(a) The term combustible liquid means any liquid having a flashpoint above 80 [deg]F. (as determined from an open cup tester, as used for test of burning oils). In the regulations of this part, combustible liquids are referred to by grades, as follows:
(1) Grade D. Any combustible liquid having a flashpoint below 150 [deg]F. and above 80 [deg]F.
(2) Grade E. Any combustible liquid having a flashpoint of 150 [deg]F. or above. [CGFR 69-53, 34 FR 11265, July 4, 1969, as amended by CGD 73-96, 42 FR 49025, Sept. 26, 1977]