Flammable Liquid (Class I Liquid)
Any liquid that has a closed-cup flash point below 37.8 °C (100 °F), as determined by the test procedures and apparatus specified in NFPA 30. See 5.2. Flammable (Class I) liquids are subdivided into Classes IA, IB, and IC (reference NFPA 30.
API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, Third Edition, December 2012, Global Standards