A.pump bearings in poor condition
B.excessively worn actuator-piston packing
C.broken directional control valve centering springs
D.low hydraulic oil viscosity
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A.a spring
B.an electromagnet
C.the force of gravity
D.refrigerant pressure
A.viscosity will decrease
B.volume will increase
C.volume will decrease
D.pour point will be reduced
A.a shortage of refrigerant
B.the compressor running continuously
C.liquid refrigerant returning to the compressor
D.the compressor short cycling on the high pressure cutout
A.evaporation is accomplished in a vacuum
B.due to the higher temperature of the incoming feed
C.due to the latent heat of evaporation principle
D.evaporation in a submerged medium produces more distillate
A.the bow
B.the stem
C.the port side
D.the starboard side
最新試題
A pressure drop through the refrigerant liquid line may cause （）.
The major source of chemical contaminants in hydraulic fluid is （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
The general purpose of a heat exchanger is to （）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.
The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）
One cause of high head pressure occurring in a refrigeration system can be （）.
If the thermal bulb of an expansion valve is incorrectly placed at the center of the coil instead of the end, it will （）.
The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.