Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Refrigeration & Air Conditioning (Set 20)
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Question 1 of 30
The low-pressure cutout switch settings vary with the refrigerant used and the temperature application. If the low-pressure cutout switch for a particular application is set with a cut-in pressure of 5 psig, what would be the cutout pressure if the differential is 7.5 psig?
Browse Questions in Set 20
30 MCQs #1 The low-pressure cutout switch settings vary with the refrigerant used and the temperature application. If the low-pressure cutout switch for a particular application is set with a cut-in pressure of 5 psig, what would be the cutout pressure if the differential is 7.5 psig? #2 A container unit's microprocessor-controlled temperature controller is set at -28.9 ° C, appropriate for a frozen cargo of ice cream. In this mode of operation, according to the illustrated temperature controller functional diagrams, what should be the operational status of the unit if the actual box temperature is -18.0 ° C? Illustration GS-RA-035
Illustration GS-RA-035: the U.S. Coast Guard has not released this illustration. #3 Which of the following electrically operated refrigeration system valves would be most appropriate for use as a 2 position diverting hot gas bypass solenoid valve? Illustration GS-RA-19
Illustration GS-RA-19: the U.S. Coast Guard has not released this illustration. #4 Through which of the components shown in the illustration is flash gas formation a normal occurrence? Illustration GS-RA-25
Illustration GS-RA-25: the U.S. Coast Guard has not released this illustration. #5 Which of the statements listed is applicable to the thermostatic expansion valve shown in the illustration? Illustration GS-RA-07
Illustration GS-RA-07: the U.S. Coast Guard has not released this illustration. #6 In the multi-evaporator refrigeration system shown in the illustration, what is the proper name for the valve labeled "29"? Illustration GS-RA-12
Illustration GS-RA-12: the U.S. Coast Guard has not released this illustration. #7 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? Illustration GS-RA-06 #8 Which of the following illustrated expansion valves is designed to maintain a constant evaporator pressure rather than a constant evaporator superheat? Illustration GS-RA-24
Illustration GS-RA-24: the U.S. Coast Guard has not released this illustration. #9 In the illustrated refrigeration system, what is the proper name for the component labeled "A"? Illustration GS-RA-12
Illustration GS-RA-12: the U.S. Coast Guard has not released this illustration. #10 What is the drive arrangement of refrigeration compressor shown in figure "B" of the illustration? Illustration GS-RA-41 #11 If outside air at 80 degrees F and 70 percent relative humidity is conditioned, what will be the resulting dew point temperature of the air just before it comes into contact with the cooling coil? Illustration GS-RA-22
Illustration GS-RA-22: the U.S. Coast Guard has not released this illustration. #12 For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes? #13 Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system? #14 Which of the following is true concerning the class "A" air conditioning system shown in the illustration as used to condition the air of large public spaces? Illustration GS-RA-09
Illustration GS-RA-09: the U.S. Coast Guard has not released this illustration. #15 A room humidistat initiates the lowering of the humidity of the conditioned supply air to a space, while the actual process is accomplished by what means? #16 To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, what should be done? #17 Which of the following methods is normally used to control the circulated air temperature of an air conditioning system using chilled water circulation? #18 The introduction of outside air to the air conditioning system is 90°F with a relative humidity of 60%. The air has been conditioned to 70°F with a relative humidity of 80%. Using the psychrometric chart, shown in the illustration, determine the quantity of moisture removed from one pound of the conditioned air. Illustration GS-RA-22
Illustration GS-RA-22: the U.S. Coast Guard has not released this illustration. #19 In an air conditioning system, moisture is removed from the air by what means? #20 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? Illustration GS-RA-07
Illustration GS-RA-07: the U.S. Coast Guard has not released this illustration. #21 In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decompose and form what chemical substance? #22 Personnel servicing refrigeration systems that exposes them to commonly used refrigerants should wear what type of personal protective equipment? #23 If a refrigeration compressor were short-cycling on the low pressure cutout switch, what is the most probable cause? #24 A refrigeration unit will tend to short-cycle when operating under what conditions? #25 Which of the listed statements describes the method used to determine the amount of superheat present in the suction gas leaving the evaporator coil? Illustration GS-RA-16 #26 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? Illustration GS-RA-16 #27 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. #28 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? #29 Expansion tanks when used in a ship's low temperature hot water heating system may be of the open or closed type. Referring to the illustrated central-station hookup for a hot water heating system drawing, what would be the normal temperature range of the water? Illustration GS-0151 #30 Referring to illustrated diagram, what type of HVAC system is shown? Illustration GS-RA-43
Illustration GS-RA-43: the U.S. Coast Guard has not released this illustration.
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