A device for controlling the release of gas from a pressurized container includes a plug comprising a passage therethrough and a diaphragm within the passage. The diaphragm is configured to initially prevent flow of gas through said passage, and is rupturable or displaceable to allow gas to flow through said passage once said diaphragm is ruptured or displaced. The device further comprises a screw located within the plug and comprising a lance configured to move towards said diaphragm upon rotation of the screw. The lance is configured to rupture or displace the diaphragm so as to allow flow of gas through the passage and out of the plug, once the screw is rotated a predetermined amount.