Nate Nagel wrote:

subject says all, I was given an old air compressor minus the compressor
and motor - would like to use it as a portable compressed air tank.
McMaster-Carr sells schraeder valve to NPT fittings for cheap, but don't
I need some kind of pop off valve to make this legit? Also will a
standard radiator petcock suffice as a drain valve or do I need
something more substantial? I guess my lack of finding the pop off
valve on a quick web search (maybe I'm not using the right keywords?) is
keeping me from hacking this together.

For little more than the cost of the fittings, fill valve, safety relief
valve, etc. to put it together, you can buy a complete new portable air
tank from Harbor Freight in your choice of 5-10 gal sizes and in either
steel or aluminum.