🔍 Key Concepts

• Fuel oil tank venting systems on ships and why tanks must be able to "breathe" as fuel level and temperature change • The purpose of screens or flame arrestors installed at vent outlets • The difference between stopping liquid, vapor, air, and flame propagation in a vent line

💭 Think About

• If a tank is being filled or emptied, what needs to be able to move freely through the vent (air, vapor, liquid?), and what would be dangerous to block? • In a deck fire near a vent head, what hazard exists if the flame can travel back down into the tank, and what device or feature of the vent is intended to stop that from happening? • Which option would still allow safe pressure equalization of the tank while protecting against an external fire hazard?

✅ Before You Answer

• Make sure the correct choice does not block normal tank breathing (air/vapor in and out) during loading or temperature changes • Focus on the role of screens or gauze at the vent opening, not the whole vent line • Think about which option directly addresses the risk of fire or explosion inside the tank originating from a fire on deck