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单选题
When you adjust a thermostatic expansion valve, （）.
A
refrigerant must be bled off the sensing line before adjustments are made
B
all refrigerant must be pumped into the receiver before adjustments are made
C
time must be allowed for conditions to stabilize in the evaporator before further adjustments are made
D
all refrigerant must be routed through the dehydrator while changing the superheat setting
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更多 “单选题When you adjust a thermostatic expansion valve, （）.A refrigerant must be bled off the sensing line before adjustments are madeB all refrigerant must be pumped into the receiver before adjustments are madeC time must be allowed for conditions to stabilize in the evaporator before further adjustments are madeD all refrigerant must be routed through the dehydrator while changing the superheat setting” 相关考题
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When replacing a thermostatic expansion valve sensing bulb, it is necessary toA.apply a light film of oil to increase heat transferB.apply a light film of oil to prevent oxidationC.apply a heavy coating of grease to function as a heat sinkD.carefully coat the device with silicone sealant to reduce the effects of convective cooling
考题
A thermostatic expansion valve is properly controlling evaporator superheat. Adjusting this valve to lower the superheat will result in a/anA.evaporator pressure decreaseB.evaporator coil over-feedC.evaporator capacity increaseD.expansion valve diaphragm rupture
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单选题During working, thermostatic expansion valve should be （）.A
either all the way open or all the way closedB
normally fully openC
throttled depending on loadD
controlled by liquefied pressure
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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
考题
单选题A three-way thermostatic control valve regulates the diesel engine cooling water temperature by passing a portion of the water （）.A
around the engineB
around the coolerC
to the expansion tankD
overboard
考题
单选题If the operating element of a thermostatic valve installed in a diesel engine cooling system malfunctions, it may result in （）A
a low level in the engine expansion tankB
excessively high coolant pressureC
improper temperaturesD
malfunctioning of the jacket water heater
考题
单选题A ruptured diaphragm in a thermostatic expansion valve will cause the valve to （）.A
openB
closeC
remain in its positionD
flood the evaporator with refrigerant
考题
单选题The scale trap is located between the （）A
king valve and the expansion valveB
solenoid valve and expansion valveC
evaporator and receiverD
compressor and evaporator
考题
单选题What is the function of thermostatic expansion valve in a compression refrigeration system?（）A
nonexistentB
for controlling pressureC
for controlling superheatD
for controlling the solenoid valve
考题
单选题Thermostatic expansion valve are （）.A
either all the way open or all the way closedB
normally openC
throttled depending on loadD
controlled by suction pressure
考题
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
考题
单选题Which of the following statements is correct concerning a typical shipboard multi-coil refrigeration system?（）A
The liquid receiver functions to collect and remove non-condensable gasesB
A thermostatic expansion valve is used to control refrigerated space temperatureC
Refrigerant temperature in an evaporator is directly related to refrigerant pressureD
Dehydrators must be used continuously in a refrigeration system
考题
单选题A thermostatic expansion valve is properly controlling evaporator superheatAdjusting this valve to lower the superheat will result in a/an （）.A
evaporator pressure decreaseB
evaporator coil over-feedC
evaporator capacity increaseD
expansion valve diaphragm rupture
考题
单选题When the heat load begins to increase, the needle valve of an expansion valve will（）A
move in an opening directionB
move in a closing directionC
either open or closeD
not move at all
考题
单选题A solenoid valve used in a refrigeration system should be installed （）.A
with the axis of the solenoid horizontal, sensing temperature of the box, and upstream of the thermal expansion valveB
upright, sensing temperature of the box, and upstream of the thermal expansion valveC
upright, sensing temperature of the box, and downstream of the thermal expansion valveD
upright, sensing heat of the tail coil, and upstream of the thermal expansion valve
考题
单选题A cracked diaphragm in a thermostatic expansion valve will cause the valve to （）.A
return to a neutral positionB
flood the evaporatorC
openD
close
考题
单选题Which of the listed statements is correct concerning refrigeration systems?（）A
Dehydrators must be used continuously in a refrigeration systemB
A 25 ton refrigeration system has the same cooling effect as melting 25 tons of ice in 24 hoursC
A thermostatic expansion valve is used to control refrigerated space temperatureD
The liquid receiver functions to collect and remove non- condensable gases
考题
单选题The thermostatic valve has a throttling action, that is to say the valve can（）A
stop the refrigerant from flowingB
force the refrigerant to flowC
cause the refrigerant pressure to riseD
cause the refrigerant pressure to fall
考题
单选题Which of the listed statements is a characteristic of the liquid charged power element used with thermostatic expansion valves?（）A
At the designed operating temperature, the liquid refrigerant charge has changed to a vaporB
The liquid refrigerant tends to collect at the bellows or diaphragm and reduces the valve sensitivityC
The sensing bulb is empty of liquid refrigerant charge at the designed operating temperatureD
The sensing bulb is never emptied of liquid refrigerant under normal operating conditions
考题
单选题When the refrigeration demand is small,（）A
the expansion valve will move toward the wide open positionB
the expansion valve will move toward the closing positionC
the feeler bulb will conveys the high temperatureD
the superheat degree will raise
考题
单选题Thermostatic expansion valves can be adjusted for （）.A
suction pressure onlyB
head pressure onlyC
superheat onlyD
suction pressure and box temperature
考题
单选题To correct the condition of slugging and flooding back in a refrigeration system, it may be necessary to （）.A
re-adjust the discharge pressureB
clean the expansion valve screenC
add refrigerantD
adjust the expansion valve
考题
单选题The low pressure side of a refrigeration system is considered to exist from the （）.A
expansion valve to the compressorB
receiver to the expansion coilC
expansion valve to the evaporatorD
condenser to the expansion valve
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
考题
单选题The jacket water temperature in a diesel engine closed freshwater cooling system is normally controlled by （）A
regulating the level of corrosion inhibitor in the primary cooling systemB
the level of the freshwater expansion tankC
varying the engine load to meet temperature requirementsD
the operation of the thermostatic valve
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