Fire in Notre Dame in Paris

[John Cuthber]

Just now, koti said:

I can’t quote him on iphone on iOS 12.2 with Safari. Windows 10 with Chrome same thing. 

Nor can I, but I can quote you.

[koti]

16 minutes ago, John Cuthber said:

Nor can I, but I can quote you.

I think I can quote everybody except him. The forum engine seems to have a specific sense of humour. 

[Phi for All]

A German acquaintance showed me his paycheck stub several years ago, to show that everyone had to pay their share for the upkeep on ancient churches and castles. I remember thinking that would be an interesting thing to see conservatives fight over in the US. Half would decry any new taxes, the other half would jump at the chance to mix church and state.

[koti]

49 minutes ago, Phi for All said:

...ancient churches and castles...

 

...I remember thinking that would be an interesting thing to see conservatives fight over in the US...

 

I’m thinking how to turn this into a funny pun towards Americans but I’ll just leave the above since it does a good job on its own  

[CharonY]

4 hours ago, dimreepr said:

Lucky you... 

To us, it's a burden...

Quoted to test quoting (the multiquote button works, but the other does not). Also, it should be noted that many American historic buildings are built less resilient than many of those in Europe (as especially smaller houses are typically wooden constructs). Although you occasionally do find some odd things in the wall(s) in the old homes, once you get the permit to do something with them...

3 hours ago, Phi for All said:

A German acquaintance showed me his paycheck stub several years ago, to show that everyone had to pay their share for the upkeep on ancient churches and castles. I remember thinking that would be an interesting thing to see conservatives fight over in the US. Half would decry any new taxes, the other half would jump at the chance to mix church and state.

I think that may be the tax for the Church. I.e. the state collects from members of the Catholic and evangelic church. However, non-members generally do not pay directly (but can be levied indirectly from the employer somehow).

[swansont]

15 hours ago, CharonY said:

it should be noted that many American historic buildings are built less resilient than many of those in Europe (as especially smaller houses are typically wooden constructs). Although you occasionally do find some odd things in the wall(s) in the old homes, once you get the permit to do something with them...

We came after the "let's build everything out of stone, to protect us from men with swords and arrows" phase

Plus we had an abundance of wood.

[Enthalpy]

On 4/16/2019 at 5:55 PM, Airbrush said:

Ancient buildings like that should have some kind of exterior, automated fire hose that can be controlled by joy stick guided by cameras, so it can reach the roof of the entire building.

This is already complex technology, prone to failure and exposed to sabotage.

----------

As an old engineer, I've a gut feeling that

• Sprinklers that open when heat melts a valve and let water flow by gravity have decent chances to do more good than harm.
• But actively controlled hoses would go crazy and make damages more often than they mitigate a fire.

Compare with the automatic anti-stalling piece of software. Not very complicated neither: check few sensors, pull the stick. But it went crazy on two flights recently.

Or compare with the electronic smoke detectors we have in the houses presently. Good that they don't inundate the rooms every time they sound the alarm without a reason.

This gives a sense of what complexity engineers can reliably master: it's very, very little. We need to fail several times, preferably at the beginning of the career on less important projects, to get this modesty.

Automated or remotely controlled fire hoses would also need electricity, cameras and so on. In a degraded and stressful situation like a fire, you typically lose these resources when you need them.

Firefighters do rely on technology, but the resources are brought from a place away from the fire, they are maintained daily, and are used regularly by people who train for it and have close control over the machines. Quite different from a remotely controlled device supposed to idle for thirty years and work when needed.

----------

How usual sabotage is, we can only guess. How far sabotage goes, we have examples.

At the very Notre-Dame de Paris, dozens of statues were beheaded two decades ago, shortly after a similar sabotage happened in an other European country, friend and ally of France. Imagine: there are hundreds of cops, in uniform or not, in and around the cathedral. The group could enter the site, break the heads bang bang bang, and get away unnoticed.

Or Ariane flight 36. The public learnt about a cloth in a propellant pipe, but there was also a leak in an other engine, a fire in a third, pogo oscillations in a fourth. This flight was "doomed", as they say. Few months later, the same happened at a US launcher, despite they probably expected it.

With that in mind, the usual sprinkler has some resilience. Saboteurs need physical access to a limited location. Melting the valves needs some serious means, cutting the unexposed pipes too.

My proposal with the tank on the ground is already less resilient. More locations can be attacked, and they're easier to access. It needs pressure in the tank or pumps and electricity. If controlled from the ground, sabotage is easier. Whether the net balance is still favourable as for passive sprinklers under a pool?

