Calibrating device and method for calibrating a film tube

A method for calibrating a film tube, wherein the outer diameter of the film tube is adjusted by an excess gas pressure in the interior of the film tube, wherein the film tube is calibrated using at least one guidance element and at least one guidance surface, wherein with the at least one guidance element comprising an inlet element and an outlet element, wherein each of the inlet and outlet elements comprises a plurality of encircling elements connected among each other by one or more elastic elements and is connected to one or more support elements, to which the at least one guidance surface is assigned, which the outer surface of the film tube faces, the exterior diameter of the film tube is limited and the film tube is guided in a region which has a guidance length, wherein the each encircling element is made from a solid material possessing a thickness that prevents the cross-sectional shape of the inlet and outlet elements from changing under an application of force that does not lead to the inlet and outlet elements being destroyed, wherein the film tube defines an axis of symmetry, wherein the distance of the at least one guidance surface and/or of the at least one guidance element to the axis of symmetry is alterable by the one or more support elements, wherein the film tube is guided by the calibrating device in the direction of gravity, wherein above, or in an inlet region of the at least one guidance element, a liquid reservoir is situated, from which the liquid is directed out of the liquid reservoir to the outer periphery of the film tube, wherein the film tube is surrounded by a closed liquid film, and wherein the guidance length is adjusted or constant, independent of the distance of the guidance surface and/or of the guidance element to the axis of symmetry.