The company's Model PRG-11/123-C3 and PRG-113-C3 microprocessor-controlled ultra-high efficiency purge unit for low-pressure centrifugal chillers is ARI certified and UL listed. The units does not have to be mounted on top of the chiller, and the refrigerant charge does not have to be pulled to install. The microprocessor controller operates only when necessary, and the purge operates independent of chiller operation.