Abstract: A gasket made of a rubber-like elastic body attached to an attaching groove provided in at least one out of two members to seal a gap between the two members includes a first sealing surface coming into surface contact with a surface of a first member. A second sealing surface comes into surface contact with a surface of a second member. A third sealing surface comes into surface contact with a side surface of the attaching groove, and a pressure receiving groove opened to a side receiving sealing fluid pressure which is on an opposite side of the third sealing surface and provided so as to be parallel to the first sealing surface and the second sealing surface.

Abstract: A raw material is dispersed around a rotating separator main body having a plurality of classifying blades annularly arranged on the main body and is exposed on a rising flow of classifying air so as to sift off crude powder which cannot be entrained on the flow of the classifying air. The remaining raw material entrained on the classifying air is peripherally introduced into the separator main body for classification into fine and crude powders, the fine power being the powder which is allowed to pass through the classifying blades while the crude powder is the powder which is not allowed to pass. A dispersion plate is arranged between the separator main body and a raw material inlet above the separator main body to receive and disperse the raw material from the inlet. The dispersion plate is rotatable at number of revolutions different from that of the separator main body.