"Blair P. Houghton" wrote:
>
> The newer Weber Genesis models have a spring-scale hanger
> for the tank, but it's useless. Mine registered "empty"
> about ten fires ago.

That may have been the right time to have it refilled.
Running it until you no longer get a flame will force
some of the heavy impurities in the gas (which will
accumulate in the tank, because that's the lowest
pressure these molecules will see between the
refining plant and your burner) to vaporize. Some
of these impurities, such as molecules based on
the napthalene and anthracene core structures, can
be very carcinogenic.

Just because you _can_ do it, doesn't mean you
_should_ do it. The people who designed the scale
may have considered mechanisms that are unknown
to you.