🔍 Key Concepts

• 46 CFR Subchapter F or J sections on tank vents and overflow piping • Purpose of tank venting and the risk of flooding/contamination if vents are below the deep load waterline • Difference between manual closures, automatic closures, and relief valves

💭 Think About

• Ask yourself: If a vent ends below the deep load waterline, what is the main danger, and what feature would most directly and automatically prevent seawater from entering the tank through that vent? • Which options protect against both overpressure/vacuum in the tank AND ingress of water through a low‑level vent without depending on a crew member to remember to operate it? • Look at the answer choices: Which device is specifically designed to close itself when water reaches it, rather than just relieving pressure or relying on someone to shut it?

✅ Before You Answer

• Verify in 46 CFR that when a vent terminates below the deep load waterline, it must have an automatic means to prevent water from entering the tank through that vent. • Check which listed fittings are primarily for pressure/vacuum relief versus which are specifically for automatic closure against water entry. • Confirm that the regulation does not rely solely on a manual or normally open device that needs human action to protect the tank when the ship trims or heels.