The Art of Reading Smoke PDF

The Art of Reading Smoke David Dodson Reading smoke to predict re behavior within a structure is becoming...

The Art of Reading Smoke David Dodson Reading smoke to predict re behavior within a structure is becoming part of the “basics” for O cers O cer that watch smoke will make better decisions than one focused on aming Faster darker smoke closer to re, slow lazy smoke further from re Smoke with same velocity/ color from multiple openings the re is in a concealed space or deep seated re (smoke is pressure forced through closed doors and openings and color and velocity are neutralized) Smoke is an aggregate of solids, aerosols and re gases that are toxic, ammable and volatile Aerosols - hydrocarbons (tar/oil) Hot smoke is extremely ammable and will ultimately dictate re behavior “Sucker punch” - relying on aming for tactics Pyrolysis - material o gassing without ames Smoke gas just above the ashpoint ignite from a small spark (ember or failing light bulb) Smoke gases just above ignition temperature just need the right air mixture Ignition in a pressurized room leads to an explosive surge Causing re to spread within the smoke ow changing normal re dynamics Volume switch occurs as the front door is opened for an aggressive attack between air and smoke (smoke and air trade places) Faster darker smoke closer to re, slow lazy smoke further from re Smoke with same velocity/ color from multiple openings the re is in a concealed space or deep seated re (smoke is pressure forced through closed doors and openings and color and velocity are neutralized) Smoke must be analyzed in proportion to the building Smoke is e ected by wind, thermal balance, re streams, openings, sprinkler systems fl ffi fl fi ff ff fl ffi fi fl fl fi fi fi fi fl fl fi fi fi fi fi fi fi fi 4 Key attributes of smoke leaving a structure (volume, velocity, density, color): 1. Volume Amount of fuels o gassing within a given space Low mass contents = little ame with large volumes of smoke 2. Velocity (pressure) “how hot and where” Speed and ow of smoke leaving a building 2 causes of pressurization: 1. heat - slow gradual rise after leaving building 2. volume - slow and balance with outside air ow Smoke Flow Characteristic: Turbulent (Agitated, angry or boiling smoke) Flashover is likely/ ash over warning sign Rapid molecular expansion is restricted by the box (box can’t absorb anymore heat = ashover) Flashover delayed by Improper air mix Laminar (smooth, straight-line smoke) Box can still absorb heat leaving a more stable smoke ow Comparing smoke ow from 2 di erent openings: Faster smoke from the smallest opening is closer to seat of re (accurate shortcut) Thick laminar smoke can be ignited by the ame source due to smoke continuity 3. Density (thickness) Tells you how bad things are going to be Smoke is fuel and thicker smoke will spread re farther Thicker the smoke the more spectacular ashover or re spread is due to fuel continuity Thick laminar smoke can be ignited by the ame source due to smoke continuity Thick black smoke reduces the chances of life sustainability do its toxicology Thick laminar smoke can be ignited by the ame source due to smoke continuity Few breathes unconscious and death Zero Visibility Smoke Crawling through ignitable fuel Smoke ignites at lower temperatures due to low mass and plastics fl ff fl fl fl fl ff fl fl fl fl fl fi fi fl fi  4. Color Color is only true for single commodity res Stage of heating: White smoke - initial heating of a material (moisture) White smoke that has its own velocity indicates distance from re (cooling based on distance) White smoke that is slow and lazy indicates early stages Smoke dries out: Tan/ Brown smoke - wood materials Un nished wood gives o a distinctive brown smoke indicating re is moving from contents to structure Brown smoke form structural spaces with OSB or LVL can indicate a loss of strength Grey - plastics, stained or painted Black Smoke (carbonization) further heated Flame pushed smoke - high velocity very thin ( re nearby) Black Fire High volume, turbulent velocity, ultra dense and black Temperatures of more than 1000* Smoke is charring, heat damaging steel, causing death Sign of impending autoignition or ashover Reading Smoke Practice by using raw video footage Vocalize what you see to improve recognition speed How much, how fast, how thick and what color Tool to help you make better tactical decisions Intellectually aggressive as opposed to arbitrarily aggressive fi fi fi ff fl fi fi