methods and apparatus for efficient utilization of a cryogen in inerting of solid and molten metals are presented . one method and apparatus of the invention includes providing a source of liquid cryogen ; transporting the liquid cryogen through a conduit connected to the source of liquid cryogen to a gas / liquid separator , wherein a portion of the liquid cryogen transforms into gaseous cryogen en route ; transporting a portion of the liquid cryogen through a first conduit connecting the gas / liquid separator to a cryogen supply nozzle ; transporting the gaseous cryogen through a second conduit connecting the gas / liquid separator to a cryogen supply nozzle ; and flowing at least a portion of liquid cryogen and at least a portion of the gaseous cryogen through the cryogen nozzle separately and near a surface of solid or molten metal . thus liquid that transforms into gaseous cryogen en route from storage is not vented and not wasted , but used in inerting of solid or molten metals .