On Fri, 21 Feb 2014 10:49:48 -0500, "Jim Wilkins"
wrote:

"Joe Gwinn" wrote in message
...

So, what if one uses the propane bottle upsidedown, with a drain
valve
at the bottom of a bit of iron pipe, and the air fittings on a T off
the vertical drainpipe?

(I don't plan on doing this, but it seems the obvious question to
me.)

Joe Gwinn

The air inside will still be at 100% humidity.

This shows the vapor pressure of water versus temperature, equivalent
to 100% humidity. Atmospheric pressure is 760mm of Mercury:
http://hyperphysics.phy-astr.gsu.edu...kin/satvap.gif

When the compressor forces 10 gallons of air + water vapor into a 1
gallon tank the excess water will condense into liquid until its vapor
pressure falls to the line.

I have a couple of air pigs retrieved from an old poly foam dispensing
setup. They're nylon coated and have lasted nearly 40 years now. In
all that time, I've removed maybe 2 drops of water from them. I shake
them and never seem to hear liquid inside. They're filled from my main
HF 30gal upright compressor and used as mobile tanks. I haul the
little IR 3/4hp pump to refill them at remote sites when necessary.

Why couldn't someone use a jug of gas tank protective coating to make
a propane tank safer? They're already rated for 120PSI. Running
them upside down and ported for water removal is another good (and
easy to accomplish) task.

--
Cogito, ergo armatum sum.

(I think, therefore I am armed.)