Abstract: A filter system for filtering a fluid has a filter housing with filter housing head module and housing cover. The filter housing accommodates a filter element with raw side and clean side. A fluid inlet is in fluid connection with the raw side of the filter element. A fluid outlet is in fluid connection with the clean side of the filter element. The filter housing head module has a tube section as a main channel connecting the clean side of the filter element to the fluid outlet when the housing cover is attached to the filter housing head module. The tube section projects into the clean side of the filter element and has a ball valve seat of a ball valve for closing or opening the main channel. The filter housing head module has a pump chamber of a pump as a bypass channel bypassing the ball valve seat.

Abstract: A filter for filtering fluid has a filter housing with fluid inlet for fluid to be filtered and fluid outlet for filtered fluid. A filter element arranged in the filter housing separates fluid inlet fluidically from fluid outlet. A bypass valve arrangement is arranged fluidically between fluid inlet and fluid outlet such that it fluidically connects in an open state fluid inlet to fluid outlet. The bypass valve arrangement has a valve closure body arranged movably in the valve housing between a closed position and an open position. The bypass valve arrangement has a valve seat element with valve seat. The valve closure body rests sealingly at the valve seat in closed position. The valve seat element is connected to a part of the valve housing by a mechanical connection realized by relative rotation between valve seat element and part of the valve housing about a valve axis.

Abstract: A flange for a filter insert for separating oil aerosol from air has a flange region with radial contact surface for supporting the flange; an axial first wall region adjoining radially inwardly the flange region; a radial cover region adjoining an end of the first wall region opposite the flange region; a second axial wall region adjoining radially inwardly the cover region and surrounding a central cutout. Radial lifting regions adjoin an end of the second wall region opposite the cover region and extend into the central cutout. First and second wall regions and cover region are concentric to each other. The lifting regions are arranged exclusively in a radially outer region of the central cutout. A coaxial imaginary circle with outer circumference defined by radially innermost points of the lifting regions has a radius of at least three fourths of a radius of the second wall region.

Abstract: A flange for a filter insert for separating oil aerosol from air has a flange region with radial contact surface for supporting the flange; an axial first wall region adjoining radially inwardly the flange region; a radial cover region adjoining an end of the first wall region opposite the flange region; a second axial wall region adjoining radially inwardly the cover region and surrounding a central cutout. Radial lifting regions adjoin an end of the second wall region opposite the cover region and extend into the central cutout. First and second wall regions and cover region are concentric to each other. The lifting regions are arranged exclusively in a radially outer region of the central cutout. A coaxial imaginary circle with outer circumference defined by radially innermost points of the lifting regions has a radius of at least three fourths of a radius of the second wall region.