Flammable Range Posted on 11th November 201530th May 2022 by ThePD (The Project Definition) Flammable Range is the percent range of vapor in air necessary for combustion to occur between the lower and upper flammability limits. Related Definitions in the Project: The HSE Management Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in HSE and tagged fire, flame, hse, safety. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.