🔍 Key Concepts

• Fuel oil tank vent design and purpose on tank vessels • Role of flame screens / corrosion‑resistant gauze in vent lines • Movement of vapors vs. flames vs. liquid through a vent opening

💭 Think About

• What normally needs to pass freely through a fuel tank vent during loading, discharging, and temperature changes? • What hazard from outside the tank is especially dangerous if it can travel back into the tank through the vent? • Which options would interfere with the primary safety function of a vent (pressure equalization) if they were the main purpose of the screen?

✅ Before You Answer

• Confirm that the vent must still allow pressure relief and vapor flow to avoid tank over/under‑pressure • Consider which option best matches the purpose of a screen made of corrosion‑resistant metal gauze often called a flame screen • Eliminate any choice that would trap vapors inside the tank or block normal venting, as that would be unsafe