There are a variety of applications for filters and separators In offshore petroleum and natural gas recovery. They include sea water filtration prior to injecting the water into the well in order to increase the delivery pressure. Other important applications arise in processing the mixture of oil/gas, water, and sand coming up from the well. This mixture is separated in single stages on-site. Additionally filters play a decisive role for the functionality of the essential safety system in oil and gas production: the blowout preventer (BOP). BOPs prevent oil and gas from blowing out of the bore hole at high pressure when it can ignite and cause serious environmental damage. A BOP consists of a series of mechanical devices and/or valves, which seal up the gap between the bore hole and surrounding rocks if pressure peaks occur. The mechanical devices and valves are operated hydraulically. Filters ensure that the hydraulic fluids meet the quality demands.