Slide #58 - Metal Color Temperature Chart

In this slide, Gage produces a nice chart of metal colors at various temperatures. He aslo shows a nice glowing piece of something that's coming up out of the debris pile, and makes a simple statement that is completely beside the point.

The chart is quite accurate. Gage has helpfully added some data, but I don't dispute any of that.

Well, perhaps one figure...

Eagar's WTC Air Temperature

To hear Gage tell it, someone named Eagar seems to have determined that the air temperatures in the WTC were only at 1,200° F (650° C). This is a reference to a Journal of Mechanics (JOM) December 2001 article cowritten by Dr. Thomas Eagar and Christopher Musso, Why Did the World Trade Center Collapse? Science, Engineering, and Speculation.

The maximum flame temperature increase for burning hydrocarbons (jet fuel) in air is, thus, about 1,000° C -- hardly sufficient to melt steel at 1,500° C.

But it is very difficult to reach this maximum temperature with a diffuse flame. There is nothing to ensure that the fuel and air in a diffuse flame are mixed in the best ratio. Typically, diffuse flames are fuel rich, meaning that the excess fuel molecules, which are unburned, must also be heated. It is known that most diffuse fires are fuel rich because blowing on a campfire or using a blacksmith's bellows increases the rate of combustion by adding more oxygen. This fuel-rich diffuse flame can drop the temperature by up to a factor of two again. This is why the temperatures in a residential fire are usually in the 500° C to 650° C range.

There it is, correct? Dr. Eagar and his graduate student have just said that the air temperature in the WTC was 650° C, right?

Wrong. Dr. Eagar continues:

...It is known that the WTC fire was a fuel-rich, diffuse flame as evidenced by the copious black smoke. Soot is generated by incompletely burned fuel; hence, the WTC fire was fuel rich -- hardly surprising with 90,000 L of jet fuel available. Factors such as flame volume and quantity of soot decrease the radiative heat loss in the fire, moving the temperature closer to the maximum of 1,000° C. However, it is highly unlikely that the steel at the WTC experienced temperatures above the 750-800° C range. All reports that the steel melted at 1,500° C are using imprecise terminology at best.

Two quick things: Dr. Eagar certainly doesn't think the steel melted as the building stood, and he is talking about the Towers, not Building 7.

But it is Dr. Eagar's judgment, based on the sooty, fuel-rich fires, that the fires in the WTC Towers could have burned much hotter than an ordinary office fire. No higher than 750-800° C (1375-1575° F), to be sure, but still environmental factors easily played a part in contributing to higher temperatures than normal in an office fire.

Regardless of this, Dr. Eagar most definitely did not say that air temperatures in WTC 1, 2, or 7 were only 650° C. In this, Gage has badly misquoted the article.

The Debris Pile Picture

None of that has anything to do with the picture he shows. The crane is clearly pulling a piece of something out of the debris pile. There is no indication of when this picture was taken. And it's clearly very hot.

So?

Conditions under the Pile have nothing to tell us about conditions before the building collapsed. In the last slide rebuttal, I demonstrated that thermite could not last long enough to maintain the months of radiant heat from the debris piles. It had to be ordinary fires, fueled by the contents of three gigantic office buildings.

Human civilization took great leaps when it discovered the secrets of smelting various metals. This required ingenuity in building up the temperatures required to adequately temper and purify different elements and alloys.

Yet it didn't take the discovery of the thermite reaction to acheive these temperatures. The principles of the furnace are a crucial part of the blacksmith's art. Using materials that do not burn hot enough to perform the desired work, a furnace collects heat, focusing it where it is needed. Variables such as amount of fuel, the thickness of the furnace walls, and the availability of oxygen gave the blacksmith the ability to acheive far hotter temperatures than with a simple fire burning out in the open.

The conditions under the Pile mimicked a furnace quite well. There was ample fuel. It was ground down to dust, making it much more potent and quick-burning. The other debris in the Pile certainly gave sufficient thickness to the walls of this ad hoc furnace.

And what's more, all accounts of molten metal are from human beings. Where they were, oxygen could easily reach.

So, nice picture, Mr. Gage. Too bad it doesn't prove anything.

Hydrocarbon Fires

This is dealt with up above, but a restatement is in order. It doesn't matter how hot the fuel burns if the heat thus generated can't escape. Dr. Eagar says that the soot would have help give the WTC Tower fires a boost in temperature, and conditions under the Pile were certainly enough to capture heat.

In fact, knowing this shows just how hot the fires actually were under the Pile. Despite the insulating properties of the debris, heat was still escaping at such high rates, all from the ample, quickly burning fuel supply.

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