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Pnematic Venting Idea

Unread postPosted: Fri Mar 16, 2007 11:28 am
Author: jjjd
I wave a new idea to vent combustions without having to open an end cap and such, have a smaller chamber next to your combustion chamber and have it hooked up to an oxygen canister. after your shot open the ball valve from the smaller chamber and the pressure will push out the exhaust. this will also provide a better burn rate for the next shot.

I would still have a chamber fan inside but make sure it is behind the opening for the oxygen chamber.

Do you guys think this would work out good, or be unsafe from the oxygen mix with propane? I am using all sch 40 parts for this, all 250psi +.

Thanks, Andrew

Unread postPosted: Fri Mar 16, 2007 11:32 am
Author: spudkilla
Why not just a simple canister/tank of compressed air instead of oxygen.

Unread postPosted: Fri Mar 16, 2007 12:03 pm
Author: risto
jjjd! ah! i had an idea so similar to this but i was keeping it secret so i could use it for the contest!

grrr!

haha, well, i have plans drawn up on how i was going to get it to work and all and from what i can tell, it will work, but i'm going to do a few experiments tomorrow to see if it actually does.

haha, great minds think alike, no?

EDIT: i just finished reading all your post:

DO NOT USE PURE OXYGEN! THAT IS DISASTROUS! My plan was to use a compressed air tank. NEVER- UNDER ANY CIRCUMSTANCE -HAVE PURE OXYGEN IN A COMBUSTION CHAMBER!!!! (if you value your life at least)

Unread postPosted: Fri Mar 16, 2007 12:17 pm
Author: jjjd
I wanted to use oxygen for the simplicity of having it with me in a backpack or strapped to the gun, i just don't want to have to use a bike pump or air compressor all the time. I was thinking of taking an old propane canister and refiling it with air in order to vent, but I am not sure if attaching an air compressor to the valve head would fill it. what do you think?

Unread postPosted: Fri Mar 16, 2007 12:53 pm
Author: The_Engineer
the problem That I see is that in order to push out all the combustion by-products you will have to add a lot of oxygen after each shot. If you plan on adding enough propane to have a complete reaction be carful the force will be about five times bidder and much faster. The other alternative is just refill the chamber with some oxygen to regain the oxygen to inert gas ratio previously present in air. If you do that you could have normal power shots.

Unread postPosted: Fri Mar 16, 2007 12:56 pm
Author: The_Engineer
Also I am not sure about refilling a propane tank with compressed air. Propane is a liquid when compressed and thus does not require nearly as much pressure as you would need with air.

Unread postPosted: Fri Mar 16, 2007 12:59 pm
Author: The_Engineer
PS I looked it up and vapor pressure of propane is up to 170 psi when at 100 deg F. So I guess\ you could refill a propane tank, just be carful they ar not designed for that use.

Unread postPosted: Fri Mar 16, 2007 1:13 pm
Author: A-98
arg! theres an edit button you know....(im not angry, just annoyed...hard to tell the difference when in text)

Unread postPosted: Fri Mar 16, 2007 5:04 pm
Author: MrCrowley
Why have the second chamber at all? Apart from the oxygen boost for next shot. Just use a big ball valve like 1.5" to vent the chamber and turn your chamber fan on.

Unread postPosted: Fri Mar 16, 2007 7:07 pm
Author: benstern
Extra oxygen won't friggen matter if you have a fuel meter, you will already be attaining the best possible mix!!!!!! :evil: :evil:

pure oxygen is not explosive or combustible in any way.... it is simply an oxidizer.

Either use a fan, run around with your spudgun above your head like a retard, or use a compressor and quick connect.

Unread postPosted: Fri Mar 16, 2007 7:08 pm
Author: jjjd
This would just have a solenoid, this way it would be faster/ easier , no opening the ball valve

Unread postPosted: Fri Mar 16, 2007 7:36 pm
Author: chaos
risto:: DO NOT USE PURE OXYGEN! THAT IS DISASTROUS! My plan was to use a compressed air tank. NEVER- UNDER ANY CIRCUMSTANCE -HAVE PURE OXYGEN IN A COMBUSTION CHAMBER!!!! (if you value your life at least)


i find that hard to comply with, i have known somebody with nearly exact same cannon as mine and they used pure oxygen, it was a lot more powerful, but it did no harm.

peace
chaos

Unread postPosted: Fri Mar 16, 2007 8:20 pm
Author: benstern
Have you people even read my post, or am I going to have to beat the ignorance out of you myself!?!?!?

This would just have a solenoid, this way it would be faster/ easier , no opening the ball valve

Solenoid valves need pressure to work!! Atmospheric pressure plus the infinitesimally small vacuum created by a fan won't work.

Unread postPosted: Fri Mar 16, 2007 8:57 pm
Author: medievalman
benstern wrote:pure oxygen is not explosive or combustible in any way.... it is simply an oxidizer.


You are right, pure oxygen is not combustible, but as soon as it is added to something that is(in this case, propane) it becomes extremely volatile, increasing the power of the combustion(or at least the speed) significantly.

Unread postPosted: Fri Mar 16, 2007 10:57 pm
Author: benstern
WRONG WRONG WRONG WRONG!!!!!!

Oxygen cannot become "extremely volatile." An oxidizer does not become volatile. The saltpeter in gunpowder does not become volatile... the charcoal does.

Propane needs a certain percentage of oxygen to burn correctly.

In typical atmospheric air the best propane ratio to air is 4.18952% (I memorized that)

Using the chart below... which I made a few (eight to be exact) months ago and dug up just to teach you sorry butt.... we can see how this works.

<img src="http://img459.imageshack.us/img459/2274/concentrationpx5.gif">

If you increase the oxygen content in the gases but into the chamber you must also increase the amount of propane put in the chamber. However now it is considered a hybrid, now isn't it?