In the axial separator, operating on the principle of the centrifugal forces, the effect of dedusting is conditioned by the kind of a whiled gas flow. In the dependence of the vane shape changes the gas velocity distribution as well as the separation efficiency and the pressure drop. The paper presents a theoretical investigation of the influence of the blade shape on the dust collection effect for the vane geometry described by the equation (3). Dimensionless numbers formulate criteria for determination of the usefulness of the whirling gas in dedusting installations. The results of the mathematical analysis are illustrated with the aid of the diagrams.