reduced;

• The filtering accuracy does not match the actual pollution situation;

• The filter is installed in a non-optimal position, causing short flow or too high flow rate.

Solutions:

• Replace high-quality, multi-layer folded filter elements to improve the pollution-holding capacity and life;

• System Conduct oil contamination level detection (NAS/ISO) and scientifically select filtration accuracy;

• Optimize the installation position, avoid high-impact areas and vibration sources, and control the flow rate within a reasonable range.

5. Leakage and oil seepage

Fault manifestations:

• Oil stains and dripping appear on the filter housing, interface or seal;

• Oil pressure drops, system efficiency decreases;

• Surrounding environmental pollution, and safety hazards.

Possible causes:

• Aging, cracking or oil-resistant material of the seal ring;

• Unsecured installation of the joint, loosening caused by long-term vibration;

• Corrosion or mechanical damage to the filter housing.

Solutions:

• Regularly replace seals and use oil-resistant and temperature-resistant materials such as fluoro rubber (FKM);

• Check the installation location for tightness, and it is recommended to use anti-loosening washers;

• The filter housing should be made of corrosion-resistant galvanized material or stainless steel to improve durability.

Summary

Although the hydraulic filter is small, it shoulders the responsibility of system cleaning. Its operating status directly affects the stability and life of the hydraulic system. The root cause of many major failures often begins with the neglect of filter maintenance. Therefore, enterprises should establish the concept of "prevention is better than repair" and control the whole process from selection, installation, and operation to maintenance.

Suggestions:

• Establish equipment maintenance files and regularly check system cleanliness;

• Use original genuine filter elements and accessories to prevent inferior products from being sold as good ones;

• It is recommended to replace the filter element at the same time when changing the hydraulic oil to avoid "new oil with the old element".

Only by incorporating the management of hydraulic filters into the focus of daily operation and maintenance can the high efficiency, reliability and long-term operation of the hydraulic system be fundamentally guaranteed.