"There was speculation that freezing temperatures of as low as -10C (14F) overnight had caused a crack in the tank, which then exploded under the weight of the water.... Operators say the aquarium has the biggest cylindrical tank in the world... The aquarium, which was last upgraded in 2020, is a big tourist attraction in Berlin. A 10-minute elevator ride through the tank was one of the highlights of the attraction."
The Guardian reports.
Has the biggest cylindrical tank in the world? Had the biggest cylindrical tank in the world.
I suspect there is good reason for not building large cylindrical glass water tanks and would love to hear expert opinion on water pressure inside a cylinder.
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Operators say the aquarium has the biggest cylindrical tank in the world...
Aquarium diversity is our strength.
I guess something like this is more likely to make news than the thousands/millions of people freezing in their homes because they can't afford gas for heat.
They must have assumed global climate change meant the tank would never have to deal with temperatures as low as -10 C.
The aquarium, which was last upgraded in 2020, is a big tourist attraction in Berlin.
Well, it was, anyway.
The humanity
Cylinders are the best shaped container for storing liquids as they evenly distribute pressure about the sides.
Read the article. So what happened to the fish?
I blame Tom Cruise.
And Trump, of course.
Our aquarium has a very large tank--it's big enough to run a people mover through, but it's only about 10 feet deep. That's where they went wrong. The pressure at the bottom of a 45 ft tank has to be tremendous and given the diameter of the tank, I don't see how it's possible the glass was thick enough to hold in less than perfect conditions. Of course it blew open at the first crack.
Pressure would be the same regardless of the shape of the tank.
I'd expect a cylinder to be stronger than a traditional aquarium. Fewer edges.
I'm no expert but I suspect that they are stronger than cube shaped tanks. Probably more expensive to build though.
All water tanks are cylindrical. Maybe we can get an expert up here to explain why that is. It's a real mystery.
I take it the fish died. Sounds like a P.T. Barnum trick. Couldn't keep a beluga whale alive in a tank in Manhattan. At one point he diverted water from the East River: I guess salt water, saltier than the Hudson?
A perfect metaphor for the failures of Energiewende. Unfortunately, worse is coming.
Does anyone know what Harry Dresden was doing in Berlin?
If I were still in 10th grade chemistry I could deduce the exact pressure at the bottom by using the weight of Na, Cl, H, and O along with the formula for the volume of a cylinder (pi*r^2*h) and taking the integral.
I'd also have better knees.
-XC
PS - The pressure at the bottom would be about 1.4 atmospheres since at sea level 10M deep divers experience 1 ATM of pressure. IRRC from WWII history, Berlin is about 100ft above sea level. So that probably offsets the sand and the other bits and bobs in the water. So not so much.
A column of water 45 feet high is exerting serious pressure at the base. One atmosphere every 32 feet, so about 1.5 atm. Night and day, 24/7, complex compression/tension on glass. Which I believe is brittle: has a tendency to propagate a crack from any small imperfection.
Poor fish!
Read the article. So what happened to the fish?
@Gotragonow, there’s a special deal on sushi at beer halls.
Most of the fish died; some froze. Some were in other tanks adjacent to the main one and were able to be saved and moved to other locations. It just seems like a massive screwup (a design flaw in the 2020 reno?) and just one more sign of decaying German competence, once fabled. Of course Americans have nothing to brag about in that department either.
I've stayed in that hotel; it was about 8 years ago. My husband dug up a photo of me sitting in the lobby. I'm amazed no people were seriously hurt.
All water tanks are not cylindrical, and I don't know why anyone would bother with such an idiotic statement. But: If you want to know the pressure exerted hydrostatically by a column of sea water, then you simply multiply the height in feet x 0.465 psi/ft, to get psi. It's pretty basic engineering to work out the hoop stresses and design a transparent cylindrical tank for this purpose. Too bad about all the fish. The place must smell as bad as their energy policy.
To answer a question from up above, the article says that none of the fish survived.
Next to a sphere, a cylinder is the best shape for an aquarium from a water pressure standpoint. But the strongest aquarium would be a spherical one with humans inside looking out, with the surrounding water exerting pressure toward the center.
So, it was caused indirectly by the war in Ukraine.
14 meter-high tank. Translation into American English - the tank was about 6 stories tall. It was the centerpiece of a hotel in Berlin, looks (er, looked) pretty cool to me.
All I know is to keep your gum off the glass.
https://m.youtube.com/watch?v=2v_ipqKW9vs
What an incredible beautiful structure that was! Maybe hindsight, but looking at pictures of how large it was and how it was situated right in the middle of a hotel's interior courtyard, I got a Bad Feeling--- I would have been afraid to be anywhere near it.
Reminds me of...
The Great Molasses Flood, also known as the Boston Molasses Disaster, was a disaster that occurred on January 15, 1919, in the North End neighborhood of Boston, Massachusetts.
