SpudFiles

IF YOU'VE NOTICED NO VENT, DON'T WORRY, IT'S EXPLAINED AT THE BOTTOM.

VALVE ARE WIRED TO HAVE 3 SETTINGS:
ARMED/SAFE: BOTH THE VALVES ARE TURNED OFF.
METER: V1 IS CLOSED, V2 IS OPEN
COMBUSTION CHAMBER: V2 IS CLOSED, V1 IS OPEN


PREFERABLY WIRED USING TWO SEPERATE 2-WAY SWITCHES. ONE IS THE ARMED/SAFE SWITCH. WHEN SET TO SAFE, NEITHER ONE OF THE VALVES CAN OPEN AT ALL. WHEN ARMED, YOU CAN SET THE VALVES TO EITHER METER, OR COMBUSTION CHAMBER.

1. FIRST YOU'D ARM THE GUN, MAKING SURE THE FILL SWITCH IS ON COMBUSTION. THIS MAKES SURE THE METER PIPE DOESN'T FILL WITHOUT YOU KNOWING.

(YOU COULD USE A SWITCH THAT RETURNS TO A NEUTRAL POSITION SO THAT YOU DON'T HAVE TO WORRY ABOUT WHAT SETTING IT'S ON.)

2. SET THE SWITCH TO METER, WHICH ALLOWS PROPANE TO FILL THE METER PIPE TO A PRESET PRESSURE REGULATED BY THE ADJUSTABLE PRESSURE REDUCING VALVE,

3. THEN FLIP THE SWITCH TO COMBUSTION FILL, WHICH CLOSES THE VALVE IN FRONT OF THE PRESSURE REDUCER AND OPENS THE VALVE INTO THE COMBUSTION CHAMBER, ALLOWING THE PROPANE TO FLOW THROUGH.

THE POINT OF CLOSING THE VALVE IN FRONT OF THE REDUCER IS SO THAT, AS THE PRESSURE IS REDUCED BECAUSE OF THE EXTRA VOLUME OF THE CHAMBER COMBINED WITH THE METER PIPE, THE REDUCING VALVE DOESN'T OPEN TO REACH ITS REGULATED PRESSURE AGAIN.

4. LASTLY, FLIP THE ARMED/SAFETY SWITCH BACK TO SAFETY, WHICH CLOSES BOTH VALVES SO THAT THERE WON'T BE ANY EXTRA VOLUME DUE TO THE METER PIPE.

5. FIRE THE GUN, VENT* AND REPEAT.

* FOR A VENT, I'VE LEFT IT UP TO IMAGINATION. ONE IDEA I'VE HAD BUT HAVEN'T PUT MUCH STOCK IN IS ANOTHER SOLENOID VALVE CONNECTED TO THE END OF THE CHAMBER VIA A REDUCING COUPLING, AND ANOTHER REDUCING COUPLING MOUNTED ON THE OTHER SIDE. (TO BRING THE SIZE UP ENOUGH TO MOUNT A FAN) A FAN IS MOUNTED INSIDE THE THE OUTERMOST COUPLING AND IS WIRED WITH THE SOLENOID SO THAT YOU HIT A VENT SWITCH WHICH OPENS THE VENT VALVE AND TURNS ON THE FAN AT THE SAME TIME, THUS PULLING THE AIR THROUGH AND OUT. ONCE AGAIN, JUST AN IDEA. I HAVEN'T DECIDED EXACTLY HOW I WANT TO DO IT MYSELF YET.




The benefits of the entire system is that you can regulate the pressure to a specific setting without eyeballing with a guage, and the idea would make the gun quite fast. Combined with a bolt action breech loader, you could ring crank out the potato's, but obviously it would work much better as a golf ball or tennis ball cannon, something with a hopper to hold a lot of ammo.

thats pretty sweet ive seen a lot of combustions using injected propane designed that way. ive been planning to make one similar to that in the near future.

edit: oh and i almost forgot welcome to the forums man hope you enjoy it here

Thanks. I'd say that I caught the potato gun bug, but it's more like I'm extremely infected lol. Can't resist the boom...

I have already done that. The problem is that many of the valves don't closewithour a pressure differential on the sides.

It is also easier and cheaper to do with a 3-way valve. The common would be connected to the meter pipe. The normally open port would go to the pressure regulator, and the closed until energized port goes to the chamber.

Either way you should use a check valve to protect the valves from the pressure spike.

Welcome to the forums. It is good to have a noob that knows what he is doing!

Wow... I actually didn't even fathom using a 3 way valve. Thanks... that'll save me quite a bit. although i may change up the ports... I'm wanting to keep a certain saftey factor so that nothing fills without my permission. so id run the regulator to the closed till energized, the meter to the to the commom, and the barrel to the normally open. energize it, and it fills the meter, de-energize and the meter fills combustion chamber. would that work? im open to all ideas

I'm in the process of making a 3-way system just like that, but I don't trust the electric valves not to get stuck, so I put a manually operated ball valve before the regulator. Kinda like a master saftey on/off switch.

Even if the valve does get stuck the only bad thing that could come from it is that the cannon dosn't fire, and mosr, if not all, of your propane is released.

Great idea has potetial and Welcome to Spudfiles.

Hmm, I like it, maybe I'll redo my propane sustem like that one day.