Pass Benchmark: 70% (21/30) • Standard: USCG NMC / 46 CFR
USCG Refrigeration & Air Conditioning (Set 13)
30:00
|Question 1 of 30
Question Navigator
Correct Incorrect Pending Starred
Question 1 of 30
In refrigeration systems with multiple evaporators, the metering of refrigerant to each refrigerated space evaporator is accomplished by what device?
Browse Questions in Set 13
30 MCQs #1 In refrigeration systems with multiple evaporators, the metering of refrigerant to each refrigerated space evaporator is accomplished by what device? #2 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. #3 In a refrigeration system, the bulb for the thermal expansion valve is always located where? #4 What is the purpose of the pressure transducer as shown in the illustration? Illustration GS-RA-17
Illustration GS-RA-17: the U.S. Coast Guard has not released this illustration. #5 As shown in the illustrated LP centrifugal chiller pressure maintenance system, what is its functional purpose? Illustration GS-RA-40
Illustration GS-RA-40: the U.S. Coast Guard has not released this illustration. #6 A liquid sight flow indicator in a refrigeration system is examined and gas bubbles are noted in motion with the fluid flow. What does this mean? #7 When a refrigeration compressor motor fails to start, the FIRST thing that should be checked for is what? #8 A refrigeration system is equipped with a reciprocating compressor and a water-cooled condensing unit. If the system is overcharged, the resulting high head pressure will be caused by what condition? #9 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. #10 One cause of high head pressure occurring in a refrigeration system can be which of the following? #11 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? #12 An increasing head pressure in a refrigeration system, without any corresponding change in the cooling water inlet temperature, would probably be caused by which of the following? #13 If a refrigeration system compressor crankcase is exhibiting an unusual degree of sweating or frosting and is operating noisily, what should be done? #14 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? #15 The thermostat controlling the operation of the solenoid valve to a refrigerated box evaporator senses what temperature? #16 Which of the following statements is true concerning the attached illustration? Illustration GS-RA-12
Illustration GS-RA-12: the U.S. Coast Guard has not released this illustration. #17 Which of the listed operations will cause an automatically controlled refrigeration compressor to restart if the system features a pump down cycle? #18 What is the purpose of the low-pressure cut-out switch as used as a primary controller for a refrigeration system or unit? #19 In a refrigeration system featuring low-side pump down prior to the automatic shutdown of the compressor, the temperature of the refrigerated space is controlled by the action of a thermostat wired to what device? #20 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. #21 The sensing line for the low-pressure cutout switch for a refrigeration system is typically connected at what location? #22 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. #23 Which of the conditions listed may be an indication of an excessive amount of refrigerant circulating through the system? #24 If the refrigeration compressor crankcase is sweating or frosting and is operating with an unusual noise, what is most likely the cause? #25 If a refrigeration system, equipped with a reciprocating compressor, has a liquid line solenoid valve that is leaking during the 'off' cycle, what would this cause? #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 The color and/or condition of the oil observed in the sight glass of an operating refrigeration compressor experiencing bearing wear or piston scoring would be which of the following? #28 Leaking suction valves in a refrigeration compressor are indicated by which of the following? #29 A refrigeration unit will tend to short cycle when operating under what conditions? #30 An excessive charge of refrigerant in a thermostatically controlled, air-cooled, refrigeration system using a TXV as an expansion device can cause which of the following?
Question Discussion & Notes
0Have a doubt, memory trick, or exam update? Share your insights with fellow mariners.
Loading mariner discussions...