A.pump must always be primed
B.volute must impart a radial and rotary motion of the water suction side
C.connection must guide the liquid to the lantern rings
D.stuffing box should not be allowed any water leakage
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A.change in impeller diameter
B.square of the impeller diameter
C.cube of the impeller diameter
D.impeller efficiency for large changes in the size of the impeller
A.the suction pressure to decrease
B.the suction temperature to increase
C.increased ice formation on the evaporator coil
D.excessive short cycling of the compressor
A.Lobe
B.Screw
C.Radial piston
D.Volute
A.They are particularly suited for pumping high viscosity fluids
B.They are started with the discharge valve opened
C.The flow of liquid is developed by imparting energy due to the rotation of an impeller
D.They are always mounted in a horizontal position
A.refrigerant pressure in the evaporator
B.cooling water temperature to the condenser
C.heat load in the refrigerator compartment
D.solenoid valve in the liquid line
最新試題
Which of the following statements is correct concerning heat transfer?（）
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
When the steering gear is in operation, you should （）.
A pressure drop through the refrigerant liquid line may cause （）.
If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.