| 摘要 |
The rotary drive shaft of a centrifugal pump extends vertically through a cylindrical housing and into a casing defining a bowl for the impeller of the pump. A mechanical seal and bearings for the drive shaft are positioned between the pump bowl and the interior of the housing which forms a reservoir for liquid lubricant. The impeller includes a radial shroud plate, a first set of pumping blades projecting downward from the shroud plate toward the axial pump inlet and a second set of blades or vanes projecting upward from the shroud plate. The upper vanes result in slight suction being generated in the area of the seal tending to draw lubricant from the housing reservoir through the bearings and seal. Seal failure is detected by a rapid decrease in the level of lubricant in the reservoir.
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