I bought a set of spare tanks for my brazing rig off craigslist tonight. $25 for an MC and 20 CF.
I got them home and wanted to see if there was any gas in them. I cracked the oxygen, got a "pfft" out of it and that was it. The acetylene was really tightly closed, it was pretty tough to open, but gas rushed out when I finally got it open. Happy for the possibility of bonus gas, I quickly closed it and went and got the regulator to see what it would register.
I cracked the valve open again with the regulator on this time and the tank side of the regulator pegged out at 400 PSI! Pretty sure it is acetylene in the tank, it is labeled as such of course, and has that distinct smell, I'm just concerned about this tank pressure. Usually they are around 250 PSI when I swap them out. Is this safe to use at this pressure? Should I just exchange it as is? Purge some out to get it down to 250? I hope I didn't damage that gauge! I put a different tank on and the pressure was right on where it should be.