🔍 Key Concepts

• Inert gas system safety devices on tankers • The normal function of mechanical P/V (pressure/vacuum) valves • The special role of a P/V breaker (liquid seal) in handling extreme conditions

💭 Think About

• Which device is meant for routine pressure control during loading/discharge, and which is a backup for abnormal surges? • Which option uses a liquid seal to provide an emergency path to atmosphere if tank pressure rises very quickly? • Think about which components are mainly for isolation or backflow prevention, rather than for relieving a large, sudden overpressure.

✅ Before You Answer

• Identify which component is specifically described in training material as a “secondary” or “emergency” venting device for cargo tanks. • Confirm which device works by allowing gas to bubble through a liquid column once a certain overpressure is exceeded. • Eliminate any components whose primary purpose is normal operating control (fine regulation) rather than handling overpressures beyond mechanical P/V valve capacity.