A.has continuously for a long period
B.suction pressure is below normal
C.oil level is below normal
D.starts after a long idle period
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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
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
最新試題
The general purpose of a heat exchanger is to （）.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
Which of the problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
Thermostatic expansion valves can be adjusted for （）.
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
A pressure drop through the refrigerant liquid line may cause （）.
One cause of high head pressure occurring in a refrigeration system can be （）.
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 （）.