Fire investigators have used geometric shapes, such as truncated cones, triangular, columnar, conical, v-shaped, u-shaped and hourglass-shaped patterns since the early 1940s (Rethoret 1945). Cox provides an example where using these two concepts demonstrated that a white area on a wall required consideration of the causal factors and contextual circumstances to adequately evaluate the damage. Investigations Institute, Florida (USA), Gorbett G, Meacham B, Wood C (2010b) Development and Assessment of a Decision Support Framework for Enhancing the Forensic Analysis and Interpretation of Fire Patterns. As the combustion zone is not attached to a fuel item or fuel package any longer, it becomes more difficult for the fire investigator to evaluate whether the damage was caused by a flame plume burning attached to a fuel item or if it is the UHCs burning detached from a fuel item due to ventilation-controlled conditions. The definition of fire patterns evolved to the visible or measurable physical changes, or identifiable shapes, formed by a fire effect or group of fire effects (NFPA 2008). Previous fire pattern research by the National Institute of Justice (NIJ), the National Institute of This damage begins to obscure some of the earlier lines of demarcation from the upper layer. The three compartments were similarly constructed measuring 11ft, 5in. The fourth part of the review focuses on the practice of using damage in fire investigation to assist in determining the area of fire origin. These factors included the location of water application, duration of fire burning prior to arrival, duration required to extinguish the fire, location of fire department entry, method of extinguishment, use of positive pressure ventilation (i.e. 2004). The definition of fire effects became observable or measurable changes in or on a material as the result of a fire (NFPA 2008). Ultimately, the locations of damage and fire patterns are compared to the causal factors from the physics of the fire, alternative causes and background information. A DOFD scale for gypsum wallboard was developed and tested based on the findings from these studies (Gorbett et al. A few of the studies also indicated that truncated cone patterns, specifically V-patterns, were located away from the true origin causing confusion for the investigators (Hoffmann et al. If the mud and tape were present to cover the drywall seams, then typically the damage is lesser at this area. Hydrostatic pressure differences at the ventilation opening cause the hot gases to exit the compartment and cooler air to be transferred into the compartment, assuming no external force is causing a greater pressure. The collection of high temperature gases within a compartment is also a source of heat flux that can cause damage. The characteristics of damage that have been reported in the literature to assist investigators in determining the cause of the fire pattern will be evaluated here. Several studies concerning ventilation-controlled fires throughout the years have introduced a concept of a ventilation factor (\( {A}_v\sqrt{h_v} \)) and illustrated the importance of ventilation openings on a fires growth by analyzing the size of ventilation openings, locations of these openings within the compartment and the shear mixing that occurs at the interface of the opening (Kawagoe 1958; Thomas and Heslden 1972; Harmathy 1972; Thomas and Bennets 1999; Utiskul 2007; Sugawa et al. a Depth of Calcination Tool Developed for Constant Pressure Measurement, (b) 6.6lbf (3kgf) Confirmation (Barnott et al. This type of damage was noted in the USFA study with specificity (Shanley et al. From this work, the researchers used gravimetric measurements of these filters to demonstrate and validate an analytical model for smoke deposition based on thermophoresis. 2003). The mixing of the air and UHCs has been shown to occur at the opening, along the gravity flow, around objects within the flow and opposite the opening along walls, specifically for doors (Abib and Jaluria 1992a, b; Quintiere and McCaffrey 1980). 2006). This study also noted that it was evident that the water did not wash all of the deposited material away from the wall or ceiling surface because the patterns had a color which was lighter than the surrounding area but not as light as a clean burn or protected area (Shanley et al. Lines of demarcation are the borders defining the differences in certain heat and smoke effects of the fire on various materials. The ventilation opening was located in the wall opposite of this furniture. Furthermore, this process has not been widely tested for reliability or validity. 2006). Thermophoretic forces between the gas and surface lining are greatly dependent on the burning regime of the fire. Learn. 1980). 1977; Brannigan et al. This same damage near the drywall seams was identified in the Claflin study (2014) (Fig. The first of which is the standoff distance between the fuel item burning and the damaged surface. 2006; Hicks et al. More experienced fire investigators would mentor less experienced fire investigators, unfortunately in some cases, passing on what has since become realized as a collection of myths (NFPA 2014). Flashcards. Cue 5-increased area and magnitude of damage under the window. However, ventilation becomes one of the more prominent influences of damage when the compartment has transitioned into ventilation-controlled conditions. National Fire Protection Association, Quincy (USA), NFPA (2014) NFPA 921-Guide for Fire and Explosion Investigations. 