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

USCG Refrigeration & Air Conditioning (Set 10)

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Question 1 of 30

In a refrigeration system, the bulb for the thermal expansion valve is always located where?

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30 MCQs

#1 In a refrigeration system, the bulb for the thermal expansion valve is always located where? #2 Concerning the proper installation of the sensing bulb of a thermal expansion valve that is attached to the evaporator tail coil on a horizontal run, what statement is true? #3 When the sensing bulb of a thermostatic expansion valve is charged with a fluid different from the charge used in the system, what name of the charge is associated with the power element? #4 A typical shipboard domestic multi-box refrigeration system operates with one compressor and condenser. What is the purpose of the sensing line connected to the thermal bulb at the evaporator coil outlet? #5 Refrigerant flow through a thermostatic expansion valve is greatest under what conditions? #6 In a vapor compression type refrigeration cycle, the refrigerant temperature decreases the most when passing through which system component? #7 The thermostatic expansion valve in a refrigeration system further opens when the diaphragm flexes downward. With all other conditions being the same, what single condition causes this? #8 In refrigeration systems with multiple evaporators, the metering of refrigerant to each refrigerated space evaporator is accomplished by what device? #9 A thermostatic expansion valve is properly controlling evaporator superheat. Adjusting this valve to lower the evaporator superheat setting will result in which of the following? #10 When replacing a thermostatic expansion valve power element, what is true concerning the thermal bulb? #11 Expansion valve maintenance should include which of the following procedures? #12 Which statement about calibrating a newly installed thermostatic expansion valve is correct? #13 Which of the installation steps listed is necessary for the proper operation of the thermostatic expansion valve? #14 What maintenance may be carried out on a thermostatic expansion valve? #15 When a thermostatic expansion valve is installed in a refrigerated container unit, the sensing bulb almost always requires insulation. Why is this so? #16 Which of the following statements describes the accepted method for testing a thermostatic expansion valve? #17 Concerning the proper installation of the sensing bulb of a thermal expansion valve that is attached to the evaporator tail coil on a horizontal run, which statement is true? #18 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? #19 If the superheat value of the thermostatic expansion valve is adjusted too high, what would be the result? #20 A small obstruction at the thermostatic expansion valve inlet will result in which of the following conditions? #21 An obstructed expansion valve may be indicated by an incompletely cooled evaporator and what other symptom? #22 Vapor bubbles present in the liquid upon arrival to the thermal expansion valve in a refrigeration system may cause erosion of the expansion valve's needle and seat. This, in turn, could cause what condition? #23 Moisture entering a typical refrigeration system will most likely produce what effect? #24 Concerning the operation of refrigeration systems, frosting or sweating of a liquid line is usually indicative of what condition? #25 If increasing the cooling water flow to a refrigeration condenser fails to lower the condenser pressure, the probable cause may be due to what condition? #26 In an operating, water-cooled, multi-box refrigeration system, both low discharge and high suction pressures are being simultaneously experienced. The probable cause for this condition is which of the following? #27 High suction pressure accompanied by low suction temperature to a refrigeration system compressor is caused by which of the following? #28 Low compressor head pressure in a refrigeration system can be caused by which of the following? #29 During tests to discover why a refrigeration compressor is running continuously, it is determined that the refrigerated space temperature is slightly above normal without ever reaching the desired minimum temperature. Suction and discharge pressures are normal for the corresponding box temperature. In this situation, what should you suspect? #30 When a refrigeration compressor motor fails to start, the FIRST thing that should be checked for is what?

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