A purger is an essential component for the proper and efficient operation of an industrial refrigeration system. A purger gathers, separates and expels non-condensable gases from the system. Successfully purging non-condensables from a refrigeration system leads to increased refrigeration capacity, improved system efficiency, and enhanced system safety.

In this article, we review the types of non- condensable gases (NCG) that can accumulate in systems, consequences of NCG, purger operation, application considerations and factors that influence purger performance. Our emphasis is on vapor compression-based industrial refrigeration systems that use anhydrous ammonia as the refrigerant because this choice covers the majority of industrial systems in use today.