Fire Extinguishers
Fire extinguishers are handheld devices designed to extinguish or control small fires, usually in emergencies. They are not meant for large out-of-control fires that require professional fire brigade intervention. Typically, they consist of a cylindrical pressure vessel filled with an extinguishing agent and a propellant.
| Type | Fire Classes | How It Works | Characteristics |
|---|---|---|---|
| Water Extinguishers | Class A (solids like wood, paper, textiles) | Sprays water to cool burning materials and prevent re-ignition |
Effective on solids, not suitable for electrical or flammable liquid fires. Types: water jet, spray, additives, mist/fog. |
| Foam Extinguishers | Class A & B (flammable liquids) | Foam seals liquid surface to starve fire of fuel |
Suitable for wood, paper, and liquid fires such as petrol. Cream label. |
| Dry Powder Extinguishers | Class A, B, C (solids, liquids, gases) and electrical fires | Coats fuel with a layer to smother fire; does not cool |
Multi-purpose use, but causes visibility loss and breathing issues. Blue label. |
| Carbon Dioxide (CO₂) Extinguishers | Class B & Electrical fires | Smothers fire by displacing oxygen |
Leaves no residue. Suitable for electrical fires and flammable liquids. Black label. |
| Wet Chemical Extinguishers | Class F (cooking oils and fats) | Cools and chemically reacts to suppress fire | Mainly used in kitchens for deep-fat fryer fires. |
Key Notes
- Stored-pressure extinguishers have the expellant gas and agent in the same chamber; most common type.
- Cartridge-operated extinguishers have expellant in a separate cartridge and are common in industrial settings.
- Some old extinguishers used toxic agents like carbon tetrachloride, now discontinued.
- Fire extinguishers are color-coded by type for easy identification (e.g., red for water, cream for foam, blue for powder, black for CO2).
- Always select the appropriate extinguisher type for the fire class to avoid worsening the fire or creating hazards.
Fire Classifications (for choosing extinguishers)
- • Class A: Solid combustibles (wood, paper, textiles)
- • Class B: Flammable liquids (petrol, oils)
- • Class C: Gases
- • Class D: Metals
- • Class E: Electrical apparatus (not a formal class but commonly referenced)
- • Class F: Cooking oils and fats