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Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

theguardian.com

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Re: Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

#211

Post by jws »

bombcar wrote: post #137
barbegal wrote: post #117

From an engineering perspective these sorts of acrylic tanks are a nightmare to ensure they are safe. The seams are impossible to inspect rigorously so the only real way of checking that they are safe is to load them with an excess pressure ( https://en.wikipedia.org/wiki/Hydrostatic_test ). This can't be done with a tank of this size so the engineers can only real fall back on giving the tank excessive safety margin…

Is there no way to detect cracks or is it just prohibitively expensive to do so? I know that metal fatigue is a known thing that airlines check for and when they went to carbon fiber they had to develop tools to detect fatigue/cracks.

Acrylic and water have virtually the same index of refraction, so if the crack forms on the wet side of the wall and wicks in water you will not detect it visually.

It forms the basis of some magic tricks involving walking on or supporting things in water. (I say some, the rest are totally magic and you should enjoy them.)

Re: Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

#212

Post by sidlls »

pvaldes wrote: post #145
sidlls wrote: post #116

Earlier quoted context omitted.

Settlement of the building it's housed in, temperature variations (things contract and expand as temperature changes), random impacts and vibrations (e.g., road traffic, heavy construction nearby), and so on. All of these contribute to fatigue.

A tropical aquarium is keep at the same temperature. Unless somebody would disconnect it to save energy or the termostat[s] would fall, shouldn't have experienced a lot of changes in their volume by this.

It’s unlikely a structure this size has a temperature uniform enough consistently over time to avoid thermal fatigue.

Re: Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

#213

Post by anenefan »

gambiting wrote: post #54
anenefan wrote: post #34

That's a real shame only a few fish survived. It's fortunate only two people hurt. That looks nasty from the picture. Maybe next time less brittle acrylic. Off the top of my head a 14 m high tower of water - there would have been approx 20 psi at the bottom of the tank.

Just fyi - acrylic is actually less brittle than glass.

To be clear ... less brittle acrylic isn't glass.

Re: Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

#214

Post by jacquesm »

swader999 wrote: post #206
jacquesm wrote: post #201

Earlier quoted context omitted.

There are some eye witness accounts about corrosion around the base of the tank. One way in which that could have caused this is because corroded metal takes up more space than the original and this could put point stresses on the acrylic. I haven't seen any engineering drawings (I did try to find some but there are only pretty pictures) so I'm not sure how much effect that would have but keeping the base corrosion f…

That is fair. Security tapes might tell a lot as well.

Those will definitely be interesting, if they are leaked. Let's hope the cameras have a high frame rate because the first couple of frames will be the most interesting with respect to where the failure started and how it propagated.

In the Panama City there is an overhead swimming pool many meters above the restaurant floor. I've dined there a couple of times and never feel quite comfortable with that much water hanging over me supported by a sheet of acrylic.

After this that feeling is likely not going to be any less :)

Re: Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

#215

Post by pantalaimon »

barbegal wrote: post #117

From an engineering perspective these sorts of acrylic tanks are a nightmare to ensure they are safe. The seams are impossible to inspect rigorously so the only real way of checking that they are safe is to load them with an excess pressure ( https://en.wikipedia.org/wiki/Hydrostatic_test ). This can't be done with a tank of this size so the engineers can only real fall back on giving the tank excessive safety margin…

The thing was just recently reopened after revision, here is an interview after the overhaul: https://www.domaquaree.de/de/Modernisierung-AquaDom.html

Interesting bit:

> It got a little tricky when taping off the glass envelope with foil to prevent possible cracks. Acrylic glass is a sensitive material that absorbs water over time. If it then dries out too quickly, cracks can appear even in the glass walls, which are up to 20 centimeters thick.

Re: Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

#218

Post by sirsinsalot »

bombcar wrote: post #140
boppo1 wrote: post #120

Earlier quoted context omitted.

Doesn't seem crazy, my tires hold 38 psi.

PSI is a measurement that can be hard to translate between various items like tires and tanks and foundations: https://www.engineeringtoolbox.com/building-foundations-load... Massive tractor tires can be 50+ psi and when they pop it is devastating.

Even my compact saloon cars tires take 45psi

Re: Cylindrical aquarium housing 1,500 exotic fish bursts in Berlin

#219

Post by CoastalCoder »

barbegal wrote: post #173
plastiquebeech wrote: post #163

Earlier quoted context omitted.

Impossible to manufacture? Or financially impossible to build a factory for the purpose and larger infrastructure to accommodate transportation? I'm curious if there is something about acrylics which makes it impossible to make very large single pieces.

I guess you could transport it at immense cost. But you'd also need a machine capable of moulding or extruding it this big. Current maximum for plastic pipes is about 3.5m diameter https://www.agru.at/en/applications/agruline/grand-opening-r... so you'd need something which is capable of more than 3 times the diameter.

Could one pour liquid acrylic into a mold (like with a concrete foundation), rather than extruding it?
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