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At 07:42 AM 9/21/2007, Peter St. John wrote:<br>
<blockquote type=cite class=cite cite="">Thanks all; a couple of people
sent me this same article:<br>
<a href="http://www.tomshardware.com/2006/01/09/strip_out_the_fans/">
http://www.tomshardware.com/2006/01/09/strip_out_the_fans/ </a><br>
<a href="http://www.tomshardware.com/2006/02/02/strip_out_the_fans/" eudora="autourl">
http://www.tomshardware.com/2006/02/02/strip_out_the_fans/</a>
<a href="http://www.tomshardware.com/2006/02/02/strip_out_the_fans/" eudora="autourl">
</a><br>
<br>
They tried immersion in "ion-free" water (which I would not
have considered; I thought that since the water molecule is electrically
asymmetrical, it would always conduct a little...? but I'm not a
physicist, I just claim to be RGB at book signings) which worked for
seconds at a time before crashing, apparently no harm to the h/w though;
then vegetable oil (which they felt looked cool with a transparent
plexiglass case) which worked better, but still too much conductivity for
the scale of pins on the CPU. So they sealed the CPU, and then all seemed
fine. They suggest motor oil would be better. Kyle says the latter link
is followup, I haven't read that yet. <br>
Peter</blockquote><br><br>
DI water works for HV equipment.. it's used for cooling high power vacuum
tubes, for instance, but there is always some leakage current.
<br><br>
oil is used to cool all sorts of things (think power distribution
transformers). Vegetable oil spoils: very bad. motor oil has
all sorts of additives. No.. what you want is electrical insulating
oil, such as Shell Diala AX.. low viscosity, clean, designed for the
purpose. <br><br>
The disadvantage of oil? It's a mess if you have to remove the
stuff.<br><br>
What do they use in high dollar gear that really needs this?
Fluorinert, such as FC77. Totally inert, very low viscosity,
doesn't tend to cling to the electronics, etc. available in a variety of
boiling points so you can do "ebullient cooling" (aka 2 phase
cooling)which doesn't need a pump, and is a lot more flow than straight
convective flow. You can also pump and spray it on the board.
It's about a specific gravity of 2. <br><br>
But.. it's about $500-600/gallon, so don't spill it.<br><br>
And, it dissolves enough oxygen that rats can be immersed and breathe it
and survive to wiggle another day.<br><br>
<br>
Compared to Diala AX (about $40 for a 5 gallon pail) Fluorinert is in a
different league.<br><br>
<x-sigsep><p></x-sigsep>
James Lux, P.E.<br>
Spacecraft Radio Frequency Subsystems Group<br>
Flight Communications Systems Section<br>
Jet Propulsion Laboratory, Mail Stop 161-213<br>
4800 Oak Grove Drive<br>
Pasadena CA 91109<br>
tel: (818)354-2075<br>
fax: (818)393-6875</body>
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