Chapter 13 Me Flashcards
The primary goal of fire cause determination is to
- Memorialize conditions found on arrival of the incident
- Identify and preserve potential physical evidence
- Document activity performed during fire suppression
- Note any unusual situations or human encounters during the incident
The process of determining the origin, cause, and development of a fire or explosion
A fire investigation
Most fire investigators are certified to meet NFPA
NFPA 1033
Fire and explosion investigations follow NFPA
NFPA 921
The first step in fire cause determination is ?
To identify the area of origin
- The exact physical location where a heat source and a fuel first interacted
- Usually determined by examining fire damage and patterns
Area of origin
As fire burns, it spreads up and out in a U or V shape pattern. Origin is usually at the base of the shape. This is also known as?
Movement pattern
-Indicated how much heat was transferred to surrounding area/objects
- May produce line of demarcation that can indicate the area closest to the point where the greatest amount of heat was produced
Intensity pattern
Carbonaceous material that has been burned or pyrolyzed and has a blackened appearance
Char
-closely related to the fire intensity pattern
-the depth of char can assist in determining the direction of fire spread
-the deeper the char the longer the fire burned in that area
The circumstances, conditions, or agencies that brought about or resulted in the incident
Cause
Evaluating the cause of a fire 3 step process
- Determine source of ignition
- Determine fuel that was first ignited
- Determine circumstances or human actions that allowed the ignition source and the fuel source to come together
If 2 or more potential causes of a fire remain the cause of the fire is considered ?
Undetermined
The energy source that caused a material to ignite
The source of ignition
Nature of the material itself
Type of material
How the material is used
Form of material
A logical, systematic examination of an item and its place and function within a system, conducted to identify and analyze the probability, cause, and consequences of potential and real failures
Failure analysis
The process of determining the origin, cause, development, responsibility, and, when required, a failure analysis of a fire or explosion
Fire analysis
Used when an individual attempting to conceal information is questioned
An interrogation
How often do fire departments respond to vehicle fires?
1 in 8 fires are vehicle fires
Fire for which the proven cause does not involve an intentional human act to ignite or spread fire into an area where the fire should not be
Accidental fire cause
Fire caused without direct human intervention or action, such as fire resulting from lightening, earthquake, and wind
Natural fire cause
Fire that is intentionally ignited in an area or under circumstances where and when there should not be a fire
Incendiary fire cause
Classification of fire when the cause cannot be proven to an acceptable level of certainty
Undetermined fire cause
The most frequent ignition cause in residential fires is?
Unattended cooking
Second most common cause in residential fires is?
Smoking materials
Third leading cause of residential fires is?
Heating
Chemical decomposition is called ______, a process in which material is decomposed, or broken down, into simpler molecular compounds by the effects of heat alone; ____ often precedes combustion
Pyrolysis
Maliciously and intentionally or recklessly starting a fire or causing an explosion
Arson
A fuel or oxidizer intentionally used to initiate a fire or increase the rate of growth or spread of a fire. Often an ignitable liquid
Accelerant
A solid or liquid fuel used to intentionally spread or accelerate the spread of a fire from one area to another.
Usually leaves a distinct fire pattern that resembles the materials shape
Trailer
National statistics indicate ___ % of structure fires are intentional
6%
What are the 6 basic motives for arson?
- Profit: to collect insurance money
- Crime concealment: to destroy evidence / to create distraction
- Excitement: thrills, attention or recognition
- Spite/revenge: involves intense feelings
- Extremism: to bring attention to a cause
- Vandalism: to cause damage for own sake
NFIRS data can be used to?
- Identify risk factors and trends
- Plan utilization of resources
- Inform state and national understanding of overall fire problems
- Direct resources and change laws
Wildland fires are influenced by environmental conditions, including?
- Topography
- Fuel load
- Wind
- Weather
The systematic pursuit of knowledge involving the recognition and definition of a problem; the collection of data through observation and experimentation; analysis of the data; the formulation, evaluation, and testing of hypothesis; and, where possible, the selection of a final hypothesis
Scientific method
Determining the area of origin requires the analysis of information from 4 sources
- First: The physical marks, or fire patterns, left by the fire
- Second: the observations reported by persons who witnessed the fire or were aware of conditions present at the time of the fire
- Third: analysis of the physics and chemistry of fire initiation, development, and growth as an instrument to related known or hypothesized fire conditions capable of producing those conditions
- Fourth: noting the location where electrical arcing has caused damage, as well as the electrical circuit involved
Cause and origin interviews are typically conducted at?
The fire scene
Wildland fires are influenced by environmental conditions, including?
- Topography
- Fuel load
- Wind
- Weather
Such fires tend to spread vertically through convection, from low vegetation to taller vegetation, and horizontally through radiation
Many accidental fires result from _____ that are not intended to start or spread fire
Human activities
The most common electrical fire is?
Misuse by the occupant
-such as overloading electrical circuits
Indicators of an incendiary fire typically fall under 5 general categories
- Disabled built in fire protection
- Delayed notification or difficulty in getting to the fire
- Accelerants and trailers
- Multiple points of origin
- Tampered or altered equipment
