NFPA updated NFPA 499: Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas (2021 edition) with a revised definition of “combustible flyings”.
The new term is combustible fibers/flyings. They also added a definition for ignitible fibers/flyings.
The classification of combustible fibers/flyings has been clarified. These changes correlate this recommended practice with dust and electrical standards and ensure that material posing a flash-fire or explosion hazard is evaluated as hazardous (classified) locations regardless of particle size. Classification of portable electronic products (PEPs) has been included to correlate with UL 121203, Portable Electronic Products Suitable for Use in Class I and II, Division 2, Class I, Zone 2 and Class III, Division 1 and 2 Hazardous (Classified) Locations. Area electrical classifications have been revised throughout the document to correlate with the NEC electrical classification.