@Draconis: Modify? It's just a matter of threading on one of these adapters and possibly removing the valve core from the propane bottle to improve flow. No big deal really. In fact I made this same suggestion to Doom some time ago as an alternative to his Catalina cylinder.
The universal danger of flammable gas is why we rejected that idea. That and the retarded flow rate through such a small orifice. There are many better options for reuse of old tanks. How about nice steel or aluminum paintball tanks? I have had luck getting some which were out of date and thus not suitable for CO2 use anymore, for FREE. Or empty disposable fire extinguishers? They have nice aluminum bodies available in various sizes and are, again, FREE.
Yes, the only downsides to using throwaway propane cylinders are
1. You have to empty them using a camp stove, then finish it by venting it outside for quite a long time. Make sure to tie or weigh it down with something, then depress the valve stem using the tank fitting adapter to vent it out. DO NOT HOLD THE TANK WHILE DOING THIS, it will get cold enough to freeze your skin to it because the propane is undergoing a phase change from liquid to gas. Also obviously do it away from a flame source.
2. Even after being emptied they smell.
Yeah, that isn't really an accepted method for evacuating a cylinder of flammable gas, and that is EXACTLY why I suggested not posting it. This is against my better judgement, because I can just see some doing something wrong and freezing off their finger, bowing up their face, or gassing themselves to death... You need to remove the schrader valve completely and fill the entire tank with a non-flammable liquid. Water works and is cheap. The tank must be completely immersed and left upright to vent for at least one hour. There will continue to be propane that exits the metal structure of the tank during that period. Do NOT pressurize air in a cylinder that has not been liquid displacement evacuated, as it has a possibility of igniting the propane still embedded in the tank walls.
You guys have met some of our members, right? Would you really trust them to be doing something like this? And to know when they should NOT be doing it? So go ahead, be cavalier with the retards. None of them live near me anyway.
Edited by Draconis, 04 March 2011 - 09:04 PM.