Pfeiffer Vacuum DuoLine two-stage high-performance rotary vane pumps cover low and medium vacuum applications, with pumping speeds of 1.25–11 m3 h–1. The DuoLine has a long service life and a pumping speed that is independent of the type of gas. The compact design and optimised cooling make the pumps suited for system integration. Operating noise has been significantly reduced; for example, the Duo 1.6 reaches a value of 44 dB (A) at 50 Hz. Switchable motors allow the connection voltage to be changed between 115 V and 230 V. The integrated, hydraulically controlled high-vacuum safety valve ensures high operational safety. An integrated connection point for oil return simplifies retrofitting of an oil mist filter.