USCG Exam PracticeLube oil and fuel oil systems
When selecting the gravity (dam) ring size for a lube-oil purifier, what is the critical consequence of installing a dam ring that does not match the density of the oil being processed?
- A. The bowl speed will be insufficient to generate adequate centrifugal force for separation.
- B. The disc stack spacing will be incorrect, reducing the effective separation area.
- ✓ The oil-water interface inside the bowl will be mispositioned, causing either oil carryover into the water outlet or water carryover into the clean oil discharge.Correct
- D. The water seal will be established too quickly, causing the purifier to operate in clarifier mode.
Why C is correct
NAVEDTRA 14075 §3-4 states that the position of the oil-water interface inside the bowl is set by the size of the gravity (dam) ring, which must match the oil's density. If the wrong ring is used, oil will spill over into the water outlet or water will carry over into the clean oil discharge, sending contaminated oil back to the engine. Dam ring selection does not affect bowl speed or disc stack spacing.
Cited:NAVEDTRA 14075 §3-4