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单选题
Air entering an air-cooled refrigeration system is indicated by （）.
A
frosting of the liquid line
B
higher than normal head pressure
C
a clear sight glass
D
abnormally cold reefer boxes
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insufficient condenser cooling waterB
excessive condenser cooling waterC
air in the refrigeration systemD
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an improper rudder responseB
hammering noises in the equipment or transmission linesC
popping or sputtering noisesD
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考题
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the pump over-speedingB
an improper rudder responseC
bubbles in the sight glassD
ram relief valves lifting
考题
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the condenser is completely shutdown first
考题
单选题Refrigerant is normally sub-cooled in a refrigeration or air conditioning system condenser to （）.A
maintain adequate coil back pressureB
prohibit flashing in the liquid lineC
reduce refrigerant volume in the systemD
reduce compressor discharge line loading
考题
单选题Air or noncondensable gas is removed from a refrigeration system by a （）A
separating chamberB
system of bafflesC
purge valveD
vacuum reducing valve
考题
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the steering pumps overspeedingB
a jammed open relief valeC
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考题
单选题The presence of air in the condenser of a refrigeration system will （） the condensing pressure.A
increaseB
reduceC
maintain constantD
None of the above is true
考题
单选题（）are supplied by main switchboard directly.A
Suez Canal searchlight, air compressor and air conditioning compressorB
Air compressor, boiler blower and refrigeration plantC
Boiler blower, Suez Canal searchlight and refrigeration plantD
Suez canal searchlight, air compressor and boiler blower
考题
单选题In the refrigeration system, a shortage of refrigerant is indicated by （）.A
the compressor short cycling on high pressure cut out switchB
high suction pressureC
high head pressureD
bubbles in the sight glass
考题
单选题A liquid sight flow indicator in a refrigeration system is examined and gas bubbles are noted in motion with the fluid flowThis means （）.A
the system is fully chargedB
there is air leaking in from the condenserC
ice crystals are forming in the refrigerantD
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单选题What is NOT a function of the air supply of a covered lifeboat?（）A
Provides air for engine combustionB
Pressurizes water spray systemC
Provides air for passenger respirationD
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单选题Which of the listed operating conditions would have the greatest effect on the volumetric efficiency of an operating reciprocating air compressor?（）A
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The temperature of the air entering the compressorC
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loss of flow in the fuel systemB
loss of pressure in the air systemC
loss of flow in the lubricating systemD
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考题
单选题An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.A
oil foaming in the compressorB
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higher than normal discharge pressure with a normal box temperatureD
the compressor to run continuously
考题
单选题The compressor in an air-cooled condensing refrigeration system is short cycling on the high pressure cutout switch（）A
system is overcharged with refrigerantB
system is low on refrigerantC
discharge valves are leaking excessivelyD
discharge valves are leaking slightly
考题
单选题Refrigerant entering the compressor of a refrigeration system should be in which of the following conditions?（）A
Sub-cooled liquidB
Sub-cooled vaporC
Superheated vaporD
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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
考题
单选题While troubleshooting a refrigeration system for low head pressure, liquid refrigerant flooding back from the evaporator is determined to be the causeIt may be necessary to （）.A
change the expansion valve adjustmentB
readjust the water regulating valve to increase the flow of waterC
purge air from the condenserD
clean the waterside of the condenser
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单选题A purge recovery system is used in a centrifugal air conditioning or refrigeration system to （）A
purge lube oil from the liquid refrigerantB
recover water purged from the systemC
separate foul gases from the receiverD
purge non-condensable gases without losing refrigerant
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单选题If an air compressor is used to supply air primarily to the combustion control system and other pneumatic controllers, the entire system is known as the （）.A
control air systemB
forced draft air systemC
supply air systemD
ships service air system
考题
单选题You are in a tropical port. The refrigeration machinery on a container loaded with air-cooled fruit fails. It cannot be repaired for 18 to 24 hours. Which step should you take to reduce the temperature rise and spoilage of the fruit?（）.A
Discharge a cylinder of nitrogen into the containerB
Shade the container and periodically hose it downC
Seal any ventilation openings and add dry iceD
Spread ice over the top layer and in any voids within the container
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