🔍 Key Concepts

• Inert gas system layout – where is the deck seal located in relation to cargo tanks and machinery space? • Backflow / flow reversal – what could move backward through the inert gas line if pressure conditions change? • Fire and explosion protection purpose of inert gas systems on tankers

💭 Think About

• Think about what would happen if the pressure in the cargo tanks became higher than in the inert gas line leading back toward the engine room. • Ask yourself which space absolutely must be protected from any flammable cargo vapors for safety of personnel and machinery. • Consider the function of a water seal: in plumbing or gas systems, what does a liquid seal usually prevent from moving from one side to the other?

✅ Before You Answer

• Identify which answer choices involve movement of vapors or gases back toward machinery spaces versus to the open atmosphere. • Decide which risk would be most dangerous to the ship and crew: vapors entering machinery space, gas escaping outside, or air getting in. • Recall that the deck seal is a type of liquid seal – confirm which direction of unwanted flow it is primarily intended to block.