VOLUTE FOR A RADIAL VENTILATOR

A spiral housing of a radial fan has a flow cross-sectional area which, starting from a housing tongue, increases in the circumferential direction, around a fan impeller which can be arranged on an axial central axis. The cross-sectional area is determined via a contour of at least one axial side part of the spiral housing. The one axial side part has an axial suction opening with an opening edge section surrounding the suction opening, which is directly adjoined, viewed in the radial direction, by a transition section extending in the circumferential direction. The transition section, in a starting section which extends from the housing tongue in the circumferential direction over a predetermined angle, is spaced apart in the axial direction relative to the opening edge section and has a course which increases the flow cross section in the circumferential direction until axial surfaces of the opening edge section and of the transition section extend in the same plane.