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Entirely New Valve Design (Balloon)

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Will it work?

Yes
1
14%
No
4
57%
I do not understand
2
29%
 
Total votes : 7
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Entirely New Valve Design (Balloon)

Unread postAuthor: Xerxys » Mon May 26, 2008 5:32 am

This is a new kind of valve( of my design) that seals the chamber with an inflatable something (probably a few ballons inside each other) and should achieve power levels upwards of those attained by the Supah valve, despite the fact this doesn't use o rings

It is attached to the pipe with a universal clip ( those metal bands which you tighten with a screw that you find on hosepipes) that is kept at a higher pressure ( and therefore inflated ) by the valve assembly.

Unfortunately you would have to keep switching back and forth between which valve was open to keep the pressure differential the same. Oh well, the power makes it worth it.

Some largish holes would be drilled in the end of the chamber inside the tee to give the balloon some purchase on the pipe

The cannon wouldn't be as tall as it is in the image but the scale is out of wack

I will be using this design for my next large-bore, but that won't be for a while as parts for a different one will arrive in about 2 days.

Anyone is free to use this design as I want to see how it comes out (although I could hardly stop you anyway)

For reference: the light green thing is the balloon, the dark green thing is a solenoid.

EDIT

I could test this for about (less than) 10 GBP with just the balloon valve, without a tee, and two schraders to fill a small (short, 3" pipe) tank with an end cap

Click on the images to see them Properly, this site doesn't like my pictures and deletes lines and whatnot
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Attachments
A Entirly New Valve Design.JPG
The valve. The tee is 4 inch but the image is poor
A Entirly New Valve Design.JPG (30.54 KiB) Viewed 529 times
implementation of the new valve.JPG
And its implementation in a launcher
implementation of the new valve.JPG (21.87 KiB) Viewed 529 times
Prototype for valve.JPG
This is how I could test it, Sorry for the scruffyness, it was done quickly
Prototype for valve.JPG (11.86 KiB) Viewed 335 times
Last edited by Xerxys on Tue May 27, 2008 3:07 am, edited 1 time in total.

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Unread postAuthor: wannabie » Mon May 26, 2008 5:40 am

Looks like an interesting concept. Although I would be worried about the strength of the balloon.

Oh and wouldn't the pressure in the chamber be higher then that in the ballon which would allow the chamber air to push the ballon out of the way?
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Unread postAuthor: Xerxys » Mon May 26, 2008 5:42 am

That's the reason for all the valves, you can keep the pressure higher in the balloon.

It would also be a layered balloon for strength and the chamber inside would have some holes in it to give the balloon purchase
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Last edited by Xerxys on Mon May 26, 2008 5:44 am, edited 1 time in total.

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Unread postAuthor: trollhameran » Mon May 26, 2008 5:44 am

It looks like it could work, but perhaps it would be an idea to use the bladder from a small football instead of a balloon as it would be stronger
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Unread postAuthor: Xerxys » Mon May 26, 2008 5:46 am

That is a good idea a small football's bladder would be perfect
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Unread postAuthor: dongfang » Mon May 26, 2008 5:58 am

Hi,

I fooled around with the same idea once: A baloon body of some kind that would hold an air/water rocket down on the launch pad. It is stuck into the throat of the rocket. Maybe with a check valve or just a small hole in the end that goes into the rocket (to fill it with air). When de-pressurized, the rocket spits it out, and takes off.

It was just an idea though; I never tested it.

Regards
Soren
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Unread postAuthor: cdheller » Mon May 26, 2008 11:33 am

http://www.drillspot.com/products/34839 ... _Ball_Plug

test balls are fairly stiff, the ends more so than the cylinder.
In practice we overinflate them to keep leaks (air and water)from screwing up test.
usually by a 1/3 at least.

I see a couple of possible glitches .

the bladder not releasing from the barrel due to lack of pressure difference or any force to offset the chamber pressure


the bladder sucking into the barrel and choking/disrupting airflow

hope this helps
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Unread postAuthor: jimmy101 » Mon May 26, 2008 11:48 am

Isn't the ballon going to have to be pressurized to the chamber pressure (or a bit more)? But part of the balloon has an external pressure equal to atmospheric.

