Atlas Copco CR15 Reciprocating Duplex Air Compressor 51CFM 15HP 460V 3Ph 120 GalNew. Old stock. Discontinued model. 15 hp motor 3 phase 230 460V Wired for 460V The CR Piston Range also comes in a two pump duplex design. A duplex design can be used to improve efficiency and or to create redundancy and give you a back up option inside a single unit. All models in the CR Series duplex piston range are cast iron, splash lubricated, 2 stage, compressors with a magnetic starter as standard and a maximum operating pressure of 175 psi.