"David A. Webb" wrote:

On Wed, 17 Dec 2003 20:56:48 -0500, Jeff Wisnia
wrote:

4. Pressurize the container to approximately 15 PSIG with LP-gas vapor. Never
purge with liquid LP-gas; to do so will cause the moisture vapor to chill and
remain in the container.

5. Fully open the container service valve and vent safely to the atmosphere.

6. Repeat the fourth and fifth steps for a total of five purgings.


And exactly how is doing this making the tank safer than if it were
filled without purging?

As soon as the tank goes from zero pressure to 15psi the first time,
the contents are no longer an explosion hazard. So why pressurize and
vent?



Of course, the possibility of ending up with an air/propane mixture in the
explosive range is infinitesimally small if you do put above some minimum amount
of propane in. But it can't be guaranteed to be so for every idiotic thing some
moron might decide to try, so the reg writers play it safe with that CYA
procedure.

I refuse to get sucked into this one again dammit!



Is it simply to remove air because the air may contain moisture?

Couldn't hurt. IIRC water can diminish or remove the odorant which is added to
propane so people can smell leaking gas.

Happy Holidays,

Jeff
--

Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can smile when things are going wrong, you've thought of someone to blame
it on."