Class, Div and Group are characteristics of the NEC (USA Electrical Code) for hazardous locations, so I suppose that you are planning to install the equipment in an American industrial plant. To be used in dusty environments, there is no NEMA enclosure type to be directly associated with. You will need a DIP (dust-ignition proof) for Div 1 locations, listed by UL or another certification agency, considering the ignition temperature of the particular dust found there. ■