Steve700 wrote:
You have neither awareness, nor integrity. That fire didn't start from the one nearly a mile above. Nobody knows where it came from because it was deliberately started and it was only happening in a fraction of the whole building. Silverstein incriminating himself saying i a decision was being made to 'Pull It", a demolition term and how could they pull it unless it was already set with the explosives???????? Good God, you are F*cking Dumb.
Right, Stevbo, it wasn't a heavy, hot section of perimeter wall and flooring coming off the burning portion of the North Tower that tore a deep gash through 18 stories in the lower floors at the SE corner of WTC 7 and set the building on fire. No no, that didn't do it. It was a Jew with a hack saw, a jug of gasoline, and a bic lighter that did it. He managed to make his way through the massive cloud of falling debris and dust and go to work on building 7.
BTW: Larry Siverstein is NOT a demolition engineer, nor was the fire commander he talked to about the situation in building 7. When he said, "pull it", he was agreeing with the fire commander who feared an imminent collapse and that the fire fighting effort inside the building was failing due to insufficient water supply. The fire commander thought it best to get the men out and Silverstein agreed. When he said, "pull it", he was referring to the fire fighting effort. IOW, pull the men out.
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All right, mostly vacant. How's that? From those pictures you posted it sure looks like less than 1/4th of the area inside on those several floors was on fire. And of course those fires were oxygen starved. The only air other than the inside those floors which was soon consumed, was the holes made by the planes and a few broken windows. And you claim to be a fireman but don't seem to know black smoke means incomplete fuel combustion. (Even in a car it means excess gas and not enough air. Gray smoke indicates oil burning --- I used to teach auto mechanics with carburetors as a specialty? Where is your brain????????????????
All right, mostly vacant. How's that? From those ... (
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I used to fight fires. Fought lots of them, little ones, big ones, house fires, building fires, high rise fires, warehouse fires, car fires, oil fires, gasoline fires, wild fires, dumpster fires, white smoke fires, brown smoke fires, gray smoke fires, orange smoke fires, green and blue smoke fires, black smoke fires, and fires with combinations of smoke colors.
And you were a teacher of auto mechanics, specializing in carburetors. You tweaked those babies to get the best possible combustion inside the cylinders. You tweaked those carbs for clean burning. OK, got it. You are the Smoke Expert. You are the world's premier Fire Science Engineer. Got it.
Fire Engineering: THE ART OF READING SMOKEATTRIBUTES OF SMOKE: VOLUME, VELOCITY, DENSITY, AND COLORVolume:Smoke volume by itself tells very little about a fire, but it sets the stage for understanding the amount of fuels that are off-gassing within a given space. A hot, clean-burning fire will emit very little visible smoke; yet, a hot, fast-moving fire in an underventilated building will show a tremendous volume of smoke. Dampened material will burn slowly and emit lots of smoke (typically a lighter color). The changes in todayâs contents (low mass) can develop large volumes of smoke even though little flame is present. Volume of smoke can help set an impression about the fire. For example, a small fast-food restaurant can be totally filled with smoke from a small fire. Conversely, it would take a significant fire event to fill the local big-box store.
Velocity:The speed with which smoke leaves a building is referred to as velocity. In actuality, smoke velocity is an indicator of pressure that has built up within the building. From a tactical standpoint, the fire officer needs to know WHAT has caused the smoke pressure. From a fire behavior point of view, only two things can cause smoke to pressurize within a building: heat and volume. When watching smoke leave the building, know that velocity caused by heat will typically rise and slow gradually after it leaves the building. Velocity caused by restricted volume will immediately slow and balance with outside airflow. If the velocity of the smoke leaving an opening is turbulent (other descriptions may include agitated smoke, boiling smoke, and âangryâ smoke), a flashover is likely to occur. Turbulent flow is caused by rapid molecular expansion of the gases within the smoke and restriction of this expansion by the box (container). This expansion is caused by radiant heat feedback from the box itself-the box canât absorb any more heat. This is the precursor to flashover. If the box is still absorbing heat, the heat of the smoke is subsequently absorbed, leaving a more stable or âlaminarâ smoke flow. The most important smoke observation is turbulent vs. laminar smoke flow. Smoke that is turbulent is ready to ignite and indicates a flashover environment delayed by improper air mix.
Comparing the velocity of smoke at different openings of the building can help the fire officer determine the location of the fire-faster smoke will be closer to the fire seat. Remember, however, that the smoke velocity you see outside the building is ultimately determined by the size of the exhaust opening. Smoke will follow the path of least resistance and lose velocity as the distance from the fire increases. To find the location of fire by comparing velocities, you must only compare like-size openings (doors to doors, cracks to cracks, and so on). A veteran commander of hundreds of fires once told me to find the fastest smoke from the smallest opening-thatâs where the fire is. In my own experience, Iâve found this to be a pretty accurate shortcut.
