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

USCG Refrigeration & Air Conditioning (Set 2)

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Question 1 of 30

If an abnormally large difference is maintained between the evaporator refrigerant temperature and the box air temperature within the refrigerated compartment, what will be the result?

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30 MCQs

#1 If an abnormally large difference is maintained between the evaporator refrigerant temperature and the box air temperature within the refrigerated compartment, what will be the result? #2 What is the color of the flame produced by a halide torch when there is no halogenated refrigerant present at the location of the exploring tube? #3 To test for a suspected large refrigerant leak from an R-22 refrigeration system in an enclosed area, how should this be done? #4 Which of the following statements is correct concerning the testing of an R-22 refrigeration system for leaks in an enclosed compartment with a halide torch? #5 Moisture in a refrigeration system can cause which of the following conditions? #6 If a refrigeration system were short of refrigerant, besides an elevated box temperature, what would be an observable symptom? #7 When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, what should be done to compensate for or to correct this situation? #8 Which of the following statements describes the accepted method for testing a thermostatic expansion valve? #9 If the superheat setting of a thermostatic expansion valve is set too low, what would be the result, assuming that the system has a single evaporator? #10 If the superheat value of the thermostatic expansion valve is adjusted too high, what would be the result? #11 A small obstruction at the thermostatic expansion valve inlet will result in which of the following conditions? #12 Excessive, prolonged oil foaming in the crankcase of a refrigeration compressor can result in what condition? #13 Which of the following conditions would indicate that the liquid line strainer in a refrigeration system has become excessively restricted and requires cleaning or replacement? #14 If the compressor is heard to knock while pumping down the low side for repairs, but otherwise the compressor sounds normal; this is a possible indication of what condition? #15 Why are dehydrators usually located in the liquid line of refrigeration systems? #16 In a refrigeration system, silica gel is found in what component? #17 Standard filter/driers used in many commercial type refrigeration units may contain what type of substance? #18 Which of the devices listed will indicate whether or not a refrigeration system's dehydrator continues to be capable of removing moisture from the circulating refrigerant? #19 Capacity control of a centrifugal refrigeration compressor can be accomplished by what means? #20 A refrigeration compressor used in a multi-box refrigeration system is designed with six of its eight cylinders able to be controlled for variable load conditions. If all of the reefer boxes are currently feeding, what percentage of the total number of compressor cylinders will be loaded after start up? #21 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? #22 A box solenoid valve used in a refrigeration system should be installed in what manner? #23 In a multi-evaporator refrigeration system, a solenoid valve is installed in the liquid line prior to what device? #24 How does a refrigeration solenoid valve differ from a modulating valve? #25 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? #26 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? #27 Besides the evaporator pressure, the thermal expansion valve reacts directly to changes in what parameter? #28 The receiver used in a refrigeration system performs what essential function? #29 In a refrigeration plant, what is one vital purpose of the receiver? #30 The safety heads of most large reciprocating compressors used in refrigeration systems are held in place by what means?

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