A remotely-controlled jet, with cameras, transmissions, electricity+electronics+software, is quite vulnerable. Easier to hamper before starting a fire, easier to misuse to make damage without a fire.

[CharonY]

3 hours ago, swansont said:

We came after the "let's build everything out of stone, to protect us from men with swords and arrows" phase

Plus we had an abundance of wood.

True. Though to be fair you managed to get your white house burned down by island folks who are infatuated with wigs. Well, they also attacked every one else at some point, hmm.

[John Cuthber]

On 4/19/2019 at 1:06 PM, Enthalpy said:

Thanks JC!

And, yes, rebuilding as it was has excellent arguments in its favour, which I'm sensitive to. It's more that NDDP was ugly to my taste, and the dark grey roof contributed much to that, so I'd catch the opportunity to build something more pretty, with a roof of nice colour, and spires on the towers at last.

==========

Trying to estimate the lead concentration sent in the air by the fire...

Smelter workers had (in some places, have) harmful amounts of lead in the body due to lead's vapour pressure. If melting pure lead at 601K, the (equilibrium!) vapour pressure is 10^-11atm. If bronze molten at 1210K contains 10%Pb, the lead vapour pressure is 10^-4atm.
wikipedia

In Notre-Dame's fire, the lead roofing melted around 600K, but the drops that landed on the burning oak beams didn't leave the flames. At 1400K, lead vapour pressure is 10^-2atm. In addition, liquid or gaseous lead in the flames made oxides that went in the atmosphere as fumes, in amounts not limited by the vapour pressure. To my opinion, this is probably the yellow smoke that I never saw over a wood fire. Or what would have been in big amount in the roof?

The firefighters may have inhaled noxious amounts, especially those who climbed in the towers. The nearby inhabitants downwind too. Inhabitants farther downwind and by-passers maybe; the smoke didn't fall down immediately, according to the pictures.

I consider prudent that all people who smelled the smoke clean the clothes they wore, and clean with a vacuum cleaner all surfaces of rooms whose window was open.

Some study mapping the amounts would be urgently needed, diagnosis in the firefighters' blood more so. Treatments to lead poisoning exist
wikipedia

It's important to recognise that smelters were exposed to lead fumes 8 hrs a day, 5 days a week for years or decades.

The one-off exposure of Parisians (residents and firefighters) would be less of an issue.
So, you need to look at the vapour pressure, the dilution, the acceptable concentration and the duration to assess the risk.

Enjoy.

[Enthalpy]

Thinking more at the yellow smoke:

• On pictures of the attic, I saw only the lead roofing, the oak structure and wooden floor, plus dust that may explain how fire started, as lighting oak in a chimney is badly difficult.
• I did see thick smoke when lighting wood, but this one was stone-dry. Half 1.5 century old, half 8 centuries, under a roof. The rest, lead, has a known yellow oxide.
• Much of the lead escaped the flames when melting, but a part felt on burning wood. Some beams were horizontal, and from the pictures the wooden floor was everywhere. If only 1% of the lead ended on burning wood, it made already tons, up to 100% or hundreds of tons.
• In the big fire, lead evaporated and oxidized. With 0.01atm vapour pressure at 1400K, evaporation goes quickly.

I had considered lead oxide as a possible explanation. Presently, tons of lead fumes seem unavoidable to me.

On 4/25/2019 at 10:22 PM, John Cuthber said:

It's important to recognise that smelters were exposed to lead fumes 8 hrs a day, 5 days a week for years or decades.

The one-off exposure of Parisians (residents and firefighters) would be less of an issue.
So, you need to look at the vapour pressure, the dilution, the acceptable concentration and the duration to assess the risk.

And my comparison with a known situation was already an attempt to reduce the uncertainty! I definitely agree that assessment is badly difficult from my armchair. But I have zero dot nothing confidence in what the French government may tell on this topic, as history already showed.

Beyond the duration, the amounts shouldn't be forgotten. As lead exits the organism very slowly, it's more or less their product that counts. Here there were hundreds of tons (or tons if most lead flew away) at flame temperature rather than many kilograms at 1210K. Or just compare the volume of yellow fume, clearly worse than at a smelter.

Between the amount of lead fumes, say tons, to the amount noxious in a human body, a milligram, the ratio is one billion. This ratio suggests the noxious amount will be exceeded at many people. A noxious amount of lead in a human body is only 1x to 10x the amount for cyanide. If 100kg of cyanide were released in the atmosphere in the middle of Paris, more people would wonder how dangerous it was. Or rather, we would already know, as cyanide acts faster than lead.

