🔍 Key Concepts

• Steam surface condenser operation in a main propulsion plant • Difference between removing air and non-condensable gases vs. condensing steam • How pressure drops when steam changes phase from vapor to liquid in a closed space

💭 Think About

• Think about what physically happens to the exhaust steam as it enters a properly cooled, tight condenser. What change of state occurs, and how does that affect pressure? • Which choice describes a device or action that mainly removes air and non‑condensables, and which describes the primary cause of the very low pressure (vacuum)? • If you suddenly remove most of the steam molecules from a space without changing its volume, what happens to the pressure? Which option best represents that process?

✅ Before You Answer

• Identify which option directly involves phase change of steam to water inside the condenser. • Distinguish between equipment that maintains vacuum (handles air leakage) and the process that creates most of the vacuum. • Verify in your engineering references how a surface condenser develops vacuum under normal steady operation, assuming it is tight and adequately cooled.