Hi Ruth,
For natural gas, the sensor is built right into the human olfactory gland. There are mercaptans in the gas that will aid any human in detecting a leak at the ppm level. Action must be taken immediately, humans can quickly become acclimated.
For LN2 it depends on the volume, a few liters should no be a big deal, now if you have 100L or more, and a leak can displace all breathable oxygen, then you might want to consider having a hardwired continuous oxygen monitor installed.
Check with you local fire official, they may provide guidance for cryogens and what volume you would need O2 sensors.
Implementing a good standard operating procedure may be your best practice.
Best,
James
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
On Behalf Of Murphy, Dr. Ruth Ann
Sent: Wednesday, August 5, 2026 5:19 PM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: [DCHAS-L] Gas Sensor
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Good Afternoon,
Are gas sensors required in chemistry labs with natural gas utilities and/or liquid nitrogen use? If so, what type of sensor is needed? Thank you!
Best,
Ruth Ann Cook Murphy, PhD
Professor of Chemistry
University of Mary Hardin-Baylor
900 College Street
Belton, TX 76513
(254) 295-4542
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