USCG Exam PracticeAir conditioning, ventilation, and compressed air
In a shipboard refrigeration system, liquid refrigerant returning to the compressor suction is called slugging or liquid floodback. Which of the following best describes why this condition is hazardous?
- A. Liquid refrigerant absorbs too much heat in the evaporator, causing the suction pressure to rise above the high-pressure cutout setpoint.
- ✓ Liquid cannot be compressed and can break valves, connecting rods, or the crankcase.Correct
- C. Liquid refrigerant dissolves crankcase oil, causing the oil-pressure safety switch to trip.
- D. Liquid refrigerant at the suction causes the condenser to flood, raising head pressure.
Why B is correct
NAVEDTRA 14075 §6-2 explains that liquid refrigerant cannot be compressed and that slugging can break valves, rods, or the crankcase — a serious casualty. The other options describe real system phenomena but are not the mechanism of damage from liquid floodback.
Cited:NAVEDTRA 14075 §6-2