Abstract: A centrifugal pump with a mechanical seal cartridge is disclosed. The pump has a pump casing, a rotatable drive shaft extending into the casing from the rear side, and an open impeller mounted on the drive shaft, this impeller having radially extending vanes with leading and trailing edges. The seal cartridge is mounted in a back plate structure of the casing so as to seal a central seal chamber formed by the back plate structure and extending around the drive shaft. This seal chamber has a circumferential wall extending around at least a forward portion of the seal mechanism and spaced therefrom so as to form an open annular space for circulation of fluid which lubricates and cools the mechanical seal.

Abstract: A centrifugal pump has an impeller rotatable by means of a drive shaft. The impeller has a plurality of radially extending vanes connected to a hub and a partial back shroud with sharpened leading edges. The pump has a pump casing with a back plate adjacent to the back side of the impeller. Spiral grooves on the back plate interact with the sharpened edges on the back shroud to aid in protecting the area between the back plate and the impeller by cutting of solids and expulsion of solids through an output port. Cutting bars on the front plate of the casing project into the pump intake and interact with front edges of the vanes to cut incoming solids in a liquid mixture. A preferred form of impeller has vanes with sharpened leading edges that extend in a generally radial plane. These vanes sweep backwardly from their leading edges and each vane is given a double twist between the leading edge and its trailing edge.

Abstract: A centrifugal pump has an impeller rotatable by means of a drive shaft. The impeller has a plurality of radially extending vanes connected to a hub and a partial back shroud with sharpened leading edges. The pump has a pump casing with a back plate adjacent to the back side of the impeller. Spiral grooves on the back plate interact with the sharpened edges on the back shroud to aid in protecting the area between the back plate and the impeller by cutting of solids and expulsion of solids through an output port. Preferably the leading edges on the back shroud are also serrated and beveled and the spiral grooves are outward threaded. A disintegrator is preferably mounted on the end of the drive shaft in the conical intake of the pump. Also, cutting bars on the front plate of the casing project into the pump intake and interact with front edges of the vanes to cut incoming solids in a liquid mixture.