The Nilfisk CFM CD 3507 EXP explosion-proof vacuum is ideal for larger combustible dust jobs, including process-integration to collect dust at the source or as part of a central vacuum system used throughout the plant. It is CSA-approved for use in Class I, Group D and Class II, Groups E, F, and G environments and constructed of non-sparking stainless steel. Nilfisk Industrial Vacuums,,(800) 645-3475. products