altitude, humidity and cooling (was Re: VAX wanted in Bristol, UK)

From: Ethan Dicks <>
Date: Tue Dec 10 15:36:13 2002

--- Carlos Murillo <> wrote:
> At 01:30 PM 12/9/02 -0800, I wrote:
> > At Pole... drives die all the time... massively dry air holds a lot
> > less heat... computers and hard disks frequently die from overheating
> > at the South Pole - the air is thinner and drier
> > and can't conduct as much heat away from CPUs and drives.
> Quite frankly, to have a system die of heat exhaustion _there_ seems
> ludicrous. As long as the assembly can withstand a steep temperature
> gradient, there's lots of cooling available, with temperature low
> enough to compensate for the decrease in specific heat many times,
> right?

Right, except that these systems are indoors in an office environment
and there isn't an adequate temperature gradient. Indoors, the temps
range from 68F to 75F, depending on the nature of the building and
its physical location (which affects winds and external cooling, thus
affecting humans who affect internal heating ;-)

The AC for the network operations center (NOC) at McMurdo is a glycol
loop, a glycol pump and two radiators, one in an airhandler, one outside
in a shelter. The outside temp fluctuates between a high of 40F for a
few days in the summer, to a typical -20F to -30F temp in the winter
and on spring/fall nights. On those occasions when the heat exchanger
fails (typically due to the fan breaker tripping), they do open windows
and cool with outside air. The room, though, is nominally kept between
60F and 65F. Not much of a gradient to the inside of a PC or server case.

(and this is somewhat on-topic because the room I'm describing was built
in the 1970s and houses (housed?) a pair of MicroVAXen and some older
Sun SPARC hardware).

Pole is worse than McMurdo - at least Mactown is on the coast and at
"sea level" (minus the effects the rotation of the Earth has on the
troposphere which is, ISTR, about 3-5% lower pressure there). I've
seen guys put multiple fans in computer cases used for data collection
to keep the operating temps down to a sane level, and these are old
enough machines that the CPUs don't come from the factory with fans on
them (486-SX/25, etc.)

You'd think things would be cool enough at the South Pole, but there's
some non-intuitive forces at work.


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Received on Tue Dec 10 2002 - 15:36:13 GMT

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