A.mixed-flow
B.axial-flow
C.centrifugal
D.displacement
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Which of the following operating features do displacement pumps bear if they are working under no-cavitation condition?()
(1) output is almost directly proportional to speed
(2) they are self-priming
(3) they will develop a discharged pressure equal to the resistance to be overcome, irrespective of speed
A.(1)and(2)
B.(2)and(3)
C.(1)and(3)
D.(1),(2)and(3)
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)
A.providing the impeller with balancing holes
B.the use of symmetrical impeller
C.neither A nor B
D.either A or B
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 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)
A.centrifugal
B.plunger
C.injector
D.water
A.discharges into a gradually widening channel
B.has stationary diffuser vanes
C.produces no kinetic energy
D.All of the above are true
A.Piston pump
B.Screw pump
C.Diffuser pump
D.Water-ring pump
A.pump entry branch
B.outlet pipe
C.impeller
D.None of the above is true
A.to fill 2 tanks at the same time
B.to use pump at a higher pressure
C.to return liquid to suction side if discharge valve is closed
D.All of the above are true
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