Seems like the conditions of the demonstration are critical here.  Indoors or outside?   If inside, what is the ACH turnover rate (particularly if in a lab space with hoods going full blast)?   CO2 has an IDLH of 40,000 ppm (4% by volume); perhaps easy to get to this in some circumstance, but harder in others.  A "leak" of CO2 won=E2=80™t generate as much as dropping 5 pounds of dry ice in a large bucket of water.

I have done SCBA training (as a firefighter) where we used theatrical fog.  It works OK; the bottle of liquid says "non-toxic" which made laugh a bit since the dose makes the poison, but if using this to simulate a leak, rather than engulfing a whole room, it has the virtue of being visible and "relatively" "non-toxic."

Is the goal to "see how a leak behaves" so that the ERT can practice visualizing an invisible (but audible?) leak and the confine the leak, evacuate the area and call HazMat, or to have them stop the leak?  The latter is clearly more complicated and risky.  Seems like a local ERT should (only) attempt to confine and evacuate.  (I'm assuming that the team will not be trained in SCBA use, but even if they are an unknown substance leak or known toxic gas leak is really something for the HazMat team under almost all circumstances.)

Dave

David C. Finster
Professor, Department of Chemistry  (and FF/hazmat technician)
University Chemical Hygiene Officer
Wittenberg University
937-327-6441
http://userpages.wittenberg.edu/dfinster/index.html

From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Alan Hall
Sent: Friday, December 18, 2015 2:00 PM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L] Gas Leak Training Input