A.protect the pump from fine soluble contaminants
B.prevent solid particles from entering the pump
C.prevent solid particles from entering the filter
D.protect the directional control valves
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A.Feed-water heater internal tube surfaces
B.Internal distillate cooler tubes
C.Flash chamber vertical surfaces
D.Distilling condenser tubes
A.Reduction of friction
B.Insulation of hot surfaces
C.Lubrication of moving parts
D.Elevation of cooler outlet temperatures
A.higher boiling temperature for a given pressure than does a pure refrigerant
B.lower boiling temperature for a given pressure than does a pure refrigerant
C.boiling pressure equal to that of a pure refrigerant at a given pressure
D.boiling point will not be affected by entrained oil
A.Degree of saturation
B.Saturation temperature
C.Superheated temperature
D.Degree of superheat
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
最新試題
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
Which of the listed pumps is NOT a positive displacement pump?（）
The general purpose of a heat exchanger is to （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
Which of the following statements is correct concerning heat transfer?（）
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
The usual symptoms of cavitation in a centrifugal pump is （）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.