There is provided a valve for controlling the release of fire suppressant from a pressurized container, said valve comprising a diaphragm configured to perforate upon action of a shockwave directed onto the surface of said diaphragm, a pyrotechnic charge arranged and adapted to combust to produce combustion products that form a shockwave directed onto the surface of said diaphragm, and a device encasing said pyrotechnic charge. The device comprises a hollow, elongate channel located over said pyrotechnic charge and directed at the center of said diaphragm so as to focus or direct said combustion products onto the center of said diaphragm. The elongate channel has a length that is at least 1.5 times its smallest width.