The term combustible liquid means any liquid having a flashpoint above 80 °F. (as determined from an open-cup tester, as used for test of burning oils). In the regulations of this subchapter, combustible liquids are referred to by grades, as follows:

(a) Grade D. Any combustible liquid having a flashpoint below 150 °F. and above 80 °F.

(b) Grade E. Any combustible liquid having a flashpoint of 150 °F. or above.

[CGFR 65-50, 30 FR 16657, Dec. 30, 1965, as amended by CGD 73-96, 42 FR 49023, Sept. 26, 1977]