I really like turning propane tanks into air tank, they last a long time as an air tank and the standard grill size holds enough air to fill 2 flat tires to 35 PSI on my car. The only problem is that I REALLY dislike removing the valve from the tank, sometimes I would even ruin the valve and not have a tank that is usable at all. On one city clean up day, I managed to get about 4 of these tanks, one was half full or propane yet and was still on the grill, I couldn't remove the regulator from the tank so I just cut the hose and went home with my new stash.
Once I remove the regulator at home, I inspected it a bit more and came up with a new way to get an air tank.
I know there are plenty of Instructables on this topic, but I have never seen it done this way before. There where tons of results that came up on "" Propane air tank" so I may have missed one.
Best of all, you only need one (1) adapter for an unlimited number of tanks.
Step 1: Remove tank adapter
Just remove the brass piece that screws into the tank from the regulator, this is easily done by clamping the regulator into a vise and using as crescent wrench to remove it, it is just standard threads which play a BIG role here.
Once it is off, you will either have a tiny, small, medium, or large hole in the end. If you have a medium to large hold, skip the next step.
In my case I had a Tiny hole, not much air will pass through that.