🔍 Key Concepts

• Flame screens (flame arresters) on ullage openings and their purpose on tank vessels • How a metal mesh or gauze affects heat transfer from a flame front • The relationship between gas temperature, ignition, and metal surfaces

💭 Think About

• Think about what actually stops a flame from propagating through a small metal mesh when the vapor on the other side is still flammable. • Ask yourself: does the main protective effect come from blocking gas flow, changing its direction, or changing the flame’s temperature? • Consider how the metal elements of the screen interact with the hot gases of the flame as they pass through.

✅ Before You Answer

• Identify how a flame arrester or flame screen is described in tank vessel safety material (what physical principle it uses). • Check which option mentions heat removal from the flame rather than just blocking or slowing gases. • Verify which choice explains why the flame cannot ignite vapors inside even though vapors can still move through the opening.