[daepp]

* An empty 5 gallon propane tank weighs approximately 16.5 lbs. It is required to be stamped on the steel handle at the top of the tank. So if you use a bathroom scale you can see if it is truly empty. It is very tough to guess if a tank is empty unless you have another one to compare with, and even then it's tough.

The weight of the tank (if filled full of water) is also required to be stamped on the tank handle. It's usually around 47 lbs.

Finally, the date the tank was manufactured is stamped on the handle. All of the tanks I've seen say "Good for 12 years from date on tank". HOWEVER, there was a change in the law (at least in CA) that now limits them to 10 years - go figure...

The tank can be re-certified one time - I think for 5 years. This too gets stamped on the handle.

So the only time I do an exchange is if my tank is getting old. And the trick here is to search through the inventory and make sure to get a newer tank!