Popular Mechanics article question

[Caper]

In this article.

http://www.popularmechanics.com/technology/military_law/1227842.html?page=4


Contains this quote.

The NIST investigation revealed that plane debris sliced through the utility shafts at the North Tower's core, creating a conduit for burning jet fuel — and fiery destruction throughout the building. "It's very hard to document where the fuel went," says Forman Williams, a NIST adviser and a combustion expert, "but if it's atomized and combustible and gets to an ignition source, it'll go off."


I have a truther telling me that NIST did no such investigation.

No, actually the investigation did no real study of the damage to the core. That is fact. Second of all burning jet fuel would have been mostly burned off in the first few seconds of the attack. Thirdly the fuel would not have done damage down the elevator shafts, which were designed to starve oxygen flow.

Can anyone link to NIST material regardinging this? Thank you.

[R.Mackey]

[From PM] The NIST investigation revealed that plane debris sliced through the utility shafts at the North Tower's core, creating a conduit for burning jet fuel — and fiery destruction throughout the building. "It's very hard to document where the fuel went," says Forman Williams, a NIST adviser and a combustion expert, "but if it's atomized and combustible and gets to an ignition source, it'll go off."

I have a truther telling me that NIST did no such investigation.

Can anyone link to NIST material regardinging this? Thank you.

Your question is a bit vague, so please excuse the complex answer.

NIST did a very thorough investigation of the fuel distribution in the 0.6 seconds after impact, but little investigation with respect to fuel that travelled into the lower structure. The impact models had several limitations:
Only considered a roughly eight-story block, and cannot consider long distances
The models did not include windows and thus overpredict scatter outside the Towers
Fluid granularity was about 1.5 liters minimum
The algorithm was a smoothed-particle hydrodynamic model, which is excessively "bouncy," but required for such a large simulation
Details are found in NCSTAR1-2B.

Regarding fuel effects lower in the Towers, there is mention in NCSTAR1-7 and 1-8, but no complex modeling, no detailed examination of flow paths, and so on. The focus is on how the lower fires affected the emergency response and behavior of occupants. These lower fires had a negligible impact on the structural collapses, so this is excusable.

The comments of your adversary are reminiscent of similar nonsense positions sometimes encountered here:

No, actually the investigation did no real study of the damage to the core. That is fact. Second of all burning jet fuel would have been mostly burned off in the first few seconds of the attack. Thirdly the fuel would not have done damage down the elevator shafts, which were designed to starve oxygen flow.

The investigation did extensive study of damage to the core, again from NCSTAR1-2B. Second, NIST predicts that only 20% burned off in the few seconds after impact, based partly on the size of the fireballs and partly on their modeling results, though this is a very coarse estimate. Third, it doesn't matter that the elevator shafts were "designed to starve oxygen flow," because there's no flow required -- the oxygen already in the shafts is sufficient for some impressive deflagrations.

In other words, your opposition is spouting nonsense, to what end I cannot tell. It would be fair to say that NIST barely treated the fuel effects in the lower structures, and I've voiced this as a criticism in my whitepaper (http://www.911myths.com/drg_nist_review_2_1.pdf), but I doubt this individual is concerned with accuracy.

[gumboot]

The notion that elevator shafts are "designed to starve oxygen flow" is ridiculous. They're designed to carry elevators, and in particular let people in and out of those elevators. Not to mention the elevator shafts were walled in drywall which would have been easily destroyed in the impacts, rendering any oxygen starving design moot.

[SezMe]

I want to underscore gumboot here. The very notion that elevator shafts were "designed to starve oxygen flow" is nonsense. Your truther needs to back this assertion up with specific design criteria. I'll bet if you go to any elevator company web site and search for "oxygen flow" you will get zero hits. Or find engineers who do elevator design and ask them what the phrase means. I'll bet again that you draw zip.

[Arus808]

my good friend works for a an elevator repair company. if the shafts were designed to "starve" oxygen flow, he'd be dead after doing his first job.

[gumboot]

my good friend works for a an elevator repair company. if the shafts were designed to "starve" oxygen flow, he'd be dead after doing his first job.


had this sudden image of a worker being lowered down an elevator shaft in one of those big cumbersome diving bells...

[SezMe]

...or wearing SCUBA gear while performing routine maintenance.

[Sparky]

This may not have applied back in the day, but all modern elevator shafts and stairwells in highrise buildings are pressurized with fresh air during activation of any fire alarm to prevent smoke migration between floors. Far from starving a fire, this would tend to feed a fire within an elevator shaft.

