Question 17 DDE04 - Designated Duty Engineer - 1000-4000 HP

The Correct Answer is D **Explanation for Option D (Bypass filtration) being correct:** The illustration MO-0182 typically depicts a system where only a small percentage (usually 5% to 15%) of the total lubricating oil flow from the main pump is diverted through a high-efficiency filter (often a depth-type or centrifugal filter) and then returned directly to the main oil sump, bypassing the main bearing supply line. The filter is often designed to remove extremely fine particulates and water, which a standard full-flow filter might miss. Since the majority of the oil is not filtered by this system before going to the bearings, and the filter operates continuously by filtering a *portion* of the oil *past* the main lubrication circuit, it is classified as a **Bypass filtration** system. **Explanation for why the other options are incorrect:** * **A) Shunt filtration:** While "shunt" is sometimes used interchangeably with "bypass" in general engineering terms, in the context of marine engine lubrication, "bypass filtration" is the standard and specific industry term for a system filtering a partial flow of oil and returning it to the sump. "Shunt filtration" is not the typical or preferred nomenclature. * **B) Full-flow filtration:** A full-flow system filters 100% of the oil before it is supplied to the bearings and critical components. If the illustration shows the filtered oil returning to the sump instead of supplying the main engine header, it is not a full-flow system. * **C) Sump filtration:** This term is generally too broad. While oil is drawn from the sump and returned to the sump, it does not describe the specific configuration of the filtration loop relative to the main lubrication circuit (i.e., whether it filters all or only a portion of the oil, or where the filtered oil is returned).