[en] Studies were made of the purification of SF₆ vapor contaminated with air for application at the Holifield Heavy-Ion Research Facility. Liquefaction appears to be a good method for recovering about 90% of the SF₆ if it is badly contaminated (15% air), and an even greater fraction can be recovered from mixtures containing less air. In cases where liquefaction is insufficient by itself, adsorption of SF₆ on activated carbon at -50⁰F is promising. Two carbon beds, each containing about 500 lb of carbon, should be sufficient. The refrigeration system for liquefaction and adsorption would have a capacity of about 2 tons. As an alternative, the use of molecular sieves to trap out the air was investigated, but such a bed would require at least 15,000 lb of molecular sieves and very long cycle times. A large-scale desublimer was also investigated and appears workable, but it would require some development effort before the design could proceed with confidence