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
The control mode in which the final control element is moved from one of two flexed positions to the other is known as （）.
The output volume of a positive fixed displacement pump can be changed only by （）.
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 （）.
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.
Which of the following statements is correct concerning heat transfer?（）
A salinity indicator is used to determine the （）.
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
Heavy wear in a particular area of the inner circumference of a packing ring may be caused by （）.