A large storage tank filled with 2.3 million US gal (8,700 m3) of molasses, weighing approximately 13,000 short tons (12,000 t), burst, and the resultant wave of molasses rushed through the streets at an estimated 35 mph (56 km/h), killing 21 and injuring 150. The event entered local folklore and residents claimed for decades afterwards that the area still smelled of molasses on hot summer days...
The molasses tank stood 50 ft (15 m) tall and 90 ft (27 m) in diameter, and contained as much as 2.3 million US gal (8.7 million L).
Did someone turn the thermostat down?
Wince @ 9:24: Thx for the history. I am trying to imagine that tsunami of goo roaring through the neighborhood. *Shudder*
Liquid under pressure gets ferocious in a hurry. Maybe the Berlin rebuild should just put up giant screens showing the fish in a remote below-ground facility?
Toroidal mmmmmmmmm donuts
A spherical container would probably distribute the force on the walls most evenly, but a cylindrical container is easier to construct. If you want to calculate the pressure at a given depth, calculus is the easiest tool and most accurate tool, but for a liquid like water in this case you can also just calculate the weight in pounds of the rectangular column of water 45 feet tall (in this example) with a base of 1 inch square to get the PSI.
As others have stated, the hydrostatic pressure at the base of a column of water (no matter what the shape) is simply the weight density of water times the height. So 1000 kg/m^3 times 9.8 m/sec^2 times 14 meters = 137,200 N/m^2 or just under 20 psi.
If we knew the diameter and thickness of the cylinder we could estimate hoop stress in the glass using a thin ring formula (stress is pressure x diameter / twice the thickness). A 23 foot diameter cylinder (which is what it looks like from the picture, a diameter of about half the height) with an assumed 4 inch wall thickness would yield a stress of ~686 psi. Google returns a tensile strength of 9400 psi for tempered glass, yielding a safety factor of 13.7, which seems like an adequate design margin (for glass away from any stress raisers like cracks or inclusions). I would imagine the manufacturer undertook a detailed stress analysis including a fracture mechanics evaluation assuming an initial flaw size, but who knows?
Of course, we don't know what grade of glass was used or the actual diameter and thickness, so this bit of engineering analysis is worth exactly what you are paying for it.
Well, I read a bit further in the article, and it states that the thickness at the base was 7 inches. So that results in a stress of 392 psi and a safety factor of 24, all other assumptions remaining the same.
The Berlin aquarium at issue is/was 25m (82 ft.) tall according to its website. I don't know where people got 14m (46 ft.) as the height because the pictures of it before the break clearly show an elevator next to it at least 6 stories high (much more in keeping with an 82 ft. height).
For those of an exacting nature, a 25m column of water (whatever the amount, whether a vertical tank 1 inch in diameter or 10 feet in diameter) exerts an outward hydrostatic pressure at the base of 80.11 pounds per square inch (psi) or 5.451 standard atmospheres (atm).
Ooopsy. I read further in the article, and it does state a wall thickness of 7 inches at the base. So that would result in a stress of 392 psi and a safety factor of 24, all other assumptions remaining unchanged.
All water tanks are cylindrical. Maybe we can get an expert up here to explain why that is. It's a real mystery.
Aliens. It's aliens.
Looking at the pictures, I have a hard time thinking temperature had anything to do with it. I'm sure the water was fairly warm; the energy content in that water is immense. The tank appears to be 'inside', so it seems to be a reasonably stable environment.
The tank appears to be on a metal structure of some kind? I can't tell. If temperature was a contributing factor, I would suspect the support rather than the glass. There's a lot of weight, and glass isn't known for it's flexibility.
Is the indication and highlight of the 'low temperature' reporter editorial, of from an actual on-site expert who is familiar with the installation? My guess the former because the expert probably said 'I don't know'.
love to hear expert opinion on water pressure inside a cylinder
Not even rocket science - more depth, more pressure.
The question should be, what were the temperature differentials around the tank from top to bottom, and how did the tank and fastening materials respond to those differentials?
Using frequent flying miles, I stayed at that hotel about 10 years or so when visiting Berlin. The aquarium was impressive.
Here's fail safe measure. If they replace the aquarium, I recommend stocking it with shrimp instead of exotic fish.
The pressure at the bottom of the tank is 19.9 psi. The sides are in tension and the bottom is in flexure unless fully supported by the floor. Glass is brittle so a crack is going to fail in tension. Steel is tough and more resistant. A cast glass tank is hard to make because of residual stress in cooling. A spherical and lesser, a cylindrical tank has less surface area for a certain volume so is usually considered cheaper. But there is no advantage in strength just lower material cost. I can make a 14 meter rectangular tank of glass just as strong. The cylinder is more an artistic statement. I
Was there gum found on the glass? I know, it sounds like an impossible mission, but I'm just saying...
AFA depth vs pressure, when I was on a Navy submarine, the rule of thumb for pumping tank contents overboard was 50 psi per 100 feet plus 25 psi. e.g. blowing the contents of a san tank at 200' would require 125 psi ((2x50) + 25).
