I've been using a Worthington 3lb tank for a couple of years. I love it, and it fits nicely under the seat. I now carry one 1lb bottle for when it runs out, but if you weigh it after use, you can usually avoid running out.

Just take it to a propane filler, it purges with the fill. They open the release valve and air is pushed out and replaced with liquid propane and vapor. I don't think you'll be able to fill it yourself since modern auto stop portable tanks do not allow rapid flow from the valve, and I also think the auto stop float will shut off the tank when upside down. Besides, it's not a good idea, and not even worth the trouble even if you could.

Those safety features were designed to protect us from ourselves!

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Neil2
Sent: Wednesday, March 22, 2017 10:02 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: advice on new propane tank

David,

Please tell the kids on FB since this could save a Vanagon, er a kids life I mean!

On Wed, Mar 22, 2017 at 6:09 AM, David Beierl <dbeierl@attglobal.net> wrote:

> They're full of air to start.  That's too lean to burn.  In use 
> they're full of propane which is too rich to burn.  You have to get a 
> new tank past the point of containing an explosive mixture before you 
> can use it or the first time you light something it could flash back 
> through the lines and blow the tank apart.
>
> Yrs,
> d
>
> On Wed, Mar 22, 2017 at 6:36 AM, Roman Haag <romanhaag@ymail.com> wrote:
>
> > So a new tank needs to be purged?  I did not know this.
> >
> > Sent from someone's plumbing
> >
> >
> > > On Mar 22, 2017, at 01:37, David Beierl <dbeierl@ATTGLOBAL.NET> wrote:
> > >
> > > Off the cuff -- I'd take it to any propane place to purge.  During
> > purging
> > > at some point there will be an explosive mixture in the tank, you 
> > > don't want to be around if it finds a spark.
> > >
> > > Yrs,
> > > d
> > >
> > >> On Tue, Mar 21, 2017 at 9:32 PM, gary hradek <hradek@yahoo.com>
> wrote:
> > >>
> > >>
> > >> I just bought a Worthington Pro Grade 4.25 lb. Empty Propane Tank from
> > >> Home Depot to use with my Colemanstove.   The 1 pound cylinders are
> > >> nowclose to 8 dollars a piece.   I was goingto fill it from the 20
> pound
> > >> tank but they say something about purging it.   Can I just fill and
> > empty
> > >> it a few timeswith propane vapor before trying to fill it with 
> > >> the
> > liquid
> > >> by inverting the 20pound tank?   I am guessing there is acharge to
> have
> > it
> > >> purged somewhere?
> > >>
> > >> Gary
> > >>
> > >>
> >
>

--
Neil2
'82 Diesel Westfalia (Ducky)
'86 Vanagon (SaVannah)
'08 170" 2500 Mega Roof Sprinter (Moby)
'90 Westfalia Subagon (SaL)
Fulltiming since August 2008
Nunquam Pendite Divendium