Abstract: A ventilating device for a gas-carrying flowing fluid medium, includes a gas collecting chamber having an open bottom, a housing below the collecting chamber, and a tube disposed substantially horizontally in the housing below the gas collecting chamber for conducting the medium and reducing the velocity of the medium, the tube defining a space surrounding the tube in the housing, and the tube having a wall with lateral openings formed therein permitting gas bubbles to rise through the wall openings into the space and from the space into the gas collecting chamber.