Seco vacuum pumps operate according to the reliable principle of rotary vane pumps without the use of foreign mediums for lubrication. The compression is almost free of pulsation and absolutely free of oil. An eccentrically installed rotor rotates in the cylinder. The centrifugal force of rotation pushes the vanes, which are sliding in slots of the rotor towards the wall of the cylinder. The vanes separate the sickle shaped space between rotor and cylinder in chambers. Because of the different size of the chambers there results a negative pressure at the suction side (SV) or a positive pressure at the pressure side (SD). The vacuum pressure and positive pressure can be regulated by regulating valves.