SpudFiles

about how much psi can a 2liter or 20 oz bottle hold safely?

100 psi I THINK not sure. ask rambo he is the authority in this.

Some people say they've had one burste at 30 some say they've filled them to 160. No ones really right or wrong.

Just fill one until it blows up, then I'd feel safe at about 30% less than that.

ok thanks for your help guys

mythbusters took one to 115psi i think. 60-80psi should be safe.

Well, I use a 1.5 litre sprite bottle and take it up to 80 psi, and have tested one to 100 psi, and it didnt show any signs of failing. My advice is to use only the Coke branded bottles, as they tend to be fairly thick, and pressure test them before use. Just fill it all the way to the top with water and pressurise to about 20 psi higher then you intend to use it at. If it dosen't streach or burst, it should hold air fairly safely.

Woo first post!

Though this is not completely proven. Coke bottles tend to burst around 108 psi... you should be able to bring it up to 100 reliably.

I have taken the 2 Litre bottles to 130psi without anytype of explosion,but I have had a bottle rip when I tried to have a pop in schrader valve in the bottle wall.Although an expansion in the bottle can indeed be felt when aired to 130psi but nothing major.

^ ^ hey when did you get here??

Wow, I love how everyone looks for these magical numbers.

Personally, I would never use a pop bottle for any component of a launcher. First because it makes your cannon look like white trash, and second because they are simply not made with any such standards in mind. Again personally, Id be scared as to take them past 60 PSI. I mean in a PVC launcher that’s when you can here the PVC start stressing noticeably. Id think going to 100PSI would only just in essence heighten your chances of a failure to a very feasible event.

As to what the burst pressure is, I don’t know. I think the only standards in which they have is to exceed the normal operating pressures, by a suitable safety factor. There not going to exceed it that much as to also factor cost into there. This <a href="http://hypertextbook.com/facts/2000/See ... l">site</a> displays a source stating that a bottle of Coca-Cola at room temperature is at 55PSI. So with 100PSI in there Id think you to by a fair amount exceed any intentions they had on what the bottle should be able to withstand in terms of internal PSI.

Say, what’s wrong with using PVC/ Metal components again? Just as to something I found funny, while it may not be as to you cause it might be true for you. Well I found a busted plastic hub cap on the side of the road, my first thought wasn’t 'how can I use this in a spud launcher!!11!!1'

Well people have been using bottles in water rockets for years, and they havn't burst from the pressuere. And, the bottles on water rockets get put under a fair bit of stress, and they don't burst. As long as you do your own pressure test on a bottle first, I am perfectly comfortable taking one to 80 psi. I filled one with water and overpressurised it, and even though I didn't burst it, I could see the top bulging and streaching. Even though it held the pressure, you could see that it was over pressureised even before it burst.

Also, I change the bottle on my launcher regularly, so even if the rapid pressurisation then depressurisation is damaging the bottle, I throw it out well before it has a chance to become noticeable.

A kid in NZ had a bottle of coke next to him in his car and he had just bought it(it was in a fridge) and after about 10min in the car for some reason it blew up giving him loads of deep cuts and had to go to the hospital. It could of been heat or a defect in the bottle but either way that doesn't sound like every coke bottle is made for such high pressures.

Coke bottles are rated to about 150psi plus they don’t frag… I once got a 2 liter coke bottle to 100psi and shot it with my pellet gun, nothing happen beyond a loud hiss and a small hole. So worst case scenario: loud pop.

mythbusters used 3 liter bottles