US Patent 8667960 Radial blower with shaped scroll profile

A powered air purifying respirator (PAPR) includes a radial blower. The radial blower includes at least an impeller and a scroll having an upper outer surface and a lower outer surface. In one embodiment, a cross section of an air passageway of the scroll includes sides corresponding to the upper outer surface and the lower outer surface, the sides having parallel slanted segments. In another embodiment, the sides may be substantially parallel and may be curved. In yet another embodiment an upper outer surface of the scroll is concave and a lower outer surface of the scroll is convex. In that embodiment, the PAPR further includes an inlet, and the inlet is disposed at the lower outer surface.