Question 33 QMED03 - Oiler

The Correct Answer is D ### 2. Explanation of Option D (Correct) **D) by stop-check valves installed in the bilge suction manifolds** This is the correct method mandated by maritime regulations (such as SOLAS and classification societies). Flooding prevention focuses on preventing external high-pressure sources (like the sea, ballast tanks, or fire main lines) from flowing backward into the engine room bilges. A **stop-check valve** performs two critical functions: 1. **Check Function (Automatic Prevention):** It automatically prevents backflow from the high-pressure side of the manifold (e.g., the sea chest connection or pump discharge) into the bilge lines when the pump is stopped or the pressure differential reverses. 2. **Stop Function (Positive Isolation):** It can be manually closed completely, providing positive isolation of the bilge suction line against the sea or high-pressure systems. This dual function ensures that the engine room bilges are protected from catastrophic flooding originating from outside the machinery space. ### 3. Explanation of Incorrect Options **A) by using a positive displacement reciprocating bilge pump** The type of pump used (positive displacement, centrifugal, etc.) affects pumping efficiency and handling of fluids, but it does not inherently prevent backflow or flooding when the system is shut down or when the bilge suction manifold is cross-connected to an external source (like the main cooling water system or an overboard discharge). Backflow prevention relies on proper valve configuration. **B) by installing a swing check before each bilge valve** A simple check valve prevents backflow automatically, but it cannot be manually controlled or positively shut off (stopped). Regulations require a means of manual isolation against the sea or high-pressure lines to ensure safety, making a simple check valve insufficient for critical flood prevention without a separate manual stop valve. **C) by installing eductors in all bilge rose boxes** Eductors are effective pumping devices that use a high-pressure motive fluid (usually from the fire main) to create suction. However, they are used for *removing* water, not *preventing the ingress* of water. Furthermore, the use of eductors must be protected by proper valving (often stop-check valves) to prevent the high-pressure motive fluid from accidentally flooding the bilge if the system is misoperated or leaks.