evil_lurker
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How much mercury is in a sphygmomanometer?
Seems like it might be a pretty decent amount.. at least a hundred grams I would think.
Noticed on ebay that they have used ones pretty cheap (under $30).
Think they would be worth scavaging the mercury out of?
Considering mercury is $60+ a pound not including hazmat fees and the fact that its not exactly easy to purchase, it might be worth investing in one
should the need arise for mercury.
Not all chemicals are bad. Without chemicals such as hydrogen and oxygen, for example, there would be no way to make water, a vital ingredient in
beer.
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chemrox
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$60 a lb for Hg? I'll buy 100# today. I dismantled one to get the Hg. I think there might have been 10g or so. It was a broken device and some of
the Hg was lost. I recovered almost as much as excess from my Bennert manometer. I'd buy one (sphygomanometer) for the Hg if the shipping weren't
too dear.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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evil_lurker
National Hazard
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Most of the peeps on the bay don't seem to realize that they are shipping hazmat materials and as such shipping in the USA on one runs around $15-20.
I've gotten some mercury on order from Cymar, I'm hoping that it will be here within a week or so... but ya know how it is with chemical companies.
[Edited on 24-3-2008 by evil_lurker]
Not all chemicals are bad. Without chemicals such as hydrogen and oxygen, for example, there would be no way to make water, a vital ingredient in
beer.
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bfesser
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I found two medical instruments, which I think were sphygmomanometers, in my girlfriend's attic last summer. Without thinking about it much, I
brought them to the county's household hazardous waste disposal center. I'm still kicking myself for that... They appeared to have at least 20 g or
more in each one. They were fairly large instruments.
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crazyboy
Hazard to Others
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I have never taken an antique sphygmomanometer apart but i've herd they contain about 1/4 pound of Hg (113.3 grams)
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Fleaker
International Hazard
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From what I've seen with them (manometers), they're around 100g of Hg.
Mercury is cheap, it's $29/lb from Flinn Scientific and they pay your hazmat fees. Sixty a pound is too much. I've got a 500g bottle of it you can
from me for 50 bucks  
Buy it by the flask and it's 8-11 bucks/lb.
Alternatively, you can hit up colleges and universities--that's how I got a lot of mercury. I was a couple months late on getting 150 kilos of it from
one local college (and saving them several thousand dollars in ''disposal'' fees).
[Edited on 24-3-2008 by Fleaker]
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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S.C. Wack
bibliomaster
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Average of several old discarded Baumanometers, after extensive cleanup: 107.5 g.
EDIT:
Since the mercury started out extremely dirty, and the result of the cleanup looks good, perhaps I should mention the method used. It was based on a
method in Brauer, without the distillation at the end. No idea how so much crap got in the mercury, but the things were pretty old. The mercury was
separated by careful pouring from as much black powdery crap as possible, and the mercury was violently shaken for 2 minutes with a cold saturated
solution of KMnO4. This converted the mercury to a dark gray sludge. The sludge was washed by shaking with water until the purple of permanganate was
gone.
The sludge was then shaken with cold dilute nitric acid for 2 minutes, giving mercury in a divided yet silvery state after decantation of the acid. A
lighter-than-mercury gray suspended solid that I suspected to be mercurous was in the acid and the mercury. The silvery sludge was washed with
portions of water using gold panning-style swirling, until no more haziness could be washed out.
The combined acid+washes precipitated a gray solid after a while, and addition of the liquid to NaOH solution did not precipitate HgO or Hg2O. The
gray solid was mixed with conc. HNO3, which turned the solid white. This white solid dissolved in the acid with water addition, and addition to NaOH
solution gave a small amount of dark solid. This solid did not seem dense enough in the water to be mercurous oxide, much of it floated on or near the
surface.
The mercury gradually coalesced by the swirling hot water washes as it became more pure. The water decanted, the container and mercury were dried by
wiping with paper towels, a mistake in retrospect. The metal is shiny and perfectly untarnished. Mercury itself does not tarnish in air, and at this
point, in a vial it looks like the vial has a perfect silver mirror. But there is a little bit of stuff floating on it, which I think is lint from the
paper towels.
This method may have no advantage over a simpler purification in this case, perhaps just simple vacuum filtering through a fine fritted filter. It may
be overkill for this source, but it does not seem to give any loss of mercury, provided that the amount and duration of HNO3 treatment is at a
minimum. I am pleased with the results and would do the same again if I could get more at the same price.
[Edited on 24-5-2009 by S.C. Wack]
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grndpndr
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I cannot recall where this info came from but if you happen to live near a recycling center for TVs/computers/refrigerators and some other electrical
devices removal of mercury switches is mandatory which hadnt occured to me, I assumed the mercury was recycled as well but i believe it costs the
companys $ to dispose of the merc switches so it just might be possible to have as many as you cared to carry.
We also have a cosiderable amount of condemned homes in this very small community(500souls advertised) that wouldnt suprise me if at least a 1/2 lb
or much more isnt inside for the taking.Maybe considered trespassing but the homes will be bulldozed w/o any effort to remove anything of value from
the merc switches to the wiring and some older homes solid lead waste pipes. (Great bullet casting material given the price of PB.)As to
purifying/filtering of foriegn matter this thread or another concerning salvaged mercury the poster used a large syringe w/o needle of course removed
the plunger and inserted a filtering material, possibly cotton IIRC
poured in the mercury to be filtered, reinserted the plunger,
then pushed the plunger vigourously i would imagine to filter through the cotton.I would think gauze the better medium for fitering foreign matter
but either one should remove any large foriegn matter.If distilling were required Id pass.
[Edited on 9-6-2009 by grndpndr]
[Edited on 9-6-2009 by grndpndr]
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