self-sustaining process of rapid oxidation of a fuel that produces heat and light

The terms, fire and combustion, are often used interchangeably, most often used in fire. Fire is a form of combustion

self-sustaining chemical reaction yielding energy or products that cause further reactions.

The terms, fire and combustion, are often used interchangeably, most often used in fire. Fire is a form of combustion

The form of energy that raises temperature.

The energy transferred from one body to another when the temperature of the bodies are different, can be measured in the amount of work it does.

Energy component of the fire tetrahedron that causes pyrolysis or vaporization of fuels, produces ignitable vapors, provides energy for ignition, causes continuous production and ignition of vapors so the combustion process can continue.

The minimum temperature to which a fuel, in air, must be heated to start self-sustained combustion without a separate ignition source.

Describes the period when the four elements of the fire tetrahedron come together and combustion begins. It can be piloted (spark or flame) or non-piloted (self-heating). All fires are the result of some type of ignition.

minimum concentration of fuel vapor and air that will ignite.

Limits below the lower flammable limit (LFL) are called too “lean” to burn.

concentration above which combustion cannot take place.

Limits above the upper flammable limit (UFL) are called too “rich” to burn.

weight of a given volume of pure vapor or gas compared to the weight of an equal volume of dry air at the same temperature and pressure.

Vapor density less than one indicates a vapor lighter than air. Vapor density greater than one indicates a vapor heavier than air.

A. In compartmentalized fires, lower oxygen levels are needed as temperatures increase, flaming combustion can occur at post-flashover conditions.

B. In oxygen rich (above 21%) areas, materials that burn at normal levels may ignite sooner and burn faster.

C. Some petroleum materials can auto ignite in oxygen rich atmospheres.

D. Oxygen rich fires are more difficult to extinguish.

E. Oxygen is the primary oxidizing agent (in fires).

F. Normal oxygen content in room air is 21%.

G. Oxygen levels as low as 14% can support a compartmental fire.

H. Room air – 21%, Unconsciousness – 9%, Death – 6%

I. Concentration of oxygen is a safety hazard to firefighters!

J. Concentrations below 18% cause fire decrease, and concentrations below 15% generally do not support a fire (with exception of compartmental fires).

1. Carbon Monoxide ( CO )

2. Carbon Dioxide ( CO2 )

3. Hydrogen Cyanide

4. Sulfur Dioxide

5. Nitrogen

6. Other gases depending on fuel being burned

A. CONDUCTION

B. CONVECTION

C. RADIATION

heat conducted from one body to another either by direct contact or by an intervening heat medium.

It depends upon the conductor (metal – good, drywall – poor)

transfer of heat energy by the movement of air or liquid.

Heated gases rise (mushrooming).

Examples: fire traveling thru elevator shafts, stairwells, balloon frame walls. Direct flame contact is actually a form of convection heat transfer. *(transfer of heat thru air or liquid).

transfer by heat waves.

Travels thru space until it reaches an opaque object.

Example- house next to house burning may have melting siding due to the transfer of heat wave.

Major source of fire spread to exposures, important to protect exposures from radiant heat. *(transfer by heat waves).

A. Heat flows from a hot substance to a cold substance.

B. A colder substance will absorb heat until temperatures are equal.

C. Warmer, Cooler, Till Equal

A. INCIPIENT (IGNITION)

B. GROWTH/FREEBURNING

C. ROLLOVER/FLAMOVER

D. FLASHOVER

E. FULLY DEVELOPED

F. DECAY/HOT SMOLDERING FIRE

1st stage

occurs when the four elements of the fire tetrahedron come together and combustion begins.

Can be caused by a spark or flame. Can occur when material reaches its ignition temperature through self-heating.

Limited to original materials ignited. Small quantity of fire gases being generated. Flame temperature about 1000 degrees F. yet the room temperature is only slightly increased. Easiest to extinguish.

2nd stage

When the temperature of a fire gets high enough, visible flames can be seen.  .

Fire plume begins to form above the burning fuel. Begins to draw air from the surrounding space into the plume. Hot gases rise, hit the ceiling and spread until they reach the walls. As the fire grows, the overall temperature increases.

the ignition of combustible gases, which have spread thru the fire area.

Differs from flashover in that only combustible gases are burning.

One reason why firefighters stay low when entering a burning building. Flame spread movement of flame away from source of ignition.

transition between the growth stage and fully developed stage of a compartment fire.

Occurs when flame flash over the entire surface of a room. Occurs because of ALL the materials in the room reaching their ignition temperatures.

Involves all exposed combustible surfaces in the compartment. Temperatures range from 900 degrees F. to 1200 degrees F. Survivability is unlikely.

all combustible materials in the compartment are involved, releasing the maximum amount of heat and producing large amounts of fire gases.

Hot unburned gases are flowing from the compartment and igniting when they enter a space with abundant air.

DECAY/HOT SMOLDERING FIRE

as fuel is consumed, the rate of heat decreases.

Amount of fire diminishes and temperatures begin to decline.

Glowing embers can maintain moderately high temperatures.

Explosion or rapid burning of gases.

Occurs when oxygen is introduced into a smoldering fire. Often caused by improper ventilation. 

The situation can be made less dangerous by proper ventilation. Open at the highest point involved. Heated smoke and gases will be released, reducing the possibility of an explosion (back draft).

A. Stay low when entering burning buildings/rooms.

B. Check closed doors for heat.

C. Proper ventilation (top).

D. Proper gear (full bunker gear and SCBA).

E. Do not disturb the thermal layer.

F. Avoid elevators, and when using stairs, spread your weight edge to edge.

G. Do not disturb the thermal layer. (don’t apply water to the upper thermal layer, properly ventilate at the top, direct fire stream at the fire base)

CLASS A – wood, paper, rubber, plastic.

CLASS B – liquids, greases, gases.

CLASS C – live electrical equipment.

A. The tendency of gases to form into layers according to temperatures.

B. Sometimes referred to as heatstratification or heat balance.

C. Hottest gases tend to be at the ceiling and cooler gases towards the floor.

D. Thermal layering is critical to firefighting operations.

Fire streams affect on thermal layering (Heat Balance)

1. Thermal layering can be disrupted if water is applied directly into the layer without proper ventilation.

2. Results in higher temperatures at the floor level and decreased visibility.

3. Firefighters may suffer steam burns if thermal layering is disrupted