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
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
A salinity indicator is used to determine the （）.
A salinity indicator is used to determine the （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
The major source of chemical contaminants in hydraulic fluid is （）.
Low compressor head pressure in a refrigeration system can be caused by（）.
Which of the following statements is correct concerning heat transfer?（）
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
Who is responsible for ensuring that someone is assigned to close the watertight doors in an emergency?（）
Thermostatic expansion valves can be adjusted for （）.