DDC Fixed Head Disks

Mike Ford mikeford at socal.rr.com
Mon Jun 11 13:18:29 CDT 2007

James A. Markevitch wrote:
>> I do recall some computer equipment that had helium in the enclosure. At least
>> that's what the labels said.
> I have a DDC 7301 drive (same manufacturer as Guy's, but different model),
> and it is definitely filled with helium.  Well, it was filled with helium
> 30 years ago ...
> The DDC maintenance manual says it requires oil-free 99.995% pure helium.
> The preventive maintenance procedure indicates that the helium tank is
> good for about 6 months (dropping from 2200psi to 300psi).
> James Markevitch

Just a thought, but while He does leak out of just about everything, 
unless something is leaking in I suspect its still He around 1 atm.

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