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DrMario
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Quote: Originally posted by ziqquratu  |
One thing to think about, however, is corrosives. The cooling coils are usually made of aluminium these days, and do not like even the tiniest traces
of acid in the atmosphere. If the coils are exposed and you have corrosives in there, you will walk in one day and find the fridge running with no
coolant (trust me, I speak from experience... one very well sealed bottle of thionyl chloride was enough to ruin the coils in a six month old, $1500
kitchen-type fridge we used in our university lab!). I suspect that you could coat them with epoxy or something resistant, but I don't know how well
that would work. Of course, in a home lab, you may well not have any corrosives you want/need to store cold anyway. |
I got myself a minifridge specifically to store corrosives: the big three (sulfuric, nitric and hydrochloric acid) along with some phosphoric acid and
H2O2. While I could never smell anything noxious in the fridge so far, it's early days (only got it a week ago) and after I read your post I decided
to place a piece of polished aluminium inside the fridge. I plan on checking it from time to time to see if there is any corrosive gas building up. Do
you think this is a good idea?
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ziqquratu
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At the least, I can't see how it could hurt. The problem, as I see it, is if you can detect a problem before it breaks through the (relatively thin)
evaporator tubing and all your refrigerant leaks out. One pin hole is all it takes...
All I can say is, if you want to be certain, the aluminium tubes which contain the coolant must never be exposed to the internal atmosphere of the
fridge. In professional lab fridges, those tubes are completely outside the chamber, behind a plastic sheet (but obviously they're still inside the
fridge's insulation!). My thought is that a layer of protective epoxy might also do the job to protect a regular fridge, but that's 100% untested
conjecture on my part!
For the items you've listed, though, I'd only keep the H<sub>2</sub>O<sub>2</sub> in the fridge; everything else is room temp
storage! Also, of those, I'd think HCl would be the biggest risk to your fridge - it's highly volatile and loves aluminium (and I would expect
HNO<sub>3</sub> to be similarly problematic). Sulfuric and phosphoric, being largely non-volatile, I would expect to be less of an issue,
but there's no real need for them to be in there anyway, as far as I can imagine.
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DrMario
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My need for storing the HCl in the fridge comes from a complete lack of a cool storage. I really don't need the fridge to be cold - I just need a
place where the temperature will not be >30C during summer days.
Still, you gave me a lot to chew on, ziqquratu.
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ziqquratu
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Meh, working in university labs, we kept all our HCl (up to 37%) at room temperature. And "room temperature" varied between 0*C and 45*C (I'm in
Australia, and our labs had terrible heating/cooling!). No problems were noticed for synthetic purposes!
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DrMario
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Okay. The thing is, I use very small amounts of the stuff, which I keep in a smaller bottle, while the larger bottles are stored away for the long
haul. I imagine you would be opening your bottles regularly, which I don't intend to do.
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ziqquratu
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It would, of course, depend on the lab, and I'm not sure of your own experience, but you might be surprised by how little mineral acid a typical
organic lab may use. Most of my work has, to date, required acids in the 1-5M range, with HCl being the most used. At a guess, I'd make up a litre of
5M HCl from the conc. acid say four times a year, and a litre of 1M perhaps once a month. I'd use sulfuric acid a couple of times a year, and the only
use I recall having for nitric acid was preparing aqua regia for cleaning, maybe once a month or so. Use by other people in the lab was probably less
than that (I work with lots of amines, so a lot of acid-base workups!). Just to demonstrate, in my previous lab with between six and ten chemists,
there was a 2.5 L bottle of 70% nitric which was open when I got there and still had a good amount remaining when I left after over 6 years! I think
in that time we used maybe 5L of sulfuric acid. We did go through a lot of HCl, though, but only on the order of a few (5-10) litres per year at most.
Furthermore, keeping the bottles closed up should, I imagine, mean they're even less likely to change concentration significantly! So long as you keep
them under reasonable conditions (a nice cool corner with reasonable ventilation, out of the sun and whatever) I'd suspect they should be fine for
quite some time.
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DrMario
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I work at two institutions. One has, what you would call, typical organic labs (some are analysis, some are synthesis labs). In that institution's
labs I have yet to see any mineral acid bottles - but I certainly did smell some (once I opened one of the chemical cabinets I was inundated by a
cloud of noxious something that had to be either nitric or hydrochloric plus random reagent aroma). The reason for the apparent lack of such acids is
that here we do a lot of masspect in addition to LC and GC. Masspec is really one of the main competencies of this department, and apparently,
inorganic acids are not compatible with it. Plenty of acetic acid though.
The other institution is kind of exactly the opposite: not much organic synthesis, but we use tons of hydrochloric, nitric, hydrofluoric, sulfuric and
phosphoric acid. And H2O2. We use so much of these, that no bottle remains unopoened for more than 24 hours, except for week-ends, and these bottles
(2.5L but more usually 5L) last for a week to less than a week, depending on the lab.
I've been working much longer with the latter institution, so my experience is "tainted" from there.
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ziqquratu
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Yeah, I know what you mean - there are big differences in acid usage between my current and former workplace. I, too, remember the joys of opening our
corrosives cabinet and getting a nice big lungful of acrid fumes - or brushing against the inside reaching for a bottle at the back and coming out
with a nice big streak of damp, corroded (and still corrosive-covered!) metal sludge on my arm! Funnily, OHS never picked that up...
I assume you want the small bottles for workplace 1; if you can just fill those small bottles in workplace 2, then you have no worries about storing
the larger bottles. If you can't do that, I'd still recommend not risking your fridge by storing those acids in it. They're perfectly stable and, in
tightly closed bottles, shouldn't be affected by evaporation or absorption of water from the air over any reasonable period of time.
Just for the record, though, I have no experience with HF, so my statements may not be appropriate for that! Definitely get advice on that from
someone who knows how to handle it.
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DrMario
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Don't worry, I have no intention of storing HF! Very little use for it. Besides, any contact with HF, however minor, results in a mandatory night at
the hospital. The nice thing about HF, though, is that it's less volatile than HCl, and that most metals corrosion is self-limiting (most metal
fluorides aren't water soluble).
Thanks to this fruitful dialogue, I have now removed the HCl from the mini fridge, made sure the cap is tight, and put a little parafilm on it for
good measure. I can't detect any HCl gas at all, so far.
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ziqquratu
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Yuh, had the experience of being exposed to HF (from hydrolysis of NH<sub>4</sub>F). Fortunately avoided the hospital - just had to wear a
glove full of calcium gluconate gel for 24h (including passing through airport security... fun times explaining that!)
Are you saying you're now storing it out of the fridge? If so, I'd say great.
If you're saying you parafilmed it up and put it back in, keep in mind my original story - ours was ruined by a VERY well sealed (sure-seal, parafilm,
cap, parafilm) bottle of thionyl chloride. I really don't think you can seal these things well enough to prevent sufficient leakage. It is a
completely closed system inside the fridge, after all, so the acid vapour will eventually make its way to any unprotected metal.
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CuReUS
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yes ,HF is a toxin in the body becaue the flouride ion messes up with the calcium metabolism of the body ,and since calcium plays a vital role in
nerve impulse transmission(acetyl choline etc) ,all your muscles and even your central nervous system could be affected
| Quote: | | Fortunately avoided the hospital - just had to wear a glove full of calcium gluconate gel for 24h |
isnt calcium gluconate also used against spills of magic acid and flourosulphuric acid
[Edited on 30-10-2014 by CuReUS]
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DrMario
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| Quote: Originally posted by ziqquratu | Yuh, had the experience of being exposed to HF (from hydrolysis of NH<sub>4</sub>F). Fortunately avoