From: Peter Zavon <pzavon**At_Symbol_Here**>
Subject: Re: [DCHAS-L] O2 Sensor Determination
Date: Wed, 18 Jul 2018 10:07:13 -0400
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Message-ID: 001901d41ea0$a3763260$ea629720$**At_Symbol_Here**

The case of “total catastrophe” is the worst case scenario and is not the one to use in determining when a room needs an O2 sensor.  You need to consider the case of a less than catastrophic leak that overwhelms existing or some (arbitrary) reduced ventilation.  If your liquid gases could include CO2, you also need to consider CO2 concentrations separately since CO2 concentration is what drives human respiration and excessive levels of CO2 can be reached long before a reduction in O2 levels is detected.


My personal experience, admittedly in industry rather than academia, has been that the “hard and fast rule” for Facilities for this sort of question should be “contact EH&S to review requirements for each installation.” Don’t forget to include a requirement for routine, documented, sensor checking and calibration.



Peter Zavon, CIH
Penfield, NY




From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU] On Behalf Of Jeffrey R. Cogswell
Sent: Tuesday, July 17, 2018 2:54 PM
Subject: [DCHAS-L] O2 Sensor Determination


Does anyone have a good reference for determining when a room needs an O2 sensor? I’m looking for an amount of liquid gas (nitrogen, argon, helium) vs cubic feet calculation. (We’re assuming total catastrophe here: no ventilation and all the cryo-liquid escapes). Dartmouth is looking at doing an overhaul of all the O2 sensors on campus. Facilities will oversee maintain/scheduling of these sensors and require a “hard and fast” rule from EHS to justify their installation.


Jeffrey R. Cogswell, Ph.D.

Chemical Inventory and Laboratory Resource Center Technician, EHS

37 Dewey Field Road, HB 6216

Hanover, New Hampshire 03755

P: 603.359.0128  F: 603.646.2622


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