[Viper Daimao]

This may not have applied back in the day, but all modern elevator shafts and stairwells in highrise buildings are pressurized with fresh air during activation of any fire alarm to prevent smoke migration between floors. Far from starving a fire, this would tend to feed a fire within an elevator shaft.

this would be a reason why you should always take the stairs in a fire?

[Sparky]

this would be a reason why you should always take the stairs in a fire?

The idea behind stairwell pressurization is to keep smoke out of the stairwells and migrating to other floors when a fire occurs outside of the stairwell. It's unlikely that a fire will occur within the stairwell since stairwells have to be of non-flammable contruction.

If someone deliberately set a fire within a stairwell, I would suggest taking the other one.

[rwguinn]

this would be a reason why you should always take the stairs in a fire?

In most buildings I have been in, they, too are pressurized when the alarm goes off--and you can only enter, not exit, on the upper floors (doors open into the stairwell.
All this is based on a design criterion which presumes the stairwell would remain intact, I think. Any of you tall-building designers care to comment? Architect? Newton's Bit?

[Sparky]

this would be a reason why you should always take the stairs in a fire?

It is a requirement that all elevator power be shut down (shunted) just prior to sprinkler activation within an elevator shaft.

Would you want to be inside an elevator if a fire occurs within a shaft and the elevator completely shuts down as the water starts pouring in on you?

I wouldn't.

[Sparky]

In most buildings I have been in, they, too are pressurized when the alarm goes off--and you can only enter, not exit, on the upper floors (doors open into the stairwell.


Here in California the Building and Fire Codes require that all stairwell doors automatically unlock during a fire alarm in order to allow fire personnel access to the floors from the stairwells. Otherwise entry/egress or egress-only is up to the discretion of the building owner.

[rwguinn]

Here in California the Building and Fire Codes require that all stairwell doors automatically unlock during a fire alarm in order to allow fire personnel access to the floors from the stairwells. Otherwise entry/egress or egress-only is up to the discretion of the building owner.

ah--
right. sorry. that actually makes sense...

[Alferd_Packer]

this would be a reason why you should always take the stairs in a fire?

It is my understanding that in a fire the call buttons can get activated from the fire (especially with the old style heat sensitive ones). If you take the elevator in a fire, the car will stop on the fire floor and the doors will open and not close again.

Not good.

[Alferd_Packer]

Here in California the Building and Fire Codes require that all stairwell doors automatically unlock during a fire alarm in order to allow fire personnel access to the floors from the stairwells. Otherwise entry/egress or egress-only is up to the discretion of the building owner.

Chicago required a retrotfit all buildings to that standard after the 2003 fire in the Cook COunty administration building killed 6 people in the stairwells.

[Sparky]

It is my understanding that in a fire the call buttons can get activated from the fire (especially with the old style heat sensitive ones). If you take the elevator in a fire, the car will stop on the fire floor and the doors will open and not close again.

Not good.

Yikes! That would be bad.

Nowadays, each elevator lobby is required to have a smoke detector within 21 feet of the centerline of the doors which, upon activation, recall the elevators to a primary recall floor, usually the 1st. If the detector is activated on the primary recall floor, recall is to go to an alternate floor, ususally the 2nd. Smoke detectors are also installed at the top of sprinkled elevator shafts to hopefully trigger recall before shunt.

Also, heat-sensitive floor call buttons aren't allowed anymore thankfully.

[Blender Head]

I have nothing to contribute other than the Truther's obfuscation of what NIST modelled for the fuel post-impact is very typical.

[Caper]

His initial critisism was with the popular mechanics article.

This magazine and its ------- pathetic article can go to hell. This one article tries to make conspiracy theories sound idiotic, thus planting a false image of reality in every reader's mind. Do you know how many people stopped asking questions about 9/11 just from this one dinky article?

A few paragraphs can be seen as a scientific explanation for the events on 9/11 that debunks any and all questions raised?

I am so sick of debunkers citing this article as a source. It doesn't even come close to explaining the real questions that are being raised.

It uses the "pancake theory" which not only has been proven wrong by engineers worldwide, but was thrown out by NIST itself!

