USCG Exam PracticeAir conditioning, ventilation, and compressed air
Why must high-pressure air for diesel engine starting be compressed in two or more stages rather than in a single stage?
- A. Single-stage compression produces excessive moisture that fouls the starting system.
- ✓ Single-stage compression to high pressure generates excessive heat.Correct
- C. Single-stage compressors cannot produce sufficient volume for engine starting.
- D. Single-stage compression causes oil carryover that ignites in the receiver.
Why B is correct
Both NAVEDTRA 14075 §7-1 and NAVEDTRA 14104 §10-3 state that compressing air to high pressure in a single stage generates too much heat, which is why two or more stages with intercooling are used. Moisture and oil carryover are separate concerns addressed by coolers and separators.