2013). A substantial degree of damage is often times found directly adjacent to or opposite of window and door openings. There has been much work towards developing methods for calculating the radiant heat transfer from a plume to secondary objects outside of the plume with varying accuracy. Other damage to walls commonly reported, that are not associated with the truncated cone discussion, are referred to as smoke and heat horizons. However, if the mud and tape are not present and the compartment transitioned to a ventilation-controlled fire, the damage around these sources of ventilation may be significant (Claflin 2014; Mealy et al. Wood and gypsum wallboard (drywall) were the only materials that had sufficient literature to review in this context. 98 0 obj <>/Filter/FlateDecode/ID[<91F1DAB77B67D07957F283104A2F7883><83C49AA1AA664D4BAE5EBD1CBF89369B>]/Index[80 32]/Info 79 0 R/Length 87/Prev 597082/Root 81 0 R/Size 112/Type/XRef/W[1 2 1]>>stream Given these findings, damage cues 1, 2 and 3 are used as the most accurate damage cues for classifying a fire pattern generated by upper layer. 2006; Hicks et al. Abib A, Jaluria Y (1992a) Turbulent penetrative and recirculating flow in a compartment fire. The areas of damage and boundaries of those areas are often referred to as areas and lines of demarcation. Shanley et al. Several examples are provided along with engineering calculations such as: Inverted Cone Patterns; Column-shaped Patterns; V-shaped or Cone Patterns; U-shapes and Double U-shaped Patterns; The legal and science professions are currently scrutinizing forensic science, which is forcing the nation to question the disciplines scientific foundation (NIJ 2009). Investigations Institute, Florida (USA), Hicks W, Gorbett G, Hopkins M, Kennedy P, Hopkins R, Thurman T (2008) Full-Scale Single Fuel Package Fire Pattern Study. 2013). Fire Pattern Indicator, U or V Fire pattern that resembles a U or V shape and indicates the direction of fire progression in that area. Incident heat flux to wall, floor, or ceiling surfaces is dependent on the HRR of the fuel and standoff distance between the flame plume and the surface of interest. 2008). Key aspects of a decision support framework include identification of decision objectives, attributes (criteria) which are important to the decision problem and the weighting (importance) of the attributes to the decision given the uncertainty and variability in the data and relationship between the attributes. Dissertation, The University of Edinburgh, Kahneman D, Tversky A (1974) Judgment under uncertainty: heuristics and biases. Cue 2-increased area and magnitude of damage across from the opening. For example, the location of fire department entry, the use of positive pressure ventilation and the change of ventilation upon arrival should result in fire patterns that are similar to ventilation-generated fire patterns. A series of nine full-scale studies, funded by the National Institute of Justice, were conducted with ignitable liquid fuel spilled on carpeted and vinyl flooring with varying ventilation scenarios (Mealy et al. 2012). Each fire pattern study has the three most common flashover correlations summarized within Additional file 1. Selecting a final area of origin hypothesis. 2014). Noted differences with this level line of demarcation are damage in corners and near ventilation openings. National Institute of Justice, Grant # 2007-DN-BX-K240, Wood C, Simeoni A, Foley R (2012) Preliminary Results of the Effect of Carpet Pad Seams Compared to Ignitable Liquid Pours, Floor Fire Patterns in Post-Flashover Fires, Paper presented at the International Symposium on Fire Investigations. For more information, contact: Fire Findings L.L.C. Examples of Fire Patterns: "Inverted Cone". The researchers report this deviation in the fire patterns was caused by the burning, melting and dripping of the plastic electronic appliance next to the television (Hoffmann et al. If they can find out which way the fire was moving, and they combine that with the layout of the land and the wind directions for . This combination of using damage in the context of the fire behavior variables was new to the profession in 1955, but then apparently lost for the next 40years. 1997). This deconstruction of the problem provides a gap analysis of the current processes and identifies areas where future work is needed. 2010). Pearson, New Jersey (USA), DeHaan J (1987) Are Localized Burns Proof of Flammable Liquid Accelerants? The authors declare that they have no competing interests. Cue 5-lines of demarcation are angled emanating from the fuel item. plastics, wood) will result in either physical or chemical changes. The results confirmed that the use of this method was appropriate for these three test fires (Shanley et al. Heat shadowing and protected areas were shown to assist investigators in determining that the fire did not originate behind certain contents (Shanley et al. This warning was strengthened over the years to say irregular, curved, or pool shaped patterns on floors and floor coverings should not be identified as resulting from ignitable liquids on the basis of observation of the shape alone (NFPA 2001). long lines of damage appearing to spread the fire from one location to another). NFPA, Quincy, MA, pp 3.1253.133, Quintiere J, McCaffrey B (1980) The Burning of Wood and Plastic Cribs in an Enclosure. Fire and Arson Investigator Journal of the International Association of Arson Investigators 11:1518, Crofton, MD, Kirk P (1969) Fire Investigation. 