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a bottle of glass for combustion chambe ? good or not

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Unread postAuthor: iisthemuffin » Fri Jul 18, 2008 1:51 pm

So why doesnt someone get a wine bottle and put it under a shield or something and pressure test it?

Then we will all know what kind of pressures a wine bottle can hold.
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Unread postAuthor: starman » Fri Jul 18, 2008 2:02 pm

iisthemuffin wrote:So why doesnt someone get a wine bottle and put it under a shield or something and pressure test it?

Then we will all know what kind of pressures a wine bottle can hold.


:roll: ...Oh brother... :roll: Because we as responsible spudders don't want to give any impression that a glass bottle is even remotely something that should be considered for use as a spudgun's combustion chamber.

How about let's not.
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Unread postAuthor: iisthemuffin » Fri Jul 18, 2008 2:05 pm

Oh believe me, i wouldnt encourage it either.

But it was said that pvc will shatter with the same affect BUT it can hold certain amounts of pressure. I was simply suggesting finding out what pressures a glass bottle COULD hold.
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Unread postAuthor: Biopyro » Fri Jul 18, 2008 2:41 pm

While I agree that glass is a poor long term solution, a champagne bottle would have a very high burst pressure. There is also the problem that you [i]can't[/] make holes in it (could cause hairline fractures), and it's a fairly small opening for venting. Basically, save yourself the trouble and get PVC. If all else fails even a plastic fizzy driinks bottle makes a good pneumatic chamber.
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Unread postAuthor: paaiyan » Fri Jul 18, 2008 3:00 pm

First: glass+heat+pressure=pain

Second:

brother361 wrote:yea your the kind of kid that gets poato guns a bad rep save yourself an arm and use pvc


Grammar; use it.
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Unread postAuthor: THUNDERLORD » Fri Jul 18, 2008 3:13 pm

iisthemuffin wrote:...But it was said that pvc will shatter with the same affect BUT it can hold certain amounts of pressure. I was simply suggesting finding out what pressures a glass bottle COULD hold.


Strangest feeling of deja vu from an earlier post today.
If you want to find out test it yourself :D
Besides, glass is much more dense than PVC and it will cause much worse injuries.
"It can hold certain amounts of pressure" DUH, No SH!z can it really?
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Unread postAuthor: Biopyro » Fri Jul 18, 2008 3:51 pm

Just poking around, it seems like no-one has actually posted test results, but a company called Somex, does make machines to test them.
Their one for PET goes up to 20 bar, and their one for glass has a limit of 68 bar. Glass is far less susceptible to the effects of heat than plastic is, so yes, you're ok.

Personally though, I'd reccomend a pneumatic with a ball valve and a 2l (plastic) pop bottle for your first cannon. They are so simple, yet still effective and impressive if you haven't used potato guns before.
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Last edited by Biopyro on Fri Jul 18, 2008 4:16 pm, edited 1 time in total.
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Unread postAuthor: Hotwired » Fri Jul 18, 2008 4:02 pm

I'd be very unhappy about using glass for combustion, it does not like shock temperature changes and this would be coupled with a pressure spike. Meh...

Still, bottles are around that are suitable for pressurised drinks or just solid enough to be lugged about in crates to the shops where they get sold and I've no doubt the puny forces of a basic combustion in there will do no harm.

Having an unreinforced ceramic container for a pressure chamber for a pneumatic is just asking for it. By "it" I mean a visit to A&E after you accidentally put too much force on say the neck with piping leverage or put it down a bit too roughly on a hard surface.
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Unread postAuthor: frankrede » Fri Jul 18, 2008 4:19 pm

I have heard that wine bottles are rated in excess of 300 psi...
But that just what I heard
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Unread postAuthor: Biopyro » Fri Jul 18, 2008 4:34 pm

I have emailed somex, so hopefully they'll reply some time next week, then we'll finally have a genuine tested answer about the pressure saftey of bottles.
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Unread postAuthor: Deadeye » Fri Jul 18, 2008 4:50 pm

Wow, way to pile on guys. Hang in there Drunkii,
As psycix basically said everything has a rating & a breaking point
I think what they are all trying to say is that they don't want to be the one to find out your answer for you.

Also, you should be applauded for seeking the answer here first, after all that is what these are for, aren't they?

Lastly, while reading this I couldn't help comparing it to some of the earlier smack downs people were getting for using DWV.
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Unread postAuthor: starman » Fri Jul 18, 2008 5:02 pm

It's not just the pressure capacity of a glass bottle. What happens when you drop it while full of air or even accidentally hit it on something hard while handling it...POWW....ouchhhh.... :cry:

Just not a good material for spudding guys...
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Unread postAuthor: brogdenlaxmiddie » Fri Jul 18, 2008 5:22 pm

PVC can take a lot more beating around than a wine bottle. Thats why, no matter what, a glass bottle shouldn't even be thought of. You can find the bursting pressure all you want, but try this nifty little experiment- Go outside on a concret surface, from a height of say, what... 3 feet, drop both a glass wine bottle and a section of PVC pipe.... Then come back and tell us what we know, the pvc will be fine and the bottle will break.
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Unread postAuthor: Biopyro » Fri Jul 18, 2008 5:30 pm

Just to clarify, I'm not finding the glass burst pressure to suggest using it in a pneumatic. Mostly I sent the email asking about PET, bottles, really I just asked about the glass out of interest. A combustion would probably be fine, but again, why risk it when there are better materials to be found everywhere!
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Unread postAuthor: Hotwired » Fri Jul 18, 2008 7:24 pm

Deadeye wrote:I think what they are all trying to say is that they don't want to be the one to find out your answer for you.


A quick materials course.

Inflexible, brittle materials are not prime choices for pressure vessels.

Glass has bugger-all elasticity, PVC on the other hand is moderately elastic. An example of such is bending a stick of each.

For that reason dropping a PVC and a glass chamber, both rated to the same pressure can have different results as their elasticity and toughness determine how they cope with the extra stress.

Encouraging use in serious spudguns is irresponsible.

That's why I said no but basic combustion should have no issue as the pressure and heat generated is negligible.
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