I sense a little bit of B/S and scare talk here.

I think that people whose tanks exploded, did nothing to purge them,
had liquids in them, and got punished.

In my case, the tank is completely free of liquids (which dried out
days ago) and the only thing that it has is vapors, if any.

If, say, it has an incredible high concentration of fuel vapors, then,
purging the tank by something like 10x the volume of air (from a home
vacuum cleaner or compressor for a few minutes), would leave, more or
less, nothing as far as vapors are concerned.

The volume of the tank is less than 4 CF, and running my 15 CFM
compressor for just 5 minutes, would provide about 20 times the volume
of air in the tank.

i