Here's what it says:

Once each tower began to collapse, the weight of all the floors above the collapsed zone bore down with pulverizing force on the highest intact floor. Unable to absorb the massive energy, that floor would fail, transmitting the forces to the floor below, allowing the collapse to progress downward through the building in a chain reaction. Engineers call the process "pancaking," and it does not require an explosion to begin, according to David Biggs, a structural engineer at Ryan-Biggs Associates and a member of the American Society of Civil Engineers (ASCE) team that worked on the FEMA report.


Engineers call the process "pancaking". This must be an industry wide term used all everytime a building collapses like this!!!! Oh wait, Buidlings never collapse that way. ******

Try to find information where popular mechanics got this information from David Biggs. I bet he did a whole lot of research on pancakes!! He may even have coined the term!

Is it true that NIST rejected the pancake thoery?

[Sparky]

Is it true that NIST rejected the pancake thoery?

NIST rejected pancake theory for collapse initiation.

[rwguinn]

His initial critisism was with the popular mechanics article.



Is it true that NIST rejected the pancake thoery?
Only for collapse initiation. Sidewall buckling due to damage and heat, resulting in a Progressive collapse initially is the proper terminology.
"Pancake" implies a whole floor fell onto the one below, failing it--erm... ah...
this resulted in the "clunkity-clunk" field of expertise...

[Sparky]

The aircraft damaged or destroyed many of the interior support columns forcing load transfer via the hat truss to the outer columns. Eventually the heat caused the outer columns to buckle as Mr. Guinn stated above causing the start of the collapse. Then (and only then) did collapse continue in a pancake fashion.

[Mr. Skinny]

It is a requirement that all elevator power be shut down (shunted) just prior to sprinkler activation within an elevator shaft.

Would you want to be inside an elevator if a fire occurs within a shaft and the elevator completely shuts down as the water starts pouring in on you?

I wouldn't.
Do you mind providing a cite for the bolded part? I'd like to read more.

[Brainster]

The notion that elevator shafts are "designed to starve oxygen flow" is ridiculous. They're designed to carry elevators, and in particular let people in and out of those elevators. Not to mention the elevator shafts were walled in drywall which would have been easily destroyed in the impacts, rendering any oxygen starving design moot.

There is certainly a desire to limit oxygen flow from the vertical penetrations of the building, otherwise you get a chimney effect where the smoke gets transported away from the fire and fresh air rushes in to replace it and feed the fire. As you point out, that would have little effect in the case of the WTC on 9-11, but it's not as if there is nothing to the desire to make the elevator shafts as airtight as possible. Of course, the "Truthers" go too far as usual and start to claim that the shafts were hermetically sealed, as if people had to pass through an airlock before entering the elevator.

[Sparky]

Do you mind providing a cite for the bolded part? I'd like to read more.

2007 National Fire Alarm Code (NFPA 72) Section 6.16.4

Send me a PM and I'll fax or email you the relevant section.

[Mr. Skinny]

2007 National Fire Alarm Code (NFPA 72) Section 6.16.4

Send me a PM and I'll fax or email you the relevant section.
I have the NFPA available at my office, though my copy is a few years old.

So, are you saying that sprinkler systems in elevator shafts have to be pre-action systems?

[Sparky]

I have the NFPA available at my office, though my copy is a few years old.

So, are you saying that sprinkler systems in elevator shafts have to be pre-action systems?

2002 edition Section 6.15.4
1999 edition Section 3-9.4

There is no mention of pre-action but all of the editions require that the heat detectors used to activate shunt have both a lower temperature rating and a higher sensitivity as compared to the sprinkler head.

If a flow switch is used it does state that all time delays or retards be removed.

The CSFM has issued a code interpretation recommending a time-delay sequence be used involving recall to allow the cabs to return to a recall floor and open the doors prior to shunt.

Elevator Power Shut-trip & Recall (http://osfm.fire.ca.gov/codeinterpretation/pdf/2006/06_128.pdf)

[Mr. Skinny]

2002 edition Section 6.15.4
1999 edition Section 3-9.4

There is no mention of pre-action but all of the editions require that the heat detectors used to activate shunt have both a lower temperature rating and a higher sensitivity as compared to the sprinkler head.

If a flow switch is used it does state that all time delays or retards be removed.

The CSFM has issued a code interpretation recommending a time-delay sequence be used involving recall to allow the cabs to return to a recall floor and open the doors prior to shunt.

Elevator Power Shut-trip & Recall (http://osfm.fire.ca.gov/codeinterpretation/pdf/2006/06_128.pdf)
Thanks very much. I'll read up on it tomorrow.