For the firefighters in the towers, the fume dilution was minimal, see the pictures. I dearly hope they used respirators and decontaminated their clothes and equipment afterwards.

People on the ground nearby seem less exposed as the fumes escaped horizontally on the pictures, but inhabitants downwind received copious amounts.

[John Cuthber]

15 minutes ago, Enthalpy said:

Presently, tons of lead fumes seem unavoidable to me.

How much does the atmosphere of Paris weigh?

Here's a hint; atmospheric pressure is 14.7 pounds per square inch.

[Enthalpy]

Here are pictures of some gothic and neo-gothic cathedrals:

 

Do you guess what is missing at Notre-Dame de Paris? Besides the roof, I mean. It makes it so clumsy.

They were foreseen initially but quickly abandoned. Viollet-le-Duc planned them when restoring the cathedral in the 19^th century but he didn't have the moneys. My opinion is that they could be built now, especially since oak would take years to dry and modern construction techniques make a cheaper roof.

4 minutes ago, John Cuthber said:

How much does the atmosphere of Paris weigh?

Here's a hint; atmospheric pressure is 14.7 pounds per square inch.

And what air amount at 50m distance, where the firefighters were? At 150m, where the first buildings are? The plume had around 50m*50m section. Put the figures together: that's an extreme concentration.

[John Cuthber]

Do you understand that smoke rises?

[Enthalpy]

No understanding needed. See the pictures.

[John Cuthber]

11 hours ago, Enthalpy said:

No understanding needed. See the pictures.

What pictures?

Anyway, since you seem to have ignored it
 

12 hours ago, John Cuthber said:

How much does the atmosphere of Paris weigh?

Google tells me that Paris is about 100 km ^2

That's about 100,000,000 m^2

And atmospheric pressure is about 100,000 N/m^2
So the weight of the atmosphere in Paris is something like 10000000000000 N

A newton is roughly the weight of 0.1Kg so that's a trillion kg

Roughly a billion tonnes.

Into which we disperse a few tonnes of lead.

Giving a mean concentration (pessimistically assuming it's all released so fast that none escapes by dispersion on the wind or whatever) of a few  parts per billion by mass.

That's not good but let's see how much difference it makes. What's the background?
http://www.euro.who.int/__data/assets/pdf_file/0020/123077/AQG2ndEd_6_7Lead.pdf 

tells me 

"Spot measurements in five French and four United States cities in 1984–1985 reported air lead levels ranging from 0.005 µg/m3 to 0.44 µg/m3 , the highest value being from Paris"

So Paris in the 80s had lead levels of 0.44 µg per m3

And a m3 of air has a mass of roughly 1kg

So that's a level of about 0.44 parts per billion by mass.

And the fire released a few ppb (m/m)

So it's a roughly 10 fold increase.

Until the wind blows or the rain falls.

So, for a few days the average lead concentration in Paris went up about 10 fold.
Not good news, but hardly worth making a fuss over.

 

Obviously, you need to look at firefighters' exposure.

Practically nil because they are not stupid and wore breathing apparatus.

 

[swansont]

On 4/19/2019 at 8:06 AM, Enthalpy said:

 Trying to estimate the lead concentration sent in the air by the fire...

Smelter workers had (in some places, have) harmful amounts of lead in the body due to lead's vapour pressure. If melting pure lead at 601K, the (equilibrium!) vapour pressure is 10^-11atm. If bronze molten at 1210K contains 10%Pb, the lead vapour pressure is 10^-4atm.
wikipedia

In Notre-Dame's fire, the lead roofing melted around 600K, but the drops that landed on the burning oak beams didn't leave the flames. At 1400K, lead vapour pressure is 10^-2atm. In addition, liquid or gaseous lead in the flames made oxides that went in the atmosphere as fumes, in amounts not limited by the vapour pressure. To my opinion, this is probably the yellow smoke that I never saw over a wood fire. Or what would have been in big amount in the roof?

The firefighters may have inhaled noxious amounts, especially those who climbed in the towers. The nearby inhabitants downwind too. Inhabitants farther downwind and by-passers maybe; the smoke didn't fall down immediately, according to the pictures.

I don't think anyone was breathing in gases at 1210K or 1400K, so I don't see why the vapor pressure matters at those temperatures.

[Enthalpy]

Here I've added the missing elements, hoping to inspire an architect. The roof has also a stable colour possible with anodized metal.

That is a cathedral rather than a clumsy building. The roof colour can be finely tuned, with titanium or more freely with aluminium. It could match clean brass, as were the roofs of Paris' monuments few years ago, or as was Lübeck's cathedral before getting the green patina. I feel it incomparably nicer than grey lead, whose only advantage is to match pigeon droppings.

