Basic Fire Methodology Flashcards
Testing the hypothesis can be done through different forms, but in the fire investigative field, it is most often done by testing and ____
Deductive reasoning
More likely true than not (more than 50 percent likely to be true)
Probable
Feasible (often used when two hypotheses hav the same level of certainty)
Possible
Not enough certainty to be considered an expert opinion
Suspected
The investigator has to approach every incident with an open mind and without presumptions or ____
Expectation Bias
Every ____ must fully understand the fundamental properties of fire and fire development to determine accurately the origin and cause of any fire or explosion event
Fire Investigator
Four components must be present for a fire to occur (also known as the fire tetrahedron)
Fuel, oxidizing agent, heat, uninhibited chemical chain reaction
The most common fuels an investigator will encounter are ____
Organic fuels, which contain carbon (e.g. wood, plastics and petroleum products
Most fires require an ____ , like oxygen from the air, to support the combustion process
Oxidizing agent
The rate at which heat is released, known as the ____; is measured in joules per second or watts
Heat release rate
An ____ provides a self-sustaining event that continues to develop fuel vapors and sustain flames even after the removal of the ignition source
Uninhibited chemical chain reaction
During a fire, materials may ____ as a result of being heated
Change their physical state
Changes in physical state due to being heated include ____ and ____
Melting; vaporization
Flames produced during the combustion process can be categorized as either ____ or ____
Pre-mixed; diffused
If a fire has a limited amount of air for combustion, an increase in the amount of visible products of combustion, such as ____, ____ and ____ will occur
Soot, smoke; carbon monoxide
The ____ should not be relied on as an indicator of the material burning
Color of smoke
Fluid flows, heat transfer, ignition and flame spread, fuel packages, heat flux and the distinction between fuel-controlled fires and ventilation-controlled fires are all components of ____
Fire dynamics
Fluids include both liquids and gases, but in fires, we are generally focused on ____
Gas flows
____ naturally moves from areas of higher temperature to lower temperature through heat transfer, measured as ____ per unit of time
Heat energy; energy flow
The study of the science, methodology and practice of temperature measurement
Thermometry
The ____ of a given fire will be a reflection of the potential energy
Total fuel load
The total fuel load does not determine ____
How fast the fire develops once ignition occurs
The ____ within a fuel package are factors that influence the speed and intensity of a particular fire, as well as the best method of fire extinguishment
Specific fuel items
The power of a fire is determined by calculating its ____, the energy being released by the individual fuels being consumed
Heat release rate (HRR)
The power of the fire is measured in either ____ or ____
Watts; kilowatts
Generally, larger flame heights correspond to higher rates of heat release, but this holds true only when the fuel packages being compared are in the ____ in a compartment
Same relative location
An ____ can be defined as either smoldering or flaming or as either piloted or autoignition
Ignition source
____ may also ignite without a piloted ignition source if the gas-air mixture is heated to its autoignition temperature
Flammable gases
____ are not only dependent on the individual fuel properties, but also the position and orientation of the fuel surfaces
Rates of flame spread
When a material melts, it flows with gravity, usually colleting on a ____ below the object and allowing the flames to spread away from the burning fuel to other fuel packages
Horizontal surface
The rate of flame spread may be accelerated through ____ produced by other burning objects and from the upper gas layers of a compartment fire
Radiant heat
Whereas flame spread involves the movement of fire across the surface of a fuel item, fire spread refers to ____ of other fuel items and ____ that may be present or located nearby
Ignition; packages
A ____ is when the size of the fire is controlled by how much fuel is burning
Fuel controlled fire
After ____, the room is said to be fully involved and progresses from fuel-controlled burning to ventilation-controlled burning
Flashover
One of the major determining factors in whether flashover will occur is the presence of a ____ with sufficient energy to radiate downward to involve exposed fuel packages
Hot gas layer
The process of air or gases being drawn into a fire, plume or jet
Air entrainment
The lowest temperature at which a combustible material ignites in air without a spark or flame
Autoignition temperature (AIT)
A relatively thin layer of flowing hot gases that develops under a horizontal surface (e.g. ceiling) as a result of plume impingement and the flowing gas being forced to move horizontally
Ceiling jet
a chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a flow or flames
Combustion
Heat transfer to another body or within a body by direct contact
Conduction
Heat transfer by circulation within a medium such as a gas or a liquid
Convection
A flame in which the fuel and air mix or diffuse together at the region of combustion
Diffusion flame
Reaction characterized by or formed with evolution of heat
Exothermic reaction
The detailed study of how chemistry, fire science and the engineering disciples of fluid mechanics and heat transfer interact to influence fire behavior
Fire dynamics
The lowest temperature at which a volatile combustible substance continues to burn in air after its vapors have been ignited (as when heating is continued after the flash point has been determined)
Fire point
A transition phase in the development of a compartment fire in which surfaces exposed to thermal radiation reach ignition temperature more or less simultaneously and fire spreads rapidly throughout the space, resulting in full room involvement or total involvement of the compartment or enclosed space
Flashover
A material that will maintain combustion under specified environment conditions
Fuel
A fire in which the heat release rate and growth rate are controlled by the characteristics of the fuel, such as quantity and geometry and in which adequate air for combustion is availabe
Fuel-controlled fire
Any articles that are capable of burning
Fuel items
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
Fuel load
A collection or array of fuel items in close proximity with one another such that flames can spread throughout the array
Fuel package
A form of energy characterized by vibration of molecules that is capable of initiating an d supporting chemical changes and changes of state
Heat
The amount of heat necessary to raise the temperature of a unit mass 1 degree, under specified conditions
Heat capacity
The measurement of the rate of heat transfer to a surface, expressed in kilowatts/m2, kilojoules/m2 sec, or Btu/ft2 sec
Heat flux
The rate at which heat energy is generated by burning
Heat release rate (HRR)
The transport of heat energy from one point to another caused by temperature difference between those points
Heat transfer
The line where the flow of the hot gas and cooler air changes
Neutral plane
A substance that promotes oxidation during the combustion process
Oxidizing agent
The conversion of a material from one state of matter to another that is reversible and does not change the chemical composition of the material
Phase change
The column of hot gases, flames and smoke rising above a fire; also called convection; column, thermal updraft or thermal column
Plume
