A.circular
B.elliptical
C.rectangular
D.hexagon
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A.suction
B.exhaust
C.pressure
D.discharge
A.draw the liquid in；force the liquid out
B.force the liquid out；draw the liquid in
C.suction；draw
D.deliver；outlet
A.throttling the pressure line
B.changing the speed of the rotor
C.either A or B
D.None of the above is tree
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? （）
(1) reciprocating
(2) rotary
(3) centrifugal
A.(1)only
B.(1)and (2)
C.(1),(2)and(3)
D.(2)and(3)
A.throttling the pressure line
B.changing the speed of the driving rotor
C.either A or B
D.None of the above is tree
最新試題
A pressure drop through the refrigerant liquid line may cause （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.
Which of the following statements is correct concerning heat transfer?（）
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
When the steering gear is in operation, you should （）.