Abstract: Closure device for a pressurized reservoir comprising a two part cap, an er locking part and a lower seal part on the base of which is mounted a rigid rod constituting measuring means. A resilient disc is displacabl to seal off a lower, apertured base of a casing of the device and lies, on the face of the base directed towards an associated reservoir. A tube traversing the base of the casing and parallel to the axis of the casing has the end adjacent to the base of the reservoir which carries a valve of which the opening is controlled by the end of the rigid rod. Opening of the valve permit inlet of liquid from the reservoir to enable the rod to be used to measure the level of liquid.