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Chapter Eighteen Part I– Fire Investigations

Chapter Eighteen Part I– Fire Investigations. FRSC 8104 Criminalistics II Professor Bensley. FRSC 8104 – Chapter 18 Objectives. After studying this chapter, the student should be able to:  Recognize the basic components required to have a fire

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Chapter Eighteen Part I– Fire Investigations

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  1. Chapter Eighteen Part I– Fire Investigations FRSC 8104 Criminalistics II Professor Bensley

  2. FRSC 8104 – Chapter 18 Objectives After studying this chapter, the student should be able to:  Recognize the basic components required to have a fire  Understand how fire scene evidence is recognized, collected, and analyzed

  3. FRSC 8104 – Chapter 18 Outline • Fire Investigation Techniques - Introduction • Why not the word arson? • Types of Fuel • Gases • Liquids • Solids Simple Pyrolysis

  4. FRSC 8104 – Chapter 18 Outline • Physical Properties of Fuels • Flammable • Combustible • Flash Point Flash Point Lab Apparatus

  5. Flash Point of Butanol • Normal butanol has a flash point in a closed cup of 29°C. It is therefore extremely flammable on a hot summer day when its vapors come in contact with a flame or spark. 

  6. FRSC 8104 – Chapter 18 Outline • Flame Point • Ignition Temperature • Turpentine has an auto-ignition temperature of 253°C. Therefore, it will not burst into flame by itself at ambient temperature.

  7. FRSC 8104 – Chapter 18 Outline • Explosive Limits • Ethylene has a lower explosive limit of 2.7% and an upper limit of 36%. Therefore, in the presence of an ignition source, if the concentration of the gas is less than 2.7% or greater than 36%, there is no risk of explosion. But if the concentration of the substance is between these two limits, the mixture could explode. The concentration of the product in the air must be kept under its lower explosivelimit, for example by using appropriate ventilation.

  8. FRSC 8104 – Chapter 18 Outline • Vapor Density • Heat of Combustion (Heat Output) • Flashover Flashover Videos: Controlled Environment Flashover http://abcnews.go.com/2020/video/arson-lab-tests-flashpoint-occurs-10590272

  9. FRSC 8104 – Chapter 18 Outline • Chemistry of Fire • Three basic reactions • Organic Compounds • Elements of combustion (Fire Triangle or Fire Tetrahedron)

  10. FRSC 8104 – Chapter 18 Outline • Introduction to Petroleum Products • Light to Heavy Classification • Classes (Types) • Natural Gas • LP Gas • Petroleum • Gasoline • Kerosene • Diesel Fuel • Fuel Oil • Lubricating Oils

  11. FRSC 8104 – Chapter 18 Outline Fractional Distillation Tower

  12. FRSC 8104 – Chapter 18 Outline • At the Scene of a Fire (The Investigation) • Purposes of Investigations • Types of Fires • Natural, Accidental, Deliberate (Incendiary) • Classifying by Cause • Direct Ignition • Electrical • Weather-Related • Mechanical

  13. FRSC 8104 – Chapter 18 Outline • General Principles of Fire Behavior • Fire Behavior Indicators • Burn Patterns

  14. Another Classic V-Pattern The pattern is typical of an overheated appliance on the kitchen countertop. The arrow points to severely burned wallboard at the base of the V-pattern where a decomposed, plastic coffee pot housing was found, the apparent cause of the fire.

  15. FRSC 8104 – Chapter 18 Outline • Heat Level (Heat Horizon) • Smoke Level (Smoke Horizon) • Low Burns • Spalling Glass

  16. 1000 mL Gasoline on Parquet Floor

  17. 1000 mL Gasoline on Vinyl Floor

  18. 1000 mL Kerosene on Parquet Floor

  19. FRSC 8104 – Chapter 18 Outline • Evidence Collection

  20. FRSC 8104 – Chapter 18 Outline • Laboratory Analysis • Extraction Methods • Solvent Extraction • Headspace

  21. FRSC 8104 – Chapter 18 Outline • Steam Distillation • Purge and Trap (Charcoal Tube) • Passive Headspace Diffusion (Charcoal Strips) Purge and Trap Schematic

  22. FRSC 8104 – Chapter 18 Outline • Analytical Techniques • FTIR (Rare) • TLC for dyes • UV-Vis (Rare) • GC/FID • GC/MS • GC/MS/MS

  23. Gasoline Chromatogram

  24. Weathered Gasoline

  25. BTEX in Gasoline

  26. Gasoline Chromatogram

  27. Diesel Fuel Chromatogram

  28. Light Petroleum Hydrocarbons

  29. Naphtha Chromatogram

  30. FRSC 8104 – Chapter 18 Outline • ASTM Classification System (2002) • ASTM E-1618 • Gasoline • Petroleum Distillates • Isoparaffinic Products • Aromatic Products • Napthenic paraffinic products • n-Alkanes • De-aromatized Distillates • Oxygenated Solvents • Others – Misc.

  31. FRSC 8104 – Chapter 18 Outline • MS Characteristic Peaks • Pristane and Phytane • Other Compounds • Gasoline Target Compounds

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