Pass Benchmark: 70% • Standard: USCG NMC / 46 CFR
USCG Engine Refrigeration (Supplementary) (Set 7)
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Question 1 of 30
The set point adjustment of the device shown in the illustration is made by rotating what component? GS-RA-14 Illustration GS-RA-14: the U.S. Coast Guard has not released this illustration.
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30 MCQs #1 The set point adjustment of the device shown in the illustration is made by rotating what component? GS-RA-14
Illustration GS-RA-14: the U.S. Coast Guard has not released this illustration. #2 Which of the lettered components shown in the illustration indicates the high pressure cutout? GS-RA-12
Illustration GS-RA-12: the U.S. Coast Guard has not released this illustration. #3 When the relief valve opens on a refrigeration compressor discharge line, it discharges high pressure refrigerant vapor to what location? #4 In addition to the indicated gauge pressure, what other information is presented on the compound gauge for the hypothetical refrigerant illustrated? GS-RA-16 #5 Which lettered component, shown in the illustration, indicates the location of the receiver? GS-RA-12
Illustration GS-RA-12: the U.S. Coast Guard has not released this illustration. #6 As shown in the illustrated LP centrifugal chiller pressure maintenance system, what is its functional purpose? GS-RA-40
Illustration GS-RA-40: the U.S. Coast Guard has not released this illustration. #7 What is the purpose of the pressure transducer as shown in the illustration? GS-RA-17
Illustration GS-RA-17: the U.S. Coast Guard has not released this illustration. #8 If the valve labeled "D" in the illustration is a suction service valve, what will the port labeled "7" be connected to? GS-RA-08
Illustration GS-RA-08: the U.S. Coast Guard has not released this illustration. #9 Seawater or low temperature central fresh water is typically provided to a ship's stores refrigeration plant for what purpose? #10 Heat is removed from the refrigerant circulating through the refrigeration system, shown in the illustration, by which component? GS-RA-12
Illustration GS-RA-12: the U.S. Coast Guard has not released this illustration. #11 When checking zinc plates, or pencil Zincs in the refrigerating system condenser, what should you do? #12 What is true concerning the accumulation of air and other non-condensable gases in a refrigeration system? #13 Through which of the components shown in the illustration is flash gas formation a normal occurrence? GS-RA-25
Illustration GS-RA-25: the U.S. Coast Guard has not released this illustration. #14 In the multi-evaporator refrigeration system shown in the illustration, what is the proper name for the valve labeled "29"? GS-RA-12
Illustration GS-RA-12: the U.S. Coast Guard has not released this illustration. #15 Which of the following illustrated expansion valves is designed to maintain a constant evaporator pressure rather than a constant evaporator superheat? GS-RA-24
Illustration GS-RA-24: the U.S. Coast Guard has not released this illustration. #16 Which of the following illustrated thermal expansion valves would be appropriate to use on an evaporator coil with a 2 psi pressure drop, where externally adjustable superheat and a replaceable power element are both desired? GS-RA-06 #17 Which of the statements listed is applicable to the thermostatic expansion valve shown in the illustration? GS-RA-07
Illustration GS-RA-07: the U.S. Coast Guard has not released this illustration. #18 Of the various possible methods shown in the illustration, which is the correct method of attaching a TXV feeler bulb to a large line (7/8" and larger) with a horizontal run? Illustration GS-RA-50
Illustration GS-RA-50: the U.S. Coast Guard has not released this illustration. #19 If the evaporator coil horizontal return line of a container refrigeration system is less than 0.875" (2.21 cm) in diameter (considered small), the thermostatic expansion valve sensing bulb should be attached where on the return line? #20 Which of the listed statements describes the method used to determine the amount of superheat present in the suction gas leaving the evaporator coil? See Illustration GS-RA-16 #21 The coil temperature measured at the expansion valve sensing bulb of an operating system is 10°F. The low side pressure with the compressor running as shown on the gauge illustrated indicates 15 psig. What adjustments or changes, if any, should be made to the system? GS-RA-16 #22 Which of the following conditions will occur if the power element of the thermostatic expansion valve shown in the illustration loses its charge? GS-RA-07
Illustration GS-RA-07: the U.S. Coast Guard has not released this illustration. #23 If the needle and seat assembly is excessively eroded, the valve cage assembly can be replaced. In replacing the original valve cage assembly rated at 1/2 tons, what would be the result if the replacement valve cage was oversized at 5 tons? GS-RA-07
Illustration GS-RA-07: the U.S. Coast Guard has not released this illustration. #24 An air-cooled refrigerated container unit using R-134a as a refrigerant has a box temperature set point of -15 °F, but it is currently operating with a stable return air temperature of 0 °F. The fresh air makeup vent is closed, the unit is operating at 460 VAC/60 Hz, and the unit is in full capacity cool (modulating valve 100% open). Using the illustrated troubleshooting guide, what would be the normal range of expected discharge pressures if the ambient air temperature is 90 °F? Illustration GS-RA-52
Illustration GS-RA-52: the U.S. Coast Guard has not released this illustration. #25 Which of the conditions listed could cause excessively low refrigerant pressure at the compressor suction of a TXV controlled refrigeration system? #26 If the running suction pressure at the refrigeration compressor of a TXV controlled air- cooled refrigeration system is below normal, which of the following can be a cause? #27 While troubleshooting intermittent failures of the ship service refrigeration system you suspect the problem is with the lube oil pressure differential switch. The recommended course of action would be: #28 The compressor on the ships service refrigeration system starts up but stops after a brief period of running. Subsequent attempts to start it produce no result. What control component would you suspect? #29 If a refrigeration compressor were short cycling on the low pressure cutout switch, what is the most probable cause? #30 A refrigeration unit will tend to short cycle when operating under what conditions?
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