Abstract: A multistage centrifugal grinder pump includes a grinder to grind a fluid, a first stage impeller, a second stage impeller, a stationary diffusor arranged between the first stage impeller and the second stage impeller to guide the fluid from the first stage impeller to the second stage impeller and a shaft to rotate the first stage impeller, the second stage impeller and the grinder. The first and second stage impellers in series and connected to the shaft in a torque-proof manner. The diffusor is a semi-open diffusor having a top wall, a radially outer annular side wall, and an open bottom side facing the first stage impeller, the top wall arranged adjacent the second stage impeller, the top wall having a central outlet opening surrounding the shaft, and the open bottom side extending beyond the first stage impeller with respect to a radial direction.

Abstract: A multistage centrifugal grinder pump includes a grinder to grind a fluid, a first stage impeller, a second stage impeller, a stationary diffusor arranged between the first stage impeller and the second stage impeller to guide the fluid from the first stage impeller to the second stage impeller and a shaft to rotate the first stage impeller, the second stage impeller and the grinder. The first and second stage impellers in series and connected to the shaft in a torque-proof manner. The diffusor is a semi-open diffusor having a top wall, a radially outer annular side wall, and an open bottom side facing the first stage impeller, the top wall arranged adjacent the second stage impeller, the top wall having a central outlet opening surrounding the shaft, and the open bottom side extending beyond the first stage impeller with respect to a radial direction.

Abstract: The present invention provides a pump impeller which has improved anti clogging characteristics, in particular through the use of an impeller vane having a specially profiled leading edge which, during operation of the impeller, forces rags or the like down along the leading edge, which increases in thickness along the length thereof, until the rags become re-entrained in the fluid and thus exit the impeller avoiding the clogging thereof.

Abstract: The present invention provides a pump impeller which has improved anti clogging characteristics, in particular through the use of an impeller vane having a specially profiled leading edge which, during operation of the impeller, forces rags or the like down along the leading edge, which increases in thickness along the length thereof, until the rags become re-entrained in the fluid and thus exit the impeller avoiding the clogging thereof.