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
The major source of chemical contaminants in hydraulic fluid is （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
Which of the following statements is correct concerning heat transfer?（）
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
A salinity indicator is used to determine the （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.