Someone should do a calculation to determine the potential for oxygen deprivation in a room where the LN2 is being discharged. A little liquid can translate to a large volume of gas and it is hard to guess just how much LN2 would be released into the room during fire quenching.
Thanks for the feedback and that’s already in her root cause analysis and corrective action.
It’s the routine use of LN2 as a “fire extinguisher” that has me concerned.
Clearly the best idea is to avoid having a fire in the first place! Do not discard any wipes contaminated with sodium into trash or sink, before quenching into isopropanol. Leave those wipes into IPA at least one hr. before disposal. This is the standard practice in any pyrophoric metal manipulations in laboratory. Lithium, sodium, and even potassium won't just catch fire unexpectedly (although Na/K alloy will do so). If they do take fire, sand is indeed the best option if Met-L-X is not available.
Tilak Chandra, Ph.D.
Chemical Safety Specialist
EH&S; Chemical Safety
30 East Campus Mall
Madison, WI 53715
I’m reviewing an incident report from one of my inorganic synthesis researchers. A little sodium, wiped off tweezers onto a kimwipe and not properly disposed, that went badly downhill. No one hurt but it sure got everyone’s heart pounding for a bit.
In the corrective action, the lab worker states they keep LN2 nearby as an extinguishing agent for small air/reactive metals fires (think size of a beaker). That just sounds all bad. In my guidance document, I state that dry sand, Met-L-X, lime, or soda ash are suitable extinguishing agents for small fires. We have our own fire department and don’t provide Class D fire extinguishers (for a long list of very good reasons).
I’m getting some push back – that using LN2 is commonplace in this lab and the default fire extinguishing agent.
Debbie M. Decker, CCHO
Campus Chemical Safety Officer (soon to be Chemistry Department Safety Manager)
Environmental Health and Safety
University of California, Davis
1 Shields Ave.
Davis, CA 95616
-- Darlene K. Slattery, Ph.D. Senior Research Chemist Florida Solar Energy Center 1679 Clearlake Rd Cocoa, FL 32922 Phone: 321-638-1449
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