Is NFPA 921 a guide or a standard?
It is the Guide for Fire and Explosion Investigations
What are the six steps of the scientific method?
Recognize the need
Define the problem
Collect the data
Analyze the data
Develop a hypothesis
Test the hypothesis
What step of the scientific method is inductive reasoning?
Analyze the data
What step of the scientific method is deductive reasoning?
Test the hypothesis
What are the four parts of the fire tetrahedron?
Fuel (reducing agent)
Heat
Oxidizing agent
Uninhibited chemical chain reaction
What kind of reaction absorbs energy, an endothermic or an exothermic reaction?
Endothermic
What is heat transfer by direct contact called?
Conduction
What is heat transfer by gas flow / air movement called?
Convection
What is heat transfer by microwave energy called?
Radiation
What is a fuel controlled fire?
A fire that is limited by the amount of combustibles.
What is a ventilation controlled fire?
A fire that is limited by the amount of oxygen.
What are the stages of fire growth?
Ignition
Growth
Flashover
Fully Developed
Decay
What is a flashover?
The transition phase from growth to fully developed, where all surfaces reach ignition temperature almost simultaneously.
What is ignition of the underside of the hot gas layer called?
Flameover or rollover
What factors influence flashover conditions?
Size of the compartment
Height of ceiling
Ventilation
Amount of fuel
Layout of fuel
Location of fire in the compartment
What are fire patterns?
The physical manifestation of the affects of fire on materials.
What are the different types of fire patterns on the walls and ceiling?
Plume Generated patterns (often V shaped)
Ventilation generated patterns
Hot gas layer patterns (Line of demarcation)
What is spalling?
The separation of chunks of concrete with explosive force caused by the expansion of water (moisture) trapped in the concrete as it turns to steam
What is char?
Pyrolized carbonaceous material
What is oxidation?
Physical change in appearance of a material resulting from the combination of oxygen.
What is alloying?
Mixing two metals heated then cooled to change their properties. Often melts at a lower temperature.
What is a clean burn?
When there was enough heat to burn away all carbon deposits (soot) on a surface leaving a "clean" surface. Occurs on non-combustible surfaces.
What is soot?
Elemental carbon produced during incomplete combustion.
What is calcination?
When chemically bound water is driven out of gypsum walls by the heat of the fire.
Does a 25 Watt light bulb expand towards the fire or pull inward away from it?
Bulbs 25 watts or less pull away. Bulbs greater than 25 watts will expand towards the fire.
What causes heat shadowing?
An object blocking the travel of radiated heat.
What is a dead load?
The weight of things attached to the building, like flooring, cloumns, and roof coverings.
What is a live load?
A load that can move, like people, furniture, wind, water, and snow.
What is compartmentation?
Design features of a building that limit fire growth to the room of origin.
What are the five building construction types?
Type I - Fire resistant
Type II - Non combustible
Type III - Ordinary
Type IV - Heavy timber
Type V - Wood frame
What is ordinary construction?
Exterior walls are masonry and frame is wood.
What is wood frame construction?
Lightweight wood construction, used in apartments, houses.
What is platform frame construction?
Each floor is a seperate platform.
What is balloon frame construction?
The wall studs extend from the foundation to the roof.
What is Ohm's Law?
V=IR
(E = I x R)
What is voltage?
Pressure
What is current?
Flow
What is resistance?
Friction, opposition to the flow
What is an overload?
Power needs exceed the circuit's capacity.
Alternating Current VS Direct Current
Alternating current - the electrons flow out from the source and then back to it, alternating directions.
Direct current - electrons flow one way.
Single Phase service
Residential. Three conductors: Two insulated conductors at 120 V each, and a bare ground wire.
Three phase system
Commercial. Four conductors: Three insulated conductors (480, 240, or 208 V), and a bare ground wire.
What is the difference between grounding and bonding?
Grounding connects the system to the earth (ground). Bonding connects to systems together so the charge stays the same between them.
What is overcurrent protection?
A device that protects the system from excess current. Includes:
Circuit breakers
Plug fuses
Type S fuses
Time delay fuses
Cartridge fuses
What are the colors of residential wires?
