Adding a vent system post-build

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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Pete Zaria
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Sun Aug 13, 2006 2:50 pm

I have an ABS combustion cannon with a 250ci chamber and various barrels. Onboard propane, chamber fan, BBQ sparker. Pretty basic, yet reliable and fun to use setup. I've put 500+ shots through it, and it fires on the first try 9/10 times.

My only complaint about firing this cannon is that I have to take off the leanout cap and vent the chamber between each shot. It's kind of a pain in the ass, and adds 15+ sec to my reload time.

I have a 2" PVC ball valve laying around. I was wondering if I could install it, via a male adapter (where the cleanout cap usually goes) and use that to vent the chamber. See drawing below. My question is, using the fan, would this provide enough airflow to effectively vent the chamber?

Image

Thanks a bunch.

Peace,
Pete Zaria.
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Dom
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Sun Aug 13, 2006 2:55 pm

Your best bet would be the Fan i believe.
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WOW!!
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Sun Aug 13, 2006 2:56 pm

Yep that will work. Just open the ball valve and turn your fan on. Got any pics of the cannon?
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Pete Zaria
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Sun Aug 13, 2006 2:56 pm

No, I already have a chamber fan with controller. I'm asking about the 2" valve. Would mounting a 2" valve onto the back of the cannon, in place of the cleanout cap, allow me to vent the chamber without having to remove anything between shots? Does a 2" valve allow enough airflow to vent a 250ci chamber using an 80mm fan?

Thanks.

Peace,
Pete Zaria.
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MrCrowley
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Sun Aug 13, 2006 3:16 pm

should do it would just take longer then removing the clean out cap where if you remove the cap more air gets out faster.just considor your self lucky you have a 2" ball valve they cost crap loads.
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WOW!!
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Sun Aug 13, 2006 4:36 pm

Yea the ball valve will work with your fan.
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Pete Zaria
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Sun Aug 13, 2006 5:45 pm

OK, then... A) is a regular, 2" PVC, DWV ball valve acceptable for use in a propane combustion gun? B) can I use all-purpose cement (ABS & PVC) to glue the PVC ball valve onto a piece of 2" ABS connected to the reducer and male adapter?

Thanks.

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Pete Zaria.
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WOW!!
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Sun Aug 13, 2006 7:47 pm

As far as I know you can use DWV for a combustion. I might be wrong tho. I dont know about connecting ABS and PVC with that glue. Meabey some one else knows.
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noname
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Sun Aug 13, 2006 7:54 pm

I'm assuming your ball valve has female threads, so just attach it to 2" ABS threads.
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M3NT4L
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Sun Aug 13, 2006 9:21 pm

Why wouldent it work? And it would be cooler-looking. But i dont know why it is so hard and annoying to open the damn endcap, its not so hard you just twist and baaaam there it is.
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Dom
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Sun Aug 13, 2006 9:41 pm

WOW!! wrote:As far as I know you can use DWV for a combustion. I might be wrong tho. I dont know about connecting ABS and PVC with that glue. Meabey some one else knows.
ABS DWV only I believe. Not PVC.
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WOW!!
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Sun Aug 13, 2006 9:43 pm

Dom wrote:
WOW!! wrote:As far as I know you can use DWV for a combustion. I might be wrong tho. I dont know about connecting ABS and PVC with that glue. Meabey some one else knows.
ABS DWV only I believe. Not PVC.
If you read Pete's post it says a PVC ball valve and ABS pipe.
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MrCrowley
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Sun Aug 13, 2006 11:18 pm

ive used DWV on my combustion fine no problems but i read somehwere your not supposed to connect ABS and PVC but whats the worse that can happen :lol:
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Jarim
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Sun Aug 13, 2006 11:52 pm

my gun is half pvc and half abs... no problems so far... but thats just me..
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MrCrowley
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Sun Aug 13, 2006 11:55 pm

yeah it should be fine.its just the joints every gets worried about about how the glue doesnt work and stuff
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