USCG Exam PracticeLube oil and fuel oil systems
An oiler notices that the lube oil purifier is discharging oil that appears cloudy and wet despite the machine running at correct speed and temperature. Which of the following is the most likely cause based on purifier operating principles?
- A. The throughput rate is too low, causing excessive dwell time and over-separation
- ✓ The gravity (dam) ring selected does not match the oil's density, allowing water to carry over into the clean oil outletCorrect
- C. The disc stack has too many discs installed, reducing the radial separation distance
- D. The bowl speed is too high, causing the water seal to be thrown outward past the oil discharge port
Why B is correct
NAVEDTRA 14075 §3-4 states that the position of the oil-water interface is set by the size of the gravity (dam) ring, which must match the oil's density. If the wrong ring is fitted, water will carry over into the clean oil outlet. Excessive dwell time from low throughput would improve, not degrade, separation.
Cited:NAVEDTRA 14075 §3-4