Hot - black or red
Neutral - gray or white
Ground - bare or green
What are some methods of electrical heat production?
Resistance heating
Short circuit
Ground fault
Parting Arc
Excessive current
What is the difference between and arc and a spark?
Sparks are thrown metal particles
Arcs are brief discharges of electricity
What is arc tracking?
Arc following salts, dusts, or liquids along a path.
What is arc mapping?
Mapping out of electrical damage in a circuit.
What is static electricity?
A stationary charge caused by movement of one object against another. Lighting is a static disharge.
What are the five conditions nessecery for Static Arc Ignition?
A Means of static generation
A means of accumulating and maintaining the charge
A static discharge with sufficient energy
A fuel source
Coexistence of the arc and fuel source
Name two fuel gasses:
LP (liquid petroleum)
Natural gas
What is the difference between tanks and cylinders for LP gas?
Tanks: storage with greater than 1000 LBs water capacity.
Cylinder: Portable, usually consumer.
What are some human factors related to fire initiation in a structure?
Improper maintenance and operation
Housekeeping
Product labels, warnings, and instructions
Recalls
Violations of fire safety codes and standards
What are the age groups and types of child firesetters?
Child 2-6, curiosity
Juvenile 7-13, psychological or emotional problem
Adolescent 14-16, stress, anger, or other psychological or emotional problems
What are the four ways of right of entry?
Consent
Exigent Circumstance
Administrative Search warrant
Criminal search warrant
What are the four rules of the Miranda warning?
Right to remain silent
Any statement can be used against you
Right to an attorney
Right to have an attorney appointed if you can't afford one
- Sixth Amendment
What is spoliation?
The loss or destruction of an object or document that is evidence
What is demonstrative evidence?
Any tangible evidence that you can touch, feel, see, or smell. Any evidence that is tangible (physical).
What is documentary evidence?
Written reports or documents relevant to the case.
What is Testimonial evidence?
Verbal testimony of witnesses
Fact witness VS Expert witness
Fact witness can only testify observations and statements of fact.
Expert witness may testify their opinion.
Daubert Rule considerations:
Can the theory or technique be tested?
Has the theory or technique been peer-reviewed and published?
Is there a known or potential rate of error?
Has it gained general acceptance in the expert's field?
What is Arson?
Causing unlawful and intentional damage, by fire or explosion, to structures, vehicles, and personal property.
What are four ways you can be exposed to chemical hazards?
Absorption (surface of skin)
Inhalation
Ingestion
Injection
Should you investigate a fire alone or in pairs?
In pairs
What are some Basic Investigation Assignments for personnel?
Photography
Note Taking
Mapping
Diagramming
Interviewing Witnesses
Evidence Collection
What are some ways to document a scene?
Photographs
Video
Notes
Drawings (sketches)
What items can cause cross-contamination at a scene?
Tools
Gear (boots, gloves, etc)
Evidence Cans
Other emergency equipment
Characteristics of evidence:
Physical state: Solid, liquid, gas
Characteristics: Size, shape, weight
Fragility: Will it disintegrate or break?
Volatility: Will it evaporate?
What is an accelerant?
Any substance used to initiate or promote fire spread.
What are the most desireable collection areas for liquid accelerants?
Lowest areas
Samples of porous or fiberous material
Cloth, paper, cardboard
Seams, tears, cracks
Edges of burn patterns
Floor drains
How much space can you fill up in an evidence can?
2/3 of the can
What data should be included with the evidence?
Date and time
Case #
Location
Brief description
Name of investigator
What is the difference between Gas chromatography and Mass spectrometry?
GC seperates mixtures into their individual components
MS further analyzes the individual components
What is the point of origin?
Exact physical location where a heat source and fuel come together and a fire begins.
What is the area of origin?
The room or area where the fire began
Recommended procedure for origin determination:
Preliminary scene assessment
Preliminary fire spread scenario development
In-depth exterior examination
In-depth interior examination
Fire scene reconstruction
Fire spread scenario report
What is a competent ignition source?
One that has sufficient energy, temperature, and time to raise the first fuel to its ignition temperature.
What are the four elements of determining a fire cause?
Ignition source
Fuel first ignited
Oxidizer present
Ignition sequence