A.blue
B.green
C.orange
D.purple
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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
A.check and regulate the water level
B.close the air cock once fires are lit
C.blowdown the gage glass
D.crack the steam stop to assure protective steam flow
最新試題
The rate of heat transfer from a hot region to a cold region is affected most by the （）.
An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.
Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）
If the relief valve on the discharge side of a hydraulic pump lifts, the cause could be （）.
A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by （）.
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 problems listed would came the discharge temperature of an R-12 refrigeration compressor to increase?（）
If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.
On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.
A salinity indicator is used to determine the （）.