making laminated glass tubes

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Hi!

I have glass tubes filled with liquid CO2 at high pressure and need to
make it safe in case the tube explodes. Currently I put it in a
protective polycarbonate tube, but I'm worried the PC might not last
long enough. Some of the tubes might be in use for 100+ years. They are
meant to be viewed by students/pupils in schools and universities. There
will probably be little UV exposure, but some tubes may be on display
permanently, though still inside.

So ... what would be the best material to fill the gap between 2
concentric glass tubes? Polyester, Epoxide, PU, Polycarbonate,
Polyvinylbutyral, ...? It should be managable with low tech equipment.

How opaque is (borosilicate) glass to UV?

Thanks, Bernhard

Re: making laminated glass tubes
Bernhard Kuemel wrote:
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Actually I first thought of filling the gap with a viscous liquid like
glycerol or silicone oil.

A test explosion of a 1 cm OD pressure tube shattered a 60mm OD
borosilicate glass tube with 7mm wall to rather large pieces. I think,
if the outer tube were not struck by the glass fragments of the pressure
tube, the protective glass tube will withstand the shock wave. The
pressure in the pressure tube (10mm OD, 5.5mm ID) may exceed 200bar. It
was up to 240 bar without breaking.

With a laminated glass tube, is there a possibility that the glass will
crack from thermal expansion of the resin layer? The resin also should
not separate from the glass as this would create additional optical
surfaces which decrease optical transparency.

Bernhard

Re: making laminated glass tubes
Bernhard Kuemel writes:

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Really, in glass? What is the application?

"Double bagging" seems a fool's errand.  Things just cascade until the
energy is absorbed.  You must disperse the energy, such as through a
stainless mesh.

Re: making laminated glass tubes
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    I'm a pretty adventurous soul, but I wouldn't keep those tubes anywhere
near me....


Re: making laminated glass tubes

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In the British Science Museum located in London, there is an exhibit
using liquid carbon dioxide in a glass tube. It is used to demonstrate
what happens when the triple point temperature is exceeded. As the tube
is heated, the interface between liquid and gas becomes invisible.

AFAIK that may have been around for over a hundred years. Why not find
out what they do and how they protect the public?

Bill

--
Private Profit; Public Poop! Avoid collateral windfall!

Re: making laminated glass tubes
Richard J Kinch wrote:
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To demonstrate the critical point. There's an image of one on
http://de.wikipedia.org/wiki/Kritischer_Punkt_ (Thermodynamik) .

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The technology is applied in e.g. car windows.

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I believe, a glass tube can take the pressure of the CO2 shock wave.
Only the splinters that hit the tube make it break, and the pressure
then drives the splinters away. But liquid or resin layer between 2
concentric glass tubes will prevent splinters hitting the outer glass
tube and disperse the impact pressure evenly.

Maybe it doesn't actually matter much, what middle layer I use. But if
the device breaks from external force a simple (viscous) liquid filler
would not hold the pieces together and then it might be dangerous if the
pressure tube exploded.

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The protective tube shall be completely clear to allow good vision of
the critical point events.

Bernhard

Re: making laminated glass tubes
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1. Substitute another liquid and tell the customers it's CO2. It can
even be a fluorocarbon that will demonstrate the triple point, but at
a lower pressure.

2. Use concentric PC tubes and test, test, test. (But visibility will
be reduced.)

3. Embed in solid transparent polymer and provide a pressure relief at
one end.

4. Use pressure rated steam boiler sight tubes and pass on the
liability to the manufacturer.

5. Buy lots of liability insurance.

DB

Re: making laminated glass tubes
snipped-for-privacy@gmail.com wrote:
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Thought of that. C2F6 has a slightly to low Tc. CFCl3 is unavailable
because it's destroys the ozone layer. And both are much more expensive
than CO2 and prossibly more difficult to handle.

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One PC tube would suffice, but it might fail if it degrades by age or UV.

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Good idea, I thought at first. But that would make heating/cooling the
pressure tube difficult.

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Hmm, if they are suitable and available at reasonable cost, that might
be it. I've seen laminated glass tubes as structural elements for
buildings, but they'd charge me around 100 EUR for 25cm pieces.

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I want to earn money, not pay. And the insurance probably would try not
to pay if they could blame me. Also I want to avoid accidents.

Thanks, Bernhard

Re: making laminated glass tubes
Bernhard Kuemel wrote:
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s/to/too. s/CFCl3/CClF3

Re: making laminated glass tubes
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Sounds like you need to do some experiments. The pressure above liquid
CO2 at room temp is about 850 psi, so if you had a tank of air or
nitrogen at 2000 psi, you can pressurize the tubes until they explode,
or don't.

If they can take 2000 psi, good, but then you'll have to test for
shock resistance, if only to cause the glass to fracture. This will
test the ability of the PC shell to hold in the explosion.

Finally, you have to get some information from the PC maker on long
term performance of their products. Atlas Material Testing Co, of
Chicago, IL, may be able to point you in the right direction. That's
what they do for a living.

Dangerous Bill


Re: making laminated glass tubes
snipped-for-privacy@gmail.com wrote:
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When I was an Assistant Professor of Natural Science in the College of
the University of Chicago I was one of the lecturers in its physics
course in 1959. We had an apparatus for displaying the critical
properties of liquid CO2 to the students. It was the liquid in a glass
tube that in turn was mounted in wooden box (thick side walls) with
glass windows front and back. Underneath was both a heater and an air
cooling device. We shone a projector light on the tube and the image was
projected on a screen in the corner of the large lecture hall. If it
were to explode the glass fragments would not blow out toward the
students. The wooden walls were very thick. The apparatus had lasted for
decades and to my knowledge never caused a problem. But it showed
beautifully the disappearance and reappearance of the meniscus.
Impressive display! And safe.
FK

Re: making laminated glass tubes
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Presumably safe. We're talking in excess of 850 psi here. The
designers of the device may have tested it, or maybe not, or
calculated the strength of the enclosure, or not. Possibly it's only
decades of good luck.

Who can predict what will happen in the long term?

Years ago, there was an incident at a lab where I worked. Plutonium
239 had been sealed in glass vials, apparently for safety reasons. A
couple of decades later, the vials were retrieved from storage, and
the first one touched exploded in the face of the man handling it.
Alpha radiation had generated an unknown pressure of helium within the
vial to a point apparently just short of the breaking strength of the
glass. The area had to be enclosed and monitored before the rest of
the vials could be moved and 'disarmed'.

DB

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