Why is a purge recovery unit typically fitted on low pressure centrifugal chillers?

Correct Answer: Option B — such a chiller can operate at a pressure below atmospheric pressure on the low side thus drawing in air through any low-side leaks

Low-pressure chillers operate below atmospheric pressure on the evaporator side, which inherently causes ambient air and moisture to infiltrate the system through gasket joints and shaft seals whenever minor low-side leaks develop.