From: Dan Kuespert <dkuespert**At_Symbol_Here**JHU.EDU>
Subject: Re: [DCHAS-L] Liquid methane experiment in class
Date: Mon, 13 Apr 2015 13:17:11 +0000
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: BD071AD9-40EF-48FC-9CD7-99E4D16414DB**At_Symbol_Here**jhu.edu
In-Reply-To <7154293993919673.WA.ras2047med.cornell.edu**At_Symbol_Here**listserv.med.cornell.edu>


Just as an aside, looking at the video, I have no trouble believing this is methane condensed with liquid nitrogen rather than methanol. Given the relative boiling points, methane is easily liquefiable using LN with very little equipment—a cold finger, a gas tap, some tubing, and a Dewar flask of LN is all that would be needed.


If you look carefully at the video, the flames skitter across the floor in a manner similar to water droplets dripped into a hot frying pan. This is Leidenfrost effect, something you would expect from liquid methane but not from methanol—you have to have a significant temperature difference between the (hot) surface and the (cold) liquid in order to see it. Methanol would simply spread in a puddle. (Just a bit of pedanticism from the thermodynamicist still in me.)

When you think about it, I'm not sure which would be worse, methanol or methane. The methane will spread out more, but the methanol would be more likely to wet the students' shoes, pants, etc. and propagate the fire more readily to an actual person. Either way it's idiotic and reckless. There are some things that are so stupid that the perpetrator should be fired immediately, and this is one of them. He had to have an idea of what would happen when he planned the demo—it's not a "I had no idea the fire would spread out like that!" situation.

regards,
dan

=============================
Dr. Daniel R. Kuespert
Homewood Laboratory Safety Advocate
Krieger School of Arts & Sciences/Whiting School of Engineering
The Johns Hopkins University
103G Shaffer Hall
3400 North Charles St.
Baltimore, MD 21218
(410) 516-5525

On Apr 13, 2015, at 9:01 AM, Ralph Stuart <ras2047**At_Symbol_Here**MED.CORNELL.EDU> wrote:

A good idea to present the history behind this issue.  Very well written.
I am sure that this will be appreciated by chemistry teachers.

Someone on the list pointed out there is a very interesting document that describes the history of industrial incidents with liquid methane (i.e. liquified natural gas or LNG) at
http://www.ch-iv.com/pdfs/Safety%20History%20of%20International%20LNG%20Operations.pdf

It's an interesting example of a Lessons Learned document for a specific product and could be the inspiration for a similar tool with regard to hydrogen as a fuel found at
http://h2tools.org/lessons

- Ralph

Ralph Stuart
secretary**At_Symbol_Here**dchas.org
Secretary
Division of Chemical Health and Safety
American Chemical Society

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