[chbot] Oxygen / Argon sensor

[Mark Atherton]

David, hello, hope you are well !

The electron-source in question needs to be kept dry, but  I do like 
your idea.

Current thought is to gently fill a thin, vertical plastic 
containerawith Ar, drop in the electron-gun, and tighten up the lid. If 
I can somehow meter the gas, and overfill by 100% things should be OK. 
The thermionic source should be at the bottom of the container.

In terms of acceptable levels of oxygen, no idea. Electron-guns 'are 
poisoned quickly' in the presences of oxygen, but that should be taken 
within the context of a normal, service life of maybe 10 years.

I am hoping that storage in Ar will extend the life on an EG from a few 
hours in air, to a few months. Just have to move swiftly when 
transferring it into the bell-jar before evaluating the whole mess.

David's suggestion gives me a simple method to calibrate the metering 
process.

Thank you everyone for suggestions.

-Mark


On 8/06/2020 12:00 PM, David Burkitt wrote:
> Why not simply fill the jar with water and have it inverted in a tank 
> of water and bubble the Argon in! The only thing displacing the water 
> is Argon so no water = 100% Argon.
> Dave
>
> On Mon, 8 Jun 2020 at 00:38, Trevor Wignall <zl3adz at gmail.com 
> <mailto:zl3adz at gmail.com>> wrote:
>
>     A slightly more refined technique used in previous centuries is a
>     canary in a cage. When it keels over, you know it isn't breathing
>     oxygen.
>
>     Argon is heavier than air,, but not dramatically so (40 rather
>     than 28 for N2 and 32 for O2), so you could get significant mixing
>     of the argon with room oxygen. (Good for the canary, not so good
>     for your device.) Of course if the argon is also cold... Perhaps
>     that is the trick - cool the argon and use a thermometer or
>     thermocouple.
>
>     Good luck.
>     Trevor
>
>     On Sun, Jun 7, 2020 at 11:41 PM Marshland Engineering
>     <marshland at marshland.co.nz <mailto:marshland at marshland.co.nz>> wrote:
>
>         Car O2 sensors have to be hot to work. There are narrow and
>         wideband units.
>         Wideband needs a lot of electronics to get reasonable readings
>         out.
>
>         Simple method, place head in jar, if you can breathe - oxygen,
>         if not argon.
>
>         Cheers Wallace
>
>
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