USCG Exam PracticeHydraulics and pneumatics
What is the primary reason high-pressure air for diesel starting is compressed in two or more stages rather than a single stage?
- A. A single-stage compressor cannot produce sufficient volume for engine starting.
- ✓ Compressing to high pressure in a single stage generates excessive heat.Correct
- C. Multi-stage compression eliminates the need for a pressure relief valve on each stage.
- D. Single-stage compression introduces too much oil mist into the receiver.
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. An intercooler between stages removes that heat of compression and also condenses moisture.