US Patent 8252079 Particle separating device for an aerosol stream

Separating device for separating liquid or solid particles from an aerosol stream, comprising an impactor with a perforated plate against which the stream flows, and an impact plate arranged at a short distance behind the perforated plate, the side of the impact plate against which the stream flows having a separating layer with an open structure; in order that the separating device will have a consistently good separating effect during operation, the perforated plate is provided on its rear side with a plurality of spacer elements bearing against the region of the separating layer against which the stream flows, the height of the spacer elements, the support surfaces formed by the spacer elements for the separating layer, and the number and arrangement of the spacer elements being selected in dependence upon the material of the separating layer such that it is ensured that the holes of the perforated plate remain free from material of the separating layer also during operation.