[dpage]

I need to test a sodium wicking system in high temperature and agitated conditions. The experiment setup seems like it is going to be pretty complicated, however, and I need some direction on where I might get a glass set-up that I could modify. The set-up is as follows:

Solid sodium pellets are placed in a glass test tube, thermally rated for up to 400 deg. C..

Oxygen is purged from the tube (argon or another inert gas introduced), and the tube is sealed (cap needs to be thermally rated for 400 C as well.)

In order to create a safety barrier between the sodium tube and the oxygen atmosphere (in the event that the tube cracks under high temperatures), The sealed sodium tube is placed inside a larger glass tube which is then filled with argon.

We now have a tube within a tube where no oxygen is present. The trick is that the sodium tube needs to be agitated. We have access to a shaking mechanism that would agitate the outer tube, but the sodium tube needs to be secured inside the outer tube. Therefore, I need a set-up with a tube inside a tube so that the inner tube is secured firmly to the outer tube.

My question is: Is there a similar type of glass set-up available to purchase that I may be able to modify? Any input on how I might do it and where I might find the necessary materials? If I can't find something I may have to construct it from scratch which will prove difficult (especially to hold up under high temperatures).

Thanks,
Dpage

[Stepan]

What is "sodium wicking system"?

This setup is a call for disaster. Elemental sodium at 400C will likely react with glass by reducing it to aluminum and silicon, which will eventually corrode the glass. 

[Enthalpy]

My intuition as well (but I'm no chemist) shouts against ceramics, especially oxides like glass, to host hot sodium.

You'll find engineering knowledge about hot sodium at nuclear breeder reactors, where sodium serves as the primary coolant (replacing hydrogen hence water as neutrons must be kept fast). They invested rather long development into handling liquid sodium. As far as I know, they use metallic tubes and vessels, with some refractory coating, maybe W (I'd stay away from Al Cr Ti Ta Nb and any metal that relies on an oxide layer...) to prevent sodium from dissolving the base metal.

As well, the least bad method found for pumping liquid sodium is by eddy currents in the sodium itself. I'd let a strong permanent magnet rotate, or use a big electromagnet, near the liquid sodium.

Design challenges are big enough that you may prefer to give up your double confinement in favour of a fire extinguisher. How many grams of sodium do you handle? Reactor designers preferred a catcher in the ground that would collect leaked sodium and insulate it from air.

[dpage]

Thank you for your suggestions--We're going to be dealing with relatively small amounts of sodium, so I think we'll go ahead and simplify the design like you suggested and just keep a fire extinguisher on hand. Also I found some material suggesting we use quartz instead of lower grade glass...
Also thanks for the info about nuclear reactor cooling systems...that led to some good research.

[vmelkon]

Sodium high pressure lights use a Al2O3 tube and they survive sodium vapor at high temperatures.

Sodium low pressure lamps survive as well and the glass looks fully transparent and is borosilicate.

http://en.wikipedia.org/wiki/Sodium_light

also, read the end of life section.