Abstract: A changeover device for an installation for recovery of the gases proceeding from a tilting converter placed in an enclosure connected to a fixed suction duct called the main suction duct. The main suction duct enables recovery of the gases which escape from the converter in the vertical position for blast. A secondary duct connected to one and the same suction device as the main duct enables the recovery of the gases in the converter in the inclined position for charging. The changeover device enables the suction to be exerted either in the main duct or in the secondary duct. It comprises a suction chamber having two superposed portions connected by a vertical junction duct projecting into the upper portion of the chamber. Around the junction duct there is a tank containing water. A vertically movable bell plunges into the tank in order to isolate the two portions of the chamber with respect to one another.