Fire dynamics
The minimum ignition energy (MIE) of most hydrocarbons is:
.25 mJ.
What is the approximate average number of firefighters killed in the line of duty each year from 2000-2010?
100
From 2002-2011 approximately how many civilians were killed by fire each year?
3,000-4,000
How many firefighters died in the Sofa Super Store fire in 2007 due to lack of understanding of fire dynamics?
9
What is a premixed flame?
A flame where air is introduced before the point of combustion
What is a laminar flame?
A flame with a clearly defined combustion zone
What is a turbulent flame?
A flame with oxidation occurring within a generalized area but not in a steady geometric pattern
The open cup test of a liquid's flash point involves which of the following?
A heating unit being adjusted to raise the liquids temperature slowly, the operator recording liquid temperature periodically, then introducing a pilot flame across the surface, the flash point being recorded as the temperature that occurred immediately before a flash fire is witnessed
Which BEST describes the temperature scale known as Fahrenheit?
A measurement of temperature used most commonly in the United States where 32 degrees is the freezing point of water
What is the definition of a sphere?
A perfectly round ball that contains volume
NFPA 921 defines fire as which of the following?
A rapid oxidation process, which is a chemical reaction, resulting in the evolution of heat and light in varying intensities
Which BEST describes the temperature scale of Kelvin?
A scale using absolute zero, where water freezes at 273.15 degrees and boils at 373.13 degrees
What is a coordinate system?
A system using X, Y, and Z coordinates
Which BEST describes the Rankine temperature scale?
A temperature measurement scale where all molecular movement ceases at zero degrees and water freezes at 491.67 degrees
Which BEST describes the temperature scale of Celsius?
A temperature scale based on the fixed points zero degrees as the freezing point of water and 100 degrees as the boiling point
Which of the following describes an endothermic reaction?
Absorbs energy heat
Which choice describes the endothermic process of pyrolysis?
Absorbs heat/energy
What is the heat of gasification?
Amount of energy that is required to produce a unit mass of flammable vapor from a combustible that is initially at ambient temperatures
Increasing the oxygen concentration causes:
An increase in temperature
What defines a gaseous state?
Atoms that collide but are not on a fixed arrangement and assume the shape of a container
The temperature to which a mixture of fuel gas and air must be raised to initiate combustion without any external heat source is called:
Auto ignition temperature
Three known conditions that can lead to firefighter fatalities are flashover, rollover, and:
Backdraft
Flammable liquids have a flash point (per NFPA 30):
Below 100 degrees Fahrenheit
How will the presence of char affect the burning rate of a fuel?
Burning rates will be slowed, and the energy required increases
The energy required to raise one gram of water one degree centigrade is a:
Calorie
A Class K fire involves what types of materials?
Certain cooking media such as vegetable and animal fats and oils
What is the term for carbonaceous material that has been burned or pyrolyzed and has a blackened appearance?
Char
Under NFPA classification, which of the following presents the most significant threat of producing ignitable vapors at ambient conditions?
Class IA
Under NFPA classification, which of the following presents the least significant threat of producing ignitable vapors at ambient conditions?
Class IIIB
A Class D fire involves what types of materials?
Combustible metals
_________, including butadiene and neoprene, are items that have been created to match the properties of natural rubbers
Elastomers
Fire prevention professionals involved in inspections are charged with identifying conditions that:
Exceed design criteria for fire protection systems, adversely affect passive fire protection elements, and hinder active fire protection and detection elements
Under the Federal Hazardous Substances Act, ignitable liquids are classified as which of the following?
Extremely flammable, flammable, or combustible
A Class B fire involves what types of materials?
Flammable gases and flammable or combustible liquids
What is a Class 4 hazardous material per the U.S. Department of Transportation?
Flammable solid
What is the main measurement used when considering the ignitability of liquids?
Flash point
_________, are plastics created with pockets of air throughout the fuel
Foams or cellular plastics
Melting is a physical change of a substance:
From solid to liquid
The fire triangle consists of which of these components?
Fuel, heat, and oxygen
fire protection professionals must utilize a full knowledge of what topics?
Fuels and fuel geometry, detection, and suppression
Caution should be used when evaluating gases because:
Gases not listed as flammable can sometimes ignite under certain conditions
Which of the following describes an exothermic reaction?
Gives off energy heat
The _______ of a material refers to the amount of energy emitted per unit of fuel mass consumed, and it varies by fuel
Heat of combustion
_______ is used to describe the amount of energy that is required to produce a unit mass of flammable vapor from a combustible that is initially at ambient temperatures
Heat of gasification
The rate at which the heat energy is generated by burning is termed:
Heat release rate
Why do aerosols ignite so easily?
High surface to mass ratio
Cellulosic materials consist of all of the following EXCEPT:
Hydrocarbons
Liquids evolving vapors that can undergo combustion with relative ease are considered to be:
Ignitable liquids
The variables considered when determining a fuel's heat release rate include all of the following EXCEPT:
Ignition temperature
The four ideal fire growth curves include all of the following EXCEPT:
Infinite
Flame spread of the soundproofing used at the Station Night Club was known to fire-testing agencies and professionals, but was not considered during which phase?
