Carbon dioxide (CO₂) fire extinguishers are designed mainly for fires involving flammable liquids and electrical equipment , i.e., Class B and Class C fires in the standard fire classification system.

Quick Scoop

  • CO₂ extinguishers are intended for:
    • Class B fuels: flammable liquids and gases (e.g., petrol, diesel, solvents, alcohols, propane, butane, natural gas).
* Class C: energized electrical equipment (computers, servers, control panels, lab equipment).
  • They are not suitable for:
    • Class A solid combustibles like wood, paper, cloth, plastics.
* Cooking oils and fats (Class K/F), or reactive metals (Class D).

What “types of fuels” means here

When the question asks, “carbon dioxide fire extinguisher are designed for which types of fuels,” it is really pointing to fuel classes :

  • Class B fuels:
    • Petrol / gasoline, diesel, kerosene.
* Oils, alcohols, many solvents and oil-based paints.

* Flammable gases like propane, butane, natural gas.
  • Electrical/equipment fires:
    • The burning “fuel” is insulation, components, wiring, or overheated devices while still energized, but these are grouped as electrical fires (often part of Class C in many systems).

So, in exam-style wording, the correct option is: “Class B and C fuels” (flammable liquids/gases and electrical fires).

Why CO₂ is used on these fuels

  • CO₂ displaces oxygen around the flame and cools the fire environment, smothering the fire without leaving residue.
  • Because it is non‑conductive and clean, it is safe around sensitive electrical and electronic equipment.
  • With liquids and gases, removing oxygen and slightly cooling the area works well as long as the discharge is controlled so the jet does not spread the burning liquid.

Where CO₂ extinguishers are commonly placed

  • Server rooms, IT racks, control rooms.
  • Laboratories with flammable solvents.
  • Workshops, garages, fuel storage and handling areas for liquid and gas fuels.

TL;DR:
CO₂ fire extinguishers are designed for Class B and Class C fires — fires fueled by flammable liquids and gases plus electrical equipment , not for ordinary solid combustibles or cooking oils.

Information gathered from public forums or data available on the internet and portrayed here.