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Aluminum water bottle air tank

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Aluminum water bottle air tank

Unread postAuthor: hyperspaz » Thu Jan 20, 2011 9:26 pm

I want to use an aluminum water bottle as an air chamber, but i dont know what kind of pressures one can handle. They're pretty cheap and look fairly strong. Do you think one could safely handle 250 psi? I'd test it, but i don't have the right equipment.

If someone else were to test it, use a coleman water bottle--they have actual threads, and are only $6 on amazon.

http://www.amazon.com/Coleman-Aluminum-Bottle-32-oz-Colors/dp/B00168ZJS8/ref=sr_1_1?ie=UTF8&s=sporting-goods&qid=1295575738&sr=1-1


Let me know your thoughts on this.
thanks!
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Unread postAuthor: saefroch » Thu Jan 20, 2011 9:50 pm

Not an advisable air chamber. They are so thin that they can be dented just by falling off a table. I also doubt their threads are compatible with anything. I'd just go the route most of us do and use sch 40 pipe fittings or a fire extinguisher (or other vessel designed for very high pressures).
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Unread postAuthor: Lockednloaded » Thu Jan 20, 2011 10:07 pm

I've used a similar bottle, it hade female 3/4" GHT threads. It was easily adapted, and it held the 160 psi I regularly put in it just fine, but it got a small dent after barely being hit, so it was decommissioned. I'd recommend some sort of rigid conduit sleeve to protect it from dents
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Unread postAuthor: jackssmirkingrevenge » Thu Jan 20, 2011 11:48 pm

Not recommended for higher pressures - that flat bottom really doesn't bode well - but similar bottles have been used in the past, some examples:

"bud gun"

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"bud gun 2"

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"snipalux"

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"onslaught"

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Unread postAuthor: hyperspaz » Thu Jan 20, 2011 11:54 pm

Thanks for your input! I found a bottle at my house that has perfect 3/4" threads. I think I'll put a couple of layers of fiberglass around it (especially the flat bottom), and only take it up to 160 psi or so.
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Unread postAuthor: jackssmirkingrevenge » Fri Jan 21, 2011 12:01 am

It's where the bottom meets the sides that you should be concerned with.

and only take it up to 160 psi or so


Assuming the bottle is around 3 inches diameter, that gives the bottom an area of around 7 in<sup>2</sup>, meaning that at 160 psi there's a force of 1120lbs trying to rip it off.
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Unread postAuthor: hyperspaz » Fri Jan 21, 2011 1:41 am

My bottle looks to be exactly the same as the one used in the "snipalux" which was pumped up to 220 psi, so if i wrap mine in fiberglass, or even filament tape (180lb tensile str/in) I should be fine getting away with 160 psi, right? I'll pump it up from a distance the first few times before getting near it.
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Unread postAuthor: ilovefire » Fri Jan 21, 2011 1:47 am

hyperspaz wrote:I'll pump it up from a distance the first few times before getting near it.


its not the first few times you should be worried about, repeated flexing of that joint will slowly weaken it, thus taking it to breaking point, im not saying it wont be able to take the 160psi im just saying you have to think about repeated stress
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why make it if it dosent shoot?
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