This has been fourth in a series of methanol related accidents. The fifth was recently involving cubscouts trying to get a green flame with boric acid and Heet, a methanol product. It occurs to me that what these and the rainbow and green flame tornado all have in common is pouring methanol from a large container onto an ongoing flame. Methanol is the flaming solvent of choice to bring out the color of the excited states of boron and other metal salt compounds. I realize that the salts on wood splints and igniting those is vastly safer. What is unfortunate about methanol in this case is that the vapor pressure concentration of methanol is squarely between its flammable limits. This way, the flame at the mouth of the bottle being poured out can advance into the headspace, where it flares up, heats up and propels the rest of the liquid out. There are other solvents that have this property (and I used the table in the Handbook of Chemistry and Physics, 76th ed, 15-14 to list them; then cleverly lost the paper) and it's worth noting. Never a great idea to pour flammable liquid on an ongoing fire, but people do this with charcoal lighter all the time (Oh, not me!). That fuel *usually* has a far lower vapor pressure than LFL (feelin' lucky today?). Ether won't flash back into the bottle as it is too rich to burn there. Bad idea for other reasons, see uTube demonstrations using gasoline to get the idea.
The "license to teach" thing is irrelevant to this; its only about psychology - understanding kids and understanding how to not let them drive you nuts. In this case it's the job of the principal and the other science teacher to ask the interviewee about their demo experience and ideas on safe practices. Science demos ideally are discussed around a table with a few other science "brains" to hopefully catch something that another missed seeing.[It was mentioned in the Texas A&M hydrazine zinc perchlorate explosion review that a few layers of reviewers, like slices of swiss cheese and a laser light, if some layers pass it , others should catch it.]
OK, off the soap-box, going home now, thanks for reading.
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU]On Behalf Of Leslie Coop
Sent: Friday, October 24, 2014 1:34 PM
Subject: Re: [DCHAS-L] Colorado methanol fire case
Perhaps someone should ask the school he went to why he wasn't taught chemical safety procedures.
On Fri, Oct 24, 2014 at 10:12 AM, Ralph Stuart <rstuartcih**At_Symbol_Here**me.com> wrote:
I was struck the story in this morning's headlines that the Former Colorado Teacher was charged with four counts of third-degree assault, a Class 1 misdemeanor in the methanol demonstration lab explosion that occurred last month.
This seems much more likely to set a precedent than the UCLA fire, which was based on labor law specific to California. I hope that people who are in Colorado will let us know how this case proceeds, as it's not uncommon for these stories to fall off the press's radar.
Leslie Coop, MS, CCHO, CHMM
Chemical Hygiene Officer/ Stockroom Manager
Willamette University - 900 State Str - Salem, Oregon 97301
lcoop**At_Symbol_Here**willamette.edu - (501) 590-6026
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