A protective device for motor vehicle airbag systems to protect the vehicle occupants utilizes a vessel whose wall piece, which can break out, is configured as part of the wall of a hollow valve block provided with the outflow orifice. The wall piece is equipped with an extension projecting into the interior of a valve block. The piston rod is guided displaceably, transversely relative to the extension in the valve block, and moved by a pyrotechnic propellent charge. The rod serves to break out the wall part and is provided with a collar which, in the event of ignition, strikes against the extension and thus leads not to a violent breaking-out, but to a pivoting of the wall piece before the final breaking-out.