Expulsion of Compressed Air and Debris from Collapsing Buildings

Thomas Green

New Member
The good old pancake theory revived. So the big squib we see on the left side at 0:21. Is it caused by the floor above it pancaking down? What made that floor fall down? The floor above it? Why no squibs from that falling floor?
 

Oystein

Senior Member
This is the most close up video I've seen. How do we explain the squib at 0:22
I hope you see that this "squib" is a dust plume that's ejected rapidly, but nowhere near the spead of sound - it's not a shockwave, it's not the exhaust of an explosive charge.
I hope you also noticed that there are no sounds of explosions just before the collapse starts.

With those out of the way, here is a little easy math on what air velocities to expect when a pancaking collapse occurs:
  • A floor is something like 3 m high, from slab to slab
  • The building seems to be something like 25 m deep (that's the width of the wall to the right in your video).
  • Compartment depth on that right hand wall is, let's say, 10 m
  • Thus, a collapsing floor compartment has an air volume of 3x25x10 = 750 m3​
  • It's outer walls are 10+25+10 = 45 m wide (three sides) and have thus an area of 135 m2​
  • I'd estimate that 1/ of the wall is open (windows), that gives us total openings through wich air can escape of 45 m2​
  • Let's say that, a few seconds into the collapse, floors pancake at a rate of 1 floor per 1 second.
  • During that 1 second, 750 m3​ of air (and dust, and smoke) are expelled through an area of 45 m2​
  • Average velocity is simply computed: vair​ = 750 m3​ / 45 m2​ / 1 s = 16.666... m/s. That's 60 km/h, 37.5 mph, 54.6 ft/s
All those assumptions are rough and dirty - this back-of-the-envelop gives us an order of magnitude.
Now air, being a fluid, has a habit of trying to escape every available opening when pressure inside rises.

"Squibs" (scare crows, because truthers habitually misuse the word - it has a meaning in the language of demolition experts different from "dust ejection") simply indicate that pressured air found a path to an opening a little distance away from where you may expect it. We would have to know the details of the internal structure and of the damage already acrued to be able to "explain" why a squib appears at a certain spot. But their existence in general is not a mystery at all.
 

Oystein

Senior Member
The good old pancake theory revived. So the big squib we see on the left side at 0:21. Is it caused by the floor above it pancaking down? What made that floor fall down? The floor above it? Why no squibs from that falling floor?
Not necessarily. It is caused by air being pressured and finding an escape. A collapse, almost by definition, is an event where the volume of a structure is reduced. The excess content of the structure, mostly air, must escape the skin of the crumpling body somewhere somehow.

If you want a specific detailed explanation for some specific dust ejection, you are asking for a level of perfection that is ridiculous and dishonest at this point in time.
Also, wholly irrelevant. Ejections of air and dust are entirely expected when a building collapses, regardless of the cause of initiation.
 

Marvin Sannes

New Member
"Expulsions" is good! What I find so similar to 9/11: Everyone who was in Southern Manhattan on 9/11 talked of
"Explosions" and the next day the term was scrubbed from the dialogue and has not been heard again in America's media. Explosion is a common description of 9/11 around the world. The Plasco Building has a very similar dialogue, "burned to the ground", "collapse". "fire". But, what we see certainly looks like explosive events - can we discuss it? Nope. These are expulsions.

[off topic material removed]
 

Oystein

Senior Member
"Expulsions" is good! What I find so similar to 9/11: Everyone who was in Southern Manhattan on 9/11 talked of
"Explosions" and the next day the term was scrubbed from the dialogue and has not been heard again in America's media. Explosion is a common description of 9/11 around the world. The Plasco Building has a very similar dialogue, "burned to the ground", "collapse". "fire". But, what we see certainly looks like explosive events - can we discuss it? Nope. These are expulsions.

[off topic material removed]
Can you describe more precisely what in the Plasco incident "looks like" an explosive event? If you are refering to videos, perhaps it would be a good idea to provide videos of known explosive events for comparison. Ideally with original sound.

You seem to think that the expulsion of air and dust "looks like" an explosive event - but you see the same for example in Verinage demolition. Also, why would you NOT expect air to be expelled at high velocity when a building collapses? Or why would you not expect high velocity air streams to transport dust as it is expelled from a collapsing building? Or what is it that you don't expect?
 

