🔍 Key Concepts

• Ballasting and deballasting sequences for fuel or ballast tanks • Purpose and location of a sea suction valve versus a pump discharge valve • How to prevent backflow and contamination between the sea, the pump, and the tank

💭 Think About

• Think through the full flow path: from the sea to the tank. Which valve is closest to the sea, which is in the middle, and which is closest to the tank? • If you stopped pumping suddenly with all valves open, where could unwanted flow or backflow occur, and which valve, if shut first, would most effectively isolate the system? • Which valve, if left open too long, could allow sea water to continue to enter or siphon, even if other valves are later closed?

✅ Before You Answer

• Identify the order of components in a typical ballast/fuel transfer line: sea chest → sea suction valve → pump → pump discharge valve → piping → tank or deck manifold valves • Verify which valve controls direct communication with the sea and what happens if it remains open • Consider which valve closure first gives you the safest isolation against unintended flooding or contamination if something goes wrong.