Re: Sulphur hexafloride

[Hugh Logan <hlogan@ix.netcom.com>]

Eric T. Lane wrote:
> A physics demonstration personality wants to use sulpher hexafloride to
> demonstrate the opposite of the helium squeeky voice effect.  He breaths
> in a lungfull of SF6 and his voice sounds gruff as he speaks.
>
> His question is where can he get SF6, hopefully reasonably cheaply, or a
> reasonable substitute high density gas that won't harm him.

A quick search of the Internet found several companies that supply
SF6 gas. Among them are Scott Specialty Gases at
http://www.scottgas.com/index.html, CFC at
http://www.c-f-c.com/charts/sf6data.htm , and Concorde Science &
Technology, Inc. at http://www.concordest.com/index.html . The latter
imports it from Russia. There are probably many other such companies
listed. I don't know about prices, but quotes are given over the
Internet.

The demonstration is listed at the University of Maryland
(http://www.physics.umd.edu/deptinfo/facilities/lecdem/h6-05.htm) with a
link to a reference on safety. PIRA 3B30.50 is also given as a
reference.

Apparently SF6 is used for plasma etching of semiconductors. High
frequency RF fields are said to produce fluoride ions for this purpose.
SF6 is also used as an insulator. I recall that it was used as an
insulator for 200 kV Cockroft-Walton power supplies for beam deflection,
velocity selection, etc. at the Princeton-Pennsylvania Accelerator more
than thirty years ago. Perhaps a semiconductor manufacturer or a nuclear
or particle physics research facility using it for high voltage
insulation could help if commercial prices are too high. I wouldn't want
to breathe it unless I knew it was sufficiently pure.

Hugh Logan