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Re: What is the limit? (was RE: multi-homing fixes)

  • From: Larry Sheldon
  • Date: Thu Aug 30 20:34:42 2001

I have been trying to avoid saying this, but this is just nonsense with
a little srinkle of "doesn't matter" here and there.

> Actually, talking about water/electricity interaction in refrigerators,
> lab equipment, etc, misses the very simple point - a probability of a leak
> is proportional (as a good approximation :) to the number of moveable
> components (PCBs, connectors, etc) in the system.  In a typical CO it's
> tens or hundreds of thousands.

I don't remember seeing anybody talking about lab equipment and refrigerators

We (some of us) were talking about liquid-cooled electronics, some of them
were talking about actual experience--mine with water-cooled CPU's.

> PS.	Water is not a good coolant, and even distilled and deionized
>         water tends to pick ions from metal parts rather quickly.  Spirits
>         are flammable;  CFCs are bad for environment.  There's also an
>         issue of toxicity.

Water is one of the better coolants--particularly when cost is considered.
The rest of that is one of the sprinkles I mentioned--water can in fact be
toxic, see

In the real, actual world, the coolant is in its own circulation system
(like houses, engines, and such), so cruft in the water is no more than
a maintenance issue every some large number of hours.

> 	Of course, everything is doable, but what is the cost?
>         Off-the-shelf components are all designed for air cooling.
> 	Switching to liquid cooling means a lot of custom stuff; which is
> 	expensive and which takes a long time to design and manufacture.

As I recall the electronic components in a water cooled 1100/90 CPU
were as "off-the-shelf" as anything else in the machine, including most
of the water system.  No more "custom stuff" any "branded" equipment,
I'd say.

> PPS	It is not voltage which matters, it's current :)  Even if leaks do
>         not cause shorts the moisture accumulation may corrode parts
>         leading to mechanical shorts, it also may cause excessive 
>         cross-talk. Sporadically malfunctioning equipment is much worse
>         than flat-out burned out.

Not sure what this all means.  Yes, we did have failures due to water leaks.
Idjits on the floor above us neglected to put the plun in the bottom of
their water tanks and pour a lot of water on us!

> PPS 	Finally, getting your hands wet makes your changes to get killed
>         by electricity _much_ higher. 48V won't do you any harm if your
>         hands are dry, it may kill if they're wet.

Als true--but then we were always careful to dry our hands before leaving the
restroom.  And checking the folks upstairs if we saw water bottles on the dock.