When There’s Smoke: A Need for Fire Causation & Origin Exists

When a fire or explosion happens, the cause is usually difficult to determine. Finding the cause of a fire requires expert investigation techniques as evidence at a fire scene is usually partially if not entirely destroyed. Forensic Analysis & Engineering’s highly qualified professional engineers and fire experts work together to “Establish Why” a fire or explosion occurred. Whether natural, accidental or incendiary, our team of highly qualified experts seek all of the factors that contributed to the incident. Forensic Analysis & Engineering’s team’s investigation efforts closely adhere to NFPA codes and other industry standards while in the course of fire investigation scenes. This results in our ability to provide you with the most accurate and comprehensive determination of the cause and origin of your fire loss.

According to FAEC’s fire expert Ken Riddleberger, CFEI, CFII, CVFI, the purpose of a fire scene examination is to search and examine the scene to uncover true facts pertinent to the cause and origin of the fire. To successfully achieve this goal the investigator needs to refer to the scientific literature for the physical constants of the various materials found at the fire scene because the investigator’s conclusions must be reached using a logical and scientific methodology.

To determine the cause of a fire, investigators rely on a number of observations and examination techniques, from telltale signs the fire flame color, to satellite imagery, and the results of various chemical tests taken on the recovered evidence.

Common Fire Observations:

Smoke

Hot smoke is extremely flammable and will ultimately dictate fire behavior. Well-ventilated, open flaming is actually a good thing; the burning process is more complete, and the solution is quite simple (wet stuff on the red stuff). Unfortunately, structure fires are rarely well ventilated. The heat gets absorbed into other materials (contents and the walls/ceiling), which, in turn, break down and begin off-gassing without flaming. It is at this point that smoke flammability begins.

Smoke volume by itself indicates very little about a fire, but it sets the stage for understanding the amount of fuels that are off-gassing within a given space. This can help you understand the relative size of the event.

Smoke leaving a building will have certain speed and flow characteristics. The combination of the two is what is frequently referred to as the smoke velocity. Smoke velocity is an indicator of the amount of pressure that has built up within the building.

The color of the smoke can also help you find the location of the hottest part of a fire. As smoke leaves an ignited fuel, it heats up other materials, and the moisture from those objects can cause black smoke to turn gray, or even white, over the rate of expansion. As smoke travels, the heavier carbon content in the smoke will fallout and become deposited on surfaces and surrounding objects. This also results in a further lightening of the visible smoke color.Fire2

Char Patterns

Depth of char is a very important indicator and can be used to show trends of fire travel over a common surface. Early publications of NFPA 921 addressed this head on:

  • Section 6.5.5 Interpretation of Char. The appearance of the char and cracks has been given meaning by the fire investigation community beyond what has been substantiated by controlled experimentation.

It has been widely stated that the presence of large shiny blisters (alligator char) is proof that a liquid accelerant was present during the fire. This is a misconception. These types of blisters can be found in many different types of fires, including those caused with accelerant, but there is no justification that the appearance of large, curved blisters is an exclusive indicator of an accelerated fire.

  • Section 6.5.5.1 It is sometimes claimed that the surface appearance of the char, such as dullness, shininess, or colors, has some relation to the use of a hydrocarbon accelerant or the rate of fire growth. Further testing has proven that there is no scientific evidence of there being any correlation, and the investigator is advised not to claim indications of accelerant or fire growth rate on the basis of the appearance of the char alone.

Other Common Indicators:

  • Line of demarcation-separates burned areas from un-burned areas
  • Flame color
  • Melting temperatures of items- Aluminum melts before Copper
  • Indication of multiple fires; incendiary fire (intentionally set) fire patterns (multiple fire locations)
  • Ceiling pattern analysis

The fire investigators at FAEC have the training, education and background to determine the origin and cause of the most challenging fires and explosions. All of FAEC’s fire investigators are Certified Fire and Explosion Investigators (CFEI) and some also are Certified Vehicle Fire Investigators (CVFI) as well, all of whom have many years of experience solving the most challenging fire loss investigations. FAEC also maintains a team of electrical engineers who further specialize in fire causation and investigation. They work in partnership with our fire origin specialists to more fully determine the specific forensic causation of the subject loss.

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