Abstract: A ring channel blower in which, in the discharge area of the ring channel blower, a cross piece-shaped interrupter has a discharge side boundary edge that is configured such that between the inner edge of the ring channel and the facing edge of the respective vanes of the impeller as they pass thereover an angle of at least 25.degree. is initially enclosed and this angle increases gradually to 90.degree. when the intersection of the boundary edge and facing impeller vane edge is at the outer edge of the impeller. The discharge side boundary edge incorporates an inner end section that is approximately tangent to the inner edge of the ring channel and an outer end section that is approximately tangent to the outer edge of the impeller, and both of these tangent sections are connected to each other by a circular arc section.