Abstract: A spiral pumping stage includes both centripetal and centrifugal pumping channels, so that the gas is pumped from the periphery to the center of the pumping stage throughout a first group of pumping channels and it is pumped from the center to the periphery of the pumping stage throughout a second group of pumping channels. Thanks to this inventive arrangement, both the gas coming from a previous pumping stage or a main pump inlet arranged upstream the pumping stage according to the invention and the gas coming from the additional side inlet can be effectively pumped by the pumping stage according to the invention.

Abstract: A rotary vacuum pump includes a first set of pumping stages having rotor discs with a first diameter and a second set of pumping stages having rotor discs with a second different diameter and further comprising an intermediate pumping stage that is particularly adapted for matching the change in the diameter of the pump rotor discs. According to the invention, the intermediate pumping stage comprises a rotor disc having an outer portion in the radial direction that is axially tapered from its inner diameter to its outer diameter and a corresponding stator stage including a spacer ring that is axially tapered from its periphery toward its center.

Abstract: A spiral pumping stage includes both centripetal and centrifugal pumping channels, so that the gas is pumped from the periphery to the center of the pumping stage throughout a first group of pumping channels and it is pumped from the center to the periphery of the pumping stage throughout a second group of pumping channels. Thanks to this inventive arrangement, both the gas coming from a previous pumping stage or a main pump inlet arranged upstream the pumping stage according to the invention and the gas coming from the additional side inlet can be effectively pumped by the pumping stage according to the invention.

Abstract: A rotary vacuum pump includes a first set of pumping stages having rotor discs with a first diameter and a second set of pumping stages having rotor discs with a second different diameter and further comprising an intermediate pumping stage that is particularly adapted for matching the change in the diameter of the pump rotor discs. According to the invention, the intermediate pumping stage comprises a rotor disc having an outer portion in the radial direction that is axially tapered from its inner diameter to its outer diameter and a corresponding stator stage including a spacer ring that is axially tapered from its periphery toward its center.