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单选题
One cause of high head pressure occurring in a refrigeration system can be （）.
A
insufficient cooling water flow to the condenser
B
a low refrigerant charge in the system
C
the liquid valve is open too much
D
high evaporator superheat
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Low compressor head pressure in a refrigeration system can be caused by ___.A.insufficient condenser cooling waterB.excessive condenser cooling waterC.air in the refrigeration systemD.excessive refrigerant in the system
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In the refrigeration system, a shortage of refrigerant is indicated byA.the compressor short cycling on high pressure cut out switchB.high suction pressureC.high head pressureD.bubbles in the sight glass
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Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?A.A shortage of liquid refrigerant.B.Excessive frost on the evaporator.C.Excessive condenser cooling water.D.Insufficient condenser cooling water flow.
考题
单选题Low compressor head pressure in a refrigeration system can be caused by（）.A
insufficient condenser cooling waterB
excessive condenser cooling waterC
air in the refrigeration systemD
excessive refrigerant in the system
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单选题Which of the following problems represent one possible cause of high lube oil consumption in a four stroke diesel engine?（）A
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单选题In a compression refrigeration plant the refrigerant is under low pressure in the （） and under high pressure in the （）.A
compressor；condenserB
condenser；evaporatorC
throttle valve；evaporatorD
evaporator；condenser
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单选题If a refrigeration compressor is short cycling on high head pressure, you should （）.A
purge the condenser if the waterside is dirtyB
check for proper water flow through the condenserC
increase the high pressure cutout settingD
reduce the cooling water flow
考题
单选题If a refrigeration compressor were short cycling on the low pressure cutout switch, the probable cause for this might be the （）.A
system was overcharged with refrigerantB
high pressure switch was improperly adjustedC
expansion valve strainers were fouledD
suction valves were leaking slightly
考题
单选题Which of the following problems could cause the high pressure cutout switch to shut down the compressor in a refrigeration system?（）A
A shortage of liquid refrigerantB
Excessive frost on the evaporatorC
Excessive condenser cooling waterD
Insufficient condenser cooling water flow
考题
单选题If the discharge valves on a refrigeration compressor are leaking badly, the compressor should （）.A
run continuouslyB
not startC
have high discharge pressureD
short cycle on the high pressure switch
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单选题The refrigeration compressor in a water cooled refrigeration system is short cycling on the high pressure cutout switch， One reason for this could be the （）.A
system is low on refrigerantB
high pressure cutout switch is improperly adjustedC
discharge valves are leaking slightlyD
discharge valves are leaking excessively
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If the head pressure of a reciprocating refrigeration compressor is excessive, （）.A
the relief valve should open before the high pressure cutoutB
the relief valve should open and allow the excess refrigerant to flow to the receiverC
the high pressure cutout switch should operate before the relief valve opensD
you should close in on the suction valve
考题
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Which cause of following will not lead to refrigeration plant short-cycle?（）A
lack of refrigerantB
refrigerant with much waterC
set defectively low pressure relayD
no cooling water
考题
单选题If the head pressure is too high,（）A
the relief valve should open before the high-pressure cutoutB
the relief valve should open and let excess refrigerant go to receiverC
the high-pressure cutout switch should operate before the relief valve opensD
close in on the suction valve
考题
单选题What separate the high pressure side from the low pressure side in a refrigeration system?（）A
Condenser and thermal expansion valveB
King and solenoid valvesC
Compressor and thermal expansion valveD
Condenser and solenoid valve
考题
单选题If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.A
refrigerant overchargeB
overfeeding by the expansion valveC
a restricted suction strainerD
due to short cycling of the compressor
考题
单选题In a compression refrigeration plant the hot, high pressure refrigerant gas is cooled by the sea water and becomes liquid in the （）.A
compressorB
condenserC
throttle valveD
evaporator
考题
单选题Which of the following may cause that the compressor cuts off on high pressure cutout in a refrigeration plant? （） (1) faulty condensing (2) too few refrigerant (3) high discharge pressureA
any of (1) and (3)B
any of (1) and (2)C
any of (2) and (3)D
any of (1), (2) and (3)
考题
单选题An increase in the heat load to a refrigeration system will cause （）.A
the suction pressure to decreaseB
the suction temperature to increaseC
increased ice formation on the evaporator coilD
excessive short cycling of the compressor
考题
单选题When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.A
increase the amount of cooling water to the condenserB
decrease the amount of cooling water to the condenserC
add more refrigerant to the systemD
remove some refrigerant from the system
考题
单选题In a refrigeration system, which of the following statements describes the actions occurring when a solenoid valves, used in conjunction with an unloader head is energized?（）A
The solenoid valves directs high pressure gas to the valve lifting device raising the suction valve off its seat and causing one specific cylinder to become unloadedB
The solenoid valves directs high pressure gas to the underside of the unloading piston, causing it to rise and allowing the recirculating ports to be openedC
When the solenoid valve becomes energized, the valve ports become closed, allowing discharge pressure to build up above the piston, shifting it and causing it to unloadD
The solenoid valve allows the refrigerant to pass from the suction chamber to the top of the unloader piston, causing the piston to lift and unload the cylinder
考题
单选题If a compressor runs continuously, the cause might be a（）A
defective thermal bulbB
clogged scale trapC
stuck high-pressure switchD
stuck low-pressure switch
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