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Chapter 11: Fire & Explosion Investigation

MINA Handbook. Chapter 11: Fire & Explosion Investigation. Investigating Fire Mishaps. What Are We Looking For?. The point of fire origin The source of ignition Why a small fire became big The reason for causalities Did the fire deviate from normal behavior

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Chapter 11: Fire & Explosion Investigation

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  1. MINA Handbook Chapter 11: Fire & Explosion Investigation

  2. Investigating Fire Mishaps

  3. What Are We Looking For? • The point of fire origin • The source of ignition • Why a small fire became big • The reason for causalities • Did the fire deviate from normal behavior The first step is to rule out arson!

  4. Determine Cause • As with any investigation look past the proximate cause for the root cause. • Suppose a fire starts in a club kitchen when a deep fat fryer ignites and spreads through the kitchen • The cause is not just “Deep fat fryer overheated.” • Was the control set too high? • Did the control contacts stick? • Why didn’t the high temperature cut-off fail to work?

  5. Fire patterns? Colors? Soot?

  6. Handout Discussion • Additional Information on Fire

  7. Investigating Explosions

  8. Types of Explosions • Mechanical • High pressure gas cylinder • BLEVE (Boiling Liquid Expanding Vapor Explosion) • Chemical • Combustion explosion • Flammable gases • Vapors of ignitable (flammable and combustible) liquids • Dusts • Low explosives • High explosives • Back draft explosions • Electrical • Nuclear

  9. Explosion Effects • Damage – low order, high order • Blast Front – rate of pressure rise vs. maximum pressure • Shrapnel effect • Thermal effect • Seismic Effect • Seated explosions • High pressure & rapid rates of rise • Craters • NonSeated explosions • Moderate pressures & rates of rise • Diffuse fuels

  10. Human Injury Criteria THRESHOLD SERIOUS WOUNDS .6 PSI: Glass 3.0 PSI: Glass 2.4 : Eardrum 3.5 : Eardrum 3.0 : Knockdown 10.0 : Knockdown 10.0 : 1% Lethal 25.5 : 90% Lethal

  11. Property Damage .15 PSI: Typical window breakage 1.0 : Houses uninhabitable 2.0 : Collapse of roofs/walls 3.5 : 50% destruction of homes 6.0 : Destruction of most buildings 9.0 : Box cars demolished 30.0 : Steel towers down

  12. Pressure (PSO) versus Distance (Quantity Distance)

  13. Evidence of Explosion • Wide dispersal of wreckage • Metal fragmentation • Shrapnel • Surface spalling • Unusual damage to heavy structures • Brittle fractures in ductile materials • Outward deformation • Radiating fire pattern • Fragment penetration force • Cratering of penetration holes • Splash • Edge turnover • Gas wash effect • Shredded or teased fabrics • Chemical residue analysis • Autopsy evidence • Witness testimony

  14. Explosion Investigation • Identify explosion or fire • Identify type of explosion • Establish origin • Establish fuel type and explosion type • Identify ignition source • Identify damage effects • Preblast & postblast fire damage

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