Re: NFPA 30
You're probably referring to the NEC Handbook, the NEC itself doesn?t list flashpoints of specific materials
Fuel Oil #6 (commonly called Bunker C) is a blend of heavy crude residuals and a lighter fuel oil such as #2. In any case, it?s typically a Class III Combustible rather than Flammable Liquid. It isn't a basis for Electrical Area Classification.