Class A- Water, Foam, Dry Powder, and CO2 Extinguishers. Class B- Foam, Dry Powder, and CO2 Extinguishers. Class C- Dry Powder, or CO2 Extinguishers. Class D- Dry Powder or CO2 Extinguishers. Class K- CO2 Extinguishers. -There are also special powders for Class D metal fires. -CO2 extinguishers have no "Post Fire Security" and the fire could re-ignite.