Thanks for the info folks. I'm gonna give it a try.
Don't know what I'll do with the tank when done. Even if I was to exchange or re-certify, it seems like a difficulty to haul around to refill vs the convenience of the 20 gal tanks.
Assuming that it is a 100 pound (23 gallon) tank, if you want rid of it let me know and maybe we can work something out. I currently use one to run the propane heater I use to warm my shop and wouldn't mind having a second.