Essentials of Fire Fighting Edition 5, Fire Behavior - Terms

Matter

Anything that which has mass and occupies space

What are the three states fuel can be in?

Gas, Liquid, Solid

Exothermic Heat Reduction

Chemical reaction between two or more materials that changes the materials and produces heat, flames & toxic smoke

Endothermic Heat Reaction

Chemical reaction in which a substance absorbs heat energy.

Combustion

An exothermic chemical reaction that is a self-sustaining process of rapid oxidation of a fuel, that produces heat & light

Fire Tetrahedron

Model of the four elements/conditions required to have a fire. The four sides of the tetrahedron represent fuel, heat, oxygen, and chemical chain reaction.

Potential Energy

Stored energy by an object that can be released in the future to perform work

Kinetic Energy

the energy possessed by a moving object

Surface to mass ratio

Surface area of the fuel in proportion to the mass

Autoignition Temperature

Same as ignition temperature except that no external ignition source is required for ignition because ther material itself has been heated to ignition temp

Fire Tetrahedron

Oxygen, Fuel, Heat, Self sustained chemical chain reaction

Conduction

Physical flow or transfer of heat energy from one body to another through direct contact or an intervening medium from the point where the heat is produced to another location or from a region of high temperature to a region of low temp

What are the two types of ignitions?

Piloted Ignition and Auto-Ignition

Piloted Ignition

Occurs when a mixture of fuel and oxygen encounter an External Heat Source

Auto-Ignition

Occurs without any external ignition

Convection

the transfer of heat energy by the circulation or movement of a liquid or gas, usually in an upward direction to a solid surface

Radiation

transfer of thermal energy from one body to another body at a lower temp through intervening space by electromagnetic waves such as infrared thermal waves, & by electromagnetic waves

Sources of Heat Energy

Chemical, Mechanical, Electrical, Light, Nuclear. Most common sources are Chemical, Mechanical, Electrical

Specific Gravity

the density of a substance relative to the density of water at a given temp.

Specific Gravity less then 1

A substance lighter then water, flouts

Specific Gravity greater then 1

A substance heavier than water, sinks

Vaporization

the process by which a liquid or solid changes to a gas. The rate of vaporization depends on the substance involved, heat, and pressure

Flash Point

Minimum temperature at which a liquid gives off enough vapors to form an ignitable mixture with air near the liquid's surface.

Fire point

Temperature at which a liquid fuel produces sufficient vapors to support combustion once the fuel is ignited. The fire point is usually a few degrees above the flash point.

Miscible

Materials that are capable of being mixed

Solubility

a measure of how much solid, liquid, or gas can dissolve in a given solvent at a given temperature

Normal Air consists of what percent of Oxygen

21%

Whats the lowest oxygen % at which Materials can ignite & burn

14%

Flammable Range

The range between the upper flammable limit and lower flammable limit in which a substance can be ignited.

Proximity and Orientation

Solid fuel relative to the source of heat also affects the way it burns.

Carbon Monoxide (CO)

Colorless, odorless, poisonous & flammable gas produced by the incomplete combustion of carbon or organic fuels.

Carbon Dioxide (CO2)

Colorless, odorless, heavier than air gas that neither supports combustion nor burns.

Incipient Stage

First stage of the burning process in a confined space in which the substance being oxidized is producing some heat but the heat has not spread to other substances nearby. During this phase, the oxygen content of the air has not been significantly reduced

Growth Stage

The early stage of a fire during which fuel & oxygen are virtually unlimited. This stage is characterized by a rapidly increasing release of heat

Thermal Layering

Outcome of combustion in a confined space in which gases tend to form into layers, according to its temperature, with the hottest gas found at the ceiling & the coolest gases at floor level

Rollover

Condition in which the unburned combustible gases released in a confined space (such as a room or aircraft cabin) during the incipient or early steady-state phase and accumulate at the ceiling level. These superheated gases are pushed, under pressure, awa

Flashover

Stage of a fire at which all surfaces and objects within a space have been heated to their ignition temperature and flame breaks out almost at once over the surface of all objects in the space.

Fully Developed Stage

Stage of burning process where energy release is at maximum rate and is limited only by availability of fuel and oxygen.

Decay

Stage of fire development when fuel is consumed & temps decreased. this stage the gose from ventilation-controlled to fuel controlled

Backdraft

Instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen-depleted confined space. The stalled combustion resumes with explosive force. It may occur because of inadequate or improper ventilation pro

Pyrolysis

Chemical decomposition of a fuel through the action of heat

Class A Fires

Involve ordinary combustibles such as textiles, paper, plastics, rubber and wood. These can be easily extinguished with water by cooling.

