NFPA 499 Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, 2008 ed. (Recmm Prac: Class of Comb Dusts and of Hazaxardous (Class) Locations for Elctr Instll in Chem Procss Areas - Amer) {325 NFC}