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单选题
Crankcase sweating in a refrigeration system is caused by （）.
A
a stuck solenoid valve
B
a shortage of refrigerant
C
too much oil in circulation
D
too much superheat
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Sweating of the refrigeration system compressor crankcase is caused by_______ .A.too much superheatB.insufficient superheatC.suction pressure too lowD.excessive refrigerant returning to the compressor
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insufficient condenser cooling waterB
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单选题A refrigeration system compressor crankcase is sweating or unusually coldThis is an indication of（）.A
a shortage of refrigerant in the systemB
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单选题Refrigeration system compressor crankcase sweating is an indication of （）.A
insufficient lube oil circulating through the systemB
excessive circulation of lube oil through the systemC
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单选题If a refrigeration system compressor crankcase is sweating, you should （）.A
add refrigerant to the systemB
adjust the thermal expansion valve to the proper settingC
adjust the float valve to the proper holding pressureD
open the hand expansion valve
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单选题An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by （）.A
restriction in refrigerant pipingB
air and non-condensable gases in the condenserC
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flooding back of liquid refrigerant from the evaporator
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单选题Excessive oil foaming in the crankcase of a refrigeration compressor can result in （）.A
overheated compressor bearingsB
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carbon deposits on the compressor piston ringsD
wax crystals forming in the lubricant
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compressorB
condenserC
receiverD
evaporator
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单选题When it is necessary to open a refrigeration system for repairs and the system will be open for more than a few minutes, the open ends of the system should be （）.A
dehydratedB
purgedC
pluggedD
evacuated
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单选题The function of （） in a refrigeration plant using Freon is to move moisture from all refrigeration system.A
filterB
filter drierC
heat exchangerD
air cooler
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单选题If a refrigeration crankcase compressor were short cycling on the low pressure cutout switch, the cause might be that the （）.A
system was overcharged with refrigerantB
system was low on refrigerantC
suction valves were leaking slightlyD
relief valve was leaking slightly
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单选题In a refrigeration system, foaming of the crankcase oil may cause the （）.A
expansion valve to overfeedB
compressor to knockC
water regulating valve to failD
crankcase drains to plug
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单选题Zinc rods are installed in the refrigeration system （）.A
liquid strainerB
liquid receiverC
saltwater condenserD
evaporator
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单选题Noise in a refrigeration compressor can be caused by （）.A
worn bearings and piston pinsB
slugging due to flooding backC
too much oil in circulationD
All of the above
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单选题Diesel engine ‘blow-by’ into the crankcase is caused by excessive ring（）A
back clearanceB
side clearanceC
gap clearanceD
taper clearance
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单选题If the refrigeration compressor crankcase is sweating, the cause may be due to （）.A
a shortage of refrigerantB
the compressor running continuouslyC
liquid refrigerant returning to the compressorD
the compressor short cycling on the high pressure cutout
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单选题Foaming of the oil in a refrigeration compressor crankcase is caused by （）.A
refrigerant boiling out of solution from the lube oilB
liquid refrigerant flooding the compressor and systemC
lube oil viscosity being reduced by refrigerant dilutionD
compressor suction pressure suddenly increasing
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单选题Refrigerant is circulated through a refrigeration system by the （）.A
compressorB
condenserC
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单选题Excessive oil foaming in the crankcase of a refrigeration compressor at start up can cause（）.A
compressor damage from improper lubricationB
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increased viscosity in the lubricantD
carbon deposit on the compressor suction valves
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单选题In the （） refrigeration compressor one end of the crank shaft extends through the crankcase house for connection, via a coupling or pulley, to an external drive motor.A
open-typeB
hermeticC
semi-hermeticD
all the above
考题
单选题The accumulation of air and other non-condensable gases in a refrigeration system will （）.A
cause a loss of the liquid sealB
create a vapor lock in the liquid receiverC
collect in the condenserD
cause foaming of the oil in the crankcase
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单选题Moisture in a refrigeration system can cause （）.A
freezing the expansion valve closedB
corrosion of system pipingC
improper temperature regulationD
all of the above
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单选题A diesel engine crankcase ventilation system （）A
prevents spark generationB
removes combustible gasesC
determines the level of combustible gasesD
provides inert gas generation in crankcase
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单选题Sweating of the refrigeration system compressor crankcase is caused by （）.A
too much superheatB
insufficient superheatC
suction pressure too lowD
excessive refrigerant returning to the compressor
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单选题Which of the listed refrigeration system components keeps the refrigerant circulating through the system?（）A
Expansion valveB
CondenserC
EvaporatorD
Compressor
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单选题Excessive oil foaming in the crankcase of a refrigeration compressor is most likely to occur（） when the compressor.A
has continuously for a long periodB
suction pressure is below normalC
oil level is below normalD
starts after a long idle period
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