Re: Secondary Internal Gaseous Insulation (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 18 Sep 2007 20:37:08 -0700
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Secondary Internal Gaseous Insulation (fwd)

Tesla list wrote:
> ---------- Forwarded message ----------
> Date: Tue, 18 Sep 2007 10:01:41 -0500
> From: Crispy <crispy@xxxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Secondary Internal Gaseous Insulation
> 
> Hello,
> 
> Has anyone ever tried preventing internal secondary arcing by filling
> the secondary with some sort of insulating gas, such as sulfur
> hexafluoride?  I think it would be fairly easy to do so, considering SF6
> would sink and could be sealed in the secondary with baffles.  I just
> can't find a good source for it.

SF6 has come down in price, but it's not an off the shelf thing you can 
pick up at the local welding place like Argon, CO2, etc.  Airgas sells 
it (look on their website under specialty gases) and you can arrange to 
pick it up at one of their locations.

Honeywell makes the stuff (perhaps in connection with their 
refrigeration equipment business?), and their website lists distributors as:
Advanced Specialty Gases
Air Liquide
Airgas
Linde
Matheson Tri-Gas
Praxair

You probably have one of these suppliers near you.  It comes in sizes 
like 10lb, 50lb, 115lb, etc. up to 26000 lb tube trailers.

You can also order it in a "lecture bottle" from a chemical supply place


You want dielectric grade or chemically pure.. don't get the reagent or 
electronic grade stuff. An Airgas CP200 size cylinder (aka a K sized 
bottle) will set you back about $1600.. that's about 115 lbs of SF6. 
The smallest Airgas cylinder listed is a CP35, which holds 17lbs of SF2 
(about 35 cubic feet when expanded to gas).. probably be around $200-250.

(I guess I should update my webpage with the latest data on sf6)