Hermetic-seal valve for a thermal-regeneration plant for depuration of emissions

A hermetic-seal valve for a thermal-regeneration plant for depuration of emissions, said valve being set in a duct (13) which connects an inlet pipe (28) for entry of an emission that is to be treated or an outlet pipe (29) for exit of an emission that has been treated, and a treatment chamber (22), said valve comprising an obturator seating (14), an obturator (16) having the shape of a truncated cone for opening and closing said obturator seating (14), and means (18) for actuating said obturator (16) via an interposed stem (20), said hermetic-seal valve being characterized in that said obturator seating (14) consists of a ring (30), one internal top end of which has a circumferential undercut (50) shaped like a truncated cone and provided with a series of radial holes (54) connected to an external fan or directly to the outside environment (56, 57), said undercut (50) being provided with a first circumferential edge (52), which has a diameter equal to the diameter of the obturator seating (14), and a second circumferential edge (53), which is located above the first edge and is of larger diameter, where both of said edges (52, 53) engage with said obturator (16) shaped like a truncated cone when said stem (20) is displaced.