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portable pressure theory...

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portable pressure theory...

Unread postAuthor: coolhippy80 » Mon Mar 03, 2008 1:24 am

dont know if this would work, the idea just came to me. have you seen those dry ice bombs people make, with dry ice in a bottle with a bit of water, which makes pressure then blows up violently... could this be used, with better materials and a pressure releif valve (that lets the pressure only get to a certain level) to make a powerfull .177 aor .22 airgun that goes around 600-900 fps? you could have a chamber, with the valve and a screw on lid (to put the ice in), then a blow gun and a barrel?
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Unread postAuthor: MrCrowley » Mon Mar 03, 2008 1:37 am

Getting the pressure is one thing, releasing it fast with a high flow valve is another. Most people find it easy enough to get the pressure, but finding a good valve is the hard part.

Not sure if it's against the rules to discuss this on the forum, it's a bit of a loophole, so if PCGUY or another mod sees fit to lock it, go right ahead.
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 03, 2008 1:41 am

...to make a powerfull .177 or .22 airgun that goes around 600-900 fps?


You can achieve this sort of performance with a long enough barrel and high pressure from a mountian bike shock pump, but you'll need something other than a blowgun if you're seeking performance and consistency.
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Unread postAuthor: coolhippy80 » Mon Mar 03, 2008 3:47 am

i am just after something fast and not too expensive.. what would i do for a pressure release valve??

mr crowley, what is wrong with it?? (honest question)
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 03, 2008 3:52 am

coolhippy80 wrote:mr crowley, what is wrong with it?? (honest question)


In the same way you can use dry ice to generate pressure for a launcher, you can also use it to make a bomb, and such talk is not relevant to this forum.

i am just after something fast and not too expensive..


Make your own piston valve - cheap, relatively easy to make and excellent performance. If you want to use normal compressor pressures with a blowgun, with a good barrel performance isn't that bad either - go here and scroll down.
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Unread postAuthor: MrCrowley » Mon Mar 03, 2008 3:55 am

Because it is a dangerous way of stupid teens seaking thrills.

A lot of teenagers use them to make 'dry ice bombs', which shouldn't be, in any way, associated with this website. So if PCGUY feels it shouldn't be discussed, that would be why.


Something fast, not too expensive and is resistant to freezing temperatures...

Good luck with that, depending on the pressures, you could use a QEV, not sure how the 'phragm would cope though. And do you want it to just be single shot?

What pressures are you thinking of?


Edit: Goddamnit it, go back to work JSR, it's 10am FFS :D
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 03, 2008 4:02 am

MrCrowley wrote:Edit: Goddamnit it, go back to work JSR, it's 10am FFS :D


Actually I'm sick at home, I greeted this morning congested and with a throat that felt like I had just orally serviced the well endowed wearer of a 40-grit abrasive prophylactic :roll: :cry:

*cough*
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Unread postAuthor: MrCrowley » Mon Mar 03, 2008 4:05 am

jackssmirkingrevenge wrote:
MrCrowley wrote:Edit: Goddamnit it, go back to work JSR, it's 10am FFS :D


Actually I'm sick at home, I greeted this morning congested and with a throat that felt like I had just orally serviced the well endowed wearer of a 40-grit abrasive prophylactic :roll: :cry:

*cough*


My God :shock:


Someone's going over their spudbux allowance today... :roll:



:D
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 03, 2008 4:15 am

MrCrowley wrote:Someone's going over their spudbux allowance today... :roll:


That happens practically every day, I don't see why this one should be any different :roll: :D
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Unread postAuthor: MrCrowley » Mon Mar 03, 2008 4:20 am

jackssmirkingrevenge wrote:
MrCrowley wrote:Someone's going over their spudbux allowance today... :roll:


That happens practically every day, I don't see why this one should be any different :roll: :D

Well I got Lord Of The Flies to read for English, so i'll just call it, Touché. :)
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Unread postAuthor: coolhippy80 » Mon Mar 03, 2008 4:31 am

like they said, i only need a small airflow. what would be the most efficient valve? i need it to be fairly small... i dont mean REALLY cheap, i just dont want to spend heaps on one. would copper work for my chamber?
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Unread postAuthor: Jared Haehnel » Mon Mar 03, 2008 7:20 am

Well I got Lord Of The Flies to read for English


Sorry to hear that MrCrowley. I hated that book bunch of kids on an island end up....never mind I won't spoil the ending for you :)
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Unread postAuthor: Ragnarok » Mon Mar 03, 2008 9:25 am

MrCrowley wrote:Well I got Lord Of The Flies to read for English

Of course, JSR has a different version of that book...

Look, a distraction!!!

Yoing!!!!!!!!!!!!!!!!!!!!!11111 one one one !!!!1111!!!!!.... And that made no sense to anyone.

To be honest, I agree. It's not that great a book. I was forced to read it for English, but fortunately managed to get out the the dreaded "write-up", by the miracle of "assignment choices" - if you're told to read two books, then write up one... make your choice wisely.

@Coolhippy: That entirely depends on the diameter of the chamber. Large bore or thin-walled copper wouldn't be suitable, but a lower diameter with thick walls might be all right - however, copper is pretty good for low temperatures, it retains strength very well even down well below dry ice temperatures.
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Unread postAuthor: jackssmirkingrevenge » Mon Mar 03, 2008 9:31 am

Ragnarok wrote:Look, a distraction!!!


For some reason I thought of Captain Obvious...

*cough*

I'm becoming delirious, better go back to bed :roll:
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Unread postAuthor: DYI » Mon Mar 03, 2008 9:35 am

One thing that nobody has mentioned yet was the velocity range; 600 - 900 fps. If you want reasonably high velocity, CO2 really isn't the way to go, as it has a fairly low SOS.

And I'm pretty sure that most copper pipe of class "M" or higher could take it fine, as long as it was reasonably low diameter. All M class copper in sizes 1" or under has failure pressures of well over 3KSI, and types L and K in those sizes are rated for roughly the pressure you'd be generating.

Steel might work, but I'd be worried about the cold making it brittle. Copper probably is the best choice for something like this, as it retains its malleability to extremely low temperatures.
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