Basics of Fire: What is Fire? Fire is a chemical reaction that produces heat and light. Learn about fire behavior, the fire triangle, and how firefighters control ventilation to suppress fires.
States of Matter
There are three main states of matter:
- Solid: Wood
- Liquid: Gasoline
- Gas: Gasoline vapor
For a material to burn, it usually needs to turn into a gas. Wood and gasoline in their solid or liquid states do not burn easily.
Example of State Changes – Water
Water changes states depending on temperature:
- Solid: Ice (Below 0°C)
- Liquid: Water (Above 0°C)
- Gas: Steam (Above 100°C)
Gasoline behaves similarly. It doesn’t burn as a liquid but as a vapor. Its flash point is about -43°C, meaning it can produce flammable vapor at very low temperatures.
Volatility and Temperature
Gasoline evaporates quickly, and its evaporation rate increases with temperature. For example, on a hot day (36°C), gasoline on asphalt will produce a lot of vapor, making it highly flammable.
Solid Fuels and Thermal Decomposition
Solids also need to turn into gas before they can burn. This process is called thermal decomposition.
How to Make Wood Burn More Easily
- Dry it – Removing moisture helps it catch fire faster.
- Preheat it – Heating it before ignition speeds up burning.
- Cut it into small pieces – Increases surface area for faster combustion.
The ignition temperature of wood depends on factors like moisture and density.
What is Fuel?
Fuel is any material that stores energy and can release it through combustion. Common fuels include wood, paper, and gasoline.
The Firefighter’s Role
Firefighters mainly use water to absorb the energy of burning materials. Water also prevents vaporization and thermal decomposition, protecting surfaces from fire.
Fire Triangle and Fire Tetrahedron
Fire Triangle
Fire needs three elements to burn:
- Oxygen
- Heat
- Fuel
To extinguish a fire, remove one of these elements:
- Remove oxygen: Cover a grease fire with a lid.
- Remove fuel: Shut off a fuel source (e.g., gas valve).
- Remove heat: Use water to cool the fire.
Fire Tetrahedron
The fire triangle can be expanded into a fire tetrahedron, which includes a fourth element:
- Chemical Chain Reaction
Firefighters usually don’t directly stop chemical reactions but focus on cutting off oxygen, fuel, or heat.
Fire Behavior and Ventilation
Fire and Airflow
- Poor ventilation: Fire burns inefficiently, creating thick smoke.
- Good ventilation: Fire burns efficiently, producing less smoke.
Reading Smoke
Smoke can indicate how a fire is burning:
- Thick, fast-moving smoke: Poor ventilation, inefficient burning.
- Thin, slow-moving smoke: Good ventilation, efficient burning.
Firefighting Strategies
Firefighters manage fires by controlling ventilation and airflow inside buildings.
- Example: Engine Airflow vs. Fire Ventilation
Just like adjusting air in a car engine affects combustion, controlling air in a burning building changes fire behavior.
Example: Bunsen Burner
- More air = Blue flame (clean burn, less smoke)
- Less air = Orange flame (inefficient burn, more smoke)
Observing Fire at a Fire Scene
Firefighters analyze smoke and ventilation to predict fire behavior.
Example Photos:
１．Heavy smoke with pressure → Fire lacks oxygen.
２．Thick smoke during firefighting → Airflow is limited.
３．Smoke exiting windows → Fire is well-ventilated.
４．Roof ventilation hole → Helps remove smoke and improve fire control.
Summary
Understanding fire behavior helps firefighters make better decisions at fire scenes. Observing smoke, ventilation, and heat allows them to control fires more effectively and work safely.
Reference page: Fire Fighting skills are crucial, and everyone must improve them.
References National Fire Protection Association (NFPA)
Leave a Reply