USCG Exam PracticeHydraulics and pneumatics
What is the primary reason high-pressure air for diesel engine starting is compressed in two or more stages rather than a single stage?
- A. A single-stage compressor cannot achieve the required volume of air.
- ✓ Compressing to high pressure in a single stage generates excessive heat.Correct
- C. Single-stage compression introduces too much oil mist into the receiver.
- D. Multi-stage compression eliminates the need for a pressure relief valve.
Why B is correct
NAVEDTRA 14075 §7-1 and NAVEDTRA 14104 §10-3 both state that high-pressure air is compressed in two or more stages because compressing to high pressure in one step generates excessive heat. Intercoolers between stages remove the heat of compression. The other options describe real concerns but are not the stated reason for multi-stage compression.