Equipment · 7 min read
Fire Extinguisher Types: Which One Fits the Hazard
The letters on an extinguisher identify the kinds of fire it can handle. Matching the extinguisher to the fuel is essential; the wrong agent can make an incident more dangerous.
The fire classes at a glance
| Class | Fire type | Common extinguisher |
|---|---|---|
| A | Wood, paper, cloth, many plastics | ABC dry chemical, water mist, water |
| B | Flammable liquids and gases | ABC dry chemical, CO2 |
| C | Energized electrical equipment | ABC dry chemical, CO2, water mist listed for the use |
| D | Combustible metals | Metal-specific dry powder |
| K | Cooking oils and fats | Wet chemical Class K |
A Class C rating does not describe a fuel by itself. It means the agent is nonconductive and suitable around energized electrical equipment; once power is removed, the underlying Class A or B hazard remains.
ABC dry chemical for general business hazards
ABC dry chemical is common in offices, retail spaces, warehouses, and vehicles because it addresses ordinary combustibles, flammable liquids, and energized electrical equipment. It leaves residue that may affect sensitive equipment.
- Use for mixed A, B, and C hazards.
- Keep clear access to the extinguisher.
- Plan for cleanup and professional service after discharge.
CO2, water mist, and wet chemical
CO2 works well on Class B and C hazards and leaves no dry chemical residue, but its discharge is short and wind can reduce effectiveness. Water mist units may be listed for specific Class A and C uses. Class K wet chemical units are designed for commercial cooking operations.
Special hazards need special agents
Class D extinguishers are selected for the specific metal present, such as magnesium, titanium, sodium, or lithium. A general ABC unit is not a substitute for a listed metal-fire agent.
- Identify the metal or chemical before selecting protection.
- Keep the listed agent near the process that creates the hazard.
- Train affected employees on the site procedure and evacuation decision.
Select and maintain the installed equipment
Selection, location, and maintenance should follow NFPA 10 (2022 Edition), the equipment listing, and the requirements of your local Tennessee authority having jurisdiction. A hazard survey is safer than choosing units by size alone.
Common questions
- What does ABC mean on an extinguisher?
- It means the extinguisher is rated for Class A ordinary combustibles, Class B flammable liquids, and Class C energized electrical equipment.
- Do restaurants need a Class K extinguisher?
- Commercial cooking operations with grease-laden vapors commonly need Class K protection and a listed hood suppression system; confirm the specific requirement with the local AHJ.
- Can I use CO2 outdoors?
- CO2 can be affected by wind and has limited discharge time, so it may not be effective for an outdoor or windy location.
- Why are Class D extinguishers different?
- Combustible metals react differently from ordinary fuels and require an agent listed for the particular metal.
Last reviewed August 2026. General guidance only — your local authority having jurisdiction has the final word on your building.