These heaters and ventilation systems are required by the NFPA to be installed in hazardous industrial locations that are exposed to explosive or ignitable chemicals. For the sake of fire safety, hazardous equipment is specially designed to not exceed the maximum temperature of the area. These heaters are ideal for oil refineries, treatment plants, paint storage units, greenhouses, and other chemical handling facilities. Class I Locations Class II Locations Class III Locations Group C & D Groups E, F, & G