From: Nora Dunkel <noradunkel51**At_Symbol_Here**WEBSTER.EDU>
Subject: Re: [DCHAS-L] Compressed gases and sparking electronics
Date: Thu, 27 Jun 2019 15:29:30 +0000
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Message-ID: BN6PR11MB15055CEF9FE3376C87890B8ECBFD0**At_Symbol_Here**
In-Reply-To <1B9735A1-A589-4423-9388-71DC45630601**At_Symbol_Here**>

Agreed—the room does need an oxygen sensor, and that's something I'm working on in parallel to the AV rack question.  Thank you for the insight about Division II environments and the gases to which they actually apply.  We don't store any flammable gases in the room—they're trucked to the point of use and only ordered when the in-use tank is nearly spent precisely because we only have a single cylinder room and use so many more oxidizers/inert gases than flammables.   (At least in our current environment—who knows what would ensue if we hired a hard-core synthetic or analytical chemist.)





From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU] On Behalf Of Daniel Kuespert
Sent: Thursday, June 27, 2019 3:33 AM
Subject: Re: [DCHAS-L] Compressed gases and sparking electronics


CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.


Actually, if the cylinders in question are oxidizers and inert gases, it would be a good idea to put an oxygen deprivation sensor in the room, annunciating outside the door (and with adequate signage so that everybody knows what it means). Many such sensors require periodic calibration, so choose one you can commit to maintaining. If the room is unventilated, then the International Fire Code requires a detector and alarm.


I doubt the room would be considered Classified (Electrical). As I recall, there's a NFPA standard (#497) relating to how to classify environments. In NFPA 70 (the National Electric Code), Division I is for those areas that have a flammable atmosphere during normal operation (like the area around outlet of a safety relief valve), while Division II has that flammable atmosphere only "under abnormal conditions." 


The thing I've seen many code inspectors try to do is interpret Division II criteria to be something like a guillotine failure of the largest line present (or here, dumping all the cylinders at once). That's taking things too far: Division II electrical classification is intended to be *abnormal* operation, not *catastrophic*. So the area a few inches around a pipe flange or valve stem, which is a potential leak point, receives a Division II classification. In this case, you might declare the area a foot or so around each cylinder valve assembly as a Class I Division II (and Group whatever is appropriate) zone and insist on things like purged enclosures. You'd only need to do that for flammables, not oxidizers or inert gases.


Hopefully, there aren't any flammables in the cylinder room if you've got oxygen and nitrous oxide cylinders present. Unless there's a proper fire separation built into the room, that *does* violate code. One of the buildings at my workplace has 2 cylinder rooms, one for oxidizers and one for flammables. I'm forever after the people in the building (and the gas vendors) for mixing them up.





Daniel Reid Kuespert, PhD, CSP


On Jun 26, 2019, at 07:23, Richard Palluzi <000006c59248530b-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU> wrote:


The problem with blast radius or explosive equivalent is what is the basis for the incident. I am sure it will be a very big number if you start from assuming ALL the cylinders fail simultaneously which is a difficult situation to be credible. How about one cylinder failing? Even that is exceptionally rare. A more likely scenario is a leak which - assuming the area is properly ventilated per code requirements - is probably going to result in nothing to a fire. And yes, even a small fire could set off another cylinder which could then add to the conflagration.


A closed gas room is actually one of the code recommended ways to store gas cylinders particularly toxic or highly toxic materials.  While the cylinders and piping should be grounded, the chance of an ESD setting off the cylinders is incredibly low so I know of no such installation that would require ESD shoes.


Recognizing that the AV is in the room might suggest several mitigative measures that are prudent, credible, and reasonable (albeit not free)).


  1. Review the system that allowed the AV to be put in the room and modify it so that it does not happen in the future.
  2. Rearrange the cylinders in the room to put them as far as possible from the AV (at least the flammable ones).
  3. Rearrange the ventilation in the room so the supply (fresh) air sweeps over the AV then on to the cylinders to be exhausted.
  4. Enclose the AV in a sealed box. If you wanted to go even further, purge it per NFPA 496.
  5. Add a combustible gas detector to the room.


In effect, do an adequate hazard analysis and risk assessment.


Richard Palluzi 



Pilot plant and laboratory consulting, safety, design,reviews, and training


Richard P Palluzi LLC

72 Summit Drive

Basking Ridge, NJ 07920



From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Yaritza Brinker
Sent: Tuesday, June 25, 2019 1:48 PM
Subject: Re: [DCHAS-L] Compressed gases and sparking electronics



Have you tried to have your professors calculate the explosive power stored in that room and translate it to something relatable to your management, like blast radius.


A few questions… largely out of my ignorance…


Is it prudent to store all of those cylinders in a closed room? 


If you have cylinders in a closed room, wouldn't it be prudent to have gas monitoring in place to alert you if a tank leaks? 


Wouldn't you be required to have ESD shoes to enter such room? 


If the AV rack is hardwired to the wall, is it properly grounded? 


Thank you,


Yaritza Brinker



From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Nora Dunkel
Sent: Tuesday, June 25, 2019 12:08 PM
Subject: [DCHAS-L] Compressed gases and sparking electronics


** External Email **

Hello all,


Curious to get this group's input… I recently discovered a large A/V rack in the gas cylinder room of my university's science building.  The A/V rack is hardwired into the wall, and is NOT spark-proof/hospital grade.  It could make sparks at any time.  In the same room, we have full cylinders of compressed oxygen, nitrous oxide, and air. The room itself likely has flammable construction.  We probably have about 50 employees in the building, plus hundreds of students during the academic terms.


All the science faculty are (rightly) having a conniption fit and demanding that the A/V rack be moved to another room.  However, the city fire chief inspected and said that "cylinders were properly stored and there was no open flame in the room", so no move was necessary, as no code was violated.  So now the administration is dragging its feet, saying that the rack doesn't need to be moved (and IT suggested that we should just plug it back in).


Are there resources out there to convince the higher level of Administration that this situation is inherently hazardous and worth the resources to correct?  Besides pedantically explaining the fire triangle/tetrahedron to them and bringing up the Apollo 1 fire?  Or are the entire biology, chemistry, physics and nursing faculty (and I) all over-reacting?


Thanks for your help,


Nora Dunkel

Chemical Safety Officer

Webster University

314-246-2244 (office)



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