On Mar 5, 2:02*am, Don Foreman wrote:
On Thu, 04 Mar 2010 21:26:15 -0800, Larry Jaques





wrote:
On Thu, 4 Mar 2010 04:44:57 -0800 (PST), the infamous Jim Wilkins
scrawled the following:

On Mar 4, 7:17*am, Larry Jaques wrote:
...
I missed the first part of this thread. What are these things for? It
looks like a propane-to-rattle-can adapter, maybe used to repressurize
flat spray cans.

Makes them round again.

If propane doesn't quickly dissolve into the contents it can
overpressure the can, that's why I used butane.
http://www.engineeringtoolbox.com/pr...re-d_1020.html

Spray cans do not fail gracefully. I'd rather not post the details as
others might try and not be so lucky.

Ouch! *Scratch that off my list of possible cool tools to have/make.

And you gave me **** about shying from a 40-joule ICD mulekick when
TIG welding, you macho devil-may-care dawg! *

Not knocking prudence, caution and dainty demurral, *but note: it
takes about 150 PSIG to pop a plastic (PET) beverage bottle. *Metal
cans are smaller and stronger than plastic bottles. *

You tried it? I'd read that they take 200. Never went over 100 myself.

I don't know if dissolution into content lowers vapor pressure or not,
and if so what the time constant might be, I'll defer to Wilkins on
chemistry. That said, I can report that I have recharged and saved
many rattlecans with propane over a period of at least two decades
with no mishaps.

If a spraycan did fail ungracefully it'd make a pop and a mess *but
it'd just rupture, no shrapnel. *Wearing protective eyeware should be
SOP in the shop anyway and this is a shop activity, not one to be
practiced in milady's parlor.

I don't know the pressure ratings, and it definitely varies with
construction. Long ago I read that they were supposed to withstand
180F without rupturing. I checked because one of my lab manager tasks
was turning off soldering irons after everyone had left, and I found a
heat gun running near flux remover cans.

I tested them in a remote sandpit in a rural area where random
gunshots etc didn't attract attention. Some blew out fairly harmlessly
when an end seam unrolled, others ripped apart at the lengthwise seam,
flattened out and became flying saw blades. Thus the warning.

The safer test is to puncture the bottom, fill them with water, plug
the hole and freeze them, preferably outdoors instead of smelling up
the fridge.

jsw