Blower for propelling a continuous gas stream with inflatable gas seals

Apparatus for propelling a continuous gas mixture stream of an inert carrier gas and an aggressive doping gas, comprising an electric motor having a motor housing filled with pure carrier gas and a shaft with a shaft extension, a radial blower having an impeller mounted directly on said shaft extension and a blower housing filled with the gas mixture and coupled to said motor housing, said impeller having a flange facing said motor and said blower housing having a wall facing said motor having an inner surface, a ring space, a hollow sealing ring inflated with compressed gas for sealing said blower housing from said motor housing when said blower is stopped, said hollow sealing ring being formed of soft material anchored at said inner surface of said wall of said blower housing, and said hollow sealing ring having a plurality of sealing lips lying against said flange of said impeller in the inflated state, and means for continuously feeding and maintaining a gas ring of pure carrier gas in said ring space for sealing said blower housing against said motor housing in an operating state.