The eccentrically mounted impeller rotates in the pump chamber.

Due to the eccentricity, as the impeller rotates the volume between two flexible blades varies.

On the suction side the impeller is relaxed and the volume therefore increased. Fluid is drawn into the resulting vacuum (Fig. 1).

The fluid is gently transported between blades whose separation distance doesn’t change (Fig. 2).

On the discharge side the impeller is compressed and the volume reduced.The resulting over pressure forces the fluid into the discharge-line (Fig. 3).