USCG Exam PracticeRefrigeration principles and systems
What is the primary hazard of liquid refrigerant entering the compressor suction, a condition known as slugging or liquid floodback?
- A. It causes the suction pressure to rise above the high-pressure cutout setpoint.
- B. It dilutes the crankcase oil, reducing lubrication to the bearings.
- ✓ Liquid cannot be compressed and can break valves, connecting rods, or the crankcase.Correct
- D. It causes the condenser tubes to foul rapidly with oil deposits.
Why C is correct
Liquid refrigerant is incompressible; if it reaches the compressor suction it cannot be compressed and the resulting hydraulic force can break suction or discharge valves, connecting rods, or the crankcase — a serious mechanical casualty. The system is arranged to ensure refrigerant is fully evaporated and slightly superheated before reaching the compressor.
Cited:NAVEDTRA 14075 §6-2