From: 8524828hau**At_Symbol_Here**COMCAST.NET
Subject: Re: [DCHAS-L] Oxygen Sensor
Date: August 30, 2012 11:39:18 PM EDT
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <009201cd8654$c95ccf10$5c166d30$**At_Symbol_Here**>

Furthermore, DO NOT enter a room for which the IDLH alarm is illuminated and/or the audible alarm is annoying.
Request that an industrial hygienist (if your institution has one) bring a portable monitor and use it to "sniff" the atmosphere in the room through a barely opened door.
If your institution does not have an industrial hygiene organization, purchase a portable monitor yourself (and periodically calibrate it so that it is dependable).  Your life depends on it.

I agree that an "alarm silencer" is an invitation to disaster.  Instead (as suggested by others) establish a regular schedule for calibration, and replace the sensors periodically (based on calibration experience and manufacturer's recommendations) so that you can trust that the monitor will not create a spate of false alarms.  False alarms encourage complacency.

David Haugen

From: "Peter Zavon" <pzavon**At_Symbol_Here**ROCHESTER.RR.COM>
Sent: Wednesday, August 29, 2012 9:11:37 PM
Subject: Re: [DCHAS-L] Oxygen Sensor

An oxygen sensor in this situation is an IDLH (Immediately Hazardous to Life or Health) warning system. DO NOT install an alarm silence switch. That is an invitation to a fatality. 


If your system goes flakey near the end of life, replace the sensors well before end of life, or do whatever else it takes to avoid a flakey system. Better yet, replace it with a system that does not have that drawback.



Peter Zavon, CIH
Penfield, NY




From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Eric Clark
Sent: Wednesday, August 29, 2012 11:02 AM
Subject: Re: [DCHAS-L] Oxygen Sensor



If there's a problem with the liquid nitrogen delivery system, then nitrogen will leak into the room and the oxygen will be displaced; and people need oxygen. 


Calibrate the oxygen sensor with calibration gasses (like an oxygen/nitrogen mixture).  We use two calibrators, 17% oxygen and 20.9% oxygen.  And the unit calibrates just like a pH meter. 

Here are a couple of tips to be aware of.  Apparently nitrogen asphyxiation does not cause a physiological panic/struggle like carbon dioxide asphyxiation does.  So if the sensor alarms, verify that it's a positive or negative alarm with a calibrator gas so you know if you really have a problem.  The sensors we use for those units last about a year and tend to go flakey toward the end of their service lives.  So you might want to install a switch to silence a false alarm; if you can't silence a false alarm, then you'll definitely need to consider hearing PPE. 



Eric Clark

Safety & Compliance Officer

Los Angeles County Public Health Lab

>>> On 8/29/2012 at  7:01 AM, in message <205AAA7AEFEF49ADB5CC346CB5D4985F**At_Symbol_Here**owu.prv>, <bjwiehe**At_Symbol_Here**OWU.EDU> wrote:

We are installing an Oxygen Sensor in a room using Liquid Nitrogen.  Question, why do you mount it in the room where loss of Oxygen would be present?  What type of training should the technician have overseeing the monitor?(ie respirator fit)



Barb Wiehe


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