Shaft sealing in a centrifugal pump can be effected by （）.

As for a hydraulic vane pump, which of the following is...

单项选择题

As for a hydraulic vane pump, which of the following is in contact with the vanes during working: （）
(1)the rotor
(2)the pump shaft
(3)the external surface of the housing

As for a hydraulic single action vane pump, the inner w...

单项选择题As for a hydraulic single action vane pump, the inner wall of the stator is usually of （） shape.

Throttling in the （） line of a centrifugal pump involve...

单项选择题Throttling in the （） line of a centrifugal pump involves the risk of the pump cavitation.