A device for setting the position of a closing element for a porthole in an open position toward the outside around an opening in a wall of a room includes a protruding part with a circular shape fastened to the wall around the opening by means of at least one fastener, and a joining part that has a first end connecting a hinged end of the closing element to the protruding part. The protruding part has at least one first groove. The joining part has a second end movable in the at least one first groove, and the movement of the second end in the at least one first groove entails movement of the closing element in the open position around the opening. In a closed position, the closing element integrally covers the protruding part in order to seal the porthole in the closed position.