USCG Exam PracticeDiesel engine principles (motor propulsion)
The thermostatic valve in a marine diesel jacket-water cooling system serves which function?
- A. It regulates seawater flow through the sea suction strainer to prevent cavitation
- ✓ It bypasses the cooler until the jacket water reaches operating temperature, then admits it to the coolerCorrect
- C. It controls the chemical treatment dosing rate to maintain correct inhibitor concentration
- D. It diverts jacket water away from the turbocharger circuit when exhaust temperatures are low
Why B is correct
The thermostatic valve bypasses the heat exchanger while the engine is cold, then progressively admits jacket water to the cooler as temperature rises, holding the outlet temperature in a narrow band regardless of load or sea temperature. (NAVEDTRA 14075 §3-5)
Cited:NAVEDTRA 14075 §3-5