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1. Basics of Fire Extinguishing
Meaning of Fire Extinguishing
- Process of stopping fire by removing heat, oxygen, fuel, or chemical reaction
- Aimed at controlling fire at the earliest stage in industrial plants
Purpose and Importance in Industrial Safety
- Protects life, equipment, and plant assets
- Prevents fire escalation and explosions
- Reduces production loss and environmental impact
- Ensures safe and continuous plant operation
Industrial Fire Risk Overview
- Chemical, pharmaceutical, and petrochemical industries handle flammable and reactive materials
- Fire risk arises from leaks, spills, electrical faults, hot work, static electricity, and process upsets
- High temperature and pressure operations increase fire severity
- Early fire control is critical to avoid major incidents
2. Principles of Fire Extinguishing
- Removal of heat
- Removal of oxygen
- Removal of fuel
- Breaking chemical chain reaction
3. Fire Extinguishing Methods
- Cooling Method
- Smothering Method
- Starvation Method
- Chemical Chain Reaction Inhibition
- Dilution Method
4. Fire Extinguishing Agents
- Water
- Foam
- Dry Chemical Powder (DCP)
- Carbon Dioxide (CO₂)
- Clean agents
- Special agents for metal fires
5. Fire Classes and Suitable Methods
Class A fires involve solid combustible materials such as wood, paper, cloth, packaging materials, and insulation.
Class B fires involve flammable and combustible liquids and Gases
Liquids an such as solvents, oils, fuels, and chemicals commonly used in process industries.
Gases such as LPG, hydrogen, methane, and propane.
Class C fires involve energized electrical equipment such as electrical panels, motors, transformers, and switchgear.
Class D fires involve combustible metals such as sodium, potassium, magnesium, and aluminum powder.
Class K/F fires involve high-temperature cooking oils and fats, typically found in industrial kitchens and canteens.
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Active Fire Extinguishing vs Passive Fire Protection
Active Fire Extinguishing
- Systems that operate manually or automatically to detect, control, and extinguish fire
- Activation required (human action or automatic detection)
- Purpose: Stop fire and limit damage
- Examples:
- Portable fire extinguishers (Water, Foam, CO₂, DCP)
- Sprinkler systems Manual
- Fire hydrant and hose reel systems
- Gas suppression systems (FM-200, CO₂, Novec)
- Foam flooding systems
- Use areas: Process units, tank farms, electrical rooms, control rooms
Passive Fire Protection
- Systems that do not extinguish fire but limit fire spread and protect structures
- No activation required, always functional
- Purpose: Fire containment, structural protection, safe evacuation
- Examples:
- Fire-rated walls, floors, and doors
- Fire-resistant cables and coatings
- Fire stopping for cable and pipe penetrations
- Structural fireproofing (intumescent or cementitious coating)
- Building compartmentation
- Use areas: Plants, warehouses, control buildings, pipe racks
Key Difference
- Active: Extinguishes or controls fire
- Passive: Restricts fire spread and protects assets
Both systems work together to ensure effective fire safety.
6. Portable Fire Extinguishers
Types and Construction
- First-aid firefighting equipment for small fires
- Common types: Water, Foam, Dry Chemical Powder (DCP), CO₂, Wet Chemical, Clean Agent
- Main components: Pressure cylinder, extinguishing agent, propellant or stored pressure, valve, safety pin, nozzle/hose, pressure gauge
Selection Criteria for Industries
- Based on fire class (A, B, C, D, E, F)
- Nature of materials handled (liquids, gases, chemicals, metals)
- Presence of live electrical equipment
- Chemical compatibility and area classification
- Compliance with statutory and safety standards
Operating Principles
- Water: Cools burning material
- Foam: Smothers fire and suppresses vapors
- DCP: Breaks chemical chain reaction
- CO₂: Displaces oxygen
- Wet chemical: Cools and seals burning surface
Limitations
- Suitable only for small, incipient-stage fires
- Limited discharge time and agent quantity
- Incorrect selection can worsen fire
- Requires trained personnel for safe operation
7. Fixed Fire Extinguishing Systems
Sprinkler Systems
- Automatically activate when temperature reaches a preset limit
- Discharge water directly over the fire area
- Used for solid combustible hazards
- Common in warehouses, raw material storage, and utility buildings
Foam Flooding Systems
- Apply foam to form a blanket over flammable liquid fires
- Suppress vapors and prevent re-ignition
- Used for flammable liquid storage and processing
- Common in tank farms, pump rooms, and loading areas
Gas Suppression Systems
- Release clean or inert gases to reduce oxygen or interrupt combustion
