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 salinity indicator is used to determine the （）.
A pressure drop through the refrigerant liquid line may cause （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
A grease gun is generally used to lubricate a （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
The output volume of a positive fixed displacement pump can be changed only by （）.
Thermostatic expansion valves can be adjusted for （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.
Which of the listed pumps is NOT a positive displacement pump?（）