Abstract: A method adapts a filter medium to predefinable parameters, such as electrostatic charge, flow-rate behavior, dynamic pressure behavior or differential pressure behavior, fraction filtration efficiency and preservation of a constant quantity and quality of fluid additives. At least one of these parameters is adapted by the targeted influencing of the surface energy of the filter medium (18).

Abstract: A filter apparatus, in particular for the filtration of hydraulic media, includes a filter housing (4) and a filter element (30) arranged in the filter housing, Air present in the filter housing (4) can be removed from the housing by suction by a degassing device (52) that generates a negative pressure.

Abstract: A delivery device for the fuel of an internal combustion engine has a fuel tank (4) from which at least one fuel pump (14, 18) delivers fuel via a fuel supply line (10) and via at least one fuel filter (12, 16) to a fuel consumer (2). The consumer (2) is connected to the fuel tank (4) via a fuel return line (20). A control device (24) is connected between the supply line (10) and the return line (20). The control device establishes a fuel-conveying connection (80) between the return line (20) and the supply line (10) when the temperature in the fuel tank (4) falls below a predeterminable threshold temperature and at a predeterminable threshold pressure in the return line (20).

Abstract: A filter device usable with diesel fuels, includes a filter element (19) exchangeably accommodated in a filter housing. A fluid pump device (46) having two pump chambers (45, 49) is part of the filter device. The pump chambers, by a pump piston (51) guided in the chambers in a longitudinally movable manner, are separated from each other fluid-tight at least in one of the two directions of movement of the pump piston. Each pump chamber (45, 49) is assigned a valve (39, 63) opening or closing oppositely to the other valve (39, 63) when the pump device (46) is actuated.

Abstract: A filter device has a filter housing (2, 4) accommodating a filter element (16) separating an unfiltered substance chamber (26) from a filtrate chamber (20) within the filter housing (2, 4). The filter element (16) is sealed against the filter housing (2, 4) by a sealing device (36, 40). The filter element (16) is mounted inside the filter housing (2, 4) using movable bearings (32, 38).

Abstract: A filter device for filtering fluids such as fuels, including diesel fuel, has a filter housing (1), within which a filter element (17) can be fastened and exchanged. The filter element has a filter medium that surrounds an inner filter cavity (25). A fluid inlet leads to the unfiltered side (27) of the filter element (17). A fluid outlet outflows filtered fluid from the filtered side (25). An equalizing tube (49) extends in the filter housing (1) up to a maximum filling level height for the filtration operation. The equalizing tube is connected to a tank return connection at a lower end of the equalizing tube and is open at an upper end (51) of the equalizing tube. The tube (49) has, at distances from the upper and lower ends of the tube, an inner control part (60) with a passage opening (61) forming a throttle point.

Abstract: A filter element, in particular for treating fluids in the form of diesel fuel, has a filter medium (14) through which the fluid can flow. The filter medium (14) contains at least one active substance having antimicrobial properties.