In general low-pressure systems with pressures below 140 kg/cm², only an intake filter is typically installed, but a return filter and an air filter should also be installed.
In general medium- and high-pressure hydraulic systems with pressures above 140 kg/cm², a return filter is usually used to control contamination concentration. However, when special reliability requirements are placed, a high-pressure line filter should be used in conjunction.
Electromagnetic proportional control valves or micro-flow regulating valves should be equipped with terminal filters to increase their reliability.
When using servo valves, efforts should be made to reduce the system's contamination concentration; therefore, both high-pressure and return filters should be used. For large-capacity systems, a circulation filter should be installed, and a terminal filter should be installed on the auxiliary piping.
