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单选题
When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will（）.
A
always be wide open when the compressor restarts
B
continue to operate as if the system were in operation
C
remain open until evaporator pressure equalizes, then close until the compressor restarts
D
always be completely closed until the compressor restarts
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更多 “单选题When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will（）.A always be wide open when the compressor restartsB continue to operate as if the system were in operationC remain open until evaporator pressure equalizes, then close until the compressor restartsD always be completely closed until the compressor restarts” 相关考题
考题
If the refrigeration compressor crankcase is sweating, the cause may be due toA.a shortage of refrigerantB.the compressor running continuouslyC.liquid refrigerant returning to the compressorD.the compressor short cycling on the high pressure cutout
考题
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
考题
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
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
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
考题
单选题In a direct expansion type multi-box refrigeration system, the compressor is set up to cycle on and off by the（）A
pressurestatB
high pressure cutoutC
solenoid valveD
low pressure cutout switch
考题
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Excessive oil foaming in the crankcase of a refrigeration compressor can result in （）.A
overheated compressor bearingsB
excess lube oil viscosityC
carbon deposits on the compressor piston ringsD
wax crystals forming in the lubricant
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
a shortage of refrigerant
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
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
考题
单选题A refrigeration unit will tend to short cycle when operating （）.A
under heavy loadsB
during hot gas defrostC
under light loadsD
during starting conditions
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If the capacity of the refrigeration compressor is too large, the saturation temperature will （）.A
riseB
fallC
be maintained constantD
None of the above
考题
单选题In the refrigeration compressor the temperature of the vapor is （） by compression.A
raisedB
risenC
reducedD
maintained constant
考题
单选题It should be ensured that only （） vapor is handled by the refrigeration compressor.A
humidityB
dryC
steamD
oil
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Diesel engine valve springs function to （）A
hold the valves openB
keep the valves off their seats until the exhaust stroke is completedC
close the valvesD
open inlet valves when the air injection cycle begins
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Which of the listed components is considered to separate the high pressure side of a refrigeration cycle from the low pressure side of the cycle?（）A
The condenser and the expansion valveB
The king valve and the solenoid valveC
The compressor and the expansion valveD
The condenser and the solenoid valve
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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