Butane Meter, (Getting Refill Tanks to Pipe Threads)

[mark.f]

Many people have used butane for a spudgun fuel. It's cheap, and the tanks are ideal for minis. Some cannons I have seen using butane are really neat, such as the Antimaterial Cannon, and FMJ's semi-automatic mini combustion platform.

But the only way I've seen it used is sort of jury-rigged into place or pressed into a Schrader valve. I've never seen an actual meter that measures out the butane.

Well, I had an idea in class yesterday. It only took a few seconds of searching McMaster to find the right products you would need.

What you need is a short, (scrap), length of 3/16" OD x .11 ID nylon vacuum hosing. For those of you who haven't seen a Ronson refill valve on butane canisters, they look very much like hose barbs. I measured the topmost, (and therefore smallest diameter), section of this valve, and it measured .114" in diameter. All you would need now would be a 3/16" OD x 1/4" MNPT compression adapter, and you're in business. Just cut a small 1/4" length of the hosing, and push it over the refill valve. Then, set the compression adapter up over this short length of hosing, and then tighten. Then, just attach it like you would a propane x 1/4" MNPT adapter to a small meter pipe.

<img src="http://i10.photobucket.com/albums/a123/ ... tanein.png">

You would also have to find a way to keep the tank pressed forward so that the refill valve stayed open. A good way to do this would be to use a piece of 1-1/4" SCH-40, (which the tanks I got SHOULD fit in), as a tank holder, and then have a bolt mounted through the pipe to where you pressed the tank forward, and then screwed in the bolt to where it kept the tank forward.

Last thing is the butane/air ratio. Volumes butane / volumes air = 3.23%, (.0323).

I think I might, (later on this year), make a small cannon that uses a butane meter. The butane refill tanks are small enough to fit smaller cannons well, and all you have to do to change out tanks is loosen the compression nut enough to allow the canister to be pulled out, but not the hosing.