FIR 4315, Fire Investigation Technician 1

Course Learning Outcomes for Unit III Upon completion of this unit, students should be able to:

3. Determine the nature and behavior of fire as it relates to fire dynamics. 3.1 Demonstrate an understanding of how fire dynamics change the fire scene.

4. Discuss the role of fire patterns in an investigation.

4.1 Detail how fire patterns help determine the origin of a fire.

Course/Unit Learning Outcomes

Learning Activity

3.1

Unit Lesson Chapter 3, pp. 22–40 Chapter 4, pp. 42–60 Article: “When Is an Origin and Cause Investigation Necessary?” Unit III PowerPoint Presentation

4.1

Unit Lesson Chapter 3, pp. 22–40 Chapter 4, pp. 42–60 Article: “When Is an Origin and Cause Investigation Necessary?” Unit III PowerPoint Presentation

Required Unit Resources Chapter 3: Basic Fire Science, pp. 22–40 Chapter 4: Fire Patterns, pp. 42–60 In order to access the following resource, click the link below. Marihugh, B. (2005). When is an origin and cause investigation necessary? Claims, 53(9), 32–33.

https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=18231576&site=ehost-live&scope=site

UNIT III STUDY GUIDE Advanced Fire Dynamics and Fire Patterns

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Unit Lesson

Basic Fire Science The basic need of a fire investigator to recreate what happened in the fire requires an understanding of not only the roles and responsibilities but the knowledge that comes with experience and expertise. Each investigator is responsible to continue training and keep up-to-date with best practices. The challenge when looking at this need for experience and practice is to make sure that the investigator is following the scientific method that has been discussed in the previous two units. The scientific method is used by investigators to follow a set process, which can be recreated, to determine the cause and origin of a fire, thereby, keeping the guessing and speculating out of the investigation. The scientific method is an approved process that has held up in court on numerous occasions (International Association of Fire Chiefs [IAFC], International Association of Arson Investigators [IAAI], & National Fire Protection Association [NFPA], 2019). The use of the scientific method while in court should be expected, in particular when testifying in arson cases. Reaching back into your early days of firefighting, you will recall the fire tetrahedron and the basic requirements to sustain a fire. When investigating a fire, the individual in charge will need to have a proper understanding of what it takes to create and sustain a fire. A fire is a chemical reaction that creates heat and light of variable intensities (IAFC et al., 2019). The fire investigator needs to realize that some fires do not just simply burn as this definition states; sometimes it requires actually investigating to figure out what happened. Another dynamic that needs to be looked at is the principle of heat transfer from fuel to fuel, as the fire spreads through a structure. The ways that heat transfers from fuel to fuel are described as conduction, convection, radiation, or direct contact. Once the materials in the room heat up to their individual ignition temperatures, the fire will spread to those items. During fire spread, there will be items such as window coverings that will burn before furniture. That is why we need to understand ignition temperature so we can see different patterns as a result of the fire progressing through the structure; this is all evidence of how the fire spread through the scene. The heat that is released during a fire will fill an enclosed room, and that heat in the air will reach the ignition temperature of furniture and other items in the room before the floor and walls, thereby, igniting the items in the room. This phenomenon will look suspicious to the untrained fire investigator, creating a question of how the fire moved across the room without direct flame contact. This concept is the basic firefighting concept of flashover. Flashover is the sudden combustion of all materials in a room due to increased heat from the fire.

Fire Patterns The initial observations that the investigator makes at the scene of a fire are significant in determining what happened. The investigator looks at the effects that the fire has taken on the fuel that burned as well as the patterns that were left by the burning of the fuel. This is how the fire investigator can put the fire scene back together. The review of the fire effects of what has burned and the patterns left by the spread of the fire help the investigator backtrack to the point of origin of the fire. Once the point of origin is determined, it is much easier to begin to piece together the ignition source and first fuel burned and how they came together. This is where the fire investigator will use his or her experience combined with science to make the determination of the point of origin as well as an ignition source and first fuel burned. None of this is examined without considering the fire dynamics that have occurred in the particular fire. The goal of this process is to look at the effects that fire had on the various fuels in the fire, how the burn patterns line up with the effects of the fire, and what dynamics were occurring while the fire was burning (Leihbacher, 2016). The logical next step is to look more closely at the effects of fire on the fuel and the patterns that are left after the fire. The fire investigator’s interpretation of the effects that the fire had on the items that were in the area of the fire will help to show an analysis of what happened during the fire. The goal of looking at the fire effects on the fuel will be to determine how fast and how hot the fire burned in a given area. This will help with determining the direction and intensity of the fire. The first effect that is analyzed is how much mass loss the fuel suffered.

