CFR › Title 27 › Part 21 › §21.2427 CFR §21.24Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy link(a)Formula. To every 100 gallons of ethyl alcohol of not less than 195 proof add:(b)Authorized use. Restricted to fuel use, comparable to specially denatured alcohol “Use Code No.” 611, 612, 613, 620, and 630.