Ellen,

After the incident at the Georgia Sperm Bank, our PD asked us to assess any spaces where a possible deficiency may occur.   We basically made some assumptions involving complete dead air (we have had a number of campus-wide power outages), calculated the volume of the laboratory (or other space), and then the size of the Dewar.  If the calculations showed that a 120 or 160L Dewar could displace enough oxygen to result in a low oxygen atmosphere, we installed local monitoring.   This included the NMR facility, a few labs using Dewars to act as a nitrogen gas source (we do not have house nitrogen), various storage rooms, and, last but not least - the room that houses SMU Athletics' cryotherapy unit.

Frankly, as alluded to, much of this is overkill.  We have had storage rooms drop down to about 19.4% when Dewars are venting as part of their pressure relief systems.  We recently had an NMR quench (that is a whole other story and involves a compressed air cylinder transported too close to the magnet).   Even then, during quenching, the oxygen in the NMR room never dropped below about 20%.  

Hi everyone,

�Just doing some benchmarking. My question is what does your institution's assessment look like in order to determine when oxygen deficiency monitoring is needed for a proposal to use a cryogen liquid in a lab?

I look forward to hearing responses.

Thanks, Ellen

Ellen Sweet

Laboratory Ventilation Specialist

Department of Environmental Health and Safety, Cornell University

American Chemical Society, Division of Chemical Health and Safety

315-730-8896

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