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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A.injector
B.positive displacement
C.centrifugal
D.centripetal
A.injector pumps
B.positive displacement pumps
C.centrifugal pump
D.centripetal pumps
A.the mechanical seal
B.packed stuffing boxes
C.either A or B
D.neither A nor B
As for a hydraulic vane pump, which of the following is in contact with the vanes during working: （）
(1)the rotor
(2)the pump shaft
(3)the external surface of the housing
A.(1) only
B.(2) only
C.(1) and (2)
D.(1),(2)and(3)
A.circular
B.elliptical
C.rectangular
D.hexagon
最新試題
A salinity indicator is used to determine the （）.
The general purpose of a heat exchanger is to （）.
If the head pressure of a reciprocating refrigeration compressor is excessive, （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
Thermostatic expansion valves can be adjusted for （）.
Which of the following statements is correct concerning heat transfer?（）
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
The major source of chemical contaminants in hydraulic fluid is （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）