Mark wrote in message .. .
Stan Schaefer wrote:


I've bought several new propane tanks, they've all had to be purged.
You DO NOT want air mixed with your propane in there. Purging
amounted to opening up the bleed screw while propane pumping was going
on, screw remained open until propane fogged out of the opening. The
tanks were then filled to proper weight.


Wrong. Very wrong.

That was an improper purge, and if liquid was coming from the bleeder
valve it was already near or at capacity.


I said "fogged", not liquid. Low-temperature vapor, not liquid drops.
I've done enough gravity filling to know the difference. They fill
by weight, kind of hard to overfill if the scale is set correctly.
Might be improperly done in your locale or by your standards, though.
It DID get rid of the air or gas in there, the actual object of the
exercise.




The last one I bled down before hauling it over to
the rental place where I get tanks filled, took less time that way.
It took about 15 minutes for the 60 lb tank to quit passing air after
I opened up the screw, there must have been a lot of pressure in
there. I suppose they use it for checking for leaks after assembly,
probably roll them through a water tank after pressurizing and look
for bubbles at the joints.


Nope.

The tank had either dry air or N2 in it to prevent air and moisture from
entering the tank which would cause rust and odorant fade. You really
did yourself no favor by bleeding it off.

Read my previous post on odorant fade, open the link and read the
article if my words not good enough.





--

Mark

N.E. Ohio

Well, it's between 6-10% humidity here in the summer, the air or gas
is venting OUT, so just how is water vapor supposed to be going back
in???? It was hauled over to the rental outfit for filling that day
anyway. It was just curious to me that there was that much compressed
gas in there already.

One of the other posters figured partial pressure on the basis of the
initial air or inert fill gas being at atmospheric pressure. It
wasn't at atmospheric pressure, for as long as it bled it had to be at
higher pressure than that. Can't be all that much higher, though, the
DOT, or whatever their successors are, would start getting on them
about shipping filled pressure cylinders. Next new cylinder I get,
I'll stick a regulator with a pressure gauge on it just for
curiosity's sake before I fill it.

Stan