[TheForge] Propane stuff (Was: Build it or buy it)

[Bruce Freeman]

Michael,

I'm not a weldor, so I don't want to presume to advise what is "safe" when =
cutting an old propane cylinder.  But I do understand something about =
what's unsafe.

Obviously, you should bleed off all tank pressure before removing the =
valve.  Valves are typically brass, partly so that they will not spark =
when installing or removing them.  (This is NOT to say there is no risk =
taking off the valve.  There's always a risk working with cylinders.)

ANY residual fuel is dangerous.  If you're cutting with oxygen (and how =
else?) then filling the cylinder with inert gas may help by displacing any =
fuel vapors, but if there's fuel on the cylinder walls (read: oil) then =
that will simply vaporize and displace the inert gas, mix with the oxygen =
you're conveniently providing, and boom!=20

If there's obvious oil on the inside of the cylinder, you might want to =
wash it out.  I'd suggest soap and detergent, though, not a flammable =
solvent.

A continuous flow of inert gas might help by diluting the flammable vapors =
below their lower flammability limit.  Nitrogen or carbon dioxide might =
suffice as the inert gas.=20

If you don't have a source of either of these two gasses, then you can =
generate carbon dioxide by adding acid dropwise to marble chips.  (If you =
use a non-volatile acid, like sulfuric, you'll have less chance of getting =
acid downstream of this carbon dioxide generator.  If you use a volatile =
acid, like muriatic, then you MUST use an acid trap downstream.  This =
could be a tube filled with very small marble chips through which the gas =
passes.)

I've head of filling the cylinder with water before cutting, but I'd be a =
little concerned about a steam explosion.  If there's proper venting for =
the steam, this could work.


>>> mspencer@tallships.ca 11/25/02 03:12AM >>>

Hi Terry --

> i cut a 100lb propane cylinder ( taking safety precautions while doing
> so. )

I would be pleased to have you directions for safely cutting up old
propane cylinders.  I vaguely recall that you told us this before but
a grep through my saved mssgs doesn't turn it up.

   Any risk to just cranking out the valve with a big wrench?

   Rinse with an organic solvent?  Not?

   Flush with lots of air?  Not air?  Inert gases are expensive.

   Some way, without expensive instruments, to test that it's free
   enough of potentially explosive stuff to safely apply heat?

   Etc. etc.

Not info I need today.  I have a growing collection of 25#
cylinders that I could make things out of but I've been a bit
hesitant.

BTW, is the "accordion" (corrugated, flexible, apparently seamless)
(nominal) 1" stainless pipe for propane a commonplace in the propane
world?  With some effort I ran down a supplier because i wanted some
flexible exhaust pipe for an 8hp Briggs and Stratton.  Comes covered
with yellow plastic here (Canada), said to be a color code for propane
piping.  Are there special connectors or fittings for this kind of
pipe or are joints normally welded?  Rated, IIRC, for 5 psi but looks
like it would stand quite a lot more if the contents weren't
dangerous, say, water f'rgzample.

- Mike

--=20
Michael Spencer                  Nova Scotia, Canada=20
               =20