Monday, September 8, 2014

"Routine experiment" or accident waiting to happen?

The world seems to be supplying material for next summers HAZWOPER course a little early this year.  Or at least forcing it to my attention.

Last Wednesday at the Discovery Museum in Reno, Nevada, 13 people, including 8 children, were injured by a chemical explosion during a "routine" fire tornado simulation (so they have been doing this, roughly this way, for years). All of the children and one (or two - the news reports conflict on this) adults were transported to the hospital with smoke inhalation and chemical and/or acid burns (this is from the news reports - though as far as I can work out basically we are talking about burns caused by exposure to flames - not chemical burns and it shouldn't be acid burns either). All but one child was released the same day. The children suffered 1st and 2nd degree burns.

This picture gives you an idea of how close the children are to the demonstration table.

As you can see, the children were sitting on the floor approximately six to 10 feet away from the demonstration table. The Washington Post reports that the museum runs the experiment as a simulation of a dust devil or tornado, using methyl alcohol and boric acid.

According to the Washington Post article Reno Fire Chief Michael Hernandez said, "the order of the chemicals got switched and caused a two- to four-second chemical flash." Then we have Reno City spokesman Matthew Brown telling the Associated Press "that the demonstration was more of a chemical flash than an explosion, “similar to if someone threw gasoline on a fire.” ??? Novel definition of the terms chemical flash and explosion here. ???

The chemical reaction they are discussing is:

H3BO3 (boric acid) + 3CH3OH (methanol) --> B(OCH3)3 (trimethyl borate) + 3H2O (water)

and commonly used to make "green fire" or "spirit fire." Basically you put some amount of alcohol into a safe container, add a teaspoon or so of boron and then use a lighter to ignite it. The resulting flame is green and very smokey. 

So the idea here is to put this whole thing on a Lazy Susan or spinning table, surround it with a mesh screen (commonly a metal trash can) and then spin it to create a 'fire tornado.'

Here is one a really nice video showing you the experiment and also how to create different colors of flames.

(DISCLAIMER HERE - This is FIRE and ALCOHOL. The typical disclaimer here is - Don't try this at home. If you are one of our HAZWOPER people - you are still on your own and if you burn anything, it is your own fault!)

Anyhow, um, I have no idea what Mr. Hernandez or Mr. Brown are thinking but no - we call already tell that their explanation of what happened is not correct. The order of adding the alcohol and the boric acid has nothing to do with what happened (you can watch demonstration videos of people adding boric acid to alcohol and vice versa). This is not some exothermic reaction run amok. The problem lies elsewhere. 

You find out from the video that the demonstrator has forgotten to add the alcohol (you can clearly hear her say that). So she reaches to the end of the table, grabs and opens a gallon bottle of methanol that is only partly filled, thus full of alcohol vapor, and then pours the alcohol onto what appears to be a hot burner (the video in the news report is out of sequence, but it looks like there was a flame on that burner then the demonstrator put the flame out, and removed that mesh screen you can see in the back).

Here you can see the flammable symbol on the REALLY BIG bottle
of alcohol. Plus the bottle is only about a quarter or so full.

This happens almost immediately when she starts pouring. Looking at the angle
 of her hand, lots of that alcohol got poured out over the table towards the left. 
It is hard to see but it appears that the bottle rockets out of the demonstrators
hand, flying off to the right with flames shooting out of the bottle.

The flames go along the table then start to spread along the floor.

Looking at this still, you can see there are actually two flames there - one is yellow-orange and is from the spilled alcohol, the other is green and would be the remains of the 'flame tornado' demonstration. The green flame disappears pretty quickly as the boric acid was used up ...

And now you can see that the flames are all basically yellow-orange.

So - how many issues can you pick out here ?  This one is a perfect example for the HAZWOPER class - it combines classroom chemistry with emergency response. Everyone who did the 8-hour should be able to pick out several things that need to be re-thought here. What do you think?

Admittedly, I am basing my analysis on obsessive re-watching of the video clips that are available and what has been reported in the news, so I could be wrong about what caused the accident - but I think my version is much more plausible than that of the Fire Chief, which is clearly incorrect (maybe he is thinking of the whole add acid to water not water to acid thing?). 

I wonder if the CSB (Chemical Safety Board) is going to weigh in on this one. There are routinely accidents in classrooms involving methanol and fire so, sadly, this is just the latest variation on a theme.

Oh, geeze there are YouTube videos of kids doing this experiment in their garage! With no safety gear! And other videos suggesting you use charcoal lighter fluid for this.

P.S. all of the images were cut from this NBC news report

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