Redi/Controls Inc. 's (Greenwood, IN) new "Purge-Guard" is designed for low-pressure centrifugal chiller purge units. It works independently of the purge unit's purge fault protection and guards against pump-out of either liquid or vapor refrigerant in the event of stuck pump-out compressor relay contacts, locked-up microprocessors, as well as purge units set in manual mode and accidentally left unsupervised.