Re: Salt Water Resistance

To: tesla-at-pupman-dot-com
Subject: Re: Salt Water Resistance
From: Terry Fritz <terryf-at-verinet-dot-com>
Date: Thu, 17 Sep 1998 22:10:49 -0600
Approved: terryf-at-verinet-dot-com
Tesla List wrote:
> 
> Original Poster: "Harri Suomalainen" <haba-at-cc.hut.fi>
> 
> >Conclusions?  (1) Salt water is a pretty lousy conductor.  (2) At least
> at
> >1.5vdc, salt water resistance seems largely to be a function of contact
> >area.  (3) I've got to find something better than plain salt water--NaCl
> >plus epsom salts perhaps?  Copper Sulphate?
> 
> Resistance does indeed depend on conductor area (roughle linearly).
> It is also inversily proportional to distance of conductors (at least
> approximately when two parallel plates are used).
> 
> Smaller ions with better mobility would usually be better. I'd assume
> copepr sulphate to be much worse conductor than NaCl is. You might
> try something like HCl (yap, corrosion problems ahead!) or some salt
> which is much more soluable in water than NaCl is.
> 
> As a thumb rule: the smaller the ion, the faster it'll move.
> 
> --
> Harri Suomalainen     mailto:haba-at-cc.hut.fi
> 
> We have phone numbers, why'd we need IP-numbers? - a person in a bus

Terry, Chip, Harri, ALL

I used a liquid rheostat as a Rballast on my 5.0kVA magnifier system.
Be careful of electrolytes, salt water electrolyte (NaCl) will
liberate chlorine gas (Cl2) when AC passes through it...

I used baking soda (sodium bicarbonate).  My ballast consisted of
three 8" x 14" x 1/8" SStl plates mounted side by side in a frame
made of salt treated 2"x6".  Middle plate was moveable by a 3/8"
fiberglass lead screw running through HDPE positioning block,
rotated by a 12VDC windshield wiper motor.  The frame was positioned
inside a "Rubbermaid special" standard 5-7gallon rectangular PE or PVC
trashcan.  Watch water heating rate, I could liberate steam with
mine.  About 3-4 tablespoons of baking soda would pass 30-40A
with approx. 30V drop with full immersion (engagement).  Worked
fine, was very cheap to build (<$20).  For higher powers, would use
a fiberglas container and vent pipe outside of building.  Be sure to
vent liquid rheostats, having a homebew steam "bomb" blow your new
magnifier is not a good testing protocol...   :^)

Regards

DAVE SHARPE, TCBOR