Vast openings reduce the wind load if useful and give room for the bells that were so badly located under the lead roof.

I get accustomed to the view faster than expected.
Marc Schaefer, aka Enthalpy

2 hours ago, John Cuthber said:

Google tells me that Paris is about 100 km ^2 [...] And the fire released a few ppb (m/m)

Hey JC, you will fool about nobody with that attempt on a forum for science. And I know with full certainty that you don't believe a second what you write.

Anyway, here's again one picture showing that pollution doesn't dilute instantly over the whole Parisian atmosphere:

Fumes flying right into  the towers with the firefighters. I hope they will decontaminate all clothes and tools.

The fumes fly then horizontally, and many Parisian buildings are higher than that. Not to forget that the fumes fall down as they cool.

2 hours ago, swansont said:

I don't think anyone was breathing in gases at 1210K or 1400K, so I don't see why the vapor pressure matters at those temperatures.

Lead vapours oxidize to make fume, or less probably condense into an aerosol. Then they fly away as ash, cool down, and are inhaled by people downwind. Vapour pressure matters to tell that lead first gets in the air.

==========

Bizarre. A French NGO that told more or less the same was threatened with cutting their subsidies. On an other forum, my similar contribution was obviously not appreciated at all. But this was all on French websites, where this is expected.

[John Cuthber]

Thanks for the picture of a cloud of smoke not affecting people because it is a hundred meters above them.

 

1 hour ago, Enthalpy said:

you will fool about nobody with that attempt on a forum for science.

At least my approach has some basis in science.

Yours ... less so.

There are people who model this sort of thing for a living.

https://en.wikipedia.org/wiki/List_of_atmospheric_dispersion_models
Why not ask them about it?

 

 

1 hour ago, Enthalpy said:

And I know with full certainty that you don't believe a second what you write.

Wrong.

1 hour ago, Enthalpy said:

I feel it incomparably nicer than grey lead,

Others won't.
There are already questions being raised about the (ver rich) church being subsidised to repair their building.
That money could be used for things that matter- like people- rather than a old building.
Do you think that what will be seen as "gold plating" it will help?

Edited April 27, 2019 by John Cuthber

[swansont]

2 hours ago, Enthalpy said:

Lead vapours oxidize to make fume, or less probably condense into an aerosol. Then they fly away as ash, cool down, and are inhaled by people downwind. Vapour pressure matters to tell that lead first gets in the air.

That’s lead oxide, which doesn’t behave the same as lead. Any lead vapor will be at a much lower temperature than 1400K very soon after vaporizing, as it expands and moves away from the flame.

[Enthalpy]

My proposal for a new roof: aluminium tiles.

6m*2m sheets are common, and the well-proven anchors in the walls shall serve further, so the main beams are 5.72m apart as were the burnt ones, and the sheet and tile length is horizontal. A higher tile overlaps a lower one, and the short sides are folded in lambda shape to repel water. The overlapping lambda is bigger to allow for thermal expansion.

60m/s gusts shall load the parts to half the yield stress. I apply 100% of 2.2kPa = rho*V²/2 on the whole surfaces. Eurocode 1991 would do that better.

The outer surfaces are of AA1080A with thick anodization for corrosion resistance and aspect. 6mm thickness and 388mm between the beamlets load the sheet to 15MPa/2. Purer alloys are badly standardized but can be tailored for that amount, in thicker sheets to keep the strength. Or use titanium, with less colour choice. Without the transept, the 102m long roof needs 216 tiles, and the sheets weigh 42t.

Humidity condenses occasionally under the roofing, so the beamlets are of AA5083. Tailor-made extrusion and some 5.4m length load the alloy to 110MPa/2. The chosen angles shall let humidity flow along the surface, not drip down. Three beamlets per tile contribute 49t to the idealized 102m roof.

The tiles hold at the beams by AA5083 end plates welded at the beamlets. Cold-drawn AA1080A wire can make corrosion-safe fastenings.

I want all weld seams airtight, between the sheets and the beamlets, and between the beamlets and the end plates. The beamlet-to-sheet seams must be much thinner than 6mm to preserve the exposed face's composition. TIG, MIG... or even FSW are possible. These alloys make seams with full strength and corrosion resistance.

A tile is fully made at the workshop: fold the sheet, weld the beamlet ends, file and clean, weld the beamlets on the sheets, clean, anneal the whole tile. Anodize at least the exposed face, but the inner face including the beamlets wouldn't hurt: grow thick oxide, soak with pigment, densify the oxide.

