SpudFiles

I am building my first cannon, and i have all the things i need. all but 1: i have what looks to be an old amerex B417 ABC (Dry Cem) fire extinguisher tank, but the thread size is odd. It has 12 threads/inch, and its silghtly smaller then 3/4. any idea what this is, or where i can find a converter? I need to convert this to 3/4 pipe thread (14 thread/inch)http://i595.photobucket.com/albums/tt40 ... 9_0433.jpg[/img]http://i595.photobucket.com/albums/tt40 ... 9_0436.jpg[/img]

Do you have the original end cap/release for this extinguisher?
I had the same problem but I discovered that the pipe inside of the FE (like in a spray can) was mounted with a standard 1/2" thread. I sawed off the release from the cap and screwed a 1/2" nipple into it from the top.

Unsure, we have different kinds of fire extinguishers around known as "tamper proof" ( ).

You could get a boilermaker(someone approved for pressure rated welding) to weld a fitting in there, or you could do it yourself.

Or take it to a plumbing store or wherever and walk around with it, trying things in the threads...

Also, if you have the right die you could thread a fitting to go in.

If you get some better measurements on the threads I'll do some looking for you.

Its almost like a garden hose outlet, but just slightly smaller. Same threads

Welcome to Spudfiles BA! To make your post a little more readable, I recommend you add a Carriage Return (Enter key) after each image you posted above. Presently, it's stretching image and text well off to the right of the screen.

Welcome to spudfiles!

If you can screw something in loosly, maybe just fill the gap up with epoxy.
You can also drill holes, tap threads and use bolts to secure the thing.

In my opinion the epoxy won't work because of the pressure. Get something close then have someone weld it in for you.