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If the suction pressure for an operating refrigeration compressor is below normal, the cause may be ______.
A.an excess of liquid refrigerant
B.the expansion valve overfeeding
C.a fouled compressor suction strainer
D.the compressor short cycling
参考答案
更多 “ If the suction pressure for an operating refrigeration compressor is below normal, the cause may be ______.A.an excess of liquid refrigerantB.the expansion valve overfeedingC.a fouled compressor suction strainerD.the compressor short cycling ” 相关考题
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When adding oil to a refrigeration system, precautions must be taken to ensure thatA.the compressor suction pressure is not too highB.all air is purged from the pump and charging fittingsC.the high pressure cutout switch is held open to prevent accidental startingD.the condenser is completely shutdown first
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Excessive oil foaming in the crankcase of a refrigeration compressor is most likely to occur when the compressorA.has run 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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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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If the suction pressure at the refrigeration compressor is below normal, the cause can beA.refrigerant overchargeB.overfeeding by the expansion valveC.a restricted suction strainerD.due to short cycling of the compress
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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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The sensing line for the low pressure cutout switch to a refrigeration system is located ______.A.in the chill box(冰箱)B.before the receiverC.on the suction side of the compressorD.on the discharge side of the compressor
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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
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Excessive circulation of the lubricating oil with the refrigerant in a refrigeration system will cause______.A.carbon deposits on the compressor suction valvesB.the evaporator temperature to increaseC.rapid corrosion of the thermal expansion valveD.no operating problems
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单选题When liquid reaches the compressor of a refrigeration system through the suction line, the condition is called （）.A
flooding backB
superheatingC
overflowingD
recycling
考题
单选题When adding oil to a refrigeration system, precautions must be taken to ensure that （）.A
the compressor suction pressure is not too highB
all air is purged from the pump and charging fittingsC
the high pressure cutout switch is held open to prevent accidental startingD
the condenser is completely shutdown first
考题
单选题Which of the listed operations will cause an automatically controlled refrigeration compressor to restart?（）A
Closing of the solenoid valveB
Closing of the expansion valveC
An increase in the suction pressureD
Decreasing the suction pressure
考题
单选题Insufficient refrigerant in a refrigeration plant may result in （）.A
high discharge pressureB
frosting of the crankcaseC
high temperature of the overboard waterD
low suction pressure of compressor
考题
单选题The only means of removing the latent heat of condensation from a refrigerant in the normal refrigeration cycle is by （）.A
passing it through the expansion valveB
condensing refrigerant in the system condenserC
passing the gaseous refrigerant through the heat interchanger on the suction side of the compressorD
maintaining a high pressure on the systems receiver
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
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
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单选题An excessive charge of refrigerant in an air-cooled refrigeration system can cause （）.A
oil foaming in the compressorB
higher than normal suction and discharge pressures with a higher box temperatureC
higher than normal discharge pressure with a normal box temperatureD
the compressor to run continuously
考题
单选题The purpose of the refrigeration system low pressure cutout switch is to （）A
protect the compressor from liquid flood backB
protect the compressor from low discharge pressureC
start and stop the compressor upon system demandD
start the compressor after a drop in the evaporator pressure
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
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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
wet saturated gasD
superheated vapor
考题
单选题The sensing line for the low pressure cutout switch to a refrigeration system is located （）.A
in the chill boxB
before the receiverC
on the suction side of the compressorD
on the discharge side of the compressor
考题
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
考题
单选题The purpose of the low pressure cut-out switch is to （）.A
maintain liquid refrigerant at the suction of the compressorB
maintain a preset suction pressure to the compressorC
start and stop the compressor at preset operating pressuresD
operate at minimum efficiency
考题
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
考题
单选题When a refrigeration compressor motor fails to start, the FIRST thing that should be checked for is a （）.A
loose expansion valve control bulbB
low differential setting on the H-PcutoutC
blown fuse in the motor circuitD
faulty suction pressure regulator
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单选题Excessive circulation of the lubricating oil with the refrigerant in a refrigeration system will cause （）.A
carbon deposits on the compressor suction valvesB
the evaporator temperature to increaseC
rapid corrosion of the thermal expansion valveD
no operating problems
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