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单选题
The refrigerant gas returning to the compressor should be ().
A
superheated
B
saturated
C
dense
D
flooded
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单选题The sudden reduction of pressure occurring within the crankcase of a refrigeration compressor during starting causes the ().A
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insufficient lube oil circulating through the systemB
excessive circulation of lube oil through the systemC
insufficient refrigerant in the systemD
an overworked compressor
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add refrigerant to the systemB
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adjust the float valve to the proper holding pressureD
open the hand expansion valve
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单选题Insufficient refrigerant in a refrigeration plant may result in ().A
high discharge pressureB
frosting of the crankcaseC
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单选题Refrigerant is normally sub-cooled in a refrigeration or air conditioning system condenser to ().A
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单选题If a liquid sight flow indicator in a refrigeration system shows gas bubbles in motion passing inside of the glass, there is ().A
too much refrigerant in the systemB
oil entrained in the refrigerantC
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单选题If a refrigeration compressor is running continuously without lowering the temperature in the refrigerated space, the trouble may be ().A
a shortage of compressor oilB
warm food in the refrigeratorC
excessive condenser cooling waterD
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单选题The temperature of a refrigerant gas is the highest ().A
at the compressor dischargeB
at the compressor suctionC
in the expansion valveD
in the receiver
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单选题Before charging a refrigeration unit, the refrigerant charging lines should be()A
flushed with clean refrigerant oilB
purged with the refrigerantC
washed with an ammonia and alcohol solutionD
grounded to compressor
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the relief valve should open before the high pressure cutoutB
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单选题Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?()A
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Sub-cooled vaporC
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单选题Under normal conditions, the refrigerant enters the compressor in an operating refrigeration system as a ().A
liquidB
dry saturated gasC
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单选题The compressor suction line conveys the refrigerant vapor from () to ().A
condenser;evaporatorB
evaporator;compressorC
compressor;condenserD
None of the above
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a modem diesel engine;exhaust gasesC
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increase the amount of cooling water to the condenserB
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