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Determining the Point of Origin

Determining the Point of Origin. Why?. Required by State Law Prevent future fires Moral obligation. Before determining the point of origin. You must determine the Area of Origin. Area of Origin. The geographic location of where the fire started ex. kitchen. Point of Origin.

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Determining the Point of Origin

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  1. Determining the Point of Origin

  2. Why? • Required by State Law • Prevent future fires • Moral obligation

  3. Before determining the point of origin You must determine the Area of Origin

  4. Area of Origin The geographic location of where the fire started ex. kitchen

  5. Point of Origin The specific location where the heat source comes in contact with the fuel

  6. For a fire to occur • You must have a heat source • You must have a fuel • You must have an act that brings the two together

  7. Steps in Determiningthe “Area of Origin” • Interview witnesses and firefighters • Examine the exterior of the structure • Examine the interior of the structure • Analyze the information gathered

  8. Step 1: Interview • Location, size, and appearance of the fire upon discovery? • Any unusual circumstances before, during, or after the fire?

  9. Step 2: Exterior Examination • Supplements information gathered in interview • Look for anything unusual • Match exterior burn patterns with interior burn patterns • ROT: heaviest auto vent stains are above the doors & windows of the room of origin

  10. Step 3: Interior Exam • Go to indicated area • Work from areas of least damage to areas of greatest damage • Evaluate the “indicators” • charring, V-patterns, light bulbs, window panes, floor damage, and multiple areas of origin.

  11. Indicators Help guide the investigator in determining the point of origin

  12. Char Material composed of carbon that has been burned and has a blackened appearance.

  13. Charring • Look for areas of lowest burning • Check bottoms & underside of furniture • Low charring indicates area of origin may be at a low level (caution: fall down) • Study the entire pattern of damage, relate low burns to entire burn pattern • Check depth of char. • ROT: char is deepest near P.O.O.

  14. More Charring • Compare char depths of similar products • Follow & diagram char patterns (least-most) • Consider all information gathered so far.

  15. Ceiling Damage Most damage directly above the area of origin

  16. Vertical Surfaces The most charred sides of vertical surfaces usually face the direction from which the fire approached

  17. V-Patterns The V-shaped burn pattern points close to or directly to the area of origin of that particular pattern

  18. Fall Down Secondary fires caused by fall down have separate v-patterns. Fall down occurs from convection or radiated heat.

  19. V-Patterns • Narrow V = fast burning • Wide V = slow burning • Burn patterns are dark or light depending on heat intensity & type of material

  20. Light Bulbs • Soften & Swell when exposed to heat • Points toward the heat source • Helps determine fire travel • Vacuum filled bulbs (low watt or automotive bulbs) • sink in on the side closest to heat source

  21. Window Panes • Compare broken glass to glass left in the pane • Smoke stains? • Location of broken glass? • May indicate fire conditions • baked on = high heat • loose soot = lower heat

  22. Floor Damage • Usually damaged less than ceiling • 20-30% of the ceiling damage • Good indicator of area of origin • Heavy char at or near area of origin • Burn through may indicate additional fuel • ex. Chair, bed, couch, etc.

  23. Spalling Chipping or breaking away of the surface of concrete as a result of high temperatures

  24. Causes of Spalling • Moisture in concrete • Green concrete • Presence of an accelerate • Closely examine concrete floors that have spalling

  25. Multiple Areas of Origin May indicate intentional burning Accidental fires may ignite items that give appearance of multiple points of origin

  26. Factors affecting fire spread • Nature of combustibles in path • Building features and layout • may assist or resist spread • Ventilation drafts

  27. Total Structural Loss • You can’t save them all • Reasons: • magnitude of fire • duration of fire • age of building

  28. Total Fire Loss • Black Holes, Grounders, Black Spots • Burn indicators may not exist • Information from witnesses, owner, and occupants can help determine the circumstances surrounding the fire loss

  29. Remaining Contents • Systematic examination can help determine • locations of contents before fire • temperature differences among areas • floor plans

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