Type III — Low-PressureQuestion 164 of 240
What is the primary purpose of a purge unit on a low-pressure centrifugal chiller?
a.To circulate chilled water
b.To lubricate the compressor bearings
c.To remove non-condensable gases such as air
d.To add refrigerant to the system
Explanation
A purge unit removes non-condensable gases, mainly air and moisture, that leak into a chiller running under vacuum and collect at the top of the condenser. Removing them lowers head pressure and restores efficiency. A high-efficiency purge unit also recovers refrigerant vapor before venting the air.
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