The worse part of this evolution was when you're done blowing a san tank overboard was the inevitable need to vent the now empty tank into the sub. Imagine the scent of venting a 1000 gallon septic tank into your apartment.
O-ring, revisited.
Thanks all for the fish updates. The original article found at Althouse and also on webarchive forgot to mention them. The survival factoid got added later. You can trust the media without exception.
Water pressure is about 44PSI/hundred feet.So a 80 ft tank is exerting less then 44 PSI at the bottom.
Which is virtually nothing. However- it adds up. A 10 ft X 10 ft area is holding back (roughly) 144 tons.
80 PSI as mentioned by Barry Sullivan is off by a bit.
Kevin said...
Operators say the aquarium has the biggest cylindrical tank in the world.
Not by height. The Royal Navy submarine escape training tank is 100 feet deep. I didn't see a width on it.
more interesting question for me is creating the tank >> looks seamless cylinder of glass of very large diameter
project details here
"There was speculation that freezing temperatures of as low as -10C (14F) overnight had caused a crack in the tank"
The tank is INDOORS. Why wasn't the heat on? Well we know why. But of course it won't be reported.
For everyone trying to put numbers to this disaster ...
Hydrostatic pressure at the bottom of a 14 meter water column is just short of 20 psi (pounds per square inch). 19.9 psi to be more precise. For reference, at sea level atmospheric pressure is about 14.7 pounds per square inch.
Engineering Toolbox
Glass is quite strong but brittle. A cylinder is a good shape for holding fluid under pressure but, assuming is isn't damaged, a cylinder is weakest where the curved walls meet the flat base. A spere is the best shape for holding fluid under pressure.
When glass breaks and you don't see anyone standing around with a hammer in their hand, it is likely caused by a manufacturing defect or a small chip or a crack.
In solid mechanics, a stress concentration (also called a stress raiser or a stress riser) is a location in an object where the stress is significantly greater than the surrounding region. Stress concentrations occur when there are irregularities in the geometry or material of a structural component that cause an interruption to the flow of stress. This arises from such details as holes, grooves, notches and fillets. Stress concentrations may also occur from accidental damage such as nicks and scratches.
Stress Riser
45.9 feet * 62.4 lbs per cu ft / 144 sq in per sq ft = 19.9 psi
"I suspect there is good reason for not building large cylindrical glass water tanks and would love to hear expert opinion on water pressure inside a cylinder."
I am quite sure that they paid a great deal of money for expert opinions before they built it. And all their experts assured them that it was entirely safe. Now go take some photos on that big, glass deck they've cantilevered out over the Grand Canyon.
I accidentally posted as Unknown twice due to me being logged in under my University.edu account. I know I should not be unknown but google has it's agenda. I wronged you.
And I am ready to apologize. I need healing, acceptance, closure, and absolution. I need help, you know. So help me, you assholes.
And on top of that, Angel, from the Rockford Files, just died. I can't take it. I can't take it all.
glass isn't known for it's flexibility.
You evidently were not around in the days of Usenet.
There were endless arguments, it seemed, about whether glass was a very viscous liquid or a solid.
John Henry
Not to be a pedant, but spheres and cylinders are not the best tank for heavy fluids. The optimum shape for minimizing stress differences is a somewhat squashed spheroid, like a water balloon sitting on a table. Kennedy Space center used to use these for fuel storage.
But, 1) I cannot find any photos or specs, and 2) it would be outrageously expensive to fab a 15 meter tall tank of this shape from glass.
So practically speaking, cylinders are it.
"Has the biggest cylindrical tank in the world? Had the biggest cylindrical tank in the world."
Good point.
This is probably one of those classic engineering fails. Some engineer didn't do the math right or had the wrong data for the materials.
They should have used Captain Scott's formula for transparent aluminum to make the water tank.
Also, I should say that temperature may have been a factor. It could be that the engineers were working on the assumption of warmer temperatures in the building but the German energy problems caused the building to drop below those temperatures.
Fred Drinkwater: you really owe it to yourself to google images of this aquarium. It's beautiful and terrifying at the same time. Also, the cylinder hollow in the middle, where they put an elevator.
A lot of the commenters here discuss the danger of large glass tanks. But the Radison Blu aquarium tank wasn't tank wasn't constructed of glass. It was made of acrylic. Acrylic is much stronger and easier to repair than glass for water tanks, but it also is subject to creep over a much shorter time period than even ordinary window glass.
Not glass. This morning's WSJ reports, The AquaDom tank is made of plexiglass and has a diameter of 11.5 meters, according to the operator’s website. The tank contained 1,000 cubic meters of saltwater and had been renovated as recently as 2020, according to the operator. The aquarium contained more than 100 different species of fish.
Giant Aquarium in Berlin Holding 1,500 Fish Bursts, Injuring Two
the height of a column of water determines the water pressure below it. additionally, per usual, the base of anything solid supports the top. i wouldn't think the circular part is a problem at all - certainly better a cylinder than a cube. in any case, it seems extra strength is needed at the edge and at the base. whoever designed it should have documented any temperature requirements.
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