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This can be determined by comparing similar items from an unburned room, comparing the damaged fuel to photos of the area before the fire. The part of the analysis that the investigator has to be careful with is whether the fuel deteriorated more quickly than other types of fuel due to its chemical makeup. The mass loss is a good judge of how hot the fire was in a particular area and how it affected the spread of the fire. The next area of review for the investigator is the charring of the wood products that have burned in the fire. The char that is present can show the investigator the direction and intensity of the fire as it moved through the area that is being analyzed. The old myths that charring means an accelerant was used or discolored charring implies flammable liquids have to be set aside, and an actual scientific method must be used to make sure that the use of flammable liquids can be eliminated. There are many more areas that need to be considered as the investigator continues the investigation such as how metal and concrete are impacted by the fire and the impact on gypsum wallboard, glass items, and smoke deposits. All of these combined will help to determine the direction as well as how fast and how intense the fire was as it spread through the structure. The investigator should be focused on trying to recreate the scene in a sketch or through a narrative explanation. Being able to move items that were in the fire back to their original position will help the investigator discover the cause and origin of the fire. Looking at the burn patterns that are left on items in the fire will help to move the decision-making process in a direction that allows for continued analysis of the fire. The patterns that are left after the fire can be very useful in showing the investigator where the origin of the fire is located. The need to understand that patterns alone are not conclusions when it comes to investigating a fire cannot be stressed enough in this situation. The patterns must be seen with other indicators as a whole to help the investigator find the origin of the fire. Remember that ventilation, ignition factors, fuel loads, and the air flow all impact fire patterns as the fire progresses through a structure.

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The ventilation of the structure is clearly important when discussing the scene of a fire; the investigator needs to realize that the ventilation will make the fire move in a direction that it was not moving. In addition, the use of hydraulic ventilation can destroy or distort the physical evidence that is present at the fire origin. When the investigator is looking at the scene, the whole of the scene needs to be considered when trying to determine the point of origin. What caused the fire is the goal; how the fire spread is an important part of that determination. The fire investigator must understand all of the evidence that is found at the scene of the fire, physical evidence as well as fire patterns, ignition source, and everything that is found that could have contributed to the fire occurring or spreading. The fire investigator takes on the responsibility of locating the evidence that helps with finding the cause of the fire, along with making sure that the evidence is photographed, documented, and collected in a manner that is consistent with the requirements of evidence collection. The evidence must be handled in a proper manner to avoid the possibility of a challenge to the processing of the evidence.

Conclusion The investigator needs to use all information that can be gathered from witnesses to help with returning items to their original location as well as helping to determine what may have happened. The idea behind this information gathering is to help to reach a conclusion on the hypotheses that the investigator has put forward. Through this process, the investigator will be able to put together all the information that has been gathered and determine if the final hypothesis can be proven correct based on all of the data that has been collected. Then the investigator can finally reach a conclusion.

References International Association of Fire Chiefs, International Association of Arson Investigators, & National Fire

Protection Association. (2019). Fire investigator: Principles and practice to NFPA 921 and 1033 (5th ed.). Jones & Bartlett.

Leihbacher, D. (2016). The geometry of fire investigation: Interpreting fire patterns. Fire Engineering, 169(1),

73–80. Suggested Unit Resources In order to access the following resources, click the links below. This article reviews flashover and discusses how it can be measured using simulations. Bruns, M. C. (2018). Estimating the flashover probability of residential fires using Monte Carlo simulations of

the MQH correlation. Fire Technology, 54(1), 187–210. https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=127473854&site=ehost-live&scope=site

This article reviews the techniques for evaluating fire patterns in a compartment fire. Gorbett, G. E., Meacham, B. J., Wood, C. B., & Dembsey, N. A. (2017). Structure and evaluation of the

process for origin determination in compartment fires. Fire Technology, 53(1), 301–327. https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=120737895&site=ehost-live&scope=site

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This article analyzes how concrete structures collapse under fire conditions. Lu, X., Ying, M., Li, Y., & Guan, H. (2017). Progressive collapse analysis of a typical super-tall reinforced

concrete frame-core tube building exposed to extreme fires. Fire Technology, 53(1), 107–133. https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=120737891&site=ehost-live&scope=site

This article reviews the impact that ventilation and weather have on fire conditions in an elevator shaft. Xue, L., Yuan, S., & He, Q. (2018). A comparative study on the influence of ventilation on weather- and fire-

induced stack effect in the elevator shafts of a high-rise building. Fire Technology, 54(1), 163–186. https://libraryresources.columbiasouthern.edu/login?url=http://search.ebscohost.com/login.aspx?direc t=true&db=bcr&AN=127473855&site=ehost-live&scope=site

Learning Activities (Nongraded) Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information. Before completing your graded work, consider completing the “Case Study” and “On Scene” exercises for Chapters 3 and 4. Completing these exercises will help you with your graded work. The exercises can be found on the following page numbers: Chapter 3: “Case Study,” p. 22 Chapter 3: “On Scene,” p. 40 Chapter 4: “Case Study,” p. 42 Chapter 4: “On Scene,” pp. 59-60 If you have any questions or do not understand a concept, contact your professor for clarification.