Physical change occurs when?

A substance remains chemically the same but changes in size, shape, or appearance.

Chemical reaction occurs when?

A substance changes from one type of matter into another, such as two or more substances combining to form compounds.

Oxidation

A chemical reaction involving the combination of an oxidizer such as oxygen in the air with other materials.

Potential energy

Represents the amount of energy that an object can release at some point in the future.

Stored energy

Kinetic energy

The energy that a moving object possesses.

BTU

Unit of measurement for heat.

Mechanical energy

The movement of two surfaces against each other creates heat of friction that generates heat and or sparks.

Conduction

The transfer of heat through and between solids

occurs when a material is heated as a result of direct contact with a heat source.

Convection

The heat transfer of thermal energy by the circulation or movement of a fluid

Radiation

The transmission of energy as electromagnetic waves such as light waves, radio waves, or x-rays without an intervening medium

Asphyxiation

Fatal condition caused by severe oxygen deficiency and an excess of carbon monoxide and or other gases in the blood

Autoignition

Ignition of combustion by heat but without a spark or flame

NFPA 921-2011- guide for fire and explosion investigations

Autoignition temps

The lowest temp at which a combustible material ignites in air without a spark or flame.

Back draft

Explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen-depleted confined space.

Buoyant

The tendency or capacity of a liquid or gas to remain afloat or rise

Carbon-based fuels

Fuels in which the energy of combustion derives principally from carbon. materials such as wood, cotton, coal, or petroleum.

Ceiling Jet

Horizontal movement of a layer of hot gases and combustion by-products from the center points of the plume, when a horizontal surface such as a ceiling redirects the vertical development of the rising plume.

Chemical flame inhibition

Extinguishment of a fire by interruption of the chemical chain reaction

Combustion

A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame

Compartmentation

The way that the arrangement of compartments creates or does not create series of barriers designed to keep flames, smoke, and heat from spreading from one room or floor to another

Endothermic reaction

Chemicals reaction in which a substance absorbs heat.

Energy

capacity to perform work, occurs when a force is applied to an object over a distance, or when a substance undergoes a chemical, biological, or physical transformation

entrain

To draw in and transport solid particles or gases by the flow of a fluid

entrainment

the drawing in and transporting of solid particles or gases by the flow of a fluid.

Exothermic reaction

chemical reaction between two or more materials that changes the materials and produces heat.

exposure fire

A fire ignited in fuel packages or buildings that are remote from the initial fuel package or building of origin

Fire point

Temp at which a liquid fuel produces sufficient vapors to support combustion once the fuel ignites.

Fire tetrahedron

model of the four elements/conditions required to have a fire. four sides represents fuel, heat, oxygen, and self-sustaining chemical chain reaction.

Fire triangle

used to explain the conditions/ elements necessary for combustion. representing heat, oxygen, and fuel

Flammable range

range between the upper flammable limit and lower flammable limit in which a substance can ignite

Flash point

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

flash over

rapid transition from the growth stage to the fully developed stage

Flow path

the space between at least one intake and one exhaust outlet. difference in pressure determines the direction of the flow of gases through this space.

free radical

electrically charged, highly reactive parts of molecules released during combustion reactions

fuel limited

Fire with adequate oxygen in which the heat release rate and growth rate are determined by the characteristics of the fuel, such as quantity and geometry

fuel load

the total quantity of combustible contents of a building, space or fire area including interior finish and trim, expressed in heat units or the equivalent weight in wood.

heat of combustion

total amount of thermal energy that could be generated by the combustion reaction if a fuel were completely burned.

Heat flux

the measurement of the rate of heat transfer to or from a surface, typically expressed in kilowatts per square meter

heat release rate

total amount of heat released per unit time.

hydrocarbon fuel

petroleum-based organic compound that contains only hydrogen and carbon, ma also be used to describe those materials in a fuel load.

incomplete combustion

result of inefficient combustion of a fuel, the less efficient the combustion.

Isolated flames

flames in the hot gas layer that indicate the gas layer is within its flammable range and has begun to ignite, often observed immediately before a flashover.

joule

unit of work or energy in the international system of units. terms of mechanical energy.

Kinetic energy

possessed by a moving object because of it's motion.

lower explosive limit

Lower limit at which a flammable gas or vapor will ignite and support combustion

Matter

anything that occupies space and has mass

Miscible

materials that are capable of being mixed in all properties

neutral plane

level at a compartment opening where there is an equal difference in pressure exerted by expansion and buoyancy of hot smoke flowing out of the opening and the inward pressure of cooler ambient temp air flowing in through the opening.

piloted ignition

moment a mixture of fuel and oxygen encounters an external heat source with sufficient heat or thermal energy to start the combustion reaction

polar solvents

flammable liquids that have an attraction to water, much like a positive magnetic pole attracts a negative pole

potential energy

stored energy possessed by an object that can be released in the future to perform work once a released

pyrolysis

the chemical decomposition of a solid material by heating. precedes combustion of a solid fuel.

reducing agent

fuel that is being oxidized or burned during combustion

rollover

condition in which the unburned fire gases that have accumulated at the top of a compartment ignite and flames propagate through the hot gas layer or across the ceiling.

self-heating

the results of exothermic reactions occurring spontaneously in some materials under certain conditions, whereby heat is generated at a rate sufficient to raise the temp of the material

solubility

Degree to which a solid, liquid, or gas dissolves in a solvent

specific gravity

Mass of a substance compared to the weight of an equal volume of water at a given temperature. less than 1 indicates a substance lighter than water. greater than 1 indicates a substance heavier than water

spontaneous ignition

initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material.

thermal conductivity

the propensity of a material to conduct heat within it's volume. measured in energy transfer over distance per degree of temperature

thermal energy

Kinetic energy associates with the random motions of the molecules of a material or object

often used interchangeably with heat and heat energy

thermal equilibrium

the point at which two regions that are in thermal contact no longer transfer heat between them because they have reached the same temperature

thermal layering

outcome of combustion in a confined space in which gases tend to form into layers, according to temperature, gas density, and pressure with the hottest gases found at the ceiling and the coolest gases at floor level

upper explosive limit

upper limit at which a flammable gas or vapor will ignite; above this limit the gas or vapor is too rich to burn.

vapor density

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

vapor pressure

the pressure at which a vapor is in equilibrium with it's liquid phase at a given temperature; liquids that have a greater tendency to evaporate have higher vapor pressures at a given temperature

ventilation-limited

the heat release rate or growth is limited by the amount of oxygen available to the fire

Watts

the SI unit of power or rate of work equal to 1 joule per second