US Patent 7607884 Centrifugal pump with mechanical seal arrangement

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.