The term flammable liquid means any liquid which gives off flammable vapors (as determined by flashpoint from an open-cup tester, as used for test of burning oils) at or below a temperature of 80 °F. Flammable liquids are referred to by grades as follows:
(a) Grade A. Any flammable liquid having a Reid[1] vapor pressure of 14 pounds or more.
(b) Grade B. Any flammable liquid having a Reid1 vapor pressure under 14 pounds and over 81⁄2 pounds.
(c) Grade C. Any flammable liquid having a Reid1 vapor pressure of 81⁄2 pounds or less and a flashpoint of 80 °F. or below.
[CGFR 65-50, 30 FR 16657, Dec. 30, 1965, as amended by CGD 73-96, 42 FR 49023, Sept. 26, 1977; USCG-2000-7790, 65 FR 58458, Sept. 29, 2000]