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smuv
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Shell Shock: Play it safe
I had a very scary chemistry related experience earlier today. Using an apparatus I made to pressurize various bottles, I pressurized a 500ml Kimax
bottle. I had previously pressure tested a different bottle of the same model to 110 psi; It was able to maintain this pressure continuously without
yielding.
As I slowly increased the pressure of the second bottle, just as the guage registered 110psi (the max of my regulator), the bottle shattered with a
deafening bang, causing my ears to ring and sending glass shards everywhere (they were quite small pieces too, not as I expected the bottle to fail).
This experience was very scary for me, although I was uninjured. I stupidly took much fewer precautions while filling the second bottle; because I
had tested the other bottle, and up until that point, I had tested many other bottles with no failure at 110psi.
Play it safe everyone...and count your blessings.
Also, I would recommend never to use a pressure vessel in a reaction at any more than .5x the maximum pressure you tested it.
[Edited on 12-30-2008 by smuv]
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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bquirky
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Glass bottles at 110 Psi !!! 
Id be wary about presurising any glass bottle beyond 1 atm any little piece of grit or defect caused by previous spot heating or anything like a
scratch can create a stress points
Plastic still go's pop but it wont spray glass everywhere.
You can make your own vesles out of PVC pipe if you don't nead to heat it too much they have the advantage of being properly rated for a given
pressure and cheap !
http://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d...
gives you some numbers.
good luck !
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JohnWW
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What pressure occurs in bottles used to contain carbonated beverages, in which CO2 is foced into the drink under pressure when bottling? And what
about the pressure due to CO2 in bottles of champagne, in which the fermentation of the grape juice is completed only after it is bottled?
[Edited on 31-12-08 by JohnWW]
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bquirky
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Its an interesting question
according to http://hypertextbook.com/facts/2000/SeemaMeraj.shtml
soft drink bottles are various pressures around 300kpa (~42psi)
My home brew beer keg on a CO2 bottle runs at about 200kpa (28psi) for a normal head of beer
http://hypertextbook.com/facts/2003/PeterHui.shtml
quotes 60-90 psi for a Champagne bottle
sounds to me like an excuse to aquire a taste for high presure french beverages 
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bquirky
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I just had a thought Im not sure if it makes a difference.
but on the surface it would seem that a bottle full of air at a given pressure would make a better bang than one that was at the same pressure but
only had a few cc's of gas
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hissingnoise
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| Quote: | Originally posted by bquirky
A bottle full of air at a given pressure would make a better bang than one that was at the same pressure but only had a few cc's of gas.
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What are you on about?
And how can one bang be "better" than any other bang?
Better for what?
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smuv
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I would say that a Champagne bottle would have a burst pressure of 200+ psi based upon what I have seen of glass bottles around this size. I would be
weary to use non-borosilicate glass in any exothermic or heated reaction though, as thermal stresses could easily crack the bottle.
@Hissingnoise better = louder I believe. The failure of the empty bottle sure was loud!
[Edited on 12-30-2008 by smuv]
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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bquirky
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pardon my warped humor, by better I facetiously meant more dangerous
my line of thinking was that since gas is compresable given two identical bottles at the same pressure one full of a liquid and the other with no
liquid and only gas.
The bottle containing the grater volume of compressed gas would contain more energy and hence produce a 'better' bang
despite the fact that they are both the same size and at the same pressure.
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hissingnoise
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I get it! More bang for your psi. I've already damaged one (my own) eardrum. . .
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hissingnoise
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Wouldn't the smaller volume of gas need a higher pressure to rupture the container?
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hissingnoise
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My physics isn't great this time of year---I should, perhaps, retract the question.
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hissingnoise
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On further thought, bquirky, both bangs should be equally loud, I, er, think. . .
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Mr. Wizard
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Hydrostatic testing of containers is the normal method if testing for pressure. A relatively non compressable liquid is used, such as water. When the
container, pipe, or hose fails, only a small amount of noise or energy is released, because the compression of the liquid and container only stores a
small amount of energy. Avoid any air or gas spaces in a container under test. They store energy and make a failure louder and more dangerous. I have
tested 40 gallon homemade tanks with a small hand operated pump designed for the purpose. The dispacement of the pump is very small, with the piston
diameter of only about 1/4" (6 mm). The pump could easily reach 500 psi. You can easily and quickly reach this pressure IF there was no air bubble in
the tank. If there was air in the tank it takes forever to pump any pressure. You then know to remove the air.
To sum up, use a safety shield and eye protection. Use water and avoid compressed gas pockets or volume. If you do not have a pump and must use
compressed air to raise the pressure on the liquid filled container, use a very small narrow line that will only cause a slight amount of air to flow
if the test fails. Wrap the tested container in a towel or fabric, using many layers. Don't use a gas that dissolves in the liquid.
There is absolutely no reason to stand next to a container when you are pressure testing it.
The more compressed air the more the danger, and the louder the bang.
