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
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
The major source of chemical contaminants in hydraulic fluid is （）.
A salinity indicator is used to determine the （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The general purpose of a heat exchanger is to （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
Pitting in the suction areas of a centrifugal pump bronze impeller is usually caused by （）.