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Date:      Tue, 15 Oct 1996 11:01:20 -0700 (PDT)
From:      Dave Babler <dbabler@Rigel.orionsys.com>
To:        freebsd-hardware@freebsd.org
Subject:   Re: sticky drives (was: your mail)
Message-ID:  <Pine.BSI.3.95.961015103846.20012D-100000@Rigel.orionsys.com>
In-Reply-To: <199610150419.NAA18931@genesis.atrad.adelaide.edu.au>

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On Tue, 15 Oct 1996, Michael Smith wrote:

> Dave Babler stands accused of saying:
> > > This is absolutely true, dropping a drive below 0 deg C is a sure fire
> > > way to damage it.  Even the non-operating temp spec on almost all mfg's
> > > disk is +5 C on the lower end.  Having done MIL-SPEC drive work that
> > > had to operate over -55 to +125 C the actual hardest part of this range
> > > was the -5 to +5 C range, condensation being a real killer.
> > 
> > Isn't the chamber where the platters reside hermetically sealed? If so,
> > how would moisture be there to condense in the first place? 
> 
> Firstly; no, the chamber is often not sealed.  If you pull a drive
> apart you will often notice that there's a breather port with a bit of
> filter material stuck over it.  Many drives will have some silica gel
> in them as well to help keep the humidity down.

I've seen that, but the one I examined looked more like a pressure relief
port. 

> Secondly, the drives are usually assembled in rooms with some nominal 
> amount of air humidity, so that even if the unit were sealed, there would
> still be moisture inside.
> 

Ah, should've figured that... I was harboring the illusion that they were
purged with dried argon or something <G>. Thanks for the info, guys!

-Dave




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