Lesson 5: FIRE

What is Fire?

is a chemical process called combustion where a material rapidly reacts with oxygen (producing heat), light, and usually smoke.

What is the Fire Triangle ?

is a foundational model in fire safety demonstrating that a fire requires three essential elements to ignite and sustain itself: oxygen, heat, and fuel. It any of these three components are removed the fire will instantly go out.

Three elements of fire

Heat, Fuel, and Oxygen

Heat

provides the energy needed to ignite a materials. The thermal energy required to raise the material to its ignition temperature so it can start burning. Ex. sparks, flames, hot surfaces, electricity.

Fuel

any combustible material that can burn. This includes solids (wood, paper), liquids (gasoline, oil), and gases (natural gas, propane)

Oxygen

acts as the oxidizing agent. A fire generaly requires the air around it to contain at least 16% oxygen to continue burning.

How the fire triangle works?

a fire only exists when all three elements are present at the same time.

Remove Heat - fire cools and stops

lowering the temparature below the ignition point stops combustian. Ex. water cooling or burning material.

Remove fuel - fire runs out of material

if there’s nothing left to burn, the fire cannot continue. Ex. clearing nearby flammable objects or shutting off a gas supply.

Remove oxygen - fire suffocates

cutting off air stops the chemical reaction. Ex. covering a fire with a lid, foam, or sand.

Classification of Fire

In the Philippines, the Bureau of Fire Protection (BFP) classifies fires into five distinct categories based on the type of fuel source involved. This classification system aligns closely with the Revised Fire Code of the Philippines (RA 9514)

Class A - Ordinary Combustibles

Fuel Source: Solid carbonaceous materials such as wood, paper, textiles, rubber, trash, and various plastics.

Common Locations: Residential living areas, corporate offices, school classrooms, and sari-sari stores.

Best Extinguisher: Water, foam, or multi-purpose dry chemical (ABC) powder.

Class B - Flammable liquids and gases

Fuel Source: Hydrocarbon compounds including gasoline, diesel, kerosene, oil-based paints, solvents, and Liquefied Petroleum Gas (LPG) tanks.

Common Locations: Gasoline stations, automotive repair bays, and residential kitchens utilizing LPG

Best Extinguisher: Carbon Dioxide (CO2), foam, or dry chemical powder.

Class C - Electrical Fires

Fuel Source: Live, energized electrical infrastructure, including overloaded extension cords, faulty appliances, circuit breaker panels, and compromised building wiring.

Common Locations: Server rooms, residential wall outlets, and crowded utility poles.

Best ExtinguisherL Carbon dioxide (CO2) or dry chemical powder. Once the power source is safely disconnected, the fire can technically transition to a Class A Fire.

Class D - Combustible Metals

Fuel Source: Volatile, highly reactive combustible metals such as magnesium, tinatnium, sodium, potassium, and aluminum shavings.

Common Locations: Inductrial chemical fcilities, manufacturing plants, and metal fabrication workshops.

Best Extinguisher: Special dry powder agents formulated uniquely for metal supression.

Class K (Or Class F in some systems) - Cooking oil fires

Fuel Source: High-temparature commercial or residential cooking oil, vegetable fats, animal grease, and lard.

Common Locations: Restaurant kitchens, fast-food chains, bakeries, and domestic cooking zones.

Best Extinguisher: Wet chemical extinguishers designed to smother the hot grease via a chemical process called saponification

What is saponification?

turning the oil into a non-flammable soap-like layer.

Stages of Fire

Incipient (Ignition), Growth, Fully Developed Stage, Decay Stage

Incipient (Ignition) Stage

The fire is just beginning or may be very small. Heat is starting to build up. Little to no smoke is produced. Only a small amount of fuel is burning. It is the easiest stage to control/stop.

Growth Stage

The fire is increasing in size and intensity. There is still enough oxygen to support rapid burning. Smoke and heat are building up quickly. Nearby aterials may start to catch fire. It can quickly turn into a fully developed fire if not controlled

Fully Developed Stage

The fire is at its strongest and hottest point. All available fuel is burning at the same time. There is heavy smoke and extreme heat. Conditions are very dangerous and survival is difficult without protection.

Decay Stage

The flames become smaller or may stop completely. The fuel is nearly finished. Smoke and heat may still be present. Dangerous gases can still remain even if flames are reduced.

RACE

Rescue, Alarm, Contain, Extinguish.

Fire Extinguisher

is a handles active safety device used to control or extinguish small fires in emergencies. It typically consists of a pressurized cylinder containing water, foam, gas, or dry chemical powder, and is operated manually to suppress flames before they become uncontrollable. Is a portable device used to put out small fires by removing one or more elements of the fire triangle.

Parts of the fire extinguisher

Discharge Hose, discharge nozzle, discharge orifice, discharge lever, discharge locking pin, data plate, body, pressure gauge, carrying handle,

Discharge Hose

the pathway that delivers the fire-extinguishing agent to the nozzle for application

Discharge Nozzle

the part that controls and focuses the extinguishing agent as it exits the fire extinguisher

Discharge Orifice

the tiny controlled opening that meters and guides the flow of the fire extinguishing agent.

Discharge Lever

the part you squeeze to activate and control the fire extinguisher

Discharge Locking Pin

it is a safety device that blocks accidental discharge of the fire extinguisher.

Data Plate (also called nameplate label)

the information tag that identifies the fire extinguisher and gives instructions for safe use and maintenance

Body

the main tank or shell that stores the extinguishing material under pressure.

Pressure Gauge

the indicator that tells you if the fire extinguisher is in working condition.

Carrying Handle

the part used to hold and move the fire extinguisher safely and securely.

Classifications of Fire Extinguisher (BFP) is based on the type of fuel feeding the fire and the chemical agent used to put it out

Dry Chemical/Dry Powder, Clean Agents, Carbon Dioxide, Foam, Wet Chemical, Smoke Detector, Fire Sprinklers, and Fire Hydrant

Dry Chemical/Dry Powder

all-purpose, refillable units filled with monoammonium phosphate. They are highly effective for suppressing Class A (wood/paper), Class B (flammable liquids), and Class C (electrical) fires by coating the fuel and interrupting the chemical reaction.

Clean Agents (E.g HFC-236fa)

a clean, ozone-friendly extinguishing agent (ODP of zero) utilized primarily for Class A, B, C, and electrical fires. It leaves zero residue and is non-conductive, making it the industry standard for protecting sensitive electronics, data centers, and museums.

Carbon Dioxide (CO2)

Ideal for sensitive electronics and class b/c fires because it displaces oxygen and leaves no residue

Foam

in the PH, foam fire extinguishers are officially identified by a red body with a blue color band or a cream/lemon yellow label. These extinguishers typically contain AFFF (Aqueous Film Forming Foam) and are best used for Class A (Solid Combustibles) and Class B (flammable liquids) fires.

Wet Chemical

contains special mixture (potassium acetate) that reacts with the oil to create a cooling, soap-like film(saponification) it smothers the fire and prevent sthe oil from splashing. Class F or Class K (cooking oils, vegetable fats, and deep fryers). Label color: yellow