🔍 Key Concepts

• Steam condenser vacuum formation – how air and non-condensable gases are removed to create/hold vacuum • Function of first-stage vs second-stage air ejectors in multi-stage systems • Difference between establishing vacuum (start-up) and maintaining vacuum (steady operation)

💭 Think About

• Think about what physically creates the initial vacuum in a large surface condenser. Which ejector stage handles the highest pressure (closest to atmospheric) air and non‑condensables? • Once a good vacuum is already established, what role does each stage play in keeping that vacuum from deteriorating? • If the first stage is shut down, can the second stage alone pull air from condenser pressure all the way up to its own suction, or is it only designed to handle already partially evacuated gas?

✅ Before You Answer

• Identify which ejector stage is designed to handle condenser pressure closest to atmospheric and start-up loads • Decide whether starting vacuum and holding vacuum require the same equipment configuration or different capabilities • Consider manufacturer design: can a second-stage ejector normally operate alone on a large seawater-cooled condenser, or is it dependent on the first stage to receive already compressed (higher vacuum) gases?