Installation and fire code inspection
The predominant factor that led to the large number of deaths at the Cocoanut Grove fire was:
Inward swinging doors
The energy required to move one kilogram one meter per second over a distance of one meter is a:
Joule
The energy required to change a liquid to a vapor is termed what?
Latent heat of vaporization
What is a liquid's flash point?
Lowest temperature of a liquid, as determined by specific laboratory tests, at which the liquid gives off vapors at a sufficient rate to support a momentary flame across its surface
The _____ is the loss of mass over time from the fuel's surface when undergoing combustion
Mass burning flux
The _________, often referred to as the burning rate, is the rate at which the fuel is losing mass while undergoing combustion and is usually expressed in kilograms per second (kg/s) or grams per second (g/s)
Mass loss rate
Temperature is a measurement of:
Molecular movement
Which of the following sets a basis for classification of flammability of liquids?
NFPA 30
A Class C fire involves what type of materials?
Natural and synthetic materials like rubber and plastics, which are energized by electrical circuits, wiring, motors, and other equipment
Should the combined gas law be used to calculate the pressure in a BLEVE?
No, due to the high pressure and unknown quantities of vapor/liquid in the container
A Class A fire involves what types of materials?
Ordinary cellulosic materials such as wood and paper as well as similar natural and synthetic materials like rubber and plastics
What are fire investigators primarily tasked with identifying?
Origin, cause, spread, responsibility, and circumstances
Investigators must first seek the ___________ and then the ____________ of a fire in order to ascertain what happened.
Origin; cause
Smoldering combustion is characterized by which of the following?
Oxidation reaction in the solid phase that produces light, and oxidation reaction in the solid phase that produces heat
What is the major source of fuel in upholstered furniture?
Polyurethane foam
What is the term used to describe the evaluation of conditions before emergencies?
Preplanning
Study of fire dynamics helps to:
Provide safety for humans and structures
Solids undergo ______ as they chemically break down to become fuel gases that can burn in the gas phase
Pyrolysis
As altitude changes, the vapor pressure of a liquid:
Remains the same
Having definite shape and volume describes what state of matter?
Solid
Heat release rates of pool fires are dependent on which of the following?
Surface area exposed to air and heat of combustion of the fuel
The standard time-temperature curve does not take into account what kind of fuels that are common today?
Synthetic Materials
What is a liquid's fire point?
Temperature at which the substance must be raised to produce sufficient vapors to sustain burning after the initial flash
Flammability limits are dependent on which of the following?
Temperature, pressure, and oxygen concentration
The combined gas law relates what three properties?
Temperature, pressure, volume
What is the effective heat of combustion?
The actual amount of energy that is released when fuel oxidizes in air
Which BEST describes rate?
The amount of energy over time or another unit of measure
What is circumference?
The distance around a circle
What is the stoichiometric mixture?
The exact proper mixture (mass of each reactant) of chemical for a chemical reaction
Smoke is defined as:
The gases, vapors, and small particles that come off from a burning substance
What is the upper explosive limit?
The highest percentage of fuel to air where combustion can occur
The term fire dynamics refers to:
The interrelationship of fuel, heat, oxygen, chemical reactions, and the physical world
What is the lower flammable limit?
The percentage of air and fuel where the lowest amount of fuel will combust
Flame spread refers to:
The speed with which the flame front (oxidation zone) moves across a fuel's surface
Miscibility and solubility are terms used interchangeably to describe which of the following?
The tendency of materials to become solutions or to retain their initial characteristics
What is a flame?
The visible, luminous body where the oxidation reaction is occurring
What is one factor responsible for the rapid fire development in today's built environment?
The volume of commodities and synthetics
Plastics that are not cured or hardened during the manufacturing process and that soften and melt when exposed to heat are:
Thermoplastics
Plastics that have been hardened into a defined shape during manufacturing and that when heated will typically not soften or melt but produce char, are called:
Thermosetting plastics
What is the definition of volume?
Three-dimensional measure expressing total space occupied by an object or contained within a compartment and expressed in cubic measure
Nearly all metals burn under the right conditions
True
What is the definition of area?
Two-dimensional measurement to determine quantity of space contained
Which BEST describes the English system of measurements?
Uses inches, feet, and miles
Which BEST describes the metric system?
Uses increments of 10
Specific gravity of vapors and gases is termed:
Vapor density
What term describes the pressure exerted by vapors leaving the liquid surface?
Vapor pressure
The auto ignition temperature of liquids is which of the following?
Well above the boiling point, ignition absent of an ignition source, identified by raising the temperature of a liquid in a controlled environment until ignition occurs
unconfined vapor cloud explosion (UVCE) is:
an explosion in a vapor cloud that is outdoors and not confined by walls and ceiling on all sides
Thermal radiation is sometimes referred to as:
power density
