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3-WAY VALVES for charging/firing 2" piston cannons.

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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3-WAY VALVES for charging/firing 2" piston cannons.

Unread postAuthor: kiwi of nitro » Mon Jun 28, 2010 4:55 am

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Notice the Mauler cannon has a 3-way valve as the trigger, when you fire the cannon, the airflow from the compressor is temporarily cut off while the pilot is vented.

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Looks like that. with the QEV on the bottom, the compressor on the left and an opening on the right.

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This is the spudtech.com valve that is called a "3-way valve", but does it allow charging and firing as I explained?

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That's another valve I found, Will it allow me to do what I want, I think it's over 4" long, way too big for the 1.5" pvc handle of my cannon.

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This one is possibly a little shorter...


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This one is shorter still but the 1/8" ports may be too small for filling a >430cu-in tank quickly and firing a QEV on a mauler valve...

LOOK, see how these either say "normally closed" or "normally open" WHHAAAT? This is confusing because in position "A" air flows from "X" to "Z" and in position "B" air flows from "X" to "Y", both positions could be called open AND closed. UNLESS THE VALVE DOESN'T DO WHAT IT I'M ASSUMING IT DOES, as shown in the above diagram.

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OK, see this one too? It uses a solenoid. I could fire my cannon electronically if this were too work, but does anyone know if that flow factor which says "0.89" is suitable for what I need? That flow factor is probably completely inaccurate because I've seen the same value on all the other completely different valves on this site, I think the value was just pasted in for all the valves...


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I want to do that, only bigger and portable and with my 20lb CO2 tank and reg.

That cannon pictured above from spudtech.com, has a C/B of 1.7, the spudwiki says that that GGDT shows the ideal ratios are around 0.2 and 0.3. Is that true? that seems ridiculous to have an air chamber 1/8th the volume of your barrel when using 125psi! I can't download GGDT on my crapple.

Spudtech's "theory" page says ideal ratios are between 2.0 and 4.0!

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I thought I'd sketch a little bit of what I'm planning to give you an idea. Maybe it's goofy, but it was easier than using MS paint, notice the 3" pvc extensions on the piston valve, they are to allow the cannon to rest on the operator's shoulder. The fill line coming out the back connects to a 20lb co2 tank strapped to the operator's back. The loading mechanism is a 2" ball valve with an SDR-21 insert which feeds golf balls from a spring-loaded clip.

Tell me what you think.
Thanks.
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Unread postAuthor: POLAND_SPUD » Mon Jun 28, 2010 5:23 am

some valves can be both NO and NC valves... some but not all... if a valve can be used as both NC and NO teh arrows are in both directions.. ohh and you also need all threaded ports

in a diagram normal position is the one on the right, the other one represents what happens when you actuate the valve (press the button etc.)

ohh you need a normally open (NO) valve for this to work the way you want it (venting the pilot volume and closing off air supply when the button is pressed). I suggest ordering MJVO-3 valve form clipppard (they are for 11$ excluding taxes and shipping... you might want to order a lever or button for it )

you will also need at least a 3/8" QEV... 1/4" might be able to vent it but personally I'd order 3/8" or 1/2" just to be sure
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Unread postAuthor: Technician1002 » Mon Jun 28, 2010 6:10 am

That cannon pictured above from spudtech.com, has a C/B of 1.7, the spudwiki says that that GGDT shows the ideal ratios are around 0.2 and 0.3. Is that true? that seems ridiculous to have an air chamber 1/8th the volume of your barrel when using 125psi! I can't download GGDT on my crapple.


For effeciency in supply air, this is correct. This uses just enough air to void the barrel and have the barrel drop to no pressure as the projectile leaves. This high effeciency point is not the max power point. The projectile has stopped accelerating as it reaches the muzzle. With a larger chamber and lower effeciency, the projectile will have higher acceleration right up to the muzzle, but it uses lots more air in a larger chamber.

I tested it with my marshmallow cannon feeding a 7 foot long tennis ball barrel. I have a video of it online. Due to the effeciency, the shot is nearly silent. The launcher;
Image

My video with sound is on a thread on trying to get a silent launcher. This becomes very quiet at about 110 PSI.

The chamber is a 16 oz propane tank. The barrel is 7 feet of 2.5 inch thinwall PVC.

The thread on finding this;
http://www.spudfiles.com/forums/failed-attempt-at-a-silent-tb-launcher-t17989.html
The video is on the second page when the quiet launch is done.
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Re: 3-WAY VALVES for charging/firing 2" piston cannons.

Unread postAuthor: jackssmirkingrevenge » Mon Jun 28, 2010 6:28 am

kiwi of nitro wrote:That cannon pictured above from spudtech.com, has a C/B of 1.7, the spudwiki says that that GGDT shows the ideal ratios are around 0.2 and 0.3. Is that true? that seems ridiculous to have an air chamber 1/8th the volume of your barrel when using 125psi! I can't download GGDT on my crapple.

Spudtech's "theory" page says ideal ratios are between 2.0 and 4.0!


There is no hard and fast rule for C:B ratios in pneumatics, it depends on your resources and requirements. A recent discussion on the subject which you will find of interest here.
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Unread postAuthor: deathbyDWV » Mon Jun 28, 2010 2:04 pm

I have the one from spudtech... It works just like the one on the mauler. The only difference is it's easier to actuate because it's a lever valve...
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