Fire is something most people recognise instantly — but few understand exactly what it is or how to stop it safely. As a professional fire equipment company serving businesses and institutions across Delhi NCR, we believe that understanding fire at a basic level is the first step to preventing it and responding correctly when it does occur. This guide explains what fire is, the three things it needs to survive, and the proven methods used to extinguish it.
What Is Fire?
Fire is a rapid chemical reaction called combustion. When a fuel — such as wood, paper, fabric, gas, or a flammable liquid — is heated to its ignition temperature in the presence of oxygen, the molecules break apart and recombine with oxygen, releasing energy in the form of heat and light. The visible flame is the zone where this reaction is happening most intensely. Smoke is the mixture of unburned particles and gases produced as a by-product.
Combustion is self-sustaining as long as three things remain present: fuel, heat, and oxygen. Remove any one of them and the fire goes out. This is the basis of the fire triangle — the most fundamental concept in fire safety.
The Fire Triangle
Fig. 1 — The fire triangle. Every fire requires all three sides simultaneously. Breaking any one side extinguishes the fire.
Classes of Fire
Not all fires are the same. Indian fire safety standards (aligned with IS norms and international BS EN 2) classify fires into five main classes based on the type of fuel involved. Choosing the right extinguisher depends entirely on the class of fire.
| Class | Fuel Type | Common Examples | Correct Extinguisher |
|---|---|---|---|
| Class A | Solid combustibles | Wood, paper, fabric, rubber, plastics | ABC Dry Powder · Water-CO₂ · Foam (AFFF) |
| Class B | Flammable liquids | Petrol, diesel, kerosene, paint, solvents | ABC Dry Powder · CO₂ · Foam (AFFF) |
| Class C | Flammable gases | LPG, CNG, acetylene, hydrogen | ABC Dry Powder · CO₂ (shut off gas first) |
| Class E | Electrical equipment | Switch panels, servers, wiring, UPS | CO₂ · ABC Dry Powder (non-conductive) |
| Class F | Cooking oils & fats | Deep fryers, cooking oil, ghee | K-Type (Wet Chemical) only |
⚠ Never use water on Class B, C, E or F fires — it can spread the fire or cause electrocution.
How to Extinguish a Fire
Every method of extinguishing fire works by attacking one or more sides of the fire triangle — removing fuel, removing heat, or cutting off oxygen. Here are the four principal methods used in professional fire suppression:
Fig. 2 — The four principal methods of fire extinguishment, each targeting a different side of the fire triangle.
1. Cooling (Removing Heat)
Applying water or a water-based agent absorbs heat rapidly, dropping the burning material below its ignition temperature so combustion cannot continue. Water-CO₂ extinguishers work this way. Important: never use water on electrical fires, flammable liquid fires, or cooking oil fires — it can scatter burning liquid, cause steam explosions, or electrocute the operator.
2. Smothering (Removing Oxygen)
CO₂ extinguishers displace oxygen around the fire, starving it of the air it needs. Foam (AFFF) extinguishers form a blanket over the fuel surface, cutting off oxygen contact. Fire blankets and dry sand work on the same principle for small fires or burning cooking oils.
3. Starvation (Removing Fuel)
Cutting off the fuel supply — shutting a gas valve, isolating a liquid feed, or creating a firebreak by clearing combustible material — removes the third side of the fire triangle. Starvation is the primary strategy for LPG and CNG gas fires: turn off the supply first, then extinguish residual flame.
4. Chemical Inhibition (Breaking the Chain Reaction)
ABC dry powder extinguishers and clean agent systems (such as FM200 or Novec 1230) work by chemically interrupting the combustion chain reaction at a molecular level. The active agents react with free radicals produced by the fire, preventing the reaction from sustaining itself. This is why ABC powder is the most versatile extinguisher — it tackles Class A, B, C, and electrical fires simultaneously.
How to Use a Fire Extinguisher — The PASS Method
All portable fire extinguishers are operated using the PASS technique, which stands for:
Always maintain a safe distance (typically 1.5–3 metres for ABC powder, 1 metre for CO₂). Keep your back to the exit so you can retreat immediately if the fire grows. If the fire does not go out within a few seconds, evacuate the building and call the fire department.
The Bottom Line
Fire needs fuel, heat, and oxygen to survive. Remove any one element and it stops. The right extinguisher for the job depends on the class of fire — ABC dry powder is the most versatile choice for most commercial premises, CO₂ is best for server rooms and electrical panels, and K-type wet chemical is essential for commercial kitchens. Ensuring your building has the correct type, correct quantity, and correctly placed BIS-certified extinguishers — and that your staff know how to use them — is the foundation of every effective fire safety plan.
Discreet Fire and Safety Solutions supplies BIS IS:2171 and IS:15683 certified fire extinguishers across Delhi, Noida, Gurugram and Ghaziabad, along with fire safety audits, AMC contracts, and staff training including live mock drills. Contact us for a free site survey and equipment recommendation tailored to your building's fire risk profile.