[Histonet] minus 80 freezer safe time in power outage

[Maria Mejia]

Hello Tim,

When I worked at UCSF, we had five -80C sub zero freezers stored in a cool room AND on those occasions, 
when a freezer did malfunction, our "safe" temperature was -50C - mostly because ALL our frozen specimens
were brain. 

We had a protocol in place for checking each freezer (weekly) for ice blockage/build-up on the door
& around the front inside, so as not to create problems w/the freezers...later.  However, when a 
freezer malfunction did occur it was mostly because of the compressor unit (some freezers have
2 compressors.) When a compressor (or any other part) on a particular freezer was replaced, this 
information was always recorded.

In any case, we never opened the door, except to quickly place 1 (5-lb) block of dry ice per shelf, to keep the 
low temperature in the freezer constant (overnight) until an outside repair technician could come & make repairs 
the next day.    **We always kept a large supply of dry ice.

During my 7 years at UCSF, there was only 1 time, we had to transfer all tissue racks into another -80C freezer.
We were very lucky, because we had just purchased a new freezer & the freezer was turned ON the night before.

Tim, I hope this helps.  Let me know if you require any further help.

Maria Mejia
Affymetrix, Inc.

On Mar 29, 2013, at 8:16 AM, Morken, Timothy wrote:

> Hi all, For a minus 80 freezer what would you consider a "safe" time period that it can go without power before the temperature gets too high and contents need to be transferred (assuming door stays closed)?  I'm thinking -40 would be a cutoff temp to move samples. Anyone else think differently about that?
> 
> Thanks for any info!
> 
> 
> Tim Morken
> Supervisor, Electron Microscopy/Neuromuscular Special Studies
> Department of Pathology
> UC San Francisco Medical Center
> 505 Parnassus Ave, Box 1656
> Room S570
> San Francisco, CA 94143
> 
> (415) 353-1266 (ph)
> (415) 514-3403 (fax)
> tim.morken <@t> ucsfmedctr.org<mailto:tim.morken <@t> ucsfmedctr.org>
> 
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