Day 12: Fire Extinguishers – Types, Colour Codes, Use & PASS Method

(Basic to Advanced Explanation)**

Introduction

Fire extinguishers are the first line of defense in any fire emergency. A fire extinguisher can control or stop a fire only when:

  • The correct type is selected

  • It is used correctly

  • It is used at the early stage of fire

Using a wrong extinguisher can increase fire, cause explosion, or electric shock.

1. What Is a Fire Extinguisher

A fire extinguisher is a portable pressure vessel containing an extinguishing agent used to control small, initial-stage fires.

👉 Fire extinguishers are not for large or uncontrollable fires.

2. Main Parts / Components of a Fire Extinguisher

Every fire extinguisher has these basic components:

  • Cylinder (Body) – Stores extinguishing agent

  • Extinguishing Agent – Water, foam, CO₂, powder, etc.

  • Propellant Gas – Pressurized gas to push agent out

  • Safety Pin & Seal – Prevents accidental discharge

  • Operating Lever – Controls discharge

  • Nozzle / Hose – Directs agent to fire

  • Pressure Gauge (except CO₂) – Shows pressure condition

3. Fire Extinguisher Colour Codes (IMPORTANT)

Extinguisher TypeColour CodeWhy This Colour
WaterRed bodyStandard fire safety colour
FoamRed body + Cream bandIdentifies liquid fire use
Dry Chemical Powder (DCP)Red body + Blue bandMulti‑purpose (ABC)
CO₂Red body + Black bandGas based extinguisher
Class D (Metal)Red body + Yellow bandSpecial metal fires
Wet ChemicalRed body + Yellow bandCooking oil fires

👉 Colour bands help quick identification during emergency.

4. Types of Fire Extinguishers – Detailed Explanation

A. Water Type Fire Extinguisher

🔴 Colour Code

  • Red body (No colour band)

🔥 Fire Class

  • Class A only

📍 Where Used

  • Offices

  • Stores

  • Accommodation

  • Paper & wood areas

⚙️ How It Works

  • Water absorbs heat

  • Reduces temperature below ignition point

  • Fire stops due to cooling

❌ Why NOT to Use on Other Fires

  • Electrical → electric shock

  • Oil/gas → fire spreads

B. Foam Type Fire Extinguisher

🟤 Colour Code

  • Red body + Cream band

🔥 Fire Class

  • Class A

  • Class B

📍 Where Used

  • Fuel storage

  • Painting area

  • DG set

  • Chemical stores

⚙️ How It Works

  • Forms foam blanket over liquid

  • Cuts oxygen supply

  • Gives partial cooling

❌ Limitation

  • Conducts electricity → unsafe for electrical fires

C. CO₂ (Carbon Dioxide) Fire Extinguisher

⚫ Colour Code

  • Red body + Black band

🔥 Fire Class

  • Class B

  • Class C

📍 Where Used

  • Electrical panels

  • Switch rooms

  • Server rooms

  • Control rooms

⚙️ How It Works

  • CO₂ displaces oxygen

  • Oxygen level drops below combustion limit

  • Fire stops due to oxygen starvation

⚠️ Important Limitations

  • No cooling effect

  • Fire can re‑ignite

  • Not effective in open/windy areas

D. Dry Chemical Powder (DCP) Fire Extinguisher

🔵 Colour Code

  • Red body + Blue band

🔥 Fire Class

  • Class A

  • Class B

  • Class C

📍 Where Used

  • Construction sites

  • Workshops

  • Gas cylinder areas

  • Electrical zones

⚙️ How It Works (ADVANCED)

DCP works in three ways:

  1. Breaks chemical chain reaction

  2. Smothers fire

  3. Partially blocks heat

👉 That is why it is called ABC extinguisher

⚠️ Limitations

  • Leaves powder residue

  • Can damage sensitive equipment

  • No cooling → re‑ignition possible

E. Class D Fire Extinguisher (Metal Fire)

🟡 Colour Code

  • Red body + Yellow band

🔥 Fire Class

  • Class D only

📍 Where Used

  • Fabrication shops

  • Metal cutting units

⚙️ How It Works

  • Special powder absorbs heat

  • Forms crust on burning metal

  • Cuts oxygen contact

❌ Water / CO₂ can cause violent reaction or explosion

F. Wet Chemical Fire Extinguisher

🟡 Colour Code

  • Red body + Yellow band

🔥 Fire Class

  • Class K

📍 Where Used

  • Canteens

  • Kitchens

  • Cooking oil areas

⚙️ How It Works

  • Chemical reacts with hot oil

  • Forms soap‑like foam layer (saponification)

  • Cools oil + cuts oxygen

5. How to Select the Correct Fire Extinguisher

Fire MaterialFire ClassCorrect Extinguisher
Wood / PaperClass AWater / Foam / DCP
Petrol / DieselClass BFoam / CO₂ / DCP
ElectricalClass CCO₂ / DCP
MetalClass DClass D Powder
Cooking OilClass KWet Chemical

6. PASS Method – Why It Works

  • Pull → Activates extinguisher

  • Aim (base) → Fire energy source

  • Squeeze → Controlled discharge

  • Sweep → Covers full burning area

👉 Always keep exit behind you.

7. Inspection & Maintenance

  • Pressure gauge in green

  • Seal & pin intact

  • No damage or leakage

  • Monthly inspection

  • Refill after use

8. Legal Requirements & IS Codes (India)

📜 Factories Act, 1948 – Section 38
Fire‑fighting equipment mandatory.

📜 BOCW Act, 1996 & Rules, 1998
Fire protection required at construction sites.

IS Codes

  • IS 2190 – Selection, installation & maintenance

  • IS 15683 – Portable fire extinguishers

Conclusion

Fire extinguishers work on science, not luck.
Correct colour code recognition, fire class knowledge, and working principle save lives.

👉 Right extinguisher + right knowledge + right action = safe workplace


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