Page 3 of 3

Unread postPosted: Sun Jul 20, 2008 12:22 am
Author: jimmy101
A glass soda bottle should have a pressure rating about the same as a plastic soda bottle. It should be able to handle the pressure of a generic combustion or a low (<100 PSIG) pneumatic without any real problems (unless you drop it while it is pressurized).

The reasons for NOT using glass are mostly not related to what pressures it might be able to handle.

How do you connect the barrel to the bottle?

For a combustion, how do you install the spark and vent the chamber?

If you want something cheap, just use a plastic soda bottle. Plastic is much easier to work with than is glass.

A non-pressure rated glass bottle would be a really dumb idea. You would want a bottle that is normally pressurized, like a soda bottle, not a bottle that is not normally pressurized such as a milk bottle.

Unread postPosted: Sun Jul 20, 2008 12:46 am
Author: Pilgrimman
Aside from all that has been pointed out, you might think that a thicker glass bottle would be better. DON'T DO IT. If the glass is thicker, it will heat unevenly and be more prone to cracking.

Unread postPosted: Sun Jul 20, 2008 3:57 pm
Author: Biopyro
From Somex

a typical pressure requiremnet for a PET bottle would be 135 psi, hold for 13 seconds, the pressure is then increased to 200psi, the volum of the bottle will increase by 30-50% of its original volume during this test.

Typically for users of PET bottles the same test will apply regardless of bottle volume,however the designers may have different standards - I am not aware.

Glass - depends in returnable or 'one way' can be as low as 150psi for a 250ml and as high as 700 psi for a Sparkling Wine or returnable bottle.



Brian O Keeffe

Unread postPosted: Tue Jul 22, 2008 2:40 pm
Author: sirspuddest
Depends on which type of glass you use, I suppose.

The average pressure exerted on the wall of a wine bottle is about 80psi (for VERY prolonged periods), so I don't see why you couldn't use it for a combustion.

You probably could pull it off, but I wouldn't try it to begin with. Just goin' with my gut instinct on this one.

I didn't really read any of the posts in this thread besides the first, so please forgive me if I'm restating something that's already been said.

Unread postPosted: Thu Jul 24, 2008 5:12 am
Author: psycix
sirspuddest wrote:Depends on which type of glass you use, I suppose.

The average pressure exerted on the wall of a wine bottle is about 80psi (for VERY prolonged periods), so I don't see why you couldn't use it for a combustion.

You probably could pull it off, but I wouldn't try it to begin with. Just goin' with my gut instinct on this one.

I didn't really read any of the posts in this thread besides the first, so please forgive me if I'm restating something that's already been said.

When the pressure builds up slowly, and is held for a long time, I believe that it can hold that pressure. But if the pressure is built up in a few milliseconds, I think glass is not flexible enough to handle the shockwave.

Unread postPosted: Thu Jul 24, 2008 2:59 pm
Author: rp181
the difference is impact strength. Glass has relly high tensile stregth, but really low impact strength.

Unread postPosted: Sun Jul 27, 2008 1:37 pm
Author: sirspuddest
psycix wrote:
sirspuddest wrote:Depends on which type of glass you use, I suppose.

The average pressure exerted on the wall of a wine bottle is about 80psi (for VERY prolonged periods), so I don't see why you couldn't use it for a combustion.

You probably could pull it off, but I wouldn't try it to begin with. Just goin' with my gut instinct on this one.

I didn't really read any of the posts in this thread besides the first, so please forgive me if I'm restating something that's already been said.

When the pressure builds up slowly, and is held for a long time, I believe that it can hold that pressure. But if the pressure is built up in a few milliseconds, I think glass is not flexible enough to handle the shockwave.


Ah, you're right.

I suppose I didn't even think to take that into account.

Unread postPosted: Sun Jul 27, 2008 2:14 pm
Author: microman171
Watch your words!
Okay, glass will shatter and penetrate your vital organs if you use it as a pressure chamber BUT...
what happens to PVC when it blows?
Indeed! It also shatters into bits, to which "sharper then a razor" applies, and on top of it, people are holding it!
Bright side is, that it can hold a certain pressure, and if you dont go beyond that pressure, it will not shatter.


Remember Mr Crowleys story?