1 and 2). He reports a 5.7% success rate of determining the correct quadrant where the fire was started. 11). It was once thought that narrow V-patterns were produced by a fast developing fire and wide V-patterns were produced by a slow developing fire (Kennedy and Kennedy 1985). The following statistics were accumulated while performing the literature review and summarized here for ULG fire patterns. Six tests were completed with television sets placed inside a wood entertainment center. [1] It is called U shape development because of the shape of the letter U in correlation to a graph, skills developed in the U shaped fashion begin on a high position on a graph's Y-axis. The implication is that common furnishing items, which normally require a minimum irradiance approaching 20kW/m2 for ignition, would stand little hazard of fire involvement if placed at least 1m away from the initial source (Babrauskas 1981). These results were found to be statistically significant using a chi square distribution yielding a p-value of 0.006. The principle behind fire patterns was first linked to the need to trace the fire spread (Rethoret 1945). The developing fire and the variables influencing the fire scenario control heat transfer in a compartment, including the location, the intensity and duration of the heat transfer. These geometric shapes are still currently used within the profession, however, many of the myths associated with their interpretations have fallen into disrepute. Because the varying DOFD serves as the foundation for all later interpretations, ultimately leading to an origin determination, more research is needed to either demonstrate that investigators reliably identify varying DOFD or the industry needs processes that are shown to be reliable and valid (Gorbett and Chapdelaine 2014). This project consisted of 10 separate full-scale tests to produce the first scientifically controlled and recorded research into the formation, growth and investigation of patterns produced in fires. However, this has not been demonstrated through proficiency testing done to determine the area of origin based on visible observations (Carman 2008; Tinsley and Gorbett 2013). fire pattern creation stems from the amount of heat flux on a materials surfaceover the duration of the fire.vi,vii,viii,ix Therefore, the fire plume and the various fluxes generated by it are the primary means of pattern production in the early stages of a fire. The scientific method is proclaimed throughout the document as the generic process for investigating a fire, but no specific procedural details are outlined on how to implement it into practice for analyzing fire patterns. The reported velocity of flows from wind-assisted or mechanically induced flows through the bottom of a door and window can be on the order of 10m/s (22 mph) (Kerber and Walton 2005; Madrzykowski and Kerber 2009). This was the first time that a distinction was drawn between damage caused by the fire (fire effects) and clusters of fire effects that may have characteristics that assist the fire investigator (fire patterns). International Association of Arson Investigators 61:3844, Crofton, MD, McCaffrey B, Quintiere J (1977) Buoyancy-driven counter-current flows generated by a fire source. Photograph of a Plume-Generated Fire Pattern (fire origin was located at the base of this damage-test conducted at EKU by author). Therefore, the dynamic forces that drive flow through an opening are based on fluid dynamics and fluids in motion at the ventilation opening interface and the discharge characteristics of the opening. heat, soot) begin to influence the materials within the compartment. ATF, Ammendale, MD, Pattern (2015) Merriam Webster Dictionary. NFPA, Quincy, MA, Drysdale D (2011) An Introduction to Fire Dynamics, 3rd edn. %PDF-1.5 % The rooms were instrumented with heat flux gauges, thermocouples and gas sampling probes. Duxbury, California (USA), Cooke R, Ide R (1985) Principles of Fire Investigation. The first reference that fire investigators were able to use depth of calcination for origin determination can be found in 1955, where the authors of this text relate depth of char methods to that which can also be done to spoiled plaster (drywall) or concrete may indicate the point of origin by a similar means of determining greatest damage (Straeter and Crawford 1955). Carman reports on three tests conducted at ATFs fire research laboratory in a follow-up to his 2008 work (Carman 2010). As one early fire investigation text declares, patterns are the cornerstone of all fire investigation because of their universal applicability (DeHaan 1983). These included that soot deposition can be used to aid in the area of origin determination and that the clean burn area size was proportional to the fire size (Wolfe et al. As the temperatures are higher in the room of origin it is expected that an upper layer will be affecting those surfaces higher in elevation. Fire Research Station Note No. For example, many materials must reach certain temperatures to melt, deform, or fail. 80 0 obj <> endobj There are only two studies that have focused solely on the geometric shapes from plumes (Hicks et al.

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