Regenerative Turbine Pump. The mechanical design of the regenerative pump closely resembles a typical centrifugal pump. The lightweight impeller allows an overhung impeller design to be used. This design requires only one mechanical seal to seal off the pumping chamber. The impeller is designated to float on the shaft so hydraulic forces in the pump may perfectly center the impeller to prevent metal to metal contact between the impeller and casing. A free floating impeller is much easier to install than a centrifugal pump impeller.