Using a fire extinguisher as an air reservoir.

[Dig_Gil]

As the title suggests, I've got a 3.1L fire extinguisher which I intend to use as a reservoir for the pneumatic I am building. It tolerates way more pressure than a air compressor! My idea is to remove its valve and replace it with a quick connect fitting so that I can switch it between pump (fridge compressor ) and launcher in a simple way.

My problem is that the extinguisher's valve just won't get unscrewed. Is there something dumb I should know? I've forced it with wrenches, a bench vise, I've poured lubricant into it, hammered it and even put my weight on a lever and it seems to not even budge! I've considered it might have some sort of resin around the threading, but I dunno.

I've thought I should drill the valve from top to bottom, but I'd rather preserve its threadings undamaged for reference if possible.

[bravootome]

My problem is that the extinguisher's valve just won't get unscrewed. Is there something dumb I should know? .

Had you emptied the fire extinguisher first ?

[Dig_Gil]

Yes. It was originally used for fire drills and fire equipment demonstrations. I checked myself.

[hawktalk]

i used one as a reservoir i had the same problem they do put sealant like thread lock its a bitch to get off. ended up forcing the damn thing of with all my strength and a vice. make sure you are un-tightening it in the right direction because some are left handed threads and some are right. in your case if you want to make it into a stand alone tank then i would cut it off and find someone to Tig weld a thick plate on the opening probable be a good idea to put some reinforcing inside the neck so a bigger weld can be achieved. good luck

[Dig_Gil]

I've accomplished removing the valve and for those whom it might be of interest and for completeness' sake, here's what's I've done:

I borrowed someone a comically large spanner, more specifically that thing that wikipedia calls a pipe wrench (in my language we call it "chave de grifo"/"griffin wrench"). I grasped the reservoir at the vise, and twisted the valve with the 2/3 of a meter length of the wrench (I still find it quite amusingly big). The valve's metal bent and torned and gave up. After about half a turn on the threadings, it was easy to remove by hand.

If you are interested in knowing how I carried on with the reservoir ask away!