Why Is Oil Filtration Important for Hydraulic Systems?

Hydraulic systems play a vital role in numerous industrial applications, commonly finding use in large automotives, construction equipment, and aerospace systems, among other heavy machinery. Overall, these systems rely on hydraulic oil to transmit power, lubricate components, and maintain operational efficiency. However, hydraulic oil is susceptible to contamination from various sources, such as dust, metal particles, and water. So, to ensure optimal performance and longevity of hydraulic systems, they need to be equipped with oil filtration equipment. In this blog, we will be discussing the major types of filters you may come across and why they are important to hydraulic systems.

Hydraulic Oil Filters

From the smallest fittings to its most complex actuators, every component in a hydraulic system is important, and the hydraulic oil filter is no exception. Designed to remove contaminants and impurities from the hydraulic fluid, these filters ensure cleanliness and preserve the system's overall health. With regards to this purpose, they are typically located in the pressure line, between the pump and the rest of the hydraulic system. There, the filter can act as a barrier, preventing harmful particles from circulating through the system and causing damage to critical components.

As a type of mechanical filter, the primary function of hydraulic oil filters is to trap contaminants such as dirt, debris, and metal particles which may enter the system during operation or as a result of component wear. These contaminants can lead to increased friction, accelerated component wear, reduced system efficiency, and even catastrophic system failure if left unchecked. Consequently, by removing these particles, hydraulic oil filters help maintain the system's performance, extend the lifespan of components, and reduce the likelihood of unexpected downtime.

Return Line Filters

Return line filters, as their name suggests, are positioned in the hydraulic system's return line. This location allows them to capture contaminants that have accumulated in the system during routine operation. With such a role, return line filters are essential for the fact that, despite the best efforts to filter hydraulic oil before it enters the system, some level of contamination is inevitable over time. These filters are also designed to handle a high volume of oil flow, ensuring efficient removal of contaminants and maintaining the cleanliness of the hydraulic fluid. By preventing the recirculation of debris and contaminants, return line filters help to preserve the performance and longevity of hydraulic components.

Suction Filters

Suction filters, also known as strainers, are typically located at the inlet of hydraulic pumps or reservoirs. They are responsible for removing larger particles and debris from hydraulic oil before it enters the system. While they may not capture all contaminants, suction filters play a crucial role in preventing large particles from reaching sensitive components and causing damage. With such a purpose in mind, suction filters are designed with a coarse mesh that allows for the efficient flow of hydraulic oil while trapping larger debris. Regular maintenance and inspection of these filters are necessary to ensure they are not clogged, as a clogged suction filter can lead to cavitation, reduced pump performance, and increased wear on system components.


Oil filtration is a critical aspect of hydraulic system maintenance, ensuring the cleanliness and longevity of hydraulic oil and components. Thus, investing in proper oil filtration for hydraulic systems is an investment in reliability, efficiency, and longevity. At NSN Sphere, we offer a wide variety of industrial products, including a large selection of high-quality oil filtration parts. Many parts in our inventory are subjected to rigorous quality assurance measures, tests, verifications, and assessments to ensure their quality. To begin the purchasing process on any items of interest, simply submit a Request for Quote (RFQ) form from our website and expect to receive a competitive quote for your comparisons in 15 minutes or less!


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