As shown in the illustrated LP centrifugal chiller pressure maintenance system, what is its functional purpose? GS-RA-40 Illustration GS-RA-40: the U.S. Coast Guard has not released this illustration.

Correct Answer: Option C — prevent the entrance of air into the chiller when the chiller is idle

Low-pressure centrifugal chillers operate below atmospheric pressure at idle or low loads. Pressure maintenance systems introduce refrigerant vapor or warm water to keep internal pressure slightly positive, preventing ambient air and moisture from leaking into the vessel.