- Leave no residue and are safe for equipment
- Used where water damage must be avoided
- Common in control rooms, MCC rooms, laboratories, and server rooms
Fixed DCP Systems
- Discharge dry chemical powder to rapidly knock down flames
- Interrupt the chemical chain reaction
- Used for high-risk gas and liquid fires
- Common in process units, gas manifolds, and compressor areas
Application in Industrial Areas
- Selected based on fire risk, material handled, and area classification
- Provide fast and automatic fire control
- Reduce fire spread, equipment damage, and personnel exposure
Fire Extinguishing Network – Hydrant and Hose System
Fire Hydrant System
- A fixed firefighting water distribution network used for manual firefighting
- Consists of fire water tank, fire pumps, ring main piping, hydrant valves, and accessories
- Provides continuous and high-pressure water supply during fire emergencies
- Used mainly for large and spreading fires
- Commonly installed in chemical, pharmaceutical, and petrochemical plants due to high fire load
Hydrant Types
- Yard (external) hydrants installed outdoors near roads, tank farms, and process units
- Internal hydrants (landing valves) installed inside buildings, staircases, and corridors
Fire Hose System
- Flexible hose connected to hydrant or landing valve to deliver water to the fire location
- Allows controlled and directed application of water
Hose Types
- Canvas / RRL hose used for water application
- Rubber hose used where higher durability and pressure resistance are required
Hose Accessories
- Branch pipe (nozzle)
- Hose couplings
- Hose reel for first-aid firefighting
- Fire pumps
- Hydrant Monitor
Sand Buckets
Buckets filled with clean, dry sand used for first-aid fire control
Fire types controlled
Small Class B fires (flammable liquids like solvents, oils)
Spill fires on floors, bunds, pits
Hot metal / small equipment fires
Not suitable for electrical fires when equipment is live
Operating Principle
- Fire pumps supply pressurized water to the hydrant network, if pressure is reduced in hydrant piping then pump automatically started
- Water flows through hydrant valve into the hose
- Nozzle controls jet or spray pattern for effective firefighting
Application in Industries
- Cooling of equipment, structures, and storage tanks
- Fire control in open process areas
- Boundary cooling to prevent fire spread
- Support to foam and fire monitor systems
Limitations
- Requires trained manpower for operation
- Not suitable for electrical or flammable liquid fires unless used only for cooling
- Effectiveness depends on continuous water supply and pump reliability
9. Safety Precautions During Firefighting
1. Electrical Isolation
- Trip main power and local equipment before firefighting.
- Isolate non-essential circuits to avoid electric shock and sparks.
- Use explosion-proof lighting and intrinsically safe tools.
- Confirm grounding/earthing of equipment to prevent static discharge.
2. Personal Protective Equipment (PPE)
- Fire proximity suit or flame-resistant clothing (FR).
- Self-Contained Breathing Apparatus (SCBA) in all smoke/gas areas.
- Chemical-resistant gloves, boots, helmet, face shield.
- Heat-resistant gloves and splash protection for chemical fires.
3. Toxic Gas and Smoke Hazards
- Assume smoke is toxic (HCl, SO₂, NOx, CO, VOCs, solvent vapors).
- Use SCBA; never rely on cartridge masks in fire conditions.
- Monitor atmosphere for oxygen deficiency and toxic gases.
- Control wind direction; approach from upwind side only.
4. Re-Ignition Risks
- Hot surfaces, residues, and vapors can re-ignite after extinguishing.
- Cool equipment, structures, and vessels thoroughly.
- Remove fuel sources and isolate process lines.
- Continuous fire watch and gas monitoring after fire control.
10. Legal and Standard Requirements
1. Industrial Fire Safety Regulations
- Compliance with National Building Code (NBC) fire provisions.
- State Factory Rules and Fire Service Department approvals.
- Mandatory fire detection, alarm, hydrant, and fixed suppression systems.
- Emergency exits, fire separation distances, and safe storage limits.
2. Factory and Process Safety Norms
- Factories Act and Process Safety Management (PSM) requirements.
- Hazard identification (HAZOP, HIRA) for fire and explosion risks.
- Safe handling, storage, and labeling of flammable and reactive chemicals.
- Explosion-proof equipment in hazardous classified areas.
3. Inspection and Maintenance Requirements
- Periodic inspection of extinguishers, hydrants, sprinklers, foam systems.
- Pressure testing of pipelines, cylinders, and fire water networks.
- Functional testing of alarms, detectors, pumps, and emergency power.
- Record keeping of inspections, drills, training, and corrective actions.