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Origin Matrix Analysis: A Systematic Methodology for Post-Fire Investigation and

Analysis of Compartment Fires

National Fire Protection Association Conference & Expo

Las Vegas, NV – June 2014

Additional Information May Be Obtained From: Cox, Andrew. “Origin Matrix Analysis: A Systematic Methodology for the Assessment and Interpretation of Compartment Fire Damage.” Fire and Arson Investigator, Journal of the International Association of Arson Investigators (IAAI), Volume 64, Issue 1, July 2013.

and/or Andrew Cox, Special Agent Bureau of Alcohol, Tobacco, Firearms and Explosives andrew.cox@atf.gov

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIRE ORIGIN

Open Doorway

FIGURE 1 – Hypothetical Compartment Fire

2

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIGURE 2 – Pre-Flashover Compartment Fire Conditions

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE

OXYGEN

NO FIRE

OXYGEN

NO FIRE

OXYGEN

NO FIRE

Reference: Figures 5.10.2.1-4, NFPA 921 Guide for Fire and Explosion Investigations, 2014 Edition.

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIGURE 3 – Flashover Compartment Fire Conditions

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE HEAT

FUEL GASES

OXYGEN

FIRE

HEAT FUEL GASES

OXYGEN

FIRE HEAT

FUEL GASES

OXYGEN

FIRE

Reference: Figure 5.10.2.6, NFPA 921 Guide for Fire and Explosion Investigations, 2014 Edition.

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIGURE 4 – Post-Flashover Compartment Fire Conditions

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE

NO FIRE

NO FIRE

NO FIRE

HEAT FUEL GASES

HEAT FUEL GASES

HEAT FUEL GASES

X

Reference: Figure 5.10.2.7, NFPA 921 Guide for Fire and Explosion Investigations, 2014 Edition. “X” Added by Presenter.

Flames will exist at the interface between the incoming fresh air (which contains O2) and the heated fuel gases that have accumulated inside the compartment.

Flames will NOT necessarily remain “attached” or even proximate to the solid and liquid fuels in the compartment.

Reference: NFPA 921 Guide for Fire and Explosion Investigations, 2014 Edition. Color Text and Diagramming Added by Presenter.

As depicted correctly, flames will exist at the interface between escaping heated fuel gases and the fresh air outside (which contains O2).

DAMAGE

What is Damage? Changes in materials resulting from a fire incident. Why are we Interested in Damage? Gives us clues about the nature of the fire that caused them.

1. Magnitude of Damage (Severity of the Cumulative Exposure) 2. Shape of Damage (Direction of Exposure)

NOTE: This language is slightly different than the “movement” and “intensity” terminology currently used in Section 6.4 Fire Pattern Analysis in the 2011 Edition of NFPA 921.

FACTORS AFFECTING MAGNITUDE OF DAMAGE

1. Exposure Duration.

2. Exposure Intensity.

3. Material Properties.

FACTORS AFFECTING SHAPE OF DAMAGE

The principles of heat transfer and fire dynamics will influence the shape of damage.

• Fire flows (Convection).

• Line of sight (Radiation).

• Materials (Material Properties, Construction Features).

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIRE ORIGIN

Open Doorway

FIGURE 1 – Hypothetical Compartment Fire

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIGURE 5 – Pre-Flashover Compartment Fire Conditions and Associated Cumulative Damages

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE

OXYGEN

NO FIRE

OXYGEN

NO FIRE

OXYGEN

NO FIRE

DAMAGE SCALE Light Heavy

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIGURE 6 – Flashover Compartment Fire Conditions and Associated Cumulative Damages

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE HEAT

FUEL GASES

OXYGEN

FIRE

HEAT FUEL GASES

OXYGEN

FIRE HEAT

FUEL GASES

OXYGEN

FIRE

DAMAGE SCALE Light Heavy

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIGURE 7 – Short Duration Post-Flashover Compartment Fire Conditions and Associated Cumulative Damages

