Combustible liquid:
A combustible liquid means any liquid that does not meet the definition of any other hazard class and has a flash point above 60.5 °C (141 °F) and below 93 °C (200 °F).
A flammable liquid with a flash point at or above 38 °C (100 °F) that does not meet the definition of any other hazard class may be re-classed as a combustible liquid. This provision does not apply to transportation by vessel or aircraft, except where other means of transportation is impracticable. An elevated temperature material that meets the definition of a Class 3 material because it is intentionally heated and offered for transportation or transported at or above its flash point may not be re-classed as a combustible liquid.
A combustible liquid which does not sustain combustion is not subject to the requirements of this subchapter as a combustible liquid. Either the test method specified in ASTM 4206 or the procedure in appendix H of the Code of Federal Regulations Transportation (49) Part 173 may be used to determine if a material sustains combustion when heated under test conditions and exposed to an external source of flame.