Chap 1 Flashcards
Fire Dyamics
__ __ describes the meeting point between fire science, materials science, fluid dynamics of gases, and heat transfer
Fire dynamics
All fires involve a heat producing chemical reaction between some type of __ and an __, most commonly __ in the air
Fuel
Oxidizer
Oxygen
Calcium hypochlorite, chlorine, ammonium nitrate, hydrogen peroxide, and methyl ethyl ketone peroxides are all..
Common oxidizers
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of a glow or a flame
Combustion
A rapid oxidation process, which is a gas phase chemical reaction resulting in the evolution of light and heat
Fire
Form of energy associated with the motion of atoms or molecules in solids or liquids that is transferred from one body to another as a result of a temp difference between the bodies
Heat
Measure of a avg kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale
Temperature
Physical science is the study of __ and __ and includes chemistry and physics
Matter
Energy
__ change occurs when a substance remains chemically the same but changes in size, shape, or appearance (water freezing (liquid to solid) and boiling (liquid to gas))
Physical
A __ __ occurs when a substance changes for one type of matter into another, such as two or more substances combining to form compounds
Chemical reaction
A material that will maintain combustion under specified environmental conditions
Fuel
Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials
Oxidizer
Anything that occupies space and has mass
Matter
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
Energy
Chemical process that occurs when a substance combines with an oxidizer
Oxidation
The rate at which fuel releases energy over time depends on many variables including:
Chemical composition
Arrangement
Density of fuel
Available oxygen for combustion
A fuels __ energy is the result of virbrations in molecules
Kinetic
Stored energy possessed buy and object that can be released in the future to perform work once released
Potential energy
Total amount of thermal energy (heat) that could be generated by the combustion (oxidation) reaction if a fuel were completely burned.
Heat of combustion
The heat of combustion is typically measured in..
Kj/g or MJ/kg
Energy possessed by a moving object because of its motion
Kinetic energy
Kinetic energy associated with the random motions of the molecules of a material or object; often used interchangeably with the terms heat and heat energy
Thermal energy
Types of energy:
Chemical
Thermal
Mechanical
Electrical
Light
Nuclear
Sound
Energy is measured in __ in the International System of Units (SI)
Joules (J)
The quantity of heat required to change the temp of 1 gram of water by 1 degree Celsius is..
4.2 joules
In the customary system, the unit of measurement for heat is the..
British thermal unit (Btu)
The amount of heat required to raise 1 pound of water 1 degree Fahrenheit is..
Btu
1055 J is equal to..
1 Btu
1 calorie is equal to..
4.19 J
Reactions that emit energy
Exothermic reactions
Reactions that absorb energy
Endothermic reactions
Unit of work or energy in the International System of Units (SI); the energy (or work) when a unit force (1 newton) moves a body through a unit distance (1 meter)
Joule ( J )
Chemical reaction between two or more materials that changes the materials and produces heat
Exothermic reaction
Chemical reaction in which a substance absorbs heat
Endothermic reaction
Chemical decomposition of a solid material by heating. Precedes combustion of a solid fuel
Pyrolysis
Physical process that changes a liquid into a gaseous state; the rate depends on the substance involved, heat, pressure, and exposed surface area
Vaporization
Moment when a mixture of fuel and oxygen encounters an external heat source with sufficient heat or thermal energy to start the combustion reaction
Piloted ignition
Initiation of combustion by heat but without spark or flame
Autoignition
The lowest temp at which a combustible material ignites in air without spark or flame
Auto ignition Temp (AIT)
The auto ignition temp of a substance is always __ than its piloted temp
Higher
Two modes of combustion
Flaming
Nonflaming
__ __ occurs more slowly and at a lower temp producing a smoldering glow in the materials surface
Nonflaming combustion
__ __ is commonly referred to as fire. Produces a visible flame above the materials surface
Flaming combustion
To draw in and transport solid particles or gases by the flow of a fluid
Entrain
Materials produced and released during burning
Products of combustion
Result of inefficient combustion of a fuel; the less efficient the combustion, the more products of combustion are produced rather than burned during the combustion process
Incomplete combustion
Fuels in which the energy of combustion derives principally from carbon
Carbon-based fuels
Petroleum based organic compound that contains only hydrogen and carbon; may also be used to describe those materials in a fuel load which were created using hydrocarbons such as plastics or synthetic fabrics
Hydrocarbon fuel
Heat and smoked are described as..
Products of combustion
Smoke is an aerosol comprised of gases, vapor, and..
Solid particulates
Smoke is a byproduct of..
Incomplete combustion
Examples of left over fuel from incomplete combustion..
Smoke and ash
Unburned fuel is smoke, and it has the potential to..
Burn
When the air supply is __, the level of incomplete combustion is __, which produces more smoke
Limited
Higher
__ is composed of a wide range of toxic and flammable gases and particulates
Smoke
Fatal condition caused by severe oxygen deficiency and an excess of carbon monoxide and/or other gases in the blood
Asphyxiation
Colorless, toxic, and flammable liquid until it reaches 79 degrees F. Above that it becomes a gas with a faint odor similar to bitter almonds
Hydrogen Cyanide (HCN)
Acts as a chemical asphyxiant. It’s molecules attach to hemoglobin, decreasing the bloods ability to carry oxygen
CO
CO combines with hemoglobin about __ times more effectively than oxygen
200
HCN is __ times more toxic than CO
35
HCN prevents the body from using __ at the cellular level
Oxygen
Colorless, odorless, heavier than air gas that neither supports combustion nor burns
CO2