Cutting open old LO2 tank.
 

I have been asked to cut open an old liquid oxygen tank with my plasma
cutter. The intention is to use it as a glory hole for glasswork. I
have not actually looked at the tank myself.

Are there any explosion hazards or anything I should watch out for in
terms of safety. Are LO2 tanks double walled, contain a dewar or
contain any hazardous insulating material I should be careful of?

On 10 Feb 2005 20:58:31 GMT, Ian Stirling wrote:
wrote:
I have been asked to cut open an old liquid oxygen tank with my plasma
cutter. The intention is to use it as a glory hole for glasswork. I
have not actually looked at the tank myself.

Are there any explosion hazards or anything I should watch out for in
terms of safety. Are LO2 tanks double walled, contain a dewar or
contain any hazardous insulating material I should be careful of?

LO2 tanks are almost certainly double walled, with vacuum in the middle,
and probably layers of foil or something.

Could be mylar sheeting (think "space blanket"), or Perlite also.

There is a very small chance that a fault would cause this to be
pressurised.
I'd drill a 10mm hole, to start, before starting the plasma.

I'm not sure it'll fit the desired purpose very well, either.
Just because it's good at keeping very cold things very cold,
doesn't mean that the materials used for such will be good for
high temperature insulation as well.

Actually, I lie, I'd say "Cool a LO2 tank", and start investigating
how to get it filled.

I've got a cryogen tank for liquid nitrogen (2 liter dewer flask) that
I got for a similar "hey cool, I want this" reason. It has, to
date, never been used. Based on the materials in that one, I wouldn't
consider getting it anywhere near something hot enough to melt glass.

Dave Hinz

I'm not sure it'll fit the desired purpose very well, either.
Just because it's good at keeping very cold things very cold,
doesn't mean that the materials used for such will be good for
high temperature insulation as well.

The heat from the glory hole flame never makes direct contact with the
metal. You line the inside with an insulating material(frax). You can
use a little as a metal trashcan. In this case, the glass work being
done needs an opening larger than a trashcan can provide.

On 10 Feb 2005 13:18:11 -0800, wrote:
I'm not sure it'll fit the desired purpose very well, either.
Just because it's good at keeping very cold things very cold,
doesn't mean that the materials used for such will be good for
high temperature insulation as well.

The heat from the glory hole flame never makes direct contact with the
metal. You line the inside with an insulating material(frax). You can
use a little as a metal trashcan. In this case, the glass work being
done needs an opening larger than a trashcan can provide.

Gotcha. I guess that makes sense, but I'm still not convinced that just
because something is good for cold, it'll be good for heat. As an
extreme example, styrofoam wouldn't make the transition real well. I don't
know how perlite or mylar do at high temps, or what the temp there is.

I will drill a few test holes as suggested earlier to get an idea of
what may be inside and relieve any possible differences in pressure if
it is a double wall. If it turns out that there is some insulating
material that can not be removed or has a temperature problem then it
may not be possible to use the tank.


Dave Hinz wrote:
On 10 Feb 2005 13:18:11 -0800,
wrote:
I'm not sure it'll fit the desired purpose very well, either.
Just because it's good at keeping very cold things very cold,
doesn't mean that the materials used for such will be good for
high temperature insulation as well.

The heat from the glory hole flame never makes direct contact with
the
metal. You line the inside with an insulating material(frax). You
can
use a little as a metal trashcan. In this case, the glass work
being
done needs an opening larger than a trashcan can provide.

Gotcha. I guess that makes sense, but I'm still not convinced that
just
because something is good for cold, it'll be good for heat. As an
extreme example, styrofoam wouldn't make the transition real well. I
don't
know how perlite or mylar do at high temps, or what the temp there is.

In article .com,
says...

I will drill a few test holes as suggested earlier to get an idea of
what may be inside and relieve any possible differences in pressure if
it is a double wall. If it turns out that there is some insulating
material that can not be removed or has a temperature problem then it
may not be possible to use the tank.

Most liquid cryogen tanks are double-walled with a vacuum jacket.

If so then there will be a pumpout bung someplace in the vacuum
jacket and you could pull out the plug and vent it before working
on it.

Chances are it is superinsulated (alternating layers of aluminized
mylar and open weave nexus cloth) and it may have intermediate
thermal shields attached to the neck of the inner vessel.

The neck may be made of G-10 fiberglass.

The mylar will stink and maybe catch on fire if you try to cut
through it. If I were doing this, I would a) purge the vessel
with an inert gas a few times b) vent the vacuum jacket up to
air, c) cut around the top of the outer vessel.

At this point the inner vessel can be lifted out, with all the
insulation still on it. You will be left with the larger, outer
tank basically bare.

The inner tank can be gotten at by unwrapping all the insulation
and heat shields, if any.

Jim


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On 10 Feb 2005 15:00:05 -0800, wrote:
I will drill a few test holes as suggested earlier to get an idea of
what may be inside and relieve any possible differences in pressure if
it is a double wall. If it turns out that there is some insulating
material that can not be removed or has a temperature problem then it
may not be possible to use the tank.

Maybe before you wreck it, you could put it on eBay, and then buy
something more known to be suitable? Once you make the test holes,
it's guaranteed to be junk for it's intended purpose.

Or, contact the manufacturer of the vessel and ask them about your
intended use and it's characteristics at high temperatures.