Oystein

Senior Member
Marvin,

two days ago I asked you for a clarifcation to a previous post, and also a couple of questions. Could you scrol up and quote and address these, please?

Then:
1) What is your source for the dust? 2) The suddenness is explosive, compressed air does not have this sudden signature, air compresses. And, 3) the distance from the burning floors to the explosive events. What is most certainly the signature of this as controlled demolition are the 4) same goofy arguments of plausible denial developed over many years
[off topic content removed]
1) The same sort of dust that escapes buildings being demolished with the non-explosive Verinage method or that collapse due to any other non-explosive causes (conventional demolition) - see below.
2) The "suddenness" of the dust expulsions? How do you quantify that "suddenness"? Did you quantify the suddenness of the Teheran dust expulsions, or of the WTC dust expulsions? How do they compare, for example, with the dust expulsions in this Verinage demolition (click me, I'm a YT link), or in this collapse caused by poor workmanship, or in this premature collapse during conventional demolition (another example of this)? I see very "sudden" dust expulsions in all these videos - none involve explosives. Can you explain their suddenness? Or at least acknowledge that the suddenness of dust expulsions from collapsing buildings by no means is an indication of the use of explosives?
3) What is the distance, and what is the maximum distance that overpressure can travel in that particular building? How do you know this?
4) You are begging the question. I could give you tit for tat of course - AE911Truth spreads the "same goofy arguments of plausible denial developed over many years". I think this sort of question/argument is not worthy of a rational debate.
 

Nada Truther

Active Member
The suddenness is explosive, compressed air does not have this sudden signature, air compresses.
Air compresses until the air pressure overcomes the strength of the container; then it ruptures the container at the weakest point and blows out. I would think that it would take some of the contents of the container with it, if they can be lifted out with the pressure release (i.e. dust particles created from collapsing floors, walls, etc.). Try this example... Take a Ziploc sandwich baggie, put in some powdered sugar or flour, make sure that there is some air in there and seal it. Now, squeeze the baggie. Do you think that it will pop, or the air will continue to compress? If the baggie pops, do you think that it will pull out some of the flour/sugar with it? Do you think that maybe it will come out in a jet-like fashion, resembling a "Squib"? Then you have to ask your self, if it does look that way...... Were explosives involved?

Make sure that you do it outside. It might make a mess.
 

Mick West

Administrator
Staff member
I've split this discussion off, as it's a interesting topic by itself. Something that's been discussed quit a bit over the years, but I don't know if there's a good go-to explanation that would convince people. Perhaps again, as Nada suggests, practical experiments might be illustrative.

One simple thing you can do is drop a sheet of wood. See how much air movement you get from just that. Then maybe move to large things, and dropping into a constrained space.
20170124-142037-um5hx.jpg
 

jaydeehess

Senior Member.
The above experiments illustrate concepts but are not meant to be exact replications, as so many truthers seem to expect, in my experience.
We should also be cognizant of the fact that the interior floor collapses need not have been full floor width/length. It was very likely partial floors at a time. This would have expulsions through the closest windows rather than the far side of the structure.
 

Mick West

Administrator
Staff member
The above experiments illustrate concepts but are not meant to be exact replications, as so many truthers seem to expect, in my experience.
Indeed, there's two major differences: scale and topology, with scale being the most important thing. With any scale model (like the many I've made in the past) it's important to remember you are illustrating a principle, and not exactly replicating what happened.

It seems difficult for some people to understand how something as simple as falling floors compressing air can lead to blowing out of windows and large violent expulsions of dust.


But it's really down to scale. My experiments use just a couple of cubic feet of air and maybe five pounds dropped a few feet. Scaling that up by a factor of tens thousands and you get plenty of force.
 

jaydeehess

Senior Member.
Mick, anyone who has worked in a lumber yard knows full well what happens when boards, plywood sheets, or drywall panels are dropped flat on each other. Blinking away dust and wood fibers after the first time is enough to make sure you take care the next time.
 

