An apparatus for separating gases from fluids, which apparatus includes a closed cylindrical receptacle and a cylindrical insert which divides the interior of the receptacle into an annular outer part and a cylindrical inner part. The outer part is provided with a tangential inlet for the fluid. Near the top, an opening connects the outer part to the inner part, the latter being provided with a ventilation device. The outer annular part is divided in the axial direction by a partition which ascends spirally from the tangential inlet approximately in a complete turn in the direction of the upper end face cover of the receptacle. The connection opening is formed by an annular clearance which extends over nearly the entire circumference of the receptacle. A similar annular clearance at the bottom of the receptacle connects the inner cylindrical part with the outer annular part, the latter having a tangential discharge outlet in this region.