Abstract: A valve for a pressure vessel of an automatic fire extinguishing system comprises a valve housing with a valve output opening for connecting an extinguishing line, a valve input opening for connecting the valve to the pressure vessel, a valve seat arranged between the valve output opening and the valve input opening, a low pressure chamber for connecting a triggering device and a high pressure chamber connectable with the low pressure chamber, wherein arranged in a the valve housing is a closing piston comprising a valve seat seal, which can be moved between a closing piston closed position and a closing piston open position, a pressure control unit in pressure connection with the valve input opening and the low pressure chamber for controlling the low pressure in the low pressure chamber relative to a vessel pressure of the pressure vessel and a control piston which can be moved between a control piston closed position and a control piston open position, wherein the closing piston is arranged in the closing