Abstract: A centrifugal pump with a floating ring seal (34) provided in a sealing chamber (32) for pumped fluid and web-like flat pieces arranged in the sealing area (32) between the outer wall and the floating ring seal (34) extending in a longitudinal section approximately parallel to the pump shaft (14). At least one closable ventilation opening (47) is arranged in the head area of the sealing chamber (32), in addition to one blade-like flat piece (60, 60a) which is disposed on the peripheral wall (48) on both sides of the ventilation opening (47). From a cross-sectional point of view, both flat pieces (60, 60a) are inclined towards each other and define an antechamber with a slit (70) which is parallel to the pump shaft (14) at a distance from the peripheral wall. Preferably, the blade-like flat pieces (60, 60a) are fixed to the radial wall (55) and the free blade edge parallel thereto defines a radial slit with the other radial wall.