The collected physical evidence is carefully labeled and placed in containers for transportation back to the laboratory. Cox discussed the importance of separating data and interpreting that data when discussing this new method. He argues that damage should only be viewed as data and that the researcher should “resist the temptation to interpret the meaning of individual fire effects and fire patterns separately.” . The source matrix gives the user a diagram of the compartment of interest, where the user must darken those parts of the diagram where the damage is identified and then this damage must be compared with the expected damage depending on the expected damage to the vents . Cox provided a process to better interpret the fire dynamics of the compartment that is still under development and has not undergone a major field test for user application.
Therefore, different locations in the compartment can have different temperatures at different times due to the fire. However, fuel-controlled fires can be assumed to occur that will cause higher temperatures at the plume interface with any building or surface of the contents. Heat flows to the walls within a compartment with a top layer of gas range from 5 to 40 kW / m2, depending on variable temperatures between 200 and 600 ° C (Tanaka et al. 1985). Three studies were completed in 2005 and 2008, along with a training seminar to analyze the development of the burning pattern in fires after the turnaround . This study focused on the impact of ventilation on fire cartridges and the ability of fire investigators to use fire cartridges to determine the quadrant of the room where the fire started. The test was performed in a single compartment measuring 14 by 12 by 8 feet high (4.26 m × 3.66 m × 2.4 m) that looked like a living bedroom with an open door to the outside.
Since 1992, NFPA 921 has established the de facto standard of care for the profession of fire investigation, but lacks specific procedures for determining origin . The only procedural aspect that NFPA 921 offers for the use of fire patterns for origin determination is analysis of heat and flame vectors . The scientific method is proclaimed throughout the document as the generic fire investigation process, but no specific procedural details are described on how to implement it in practice to analyze fire patterns.
Clean fire damage located on the wall opposite the doorway spread from the floor to the ceiling and had an estimated base of 6 feet. This study pointed out that flashover and ventilation were one of the most misunderstood variables, changing the production of “normal” fire patterns. In particular, “patterns were observed that indicated areas of intense combustion but were far from the point of origin and were found to be only for ventilation effects. This was observed in the chambers, which had sudden discharge conditions where clean combustion areas were under windows far from the origin. Heat and flame vector analysis was used as a process within these studies to document the direction of fire displacement, the location and extent of fire patterns, as well as a process of confirming the area of origin.
All three tests are best instrumented with three total heat flow meters, one radiant heat flux meter, three gas sensors and gas velocity probes . The tests can be burned in the whole room participation status for 7, 140 and 111 s respectively. Each test fire caused damage along the wall opposite the doorway, increasing with the longer duration of burning the entire room. This damage area in front of the door had sloping demarcation lines that stretched from floor to ceiling. Only in the source area was a clean burn area with the fire with the shortest burning time in the entire room. Clean fire damage also occurred along the wall at the doorway in the fire with the longest burning time throughout the room.
However, most of these documents also warned not to rely solely on the use of visible observations and encouraged the investigator to take samples of fire residues for analysis. Many of the early fire research texts discussed the concept of low combustion and the importance of evaluating the floor for fire patterns (Kennedy 1959; Kirk 1969). In these texts, the authors emphasized that the investigator should evaluate low burns for potential sources of ignition, but not necessarily linked the damage to flammable liquids. Kirk was even very adamant that the investigators would not conclude that the damage came from a flammable liquid, since “such an interpretation was often incorrect in another way.” . Mealy et al. designed a tool based on Ngu’s earlier work, which used a force meter with a attached hexagonal key probe .
During this phase of the compartment fire, sufficient UHCs are produced, but they lack sufficient oxygen for combustion. As a result, temperatures in the top layer will also vary depending on local variations in this combustion. A significant amount of damage is often found right next to or opposite window and doorways. As the fire continues to develop, the radius Fire Expert Investigator California of the ceiling and the gases of the top layer begin to have a more intense effect on the surfaces closest to the plume. Later in the development of a fire, an upper layer begins to form and heat begins to transfer to the wall and ceiling surfaces. The energy generated by fire, and thus the temperatures and depth of the top layer, vary depending on the time .
These two studies demonstrated a relatively predictable response of visible damage to the drywall, in accordance with the variable DOFD identified in NFPA 921 (Figures 4 and 5). Firefighters have historically relied on damage as a means of concluding where a fire started. This review evaluates the historical and current literature on this topic, with a specific emphasis on research conducted over the past 80 years regarding fire patterns. The concept of fire patterns for this assessment is divided into four components that best help assess effectiveness in determining an area of origin. The first evaluated part is the ability to assess the variable degree of fire damage along the surfaces of the compartment and its contents.