Why do we have to remove air/non-condensibles from a condenser?

• A. Because it creates air pockets.
• B. To reduce system pressure.
• C. To prevent condensation from occurring.
• D. To accelerate the flow of condensate.

Answer: (A)

Non-condensables like air don’t condense and tend to accumulate at the top of a condenser, forming an insulating gas layer that lowers the heat transfer from the condensing vapor to the cooling surface. Removing these gases prevents those air pockets, so the condenser surface stays effectively wetted by condensate and can transfer heat more efficiently. That’s why the purpose of removing non-condensibles is described as addressing the air pockets they form. The other choices don’t capture the main effect: removing non-condensables mainly improves heat transfer and condensation efficiency, not simply reducing system pressure, preventing condensation, or directly speeding up condensate flow.