RE: Corrected di-el strength of gas

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 01:00 PM 5/4/2004 -0600, you wrote:
>Original poster: "Ian McLean" <ianmm-at-optusnet-dot-com.au>
>Hi John,
>
>Very interesting.  Tetrachloromethane is another name for Carbon
>Tetrachloride is it not?  Good di-electric - shame it is a nasty carcinogen.
>
>Rgs
>Ian


Most of the halogenated hydrocarbons make fairly decent insulators. Partly 
because of their density, partly because they have electronegative ions.

You'll note hexafluoroethane (perfluoroethane) and octafluoropropane (aka 
perfluoropropane, Halocarbon H218) on the list, which are essentially 
standard alkanes with all the H replaced by F.

Likewise, most of the refrigerants work fairly well. 
DichloroDiFluoroMethane (R-12) for instance. There are regulatory issues if 
you're buying them, and the price is high enough that you wouldn't want to 
vent them willy-nilly, greenhouse gas problems notwithstanding (for what 
it's worth SF6 is a monster greenhouse gas, although there's some 
legitimate dispute about whether it's being rated fairly).

R-134a is tetrafluoroethane, readily available, and probably works as well 
as most of the other halogenated hydrocarbons.



> > -----Original Message-----
> > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > Sent: Tuesday, 4 May 2004 11:37 pm
> > To: tesla-at-pupman-dot-com
> > Subject: Corrected di-el strength of gas
> >
> >
> > Original poster: "john cooper" <tesla-at-tesla-coil-dot-com>
> >
> > I posted an error for the di-electric strength of air in a previous
> > response, the 0.4-0.7 for air was kV/mm.  Here's a new
> > partial listing for
> > some gasses (FWIW gases and gasses are both proper)
> >
> > Air, 0.97
> > Argon, 0.18
> > Carbon Dioxide, 0.82 - 0.88
> > Carbon Monoxide, 1.02 - 1.05
> > Chlorine, 1.55
> > Helium, 0.15
> > *Hexafluoroethane, 1.82 - 2.55
> > Hydrogen, 0.50
> > Methane, 1.00 - 1.13
> > Nitrogen, 1.00
> > Neon, 0.16 - 0.25
> > Nitrous Oxide, 1.24
> > *Octafluoropropane, 2.19 - 2.47
> > *Sulfur Hexafluoride, 2.50 - 2.63
> > Tetrachloromethane, 6.21 - 6.33
> >
> > *used in industry and research as di-electrics
> >
> > The di-el strength of a gas is measured as a comparison to
> > Nitrogen - 1.0
> > It was surprising for me to realize that air, which doesn't
> > provide much
> > quenching, is rated at 0.97; while Nitrogen, which quenches
> > quite well, is
> > rated at 1.00  Not much of a difference in rating for a huge
> > difference in
> > quenching ability.
> > Neon & Helium could be an interesting alternatives to Argon
> > for inducing
> > long streamer length although neon is more expensive than
> > helium.  Someone
> > asked about CO2, they'd be better off with compressed air.
> >
> >
> >
> >
> >