🔥 1C — Ignition & Products of Combustion

What is piloted ignition?

Ignition that occurs when a fuel-and-oxygen mixture encounters an external heat source with enough energy to start combustion.

What is autoignition?

Ignition that occurs without an external flame or spark when the fuel reaches the temperature required for combustion.

What is autoignition temperature (AIT)?

The minimum temperature at which fuel in air must be heated to begin self-sustained combustion.

How does autoignition temperature compare with piloted ignition temperature?

Autoignition temperature is always higher than the substance's piloted ignition temperature.

What are the two modes of combustion?

Nonflaming combustion and flaming combustion.

What is nonflaming combustion?

Combustion that occurs more slowly and at a lower temperature, often producing a smoldering glow at the fuel surface.

What are examples of nonflaming combustion?

Burning charcoal and smoldering wood or fabric.

What is flaming combustion?

Combustion that produces visible flames above the fuel surface when gaseous fuel mixes with oxygen and reaches ignition temperature.

What is the relationship between the fire triangle and nonflaming combustion?

The fire triangle illustrates the elements and conditions required for nonflaming combustion.

What is the relationship between the fire tetrahedron and flaming combustion?

The fire tetrahedron more accurately represents the conditions required for flaming combustion.

What happens when an element of the fire tetrahedron is removed?

The chemical chain reaction is interrupted and flaming combustion stops, although the fuel may continue to smolder.

What are products of combustion?

New substances produced as fuel burns, including heat, smoke, gases, vapors, and particulates.

What is smoke?

An aerosol made up of gases, vapors, and solid particulates and is a product of incomplete combustion.

Why is smoke dangerous?

It can contain toxic and flammable gases, unburned fuel, particulates, and reduced oxygen concentrations.

Why is incomplete combustion common in structure fires?

Structure fires often involve multiple fuels and limited air supplies, resulting in more incomplete combustion and more smoke.

What is complete combustion?

Under ideal conditions, the entire fuel undergoes chemical conversion into new materials.

What does complete combustion of methane produce?

Heat, light, water vapor, and carbon dioxide.

Buoyancy

primarily refers to the upward force caused by density differences.