A purge system and methods are described. The system allows purging of closed vessels in a precise and reproducible manner under microprocessor and sensor control. The process includes automated valves that allow repeated purge cycles with little or no operator attention. The purge parameters may be stored in memory for recall at a later time to repeat the purge process on the same or a different vessel. In a preferred embodiment the equipment and process allows for purging and desiccation of deep-sea vehicles without the need to carry compressed gas cylinders out to sea.