The freezing drying process is the most careful method of drying products. For this the physical phenomenon of sublimation is used. The frozen product is brought for drying into the vacuum chamber. A prerequisite for an effective drying process is therefore the appropriate vacuum. Commonly two-stage oil-sealed rotary vane pumps are used for vacuum generation, however, these have well-known disadvantages when evacuating condensable and corrosive vapours. The chemistry-HYBRID-pump RC 5 offers substantial advantages here. A chemistry diaphragm pump evacuates the oil stages of the rotary vane pump and reduces both the oxygen partial pressure and the partial pressure of the corrosive gases. As a result the reaction with the oil and corrosion attack on the pump unit are considerably reduced. By careful balancing of the pressure and temperature in the oil reservoir, the dew point for most common solvents is not reached and therefore practically no condensation occurs in use within the oil stages. The chemistry-HYBRID-pump RC 5 is therefore an outstanding solution where a vacuum under 2 mbar is needed and a corrosion and condensation problem exists. The price of the pump is only slightly more than that of a conventional rotary vane pump with all the necessary accessories such as cold trap, separator and exhaust oil mist filter.