🔍 Key Concepts

• Inert gas system (IGS) purpose and how it protects cargo tanks on tankers • Difference between positive pressure (slight overpressure) and vacuum/negative pressure in cargo tanks • Typical requirement about keeping air (oxygen) out of an inerted tank rather than exact psi values

💭 Think About

• Ask yourself: What is the main safety goal of using an inert gas system in cargo tanks? How does tank pressure help achieve that? • Which sounds more like a design or class limit (exact psi numbers) versus an operational principle that must always be followed? • If pressure drops too low in an inerted tank, what danger does that create regarding oxygen entering the tank?

✅ Before You Answer

• Verify which choice focuses on keeping oxygen out of the tank rather than quoting specific psi ranges. • Check if any option states an operating principle that should be true at all times for an inerted tank, not just under special conditions. • Eliminate options that give very specific pressure values unless you know those exact numbers are taken from a regulation you have studied.