DensityWhile velocity can help you understand much about a fire (how hot and where), density tells you how bad things are going to be. Density of smoke refers to its thickness. Since smoke is fuel-airborne solids, aerosols, and gases-capable of further burning, thickness tells you how MUCH fuel is laden in the smoke.
In essence, the thicker the smoke, the more spectacular the flashover or fire spread. Smoke thickness also indicates âfuel continuity.â Practically applied, thick smoke will spread a fire event (like flashover) farther than less dense smoke. We already know that turbulent smoke is a flashover warning sign, yet thick, laminar-flowing smoke can ignite because of the continuity of the fuel bed to a flaming source. One other point regarding smoke density: Thick, black smoke within a compartment reduces the chance of life sustainability because of smoke toxicity. A few breaths of thick, black smoke will render a victim unconscious and cause death within minutes. Further, the firefighter crawling through zero-visibility smoke is actually crawling through ignitable fuel. Modern fire tests are showing that smoke clouds can ignite at lower temperatures than fires of even 10 years ago. We can thank plastics and low-mass materials for making our job more dangerous.
Color:Most fire service curricula teach us that smoke color indicates the âtypeâ of material that is burning. In reality, this is true only for single-fuel or single-commodity fires. In typical residential and commercial fires, it is rare that a single fuel source is emitting smoke-the smoke seen leaving a building is a mix of colors. For a first-arriving fire officer, smoke color tells the stage of heating and helps to determine the location of the fire within a building. Virtually all solid materials will emit a white âsmokeâ when first heated. This white smoke is mostly moisture. As a material dries out and breaks down, the color of the smoke changes. Wood materials change to tan or brown, whereas plastics and painted/stained surfaces emit a gray smoke, as a result of the mixing of moisture and hydrocarbons (black).
As materials are further heated, the smoke leaving the material eventually becomes all black. When flames touch a surface, the surface off-gases black smoke almost immediately. Therefore, the more black the smoke, the hotter the smoke. Black smoke that is high velocity and very thin (low density) is indicative of flame-pushed smoke-the fire is nearby.Smoke color can also help you find the location of a fire. As smoke leaves a fuel that is ignited, it heats up other materials, and the moisture from those objects can cause black smoke to turn gray, or even white, over distance. As smoke travels, carbon content from the smoke will deposit along surfaces and objects, which also lightens the smoke color. That leads to the question: Is the white smoke you see a result of early-stage heating or late-stage heating smoke that has traveled some distance? To answer, just look at the velocity. White smoke that has its own pressure (push) indicates distance. White smoke that is slow or lazy is most likely indicative of early-stage heating. One more important note about smoke color: brown smoke. Unfinished wood gives off a distinctive brown smoke as it approaches late-stage heating (just prior to flaming). In many cases, the only unfinished wood in a structure are the wall studs, floor joists, and roof rafters/trusses (photo 3). This can tell you that the fire is transitioning from a contents fire to a structural fire. Using our knowledge of building construction-especially lightweight structural components and gusset plates-brown smoke issuing from gable-end vents, eaves, and floor seams becomes a warning sign of impending collapse. Remember also that engineered wood products like oriented strand board (OSB) and laminated veneer lumber (LVL or U-Micro-LamÂ) lose strength when heated. The glues of these products break down with heat and donât necessarily need flames to come apart. Brown smoke from structural spaces containing OSB or LVL can indicate that critical strength has been already lost.
Knowing the meaning of each attribute helps us paint a picture of the fire. By combining these smoke attributes, some basic observations about the fire can be made before firefighters enter a structure. Compare smoke velocity and color from various openings to help find the fireâs location. Faster/darker smoke is closer to the fire seat, whereas slower/lighter smoke is farther away. Typically, youâll see distinct differences in velocity and colors from various openings. In cases where the smoke appears uniform-that is, same color/velocity from multiple openings-you should start thinking that the fire is in a concealed space (or deep seated). In these cases, the smoke has traveled some distance or has been pressure-forced through closed doors or seams (walls/concealed spaces), which âneutralizesâ color and velocity prior to exiting the building.
Black FireâBlack fireâ is a good phrase to describe smoke that is high-volume, turbulent velocity, ultradense, and black. Black fire is a sure sign of impending autoignition and flashover.
In actuality, the phrase âblack fireâ is accurate-the smoke itself is doing all the destruction that flames would cause-charring, heat damage to steel, content destruction, and victim death. Black fire can reach temperatures of more than 1,000°F! Treat black fire just as actual flames-vent and cool.Wind, thermal balance, fire streams, ventilation openings, and sprinkler systems change the appearance of smoke. Analyze all smoke observations in proportion to the building. For example,
smoke that is low-volume, slow-velocity, very thin, and light-colored may indicate a small fire, but only if the building or box is small. This same observation from several openings of a big-box store or large warehouse can indicate a large, dangerous fire..