Enclosed processing areas (vs. outside and open processing areas) that are handling/using the following, shall be ventilated at a rate sufficient to maintain the concentration of flammable vapors within the area at or below 25% of their lower flammable limit (LFL).
- Class I flammable liquids or as OSHA calls them Category 1/2 flammable liquids,
- Class II or Class III liquids or as OSHA calls them Category 3/4 flammable liquids when they are heated to temperatures AT OR ABOVE their flashpoints
These ventilation requirements are to be confirmed by one of the following: