Carbon dioxide (CO2) extinguishers protect areas where class B (flammable liquids and gases) or Class C (energized electrical equipment) fires could occur. They may be used indoors where winds and drafts do not affect dischage or where a clean extinguishing agent is required. Typical applications include laboratories and electronic equipment.
While these extinguishers and their refills are relatively inexpensive, keep in mind that the carbon dioxide blanket over hot material does not last very long and reignition can be a very real threat. Therefore, another extinguishing medium (BC dry chemical, CleanGuard etc.) may be more appropriate for some applications.