Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR

USCG Refrigeration & Air Conditioning (Set 9)

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Question 1 of 30

A liquid line solenoid valve controls refrigerant flow to the evaporator by what means?

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30 MCQs

#1 A liquid line solenoid valve controls refrigerant flow to the evaporator by what means? #2 How does a refrigeration solenoid valve differ from a modulating valve? #3 The thermostat controlling the operation of the solenoid valve to a refrigerated box evaporator senses what temperature? #4 What is the purpose of the low pressure cut-out switch as used as a primary controller for a refrigeration system or unit? #5 The sensing line for the low pressure cutout switch for a refrigeration system is typically connected at what location? #6 Which of the listed operations will cause an automatically controlled refrigeration compressor to restart if the system features a pump-down cycle? #7 Capacity control of a centrifugal refrigeration compressor can be accomplished by what means? #8 On a modern refrigerated container unit employing suction modulation for the purposes of capacity control and capacity limitation, what happens when the applied voltage and current draw associated with the normally open (NO) suction modulation valve located in the suction line both increase? #9 To prevent motor overload during start-up of a hermetically sealed centrifugal refrigeration system, what is true concerning the compressor suction gas variable inlet guide vanes? #10 An arrow stamped on the valve body of a water regulating valve indicates which of the following? #11 During the initial cooling down of a box temperature in a refrigeration system, which of the devices listed is used to prevent excessive gas pressure at the compressor suction for the purpose of prevention of overloading of the compressor driver? #12 The rupture disc on a low pressure centrifugal refrigeration unit is used as an over pressure protection device and is set to relieve at 15 psig and is most likely to lift when the compressor is idle? Where is the rupture disc located? #13 In a refrigeration system that is not protected by a water failure switch, if the cooling water to the condenser fails, what will be the result for protective purposes? #14 The receiver used in a refrigeration system performs what essential function? #15 Refrigeration system isolation valves are specially designed with a back-seat, as well as a front-seat. For what purpose are these valves designed in this way? #16 In a refrigeration plant, what is one vital purpose of the receiver? #17 In addition to pressure, most compound and standard pressure gauges used for refrigeration service are also provided with a scale indicating what parameter? #18 Hard drawn copper tubing is commonly used in larger refrigeration systems. What statement concerning its use is true? #19 In a large refrigeration system having more than one evaporator, a king solenoid valve should be installed in what location? #20 In a refrigeration system, what component is installed directly downstream of the thermal expansion valve? #21 Refrigeration systems using forced air circulation evaporators have a tendency to cause rapid dehydration of produce in chill boxes. Which of the following will minimize this dehydration? #22 In a dry-type direct expansion refrigeration evaporator, what is true concerning the evaporator coils? #23 Zinc plates commonly found in refrigeration systems and used as sacrificial anodes are located where? #24 If a condenser coil of an air-cooled container refrigeration system becomes dirty and requires cleaning, what would be an acceptable method of cleaning? #25 Rather than design an infinite variety of thermostatic expansion valve sizes to accommodate different capacities for heat removal, some manufacturers use a few standard valve body sizes in conjunction with what other feature? #26 Constant superheat is maintained at the evaporator coil outlet of a refrigeration system or unit by the action of what device? #27 Besides the evaporator pressure, the thermal expansion valve reacts directly to changes in what parameter? #28 What is one function of the thermal expansion valve used in a refrigeration system? #29 When a refrigeration compressor is in the 'off' cycle, the thermal expansion valve will react in what way? #30 In a refrigeration system, the pressure within the power element of a thermostatic expansion valve depends directly upon what factor?

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