Sunday, October 15, 2006

Flying Circus of Physics

Word has spread through hospitals about the danger of using Purell, the hand sanitizer. Is it really true that if a spark jumps from you while you have Purell on your hands, that the Purell can burn? FCP_fan


Blogger Jearl said...

A student of mine told me that his wife, a hospital worker, had been warned of this danger. However, I cannot find a single authenticated example where a common spark has ignited the alcohol vapors coming off Purell. As I explain in the book, sparking can happen in dry weather (usually in midwinter) when the touching of clothing and skin causes electrons to move from one to the other where (because of the lack of humidity) they collect. If you become charged like this and then reach for a metal object or a faucet, a spark can jump between the object and you to neutralize your body. Because alcohol vapor can burn, presumably a spark could ignite the vapor if it is coming off your hands.
I have repeatedly tried to set my fingers on fire by pulling off a sweater on dry days, coating my fingers in Purell, and then bringing my fingers close to a nearby large metal object. (Ok, I admit that I need therapy here, but I don’t think there is a 10 step program for this particular affliction.)
Sometime I even rub the sweater through my hair, to the great concern of anyone passing my office. Never has a fire spring up on my fingers. I think the energy in a common spark is just too small to ignite the vapor, even if the electric potential I build up on my body is large.

8:22 PM  

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