I used my Harbor Freight vacumn pump (eductor) to outgas the MT propane tank I
use for a portable air tank. The tank held about 26"hg w/o any signs of
deformation. Maybe you should add a filter to your tank, that way you will
have a vacumn cleaner, (sorry, could not resist!!!)
Even after multiple flushings with air, there is still a smell of the odorant.

John H.