Filter device

A filter device for mass exchange between two media separated by a membrane in form of a hollow fiber bundle which extends over the entire cross-sectional area of a housing and whose fiber cavities form a first fluid flow path, the filter device also having a second fluid flow path, the filter device comprising:

• at least one of an inflow and an outflow chamber for feeding fluid to or withdrawing fluid from said hollow fiber bundle, said at least one of an inflow and an outflow chamber being in fluid communication with said first fluid flow path and bordering on a substantially enclosed, essentially circular or partially circular channel which is open to the ends of the hollow fibers and which is in fluid communication with at least one of an inlet and an outlet port of the filter device, said channel being located essentially centrically to the hollow fiber bundle and having a decreasing cross-sectional area in flow direction and an outer diameter which is less than a diameter of the hollow fiber bundle.