My hot oil heat transfer fluid has a flash point of 249F. We operate the hot oil heater at 550F. NFPA 497 (2017)paragraph 3.3.4 indicates that it is a Class IIIB liquid and paragraph 126.96.36.199 indicates that area classification is seldom needed. NFPA 497 (2017)paragraph 188.8.131.52.(1) indicates that it should be Class I, Division 2. Which one is correct?