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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 valve
B
upright, sensing temperature of the box, and upstream of the thermal expansion valve
C
upright, sensing temperature of the box, and downstream of the thermal expansion valve
D
upright, sensing heat of the tail coil, and upstream of the thermal expansion valve
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更多 “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” 相关考题
考题
If the head pressure of a reciprocating refrigeration compressor is excessiveA.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 the discharging valve
考题
The expansion valve used in a refrigeration system regulates theA.superheat of the gas leaving the compressorB.back pressure in the evaporatorC.temperature in the refrigerated spaceD.degree of superheat of the gas leaving the evaporator
考题
The refrigeration system low pressure cutout switch is actuated by______.A.an electric system managerB.a sensing bulb at the tail coil of the evaporatorC.pressure changes in the suction lineD.failure of the king solenoid valve
考题
材料：At 1800，the hydraulic steering system failed once again．The master realized he would require shore assistance to rectify the problem，and diverted towards Portland using the thruster to steer by．The weather at this time was south-south-west force 5．At about three hours later，the thruster drive unit failed due to a leaking fuel injector pipe on the power unit．This was replaced using the spare carried on board．Immediately following the engine restart，an adjacent fuel line failed causing shut down of the unit．With no fuel line spares available，the thruster power unit could not be used．The failure of this unit，and that of the main hydraulic steering system，left the vessel without any steering capability．At 2155，with the weather deteriorating and no steering，the master contacted the Portland Coastguard and a“Pan pan”message was broadcast．A tow to Portland Harbor was arranged and she arrived alongside at 0240 the following morning．The subsequent investigation found that the main hydraulic steering system failure was due to a seized shuttle valve in the main hydraulic solenoid valve block．The solenoid valve had been recently overhauled．It was thought that the“O”rings fitted to the shuttle valve were of either the wrong type or a defective one．The valve had seized in such a position that hydraulic pressure by-passed the system preventing use of the hand steering．问题：The vessel was steered by thruster because ________ failed．A.the hydraulic steering systemB.the solenoid valveC.the thruster driving unitD.the hand steeringThe time that the thruster drive unit failed was ________ hrs．A.1800B.2100C.2155D.0240When the hydraulic steering system failed，________．A.the hand steering system could still be usedB.the auto steering system could still be usedC.both hand and auto steering system were out of useD.neither and steering system nor auto steering system was out of useThe real reason that caused the hydraulic steering system to fail was that ________．A.no fuel line spare were availableB.the weather was deterioratingC.the“O”rings fitted to the shuttle valve were of either the wrong type or a defective oneD.the thruster power unit failed请帮忙给出每个问题的正确答案和分析，谢谢！
考题
单选题The refrigeration system low pressure cutout switch is actuated by （）.A
an electric system managerB
a sensing bulb at the tail coil of the evaporatorC
pressure changes in the suction lineD
failure of the king solenoid valve
考题
单选题When operating the air supply system in a covered lifeboat the（）.A
fuel supply valve should be closedB
hatches，doors，and oar ports should be closedC
air cylinder shut-off valve should be closedD
engine should be shut off
考题
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When it is necessary to open a refrigeration system for repairs and the system will be open for more than a few minutes, the open ends of the system should be （）.A
dehydratedB
purgedC
pluggedD
evacuated
考题
单选题Which of the following statements concerning butterfly valves is correct?（）A
Special tools are required for lapping or grindingB
It is impossible to throttle flow with a butterfly valveC
To close the valve, it is only necessary to turn the handle a quarter of a turnD
The butterfly valve should never be used in a freshwater system
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
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In a refrigeration system, foaming of the crankcase oil may cause the （）.A
expansion valve to overfeedB
compressor to knockC
water regulating valve to failD
crankcase drains to plug
考题
单选题Which of the listed items should be secured before performing any maintenance on a solenoid operated air start valve?（）A
Electric power and starting airB
Lube oil standby pump and control airC
Hydraulic switch and engage jacking gearD
Motor drain and pneumatic control system power
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Crankcase sweating in a refrigeration system is caused by （）.A
a stuck solenoid valveB
a shortage of refrigerantC
too much oil in circulationD
too much superheat
考题
单选题Moisture in a refrigeration system can cause （）.A
freezing the expansion valve closedB
corrosion of system pipingC
improper temperature regulationD
all of the above
考题
单选题To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the （）A
suction service valve as a vaporB
suction service valve as a liquidC
discharge service valve as a vaporD
charging valve as a liquid
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In a refrigeration system, if the cooling water to the condenser fails, the（）.A
box temperature solenoid valve will closeB
expansion valve will closeC
compressor will shutdownD
king valve will open
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The solenoid valve can be typed as a（）A
thermal valveB
magnetic stop valveC
bellows valveD
bimetallic valve
考题
单选题A pressure drop in the liquid line of a refrigeration system may cause（）A
the solenoid valve to seizeB
the compressor to huntC
flash gas to form in the liquid lineD
the expansion valve to freeze open
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