What Is a Hydraulic Filter?

A hydraulic filter is a component within a hydraulic system that removes damaging particulates by forcing hydraulic fluid through a porous filter element. The filter element catches contaminants and prevents them from re-entering the fluid flow and damaging other pieces of equipment further downstream. Contaminants range from dirt to water and reactive chemicals. Their size is on a scale of micrometers, meaning hydraulic filters must be properly sized to filter out even the smallest of particles.

Functions of Hydraulic Filters

Hydraulic filters are placed at various locations throughout a system to catch contaminants created at different points in the process. For ideal filtration, filters would be before and after the pump, in the return lines, off-line and within the reservoir.

Types of Hydraulic Filters

• Return lines: These filters are usually low pressure. They collect contaminants from the fluid as it returns to the reservoir and can be positioned along the return line or within the tank.
• Suction filters: Another example of a low-pressure filter, suction filters are placed at the pump inlet to ensure no contaminants enter the pump.
• Pressure lines: These filters are placed after the pump to keep expensive downstream components safe. Pressure filters have a high-pressure capability to remove internal contamination created within the system. This allows for individual component protection. Saving on downtime, maintenance and component repair or replacement costs.
• Off-lines: Also called kidney loops, these filters continue working even while the central hydraulic system is not working. An off-line filter draws the fluid from the reservoir and returns it after filtration. These filters are usually easier to maintain because of their placement within reach. Some popular types of off-line filters are the drum topper and portable filter cart, which can service multiple hydraulic systems. Another common kidney loop system is the Filter Panel. It can be mounted directly to the hydraulic system and provide 24/7 filtration if necessary.