单项选择题
Which of the following pumps will build up a bursting pressure or stall their motors if the discharge valves are closed?（） (1) gear (2) centrifugal (3) screw
A.（1）and（2） B.（1），（2）and（3） C.（1）and（3） D.（2）and（3）
Attempts are made to eliminate axial thrust in centrifu...
单项选择题Attempts are made to eliminate axial thrust in centrifugal pump by （）.
A.providing the impeller with balancing holes B.the use of symmetrical impeller C.neither A nor B D.either A or B
The amount of fluid delivered by a gear pump can be reg...
单项选择题The amount of fluid delivered by a gear pump can be regulated by （）.
A.throttling the pressure line B.changing the speed of the rotor C.either A or B D.None of the above is true
Which of the following pumps are self-priming, and can ...
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump（） (1) ejector (2) screw (3) centrifugal
A.(1)only B.(1)and(2) C.(1),(2)and(3) D.(2)and(3)