Class B Fires

Involve flammable and combustible liquids, gasses, and greases such as alcohol, cooking oils, gasoline, lubricating oils, and liquefied petroleum gas. Extinguished with appropriately applied foam and/or dry chemical agents.

Class C Fires

Involve energized electrical equipment. Household appliances, computers, transformers, electric motors, & overhead transmission lines are typical sources for Class C Fires. Turn off the power and it becomes a Class A fire.

Class D Fires

Involve combustible metals such as magnesium, lithium, potassium or sodium. Identified by bright white sparks and emissions from combustion process. Special Class D Dry Chemical agents are used.

Class A, B, C, D,K Fires

A=wood, paper, cloth (ord. combustibles)
B=burning liquids (grease, oil, gas & solvents)
C=switches, motors & elec. equip.
D=combustible metals (aluminum, magnesium)
K=cooking appliances involving combustible cooking products like veg. or animal oils & fa

Class K Fires

Involve combustible cooking oils such as vegetable or animal fat oils that burn at extremely high temperatures. Wet Chemicals are used in the extinguishing systems and portable extinguishers or these fires.

Auto Ignition Temperature (AIT)

The temperature at which a mixture of flammable vapors and air will ignite without flame or spark. also, it is the temperature an ignition source must possess to ignite a given mixture of flammable vapors.

British Thermal Unit (BTU)

The quantity of heat that is required to raise the temperature of one pound of water one degree Fahrenheit. A measure of heat quantity.

Fire

A rapid oxidation chemical reaction that produces heat and light.

Chemical Change

A change in a substance that alters chemical and sometimes physical properties.

Class A fire

A fire that involves ordinary combustible materials such as wood, paper, vegetation, fabrics, and so forth.

Class B fire

A fire involving flammable or combustible liquids.

Class C fire

Class C fires involve energized electrical equipment.

Class D fire

Involves combustible metals such as sodium, magnesium and titanium.

Class K fire

Fires Involving cooking greases and animal fats.

Conduction

The transfer of heat within a substance with no visible motion in the substance: transfer of heat by molecular contact.

Convection

The transfer of heat by motion of heated gaseous or liquid matter.

Endothermic

A chemical reaction in which the involved substance takes in heat.

Exothermic

A chemical reaction in which the involved substance gives off heat. This is the most common type of chemical reaction

Explosive Range

The percentages in the atmosphere of a flammable or combustible vapor that is neither too lean nor too rich to burn: those concentrations of vapor between the lower explosive limit (LEL) and upper explosive limit (UEL).

Flammable Range

The percentages in the atmosphere of a flammable or combustible vapor that is neither too lean nor too rich to burn: those concentrations of vapor between the lower explosive limit (LFL) and upper explosive limit (UFL).

Fire Point

The temperature to which a flammable liquid must be heated to produce a sufficient quantity of vapors to burn continuously.

Fire Retardant

A substance that retards the spread of fire.

Flammable

A substance capable of igniting easily and burning at ordinary temperatures.

Flash Point

The lowest temperature at which the vapor of a combustible liquid can be ignited in air

Gas

Matter that had no definite shape, no definite volume, but has a mass. Will take the shape and volume of the container that holds it, but can also be condensed to have a smaller volume

Heat of Vaporization

The amount of heat necessary to convert a liquid to a gas.

Ignition Temperature

The temperature to which a substance must be heated to initiate self-sustained combustion.

Liquid

A phase of matter that has no specific shape, but a definite volume, and forms to the shape of whatever is holding it

Miscibility

The degree to which two liquids can mix.

Oxidation

The chemical reaction of oxygen with other substances

Radiation

The direct transfer of energy by electromagnetic waves.

Solid

A state of matter that has definite shape and volume that does not change under normal conditions.

Specific Gravity

The ratio of a substances weight to the weight of and equal volume of water. Used to determine if a substance will sink or float in water.

Spontaneous Heating

Self-ignition caused by oxidation of organic materials.

Temperature

A measure of heat intensity.

Vapor Density

Describes the density of gases in relation to air.

Products of Combustion

heat, flame, smoke and gases

Vapor Density less then 1.

Lighter then air, Rises

Vapor Density of Air.

1

Combustion yields

Heat and Light

Energy

capacity to perform work

Mechanical Heat Energy

Generated by friction or compression movement of two surfaces against each other creates heat of friction.

Passive Agents

Are materials that absorb heat but do not participate actively in the combustion reaction.

Fuel (Reducing agent)

fuel is the material or substance being oxidized or burned in the combustion process.

What has the most impact on firefighters?

Smoke and Heat

Plume

Hot gases raise and mix with cooler air, hot gases moves horizontally across the ceiling.

Factors that Affect Fire Development

Fuel type, Availability, Ambient Conditions, Ventilation, Compartment geometry, Thermal properties of the enclosure