From: James Saccardo <James.Saccardo**At_Symbol_Here**CSI.CUNY.EDU>
Subject: Re: [DCHAS-L] Liquid nitrogen storage
Date: Fri, 19 Jan 2018 21:40:31 +0000
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Message-ID: 433b0c11c7d641e8be4f2a180e84e28b**At_Symbol_Here**CSI-EX01.FLAS.CSI.CUNY.EDU
In-Reply-To <3696a28c7a9a4b8ca87d089ba460ac53**At_Symbol_Here**WinEx15Mbx05.SHSU.EDU>

Hi Paul,

It depends on the volume in use/stored. Once you are over 55 gallons (~200L) it spurs the requirement to have atmospheric monitoring in my jurisdiction.


One dewar is about 200L and is constantly evaporating, one large dewer per/ lab unit is okay without the need to have oxygen sensors. Be sure there is a secondary egress and that aisles are not locked by the dewar.

If you store a second, as a backup, we risk exceeding this limit per control area. We use Administrative controls (policy and signs) so that two dewers are never in a single lab unit at the same time, therefore, never more that 200L per control area.


We did put a hard wired O2 detection system in our main gas cylinder storage area where we can have more than 1 dewer of LN2 at a given time interval.

Most Fire departments refer to NFPA 55 – there is also guidance from the Compressed Gas Association  (CGA p-18).


More than 200L – I say yes. If you have a pressurized cryogen system, yes again. Do what is right and then ask “am I meeting the minimum requirements of the law”.


Be Well,



From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU] On Behalf Of Battles, Paul
Sent: Friday, January 19, 2018 3:36 PM
Subject: [DCHAS-L] Liquid nitrogen storage


Hello All,


We are in the process of building a new biology building and one of the labs will regularly contain a liquid nitrogen tank. Are oxygen depletion sensors required? The only thing I have come across said “recommended if room doesn’t have adequate ventilation.”



Paul Battles


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