Mick West

Administrator
Staff member
At the other end of the spectrum there are actually examples of air blasts from falling slabs that are much bigger than the buildings:

http://www.sciencemag.org/news/1997/12/yosemites-supersonic-blast
 

Mick West

Administrator
Staff member
Mick, anyone who has worked in a lumber yard knows full well what happens when boards, plywood sheets, or drywall panels are dropped flat on each other.
And drywall is a good illustration in another way, as the falling floor will generally crush a lot of drywall on the way to the next floor, generating a lot of dust and light debris.
 

jaydeehess

Senior Member.
And drywall is a good illustration in another way, as the falling floor will generally crush a lot of drywall on the way to the next floor, generating a lot of dust and light debris.
Yeah, but in the lumber yard we tried real hard not to break the drywall sheets. We allowed customers to take home full sheets and do that themselves.
:)

OTOH, the first time I did some drywalling in my first house I did not know how one cuts drywall. So I used my circular saw. I was doing this in the basement and could barely see the stairs through the dust. At work (electronic tech at the airport at the time) I asked the older guys about it and was informed of the correct method. :(
 

Nada Truther

Active Member
It seems like most of the arguments against the dust "expulsions" being anything other than "explosive" events is... Those making the "explosion" argument can't seem to fathom where the dust comes from. They seem to think that it is only caused by pulverized concrete, and nothing else. They also, I think, seem to believe that the amount of dust that is being produced is an enormous amount. Therefore, meaning that an entire floor of concrete was turned to dust and exploded out. Many of the "squib-like" jets that we saw in the WTC are, in my opinion, not very thick, and wouldn't represent an enormous amount of crushed material. They could very well be a small amount of concrete and a large amount of crushed drywall. Or, even a small amount of drywall. Drywall does, as Jay described, make a ton of dust from just cutting or sanding it. I can only imagine how much is created during a violent collapse.
 

mm1145

Member
Round two. Drop a plastic container with some weight into a matching container that has a hole in it.
View attachment 24185

Dust shoots out of hole.
View attachment 24187
(sorry this is off topic)
can I just say I relay like your approach here. the "set-up a test and see if we can get a result" method. I like the idea that the best way to find things out is to test them and it provides a counter point to the "keyboard" conspery theorist so much of the time the argument is all about looking in detail at a video that somebody else posted of a report skimmed of a news report of a amateur video. it is nice to have somebody doing some experiments and colecting some real data. so that when we say "this is the simple explination" we can show it
 

Cube Radio

Member
At 1min 29sec in this video of the South Tower, we can powerful ejections occurring at least 50 floors below the destruction wave. Does the forum here believe that the most plausible explanation for such explosive ejections is compressed air?

 

deirdre

Senior Member.
we can powerful ejections occurring at least 50 floors below the destruction wave.
i dont see anything below the destruction wave. i just see the destruction wave... can you screen shot it and make an arrow pointing to what you consider the destruction wave and where 50 stories below is?
 

darrenr

Member
At 1min 29sec in this video of the South Tower, we can powerful ejections occurring at least 50 floors below the destruction wave. Does the forum here believe that the most plausible explanation for such explosive ejections is compressed air?
There isn't much to see at 1min 29sec but later the video shows that there are jets of dust being ejected some floors below the destruction wave. But there are never more than one or two and, given that the tower is already collapsing when they occur, I think it's safe to assume they're a consequence of some vagary of the building's construction - a weak ceiling collapsing on that floor as the building shook, maybe. Or perhaps a heavy object falling through from one floor to another.
 
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Jeffrey Orling

Senior Member
There are some puff many floors below the *collapse front* and these can be explained as pressurized air caused by local elevator drops.
 

dman

New Member
This is the most close up video I've seen. How do we explain the squib at 0:22 Source: https://www.youtube.com/watch?v=jzB-QE8Emt0&list=PLUshF3H0xxH3WcOFWzcSg_gmce0wrDolF
Have this account from 9/11 INSIDE WTC - 14 people were in Stairway B in center of North Tower making way out

12 FDNY, 1 Port Authority Police officer and Civilian Port Authority worker Also made it out when building collapsed around them

The air blast from the displaced air lifted the people off their feet - 250 lb Firemen with almost 100 of equipment were
picked up and thrown down stairs by air blast as the building collapsed

Again have people picked off feet and hurled down stairs by air blast from collapsing building

Operative phrase " The building was pancaking down from the top and, in the process, blasting air down the stairwell"
 
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Oystein

Senior Member
At 1min 29sec in this video of the South Tower, we can powerful ejections occurring at least 50 floors below the destruction wave. Does the forum here believe that the most plausible explanation for such explosive ejections is compressed air?

