Abstract: In a system in which a CO.sub.2 injection nozzle penetrates into an inverted sealed vessel from which a beverage will be served, such as a soda bottle, the preferably needle-like nozzle projects vertically through an aperture in a cap and through a normally closed hole in a septum comprising a portion of an elastomeric gasket providing a seal between the cap and the vessel. The nozzle provides a path for communication of liquid in the vessel with a source of CO.sub.2. The nozzle is formed out of a mixture of polycarbonate resin and polytetrafluoroethylene to provide for ease of insertion through the hole in the septum and into liquid in the vessel. A low friction washer between the cap and the gasket decreases torque applied to the gasket as the cap is tightened to provide compressive force.