On Thu, 18 Dec 2003 19:31:09 -0600, Richard J Kinch
wrote:

writes:

Gasoline tanks are vented to atmosphere when they are filled - so they
purge themselves.

Obviously not, if they are open to the atmosphere.
Exactly. As the fuel goes in, the air is displaced, "purging" the
tank. A propane tank is NOT open to the atmosphere, so any air in the
tank stays there.