The five fire classes
Fires are classified by what is burning. Using the wrong extinguisher on the wrong class can spread the fire or electrocute the operator — matching the class to the agent is the single most important decision.
| Class | Fuel | Recommended extinguisher |
|---|---|---|
| Class A | Ordinary combustibles — wood, paper, cloth, plastics. | ABC powder, water, foam, water mist |
| Class B | Flammable liquids — petrol, diesel, oil, solvents, paint. | ABC powder, CO2, foam, clean agent |
| Class C | Live electrical equipment — panels, servers, motors. | CO2, clean agent, ABC powder |
| Class D | Combustible metals — magnesium, sodium, lithium, titanium. | D-class special powder only |
| Class K | Cooking oils and fats in commercial kitchens. | Wet chemical (K-class) |
The seven extinguisher types
Every extinguisher sold in India is certified to IS 15683 and marked with the fire classes it is rated for. Here's how each type works and where it belongs.
ABC Dry Powder
Best for: Offices, homes, warehouses, vehicles, mixed-hazard sites
How it works: Monoammonium phosphate powder breaks the chemical chain reaction of the flame and forms a smothering crust on solids.
Pros
- Handles three fire classes in one unit
- Low cost per kilogram
- Effective in wind and outdoors
Cons
- ›Powder residue damages electronics
- ›Reduces visibility during discharge
CO2 (Carbon Dioxide)
Best for: Server rooms, switchgear, laboratories, offices with electronics
How it works: Discharges pressurised CO2 that displaces oxygen and cools the fuel — leaves zero residue.
Pros
- Safe for live electrical equipment
- No cleanup or damage to electronics
- Ideal for flammable-liquid fires
Cons
- ›Not effective on Class A deep-seated fires
- ›Risk of asphyxiation in small rooms
- ›Discharge horn can cause frostbite
Foam (AFFF)
Best for: Fuel stores, workshops, garages, paint shops
How it works: Aqueous film-forming foam blankets flammable liquid to seal vapours and cools the fuel to prevent re-ignition.
Pros
- Excellent on petrol, diesel and solvents
- Also works on Class A combustibles
- Prevents flashback
Cons
- ›Conducts electricity — not for live circuits
- ›Foam residue needs cleanup
Water (Portable & Water Mist)
Best for: Textile mills, warehouses, hotels, offices with paper and wood
How it works: Cools burning solids below their ignition temperature. Water mist adds fine droplets that also displace oxygen with steam.
Pros
- Very effective on wood, paper and cloth
- Cheap to refill
- Water mist is safer near sensitive equipment
Cons
- ›Never use on live electrical or flammable liquids
- ›Water damage risk to stored goods
Wet Chemical (Class K)
Best for: Commercial kitchens, restaurants, canteens, hotel pantries
How it works: Potassium salts react with hot cooking oil to form a soapy layer (saponification) that smothers the fire and cools the oil below auto-ignition.
Pros
- Only agent rated for cooking-oil fires
- Meets NFPA 96 and IS 15683
- Cools oil to prevent re-ignition
Cons
- ›Purpose-built for kitchens only
- ›Requires post-discharge cleanup
Clean Agent (FM-200, Novec 1230, HCFC)
Best for: Data centres, control rooms, telecom cabinets, museums
How it works: Discharges an electrically non-conductive gas that absorbs heat or interrupts the combustion chain — safe for occupied spaces.
Pros
- Zero residue, safe for electronics
- People-safe at design concentration
- Discharges in under 10 seconds
Cons
- ›Higher upfront and refill cost
- ›Best in sealed enclosures
D-Class Powder (Special Metals)
Best for: Metal fabrication, magnesium/sodium/lithium handling, laboratories
How it works: Specialised dry powder (graphite, sodium chloride or copper based) smothers burning combustible metals without reacting with them.
Pros
- Only agent safe on burning metals
- Prevents violent water-reaction
- Meets IS 11833
Cons
- ›Single-purpose — not for other fire classes
- ›Higher unit cost
How to choose for your facility
- 1. Walk the site. Note every hazard: paper stores, LPG cylinders, DBs, kitchens, workshops.
- 2. Classify each hazard. Match it to Class A, B, C, D or K using the table above.
- 3. Pick the smallest safe unit. Rating (2A, 3B, etc.) must meet or exceed the hazard's requirement per IS 2190.
- 4. Place them right. Maximum travel distance is 15 m for Class A and 9 m for Class B under Indian code.
- 5. Train and drill. Every extinguisher needs at least one trained user on the shift — book a mock drill annually.
Frequently asked questions
Which fire extinguisher is best for an office?
An ABC dry powder extinguisher handles the three most likely office fires — paper and furniture (Class A), flammable liquids (Class B) and live electrical equipment (Class C). Pair it with a CO2 unit near server racks and UPS rooms.
Can I use a water extinguisher on an electrical fire?
No. Water conducts electricity and can shock the operator or short live equipment. Use CO2 or a clean-agent extinguisher for anything energised.
What extinguisher does a commercial kitchen need?
A Class K wet-chemical extinguisher for cooking-oil fires, backed by a hood suppression system. ABC powder alone will not stop a deep-fat fire from re-igniting.
How often should extinguishers be refilled?
Every extinguisher needs an annual inspection and pressure test. Refill immediately after any discharge, and a full hydrostatic test is due every 3–5 years depending on the type (IS 2190).
Need help choosing extinguishers?
We survey your premises, classify every hazard and supply certified extinguishers with installation, signage and staff training.