Abstract: An apparatus and method for filling a CO2 system that provides carbonation and delivery of beverages to a user is provided together with a control valve for performing this method. The steps include: attaching a hose and pumping liquid carbon dioxide through an inlet fitting housed in a control valve assembly; causing the translation of a valve stem to isolate a gas port and a tank and a user port and directing the liquid carbon dioxide to a liquid port and a tank; and stopping the pumping of the liquid carbon dioxide upon reaching a pre-determined pressure and removing the hose allowing the translation of the valve stem to close the valve assembly from the atmosphere and allowing the liquid to boil to a gas to provide delivery and carbonation to the beverage.