Echoing Deirdre's request to annotate a screen shot for us, because I do not know what you are referring to.

I'd also ask you to give us YOUR most plausible explanation for "such explosive ejections is compressed air" - and also, why you call them "explosive"!
Up in post #4, I did a back-of-the-envelop calculation for the expected speed of air expulsions from a pancaking building - for a building the size of the Plasco, I found 60 km/h (40 mph, 25 m/s), +/- a liberal lot. For a building with a much larger footprint like the WTC, the expected speed would be significantly higher - on average. Perhaps 2 or 3 times as fast. Locally, the speeds could be higher still. You need to show that the dust ejections that you think you observe have a velocity closer to that of high (supersonic) explosions (1000 mph?) than to the order of magnitude I calculated (100 mph for the WTC).
Also, how do you explain that the dust made its way out the window, but the SOUND did not, when it's supposed to be a powerful "explosion"?
 

dman

New Member
The people were inside the North Tower in the center stairway B when struck by air blast as the building collapsed
around them

Used this to illustrate point of volume of air being displaced and speed at which the air can move

If your calculations are correct can reach over hurricane (75 mph, 120 kph) speeds

As for how dust reached outside of building - there were ventilation openings on mechanical floors for
outside air to be admitted

Also the speed at which displaced air is accelerated to will pop windows out of frames

Case in point - went to college at engineering school, at end of floor were lounges with large picture windows
Someone calculated that by slamming doors of rooms along hallway could create pressure wave of air sufficient to
blow window out of frame. Bunch of students practiced slamming doors in sequence until got timing right

Were able to blow window out of frame - college administrators were not amused .......

As for sound of "explosion" this is not a explosion but pressure wave of displaced air being pushed ahead of
building debris as it collapsed
 

Mick West

Administrator
Staff member
Echoing Deirdre's request to annotate a screen shot for us, because I do not know what you are referring to.
There's this, at 0:05 seconds into this video:
Source: https://www.youtube.com/watch?v=i8o-v3stbbE

20170204-102401-lax3p.jpg

However it's very clear from the video that this is an overpressure situation, the hole continues to blow out debris in a stream for at least four seconds, until the camera turns away at 0:09
20170204-102507-wtdmr.jpg

I'd suspect this is a previously broken window.
 

Oystein

Senior Member
...
However it's very clear from the video that this is an overpressure situation, the hole continues to blow out debris in a stream for at least four seconds, until the camera turns away at 0:09
...
A veeeery sloooow explosion, perhaps?

Reminds me of an old joke, where two fools have trouble with a jammed rifle. One eyes down the gun barrel and asks the other: "Now, let the bullet come slooowly..."
 

Mick West

Administrator
Staff member
Incidentally the use of the term "squib" to refer to ejections of material from a collapsing building is something entirely made up by AE911. "Squib" is an old term for a fuse, and generally refers to very small explosives. It is not an actual demolition or military term.
 

jaydeehess

Senior Member.
There's this, at 0:05 seconds into this video:
Source: https://www.youtube.com/watch?v=i8o-v3stbbE
5/100 of a second?
You mean at 5 seconds into the 22 second clip

View attachment 24321

However it's very clear from the video that this is an overpressure situation, the hole continues to blow out debris in a stream for at least four seconds, until the camera turns away at 0:09
View attachment 24322

I'd suspect this is a previously broken window.
Given the length of the shadow produced by the dust expulsion in the first still at 5 seconds, it began before the camera swung that way as well.
 

Redwood

Active Member
If these are "explosive ejections" (meaning I presume ejections caused by explosives), why isn't every window on the floor blown out, instead of only one?
 

Nada Truther

Active Member
At 1min 29sec in this video of the South Tower, we can powerful ejections occurring at least 50 floors below the destruction wave. Does the forum here believe that the most plausible explanation for such explosive ejections is compressed air?

Do the people that disagree with this being most likely compressed air have any evidence to show other actual CD buildings with just a few random puffs of debris dozens of floors below collapse that spew out in a jet like fashion? I have never seen any video of a CD where there weren't multiple bursts and puffs of debris near the explosives. And none of them seem to come out like a jet of compressed air; as these appear to be.
 

Cube Radio

Member
The puff that you suspect to be a broken window is a possibility. Elevator shaft is much less relevant, as the puff here comes below the sky lobby, which is where the elevator shafts for each of the three sections ended.
 
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