Types of Fire/FuelOxidizers

Fire Extinguishers

Fire Triangle/ Tetrahedron

Fire Trianglealso called combustion triangle

model for understanding the necessary ingredients for fire

evolved into fire tetrahedron

Elements of the Fire Triangle

Activation Energy (Heat) – to raise the material to its ignition temperature

Fuel – combustible solid , liquid or gas

Oxidizer – to sustain combustion

Fire Tetrahedronwith an additional component, chemical

chain reaction

includes the chemical chain reaction process, redox (reduction-oxidation)

same concept applies in putting out fire as that of with the fire triangle

Means of Extinguishing FireHeat Removal“cooling the fire”

water is used often which requires heat for phase change from water to steam

scraping ember from a burning structure also removes heat

turning off the electricity removes the ignition source

Means of Extinguishing FireFuel Separation“starving the fire”

can be done naturally or mechanically

performed during wildfire suppression

Means of Extinguishing FireOxidizer Removal“suffocating/smothering the fire”

water-based foams, dust and sand, or dry chemicals can be used (ex. NaHCO3, KHCO3, (NH4)H2PO4)

carbon dioxide fire extinguishers can also be used

Means of Extinguishing FireChemical Chain Reaction Inhibition“interference”

process of applying extinguishing agents

Classifications of FuelsClass A – Solids: paper, wood, plastic, etc.

Class B – Flammable Liquids: paraffin, petrol, oil, etc.

Class C – Flammable Gases: propane, butane, methane, etc.

Class D – Metals: aluminum, magnesium, titanium, etc.

Class E – Electrical Apparatus

Class F – Cooking Oil and Fat

Types of OxidizersOxygen (O2)

Air (21% O2 + 79% N2)

Air enriched with Oxygen (O2 greater than 21%)

Nitrogen Oxides (N2O)

Types of Fire ExtinguishersWater (RED)– for Class A, not suitable for

Class B

Foam (CREAM)– for Class A and B

Dry Powder (BLUE)– for Class A, B, C, and D

Carbon Dioxide (BLACK)– for Class B and E

Types of Fire ExtinguishersWet Chemical – for Class F

Metal Fires – for Class D

Halon (GREEN) – illegal; stops fire by reacting to the elements in the fire

Rules in Fighting FiresNever fight fire if:

the type of fuel /fire is unknown;

the fire is spreading rapidly beyond the spot it started

your instincts tell you not to

Using a Fire Extinguisher (PASS)Pull the pin.

Aim at the base of the fire.

Squeeze the top handle or lever.

Sweep from side to side until the fire is completely out.