Any thoughts on what kind of balloon can handle more than 100 PSI? WAG for a generic toy ballon is it'll burst at just a couple PSI. Even if you put ten of them inside each other is there even a remote chance you can get it up to >100 PSIG?
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Unread postAuthor: BC Pneumatics » Mon May 26, 2008 12:03 pm

Before I speculate about whether or not it will work, are their any advantages over a burst disk? It seems like a burst disk cannon would be cheaper and easier to construct, and be superior to this design.

Of course if you do not care about the cost, simplicity, and performance, and just want to do something different, you can disregard my statements.
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Unread postAuthor: Xerxys » Mon May 26, 2008 3:15 pm

BC, although I detect sarcasm you are kinda right, I do want to do somthing different. It also might not be worse than a burst disk. Might
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Unread postAuthor: ammosmoke » Mon May 26, 2008 3:28 pm

You changed your mind that quickly? Darn. I wanted to see it done.
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Unread postAuthor: pat123 » Mon May 26, 2008 3:39 pm

I think it will work. It will be much easier to get it to seal than a piston would be.

let me see if i get it.
1. pump more pressure into the baloon than you are planning on using in the chamber.
2. close valve to balloon and pump the chamber up to a pressure a little lower than the balloon.
3. close the valve to the chamber andopen the valve to the balloon to fire.

did i get it right?
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Unread postAuthor: rp181 » Mon May 26, 2008 4:14 pm

i tried it a while back, it leaks like crazy, and baloons keep poping.
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Unread postAuthor: BC Pneumatics » Mon May 26, 2008 4:31 pm

!!Faulty Detector Alert!!

Though I am renowned for my sarcasm, I was actually being serious in my post above. I have spent so much money on "stupid" projects and "reinventing the wheel" that it pains me to think about the actual dollar amount. The thing is, all the while I was doing it, I knew these things had superior counterparts. Sometimes you just want to try something new, and that is what these projects are about. As long as you don't expect it to be something it's not, seeing your design come to fruition is very satisfying, regardless of whether or not it is 'practical'. Mr. Goldberg would undoubtedly agree.

You may try placing a small (1/4" will do) valve behind your ammo stop, that will open the base of the barrel to the atmosphere. Then using a bladder with a small hole in it, you can open the air inlet, and the badder will start to inflate. Any air leaking through the hole will escape out of the barrel valve. (You could fill then load to avoid needing this valve, but I do not like to load a pressurized cannon if it can be avoided.) When the bladder seals off the chamber, the air 'leaking' (Though that implies it is by accident, effusing is a better word.) out of the bladder will fill the chamber. May be a simpler method of doing things. Oh, and don't forget to close the valve before firing, though even using a hole would not hurt performance a terrible amount, since it would only have to be slightly larger than the one in the bladder. (Which could not be too large, since the air must not effuse at a rate too quick to build enough pressure to inflate the bladder.)

You will also want to make sure everything is sanded down smoother than a baby's arse, so you don't puncture the bladder. You may want to look into using something like a hot water bottle for the bladder. Nice and thick, and they cannot be too difficult to inflate, as someone on TV did it with their lungs.

Edit- I just re-read this topic, and found I somehow missed the mention of using a football bladder. This sounds like another possible candidate, though a hot water bottle should have a cap that can be easily enforced with epoxy, then tapped for a very good seal. Then again, I imagine it would be pretty easy to attach a football bladder to a barb of sorts with some hose clamps. I myself prefer threads, but thats all it is, a personal preference. Also note that footballs are filled to under 20psi. I do not know if the bracing from the chamber pipe would prevent the seems from blowing out. I sort of doubt it.
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Unread postAuthor: Xerxys » Tue May 27, 2008 2:50 am

Pat 123 has got it exactly right, but I Might repeat the cycle. I explained that when I typed it up at first but I accsidently deleted and had to re-type it
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