Hydraulic Filters

Hydraulically controlled systems require filtration just as other lubricants do. However, in a hydraulic system the aggregated system is held to a far higher pressurization standard. The pressure at rest is as high as 200 -250 bar, or that same range times the normal atmospheric pressure at sea level on Earth. That number is only for transportation, when in use the hydraulic pressure is far higher. For that reason, it is dangerous to have metal and other particulates within the system, because at those pressures even a small pebble can do serious damage. Hydraulic filters are use to be certain that the materials are not in the common system areas.

The common areas of a hydraulic system are the reservoir, the control valve, the hydraulic cylinder, the control valve again, the pump and the filter. It is not always in this order, however, as the filter can be placed in several areas. First it can be placed prior to the control valve, meaning that all oil entering the system is clean. Second it can be placed after the control valve the second time on the way to the pump. This is considered inexpensive and advantageous because it does not have to be pressurized. Lastly, it can be in the configuration mentioned above where the filter if behind the pump. In this method, the liquid must move through the entire system before being cleansed. In the first system only clean lubricant moves towards the critical components of the system, and as such it has been said to improve the life of the machinery.