A valve includes a valve body having an inlet for fluid communication with a space or source containing pressurised gas, and at least one outlet. A membrane is arranged between the inlet and the at least one outlet. A membrane puncturing element is arranged for movement between a retracted, inoperative position and an extended position in which it punctures the membrane. An actuating piston is operatively coupled to the membrane puncturing element for moving the membrane puncturing element between its retracted and its extended positions, the actuating piston being received in a piston bore of the valve body. The valve body also includes a cartridge receiving chamber for receiving a sealed actuating gas cartridge. A cartridge puncturing device is provided for puncturing the actuating gas cartridge. An actuating gas flow passage communicates actuating gas released from the actuating gas cartridge to the actuating piston bore upon puncturing the actuating gas.