A device for controlling the release of gas from a pressurised container, the device comprising a plug comprising a passage therethrough, a diaphragm within said passage, wherein said 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 said plug and comprising a lance configured to move towards said diaphragm upon rotation of said screw, wherein said lance is configured to rupture or displace said diaphragm so as to allow flow of gas through said passage and out of said plug, once said screw is rotated a predetermined amount.