A.blue
B.green
C.orange
D.purple
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A.blue
B.green
C.orange
D.purple
A.excessive condenser cooling water
B.warm food in the refrigerator
C.a shortage of refrigerant
D.s shortage of compressor oil
A.either all the way open or all the way closed
B.normally open
C.throttled depending on load
D.controlled by suction pressure
When a hydraulic vane pump is working, which of the following is in contact with the vanes?（）
(1) the rotor
(2) the internal surface of the housing
(3) the external surface of the housing
A.(1) only
B.(2) only
C.(1) and (2)
D.(1), (2) and (3)
A.Control of evaporation
B.A separate means to prevent feed-water contamination
C.Power circulating pump
D.Super-heater
最新試題
Low compressor head pressure in a refrigeration system can be caused by（）.
When the steering gear is in operation, you should （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
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?（）
The rate of heat transfer between the hot and cold fluids passing through a shell-and-tube type heat exchanger will （）.
Which of the listed pumps is NOT a positive displacement pump?（）
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
The major source of chemical contaminants in hydraulic fluid is （）.
The usual symptoms of cavitation in a centrifugal pump is （）.