Centrifugal pump

A multi-stage centrifugal pump comprising:

• a pump casing;
• a shaft comprising a shaft longitudinal axis;
• impellers of pump stages arranged on the shaft rotatably within the pump casing, the shaft at one end being sealingly led out of the pump casing for connection to a drive motor, the pump casing having a chamber, provided within the pump casing, through which the shaft passes;
• a shaft ring fixedly and sealingly connected to the shaft and arranged on the shaft, the shaft ring having one side, which, at least in sections, is subjected to a pressure of the pump;
• an axial seal comprising a rotating part formed by the shaft ring or a seal part arranged on the shaft ring and comprising a non-rotating part formed by a counter-ring or a seal part which is arranged on the counter-ring, wherein the counter-ring is radially sealed with respect to the chamber and the counter-ring is axially movably guided within the chamber, the counter-ring comprising a counter-ring outer surface located at one end of the counter-ring, the counter-ring outer surface extending radially relative to the shaft longitudinal axis;
• an annular member comprising a first annular member outer surface portion and a second annular member outer surface portion located opposite the first annular member outer surface portion, the first annular member outer surface portion facing in a direction of the counter-ring outer surface, the first annular member outer surface portion being in direct contact with the counter-ring outer surface, the annular member and the shaft defining a gap, wherein the annular member is located at a spaced location from the shaft, the counter-ring being located between the shaft ring and the annular member, the second annular member outer surface portion facing in a direction of the pump casing, the second annular member outer surface portion being located at a spaced location from the pump casing, the second annular member outer surface portion extending radially relative to the shaft longitudinal axis.