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE

NO FIRE

NO FIRE

NO FIRE

HEAT FUEL GASES

HEAT FUEL GASES

HEAT FUEL GASES

DAMAGE SCALE Light Heavy

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

FIGURE 8 – Long Duration Post-Flashover Compartment Fire Conditions and Associated Cumulative Damages

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE

NO FIRE

NO FIRE

NO FIRE

HEAT FUEL GASES

HEAT FUEL GASES

HEAT FUEL GASES

DAMAGE SCALE Light Heavy

Quadrant 1

Quadrant 4

Quadrant 2

Quadrant 3

Regardless of where the fire starts, fires that burn well past flashover conditions are anticipated to present similar post-fire damages.

Open Doorway

HEAT FUEL GASES

OXYGEN

FIRE

NO FIRE

NO FIRE

NO FIRE

HEAT FUEL GASES

HEAT FUEL GASES

HEAT FUEL GASES

DAMAGE SCALE Light Heavy

FIRE ORIGIN LOCATION

Quadrant 1 Quadrant 2 Quadrant 3 Quadrant 4

FIRE GROWTH STAGE

Pre-Flashover

Flashover

Short Duration Post-Flashover

Long Duration Post-Flashover

TABLE 1 Andrew Cox, Special Agent

Bureau of Alcohol, Tobacco, Firearms and Explosives

FIGURE 9 – Depiction of Fresh Air Inflow During Post-Flashover Fire Conditions.

Open Doorway

C-Side Wall in Quadrant 2

21

Complications

Quadrant 1

Section 2

Open Doorway

DAMAGE SCALE Light Heavy

Quadrant 4

FIGURE C1-1 – Pre-Flashover Compartment Fire Conditions and Associated Cumulative Damages For Origin in Quadrant 1.

HEAT FUEL GASES

OXYGEN

FIRE

NO FIRE

HEAT FUEL GASES

NO FIRE

HEAT FUEL GASES

Quadrant 1

Section 2

Open Doorway

DAMAGE SCALE Light Heavy

Quadrant 4

FIGURE C1-2 – Flashover Compartment Fire Conditions and Associated Cumulative Damages For Origin in Quadrant 1.

HEAT FUEL GASES

OXYGEN

FIRE

HEAT FUEL GASES

OXYGEN

FIRE

HEAT FUEL GASES

OXYGEN

FIRE

Quadrant 1

Section 2

Open Doorway

DAMAGE SCALE Light Heavy

Quadrant 4

FIGURE C1-3 – Short Duration Post-Flashover Compartment Fire Conditions and Associated Cumulative Damages For Origin in Quadrant 1.

HEAT FUEL GASES

OXYGEN

FIRE NO FIRE

HEAT FUEL GASES

NO FIRE

HEAT FUEL GASES

Quadrant 1

Section 2

Open Doorway

DAMAGE SCALE Light Heavy

Quadrant 4

FIGURE C1-4 – Long Duration Post-Flashover Compartment Fire Conditions and Associated Cumulative Damages For Origin in Quadrant 1.

HEAT FUEL GASES

OXYGEN

FIRE NO FIRE

HEAT FUEL GASES

NO FIRE

HEAT FUEL GASES

FIRE ORIGIN LOCATION

Quadrant 1 Section 2

FIRE GROWTH STAGE

Pre-Flashover

Flashover

Short Duration Post-Flashover

Long Duration Post-Flashover

Three Analytical Divisions

Andrew Cox, Special Agent Bureau of Alcohol, Tobacco, Firearms and Explosives

Quadrant 4

FIRE ORIGIN LOCATION

Section 1 Section 2

FIRE GROWTH STAGE

Pre-Flashover

Flashover

Short Duration Post-Flashover

Long Duration Post-Flashover

Andrew Cox, Special Agent Bureau of Alcohol, Tobacco, Firearms and Explosives Two Analytical

Divisions