If you are a home user of an air tank, you should make sure to drain your tank when you are done using it. This gets the water out of the tank and keeps rust from forming inside the tank.

One common mistake that people make when draining the tank is to just open the drain at the bottom and assume they are done. You don't want to do this. Instead, use the pressure relief valve, which should be near the pressure regulator, to get the pressure in the tank down to about 25 psi *before* you open the drain.

If you open the drain too early, the water that comes out as the tank drains will freeze (the air that comes out is really cold, just feel it) and clog the drain. You'll think all the air and water is out, but it just can't get out. By getting most of the air before opening the drain, there is less chance of freezing.

If you drain does freeze, try wiggling it. If you still can't get the remaining air out, leave the drain valve open. Eventually the ice will melt and then the remaining water and air will be drained from the tank.