Main beams later and maybe. Good night!
Marc Schaefer, aka Enthalpy

[John Cuthber]

There is no need for everything to be "modern".

[Carrock]

2 hours ago, John Cuthber said:

There is no need for everything to be "modern".

There would have been less damage if the modern (19^th century) tower hadn't collapsed into the building. Often 'obvious' improvements like extra towers etc weren't included because the builders knew that such constructions could overload the building or cause serious damage in a fire etc.

Very old buildings still in use often are and sometimes have to be somewhat modified over the years, but the default assumption should be that as they still exist the builders were competent.

 

[Enthalpy]

3 hours ago, John Cuthber said:

There is no need for everything to be "modern".

I agree.

Apparently there would be enough oak in 2019 to rebuild the roof, but the parts would be smaller, which imposes to adapt the design, and the wood is still trunks in the forest. Such sections take a decade to dry, and if one tries to accelerate, the wood splits, and if the wood is used wet, the roof deforms. I doubt the French want to wait a decade to start rebuilding. The president told "rebuilt in 5 years". With metal, it can be finished in less than 2 years. It does make an economic difference whether visitors can come in 2 years or in 15 years. More importantly, "already healed" rather than "still wounded" makes a difference for the Parisians and French.

This is decoupled from the colour. Having lived just in front of the South side of the cathedral, I find it ugly, both in shape and colour. Rebuilding is the opportunity to improve that - obviously a matter of taste, and not a need. Both aluminium and titanium (niobium too) could be given the colour of old lead.

After receiving the blow, "rebuilt nicer than it was" is for me a better answer than "repaired as we could".

On 4/27/2019 at 5:51 PM, John Cuthber said:

Thanks for the picture of a cloud of smoke not affecting people because it is a hundred meters above them.

The picture shows the smoke flying into the towers where the firefighters were, then horizontally. Many Parisian buildings are taller than that. Smoke later falls down, that's why you smell wood fires in chimneys in towns. Due to density, lead smoke falls faster.

On 4/27/2019 at 5:51 PM, John Cuthber said:

There are already questions being raised about the (ver rich) church being subsidised to repair their building. That money could be used for things that matter- like people- rather than a old building. Do you think that what will be seen as "gold plating" it will help?

The Church seems richer in Britain. In France it isn't, nor is it perceived so. The buildings were confiscated by the Republic and often in need of repair, priests are not paid by the State except in Alsace and Moselle.

If one explains "gold colour" the French grasp the difference. If aluminium is cheaper than oak, even better.

[Enthalpy]

1 hour ago, Carrock said:

There would have been less damage if the modern (19^th century) tower hadn't collapsed into the building. Often 'obvious' improvements like extra towers etc weren't included because the builders knew that such constructions could overload the building or cause serious damage in a fire etc.

Very old buildings still in use often are and sometimes have to be somewhat modified over the years, but the default assumption should be that as they still exist the builders were competent.

With metal beams, there would have been even less fire damage.

I ignore why the spires were not built. The towers are obviously meant to carry much more weight - just observe the sections up to the present top. The spires were in the plans in 1160 but abandoned in 1240, I haven't read a reason. With present materials, they would weigh a fraction of what was possible then.

The very Notre-Dame shows that builders do how they are used to within their time. The construction spanned two centuries (if you allege it's finished without the missing spires) and the style is hybrid, the techniques too. Most other constructions had their plans heavily modified over time, before or after "completion". Check for instance the Stephansdom in Vienna, St Vitus in Prague... about every cathedral
Construction of Notre-Dame (English)
Construction of Notre-Dame (French, other details)
Stephansdom
Saint Vitus in Prague
In Notre-Dame, the transept was added later and their front increased even later, and so on and so forth.

Don't overestimate neither the knowledge of middle-age architects. Many of their buildings collapsed, others (cathedral in Strasbourg and more) could not be finished because their design was flawed. That some buildings still stand is an achievement, but don't presume present architects would do it worse. Many Parisian buildings date back to 1850-1870
Haussmann
and are on the best way to last centuries more.

If willing some sort of "original state", then I would like colours to be restored. Cathedrals were brightly painted, the inner walls, the statues... Colours fainted over time or were destroyed, for Notre-Dame when a bishop or canon let cover all walls in white in 1756 and replace stained glass by transparent one. What we see now is an ugly and badly degraded remnant of the early state. Keeping naked stone walls as is, or restoring them to their degraded state, is not a goal for me.

[dimreepr]

11 minutes ago, Enthalpy said:

With metal beams, there would have been even less fire damage.

Laminate beams seem a reasonable compromise.