[Edited on by Mr. Wizard]
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hissingnoise
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| Quote: | Originally posted by Mr. Wizard
The more compressed air the more the danger, and the louder the bang.
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Yes, but won't identical containers fail at the same pressure and produce an equal racket?
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DJF90
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You can't guarentee identically made containers will have exactly the same mechanical properties. Therefore there may be a small variation in the max.
pressure of a set of identical bottles, but they will generally fail at approximately the same pressure (as the mechanical properties shouldn't vary
that much).
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bquirky
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Being new years I had a bottle (or 3) of champaign tonight !
and had a close look at the bottle. the glass is very very thick compared to most other glass bottles and the shape of the curves seems to be be very
um.... deliberate ?
The bottom of the bottle is indented with what appears to be a perfect parabolic cone such that the glass at the base appears to be mostly under
compression, all of the bottles that i saw had a very similar shape to the wide shoulder coming up to the neck. a very large radius curve perhaps to
avoid stress points ?
when im cleaning tomorow i can crack one open andmesure the thickness of the glass at various points.
im still not lining up to pump one up too much though
lets hope the global financial crisis distracts people from terrorists in sheds with compressed air vestles and we all have a good 2009 !!
regards.
*hic*
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MagicJigPipe
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"A bottle full of air at a given pressure would make a better bang than one that was at the same pressure but only had a few cc's of gas."
I saw your second explanation. At first I thought you meant something like:
A bottle is filled with ~ .5g of a nitrogen and heated until bursting pressure. Let's say 100psi. Then a bottle with 1g of nitrogen was heated to
the same bursting pressure. Would the 1g bottle make a "bigger bang"?
Is that what you were getting at? My guess would be 'yes' because you have more mass escaping the bottle. Of course the bottle with .5g would have
to be heated to a greater temperature which might cause more failures in the glass but...
Anyway, it seems verging on subjectivity to me.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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crazyboy
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| Quote: | Originally posted by MagicJigPipe
A bottle is filled with ~ .5g of a nitrogen and heated until bursting pressure. Let's say 100psi. Then a bottle with 1g of nitrogen was heated to
the same bursting pressure. Would the 1g bottle make a "bigger bang"?
Is that what you were getting at? My guess would be 'yes' because you have more mass escaping the bottle. Of course the bottle with .5g would have
to be heated to a greater temperature which might cause more failures in the glass but...
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I think you are wrong. assuming identical conditions but different volumes of gas the container will rupture at the exact same pressure 100psi it will
just take less time in the one with more gas.
Since they both explode at 100psi and explosive power is caused by a difference in air pressure the effect will be the same regardless of the amount
contained as long as pressure and container remain constant.
If 5g gas explodes in a flask at 1000psi it will be 10 times as powerful than any amount of gas in an equal sized container exploding at 100psi.
Think of it this way. If you have a bottle and heat it up just a bit then hit it it won't really explode. but take the same bottle same amount of gas
and heat it up a lot then hit it it will explode quite violently right?
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MagicJigPipe
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Yes, you are right. Shame on me...
It would explode with the same force because you are putting the same amount of "potential energy" (net) into both. The potential energy at first is
caused by the original pressure. Right?
[Edited on 12-31-2008 by MagicJigPipe]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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Nevermore
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many champagne or a champenous bottle has been tested by me to be completely safe up to 6 atm, the cheaper one are very thin and possibly can't reach
this pressure but i didnt test them.
Nevermore!
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smuv
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@Mr. Wizard: Filling the bottle with water is very good advice, I wish I had thought of that.
I was not standing next to the bottle, it was behind a barrier. However, during previous tests I took greater precautions and wrapped the bottle
with some old carpet. What was so shocking to me, was not that the bottle failed, but the amount of energy which was released, which I had greatly
underestimated.
One thing interesting about the way the bottle failed was there were no large pieces, the largest piece was maybe 1.5 in^2, which is not as I expected
the bottle to fail. Most of the pieces were much smaller though, and I had a hell of a time cleaning up the mess.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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Ozone
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Happy new year.
I am glad your OK.
IIRC, the converse and a relevant discussion can be found here:
http://www.sciencemadness.org/talk/viewthread.php?tid=11616&...
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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vulture
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| Quote: |
A bottle full of air at a given pressure would make a better bang than one that was at the same pressure but only had a few cc's of gas.
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That's physically impossible. If you have two identical bottles at the same pressure and temperature they also have the same amount of gas inside.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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hissingnoise
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I think bquirky meant that the second bottle would have in it a large volume of incompressible liquid and a small volume of air.
What would happen when both bottles were fed with air at a high compression is the question, I think.
Takes figuring, or I'm missing something. . .
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bquirky
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Physical impossibility only means there is a hidden variable
Yes hissingnoise that is what i ment, same sized bottles, same pressure one contains some incompressible fluid
its my contention that the bottle with the larger amount of gas is more dangourus because it contains more stored energy despite the fact that they
are at the same pressure.
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