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05 March 2008 @ 03:27 am
Web meander: Impossible lamps to the incenidary from hell  
(One in an occasional series.) This is less typical of my usual meander style (not that anyone would notice, since I've posted only one other), but I just had to record this.

violetcheetah pointed me to a "Dan's Data" post about an award-winning master's-thesis-proposed energy-efficient lamp that does not -- and cannot -- actually exist. Daniel Rutter runs the numbers and concludes:
So instead of the output of a 40-watt incandescent bulb for four hours, we’ve got the output of a 6.8-watt incandescent bulb for 45 minutes. And that’s with a perfect lamp and no other losses in the system. With the best white-light lamp that humans will actually ever be able to make and million-dollar hardware for the rest of the thing giving the lowest possible losses, I think you’d actually be talking the output of a two-watt incandescent flashlight bulb for about 30 minutes. At best. [...] Yes, Mr Moulton, it certainly bloody would be a “conceptual challenge” to make a lamp that produces more than thirty times as much light as the laws of physics say is possible from the energy you put into it. That would be a pretty damn impressive achievement.
I poked around that journal site for a while and added the RSS feed to my LJ friends page, which is the only reason I saw his recent mention of chlorine trifluoride. That post includes links to a fun organic chemistry journal (by a chemist-not-pitcher named Derek Lowe) with a subcategory of "Things I Won't Work With". I'll be exploring that later.

But for now, excerpts from Lowe's entertaining post** about chlorine trifluoride:
I have not encountered this fine substance myself, but reading up on its properties immediately gives it a spot on my "no way, no how" list. Let's put it this way: during World War II, the Germans were very interested in using it in self-igniting flamethrowers, but found it too nasty to work with. [...] There’s a report from the early 1950s (in this PDF) of a one-ton spill of the stuff. It burned its way through a foot of concrete floor and chewed up another meter of sand and gravel beneath, completing a day that I'm sure no one involved ever forgot. That process, I should add, would necessarily have been accompanied by copious amounts of horribly toxic and corrosive by-products: it’s bad enough when your reagent ignites wet sand, but the clouds of hot hydrofluoric acid are your special door prize if you’re foolhardy enough to hang around and watch the fireworks.
(** Don't miss the comments section, especially the tale by Feiser N. Feiser.)

Both journals quote a passage about this exciting compound from John Clark's Ignition!, but the latter post has the more extensive quote, which I've copied here (emphasis mine):
It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water -- with which it reacts explosively. It can be kept in some of the ordinary structural metals -- steel, copper, aluminium, etc. -- because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminium keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.”
Times like this make me remember how much I liked physics and chemistry in high school, before they got hard and I got lazy ... and how fond I remain of them regardless of my lack of any actual retained knowledge of the subjects. They also make me glad the biggest safety risk I face in my job is paper cuts.
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E.T. Davidoffvettecat on March 6th, 2008 04:57 am (UTC)
Yeah, um, let's not try that...