A closure assembly for a container, the closure assembly (10,110,210) comprising a pressurised tank (60,160), a closure attached to the pressurised tank and a plug member, wherein the plug member is attached to a casing (54,154) which includes a sleeve portion (40,140) which at least partially surrounds the pressurised tank (60,160), wherein the pressurised tank (60,160) has an interior volume and a cylindrical wall (62,162) with an open end, the cylindrical wall including an annular boss member at the open end, wherein the plug member has an annular channel arranged at a first side of the plug member adapted to sealingly engage with the annular boss member of the cylindrical wall (62,162) of the pressurised tank (60,160), the channel having inner and outer concentric side walls and a channel floor, wherein the annular channel has at least one orifice extending from one of the channel floor and outer side wall to a second side of the plug member opposite the first side, wherein the orifice is arranged to be sealed from the interior volume of the tank (60,160) when the annular channel is sealingly engaged with the annular boss member in a first closed position of the closure assembly and which is arranged to be in fluid communication with the interior volume of the tank when at least part of the annular channel is no longer engaged with the annular boss member in a second firing position of the closure assembly, wherein the orifice comprises a nozzle at the second side of the plug member for ejection of pressurised liquid from the pressurised tank (60,160), wherein the plug member includes a stopper portion adapted to project inside the open end of the cylindrical wall (62,162) of the pressurised tank (60,160) in the first closed position; characterised in that the plug member includes a first seal provided in the annular channel and adapted to seal between the stopper portion and an internal surface of the annular boss member in the first closed position, and wherein the plug member includes a second seal provided in the annular channel and adapted to seal between the plug member and an external surface of the annular boss member in the second firing position. wherein the plug member is attached to a casing (54,154) which includes a sleeve portion (40,140) which at least partially surrounds the pressurised tank (60,160), wherein the pressurised tank (60,160) has an interior volume and a cylindrical wall (62,162) with an open end, the cylindrical wall including an annular boss member at the open end, wherein the plug member has an annular channel arranged at a first side of the plug member adapted to sealingly engage with the annular boss member of the cylindrical wall (62,162) of the pressurised tank (60,160), the channel having inner and outer concentric side walls and a channel floor, wherein the annular channel has at least one orifice extending from one of the channel floor and outer side wall to a second side of the plug member opposite the first side, wherein the orifice is arranged to be sealed from the interior volume of the tank (60,160) when the annular channel is sealingly engaged with the annular boss member in a first closed position of the closure assembly and which is arranged to be in fluid communication with the interior volume of the tank when at least part of the annular channel is no longer engaged with the annular boss member in a second firing position of the closure assembly, wherein the orifice comprises a nozzle at the second side of the plug member for ejection of pressurised liquid from the pressurised tank (60,160), wherein the plug member includes a stopper portion adapted to project inside the open end of the cylindrical wall (62,162) of the pressurised tank (60,160) in the first closed position; characterised in that the plug member includes a first seal provided in the annular channel and adapted to seal between the stopper portion and an internal surface of the annular boss member in the first closed position, and wherein the plug member includes a second seal provided in the annular channel and adapted to seal between the plug member and an external surface of the annular boss member in the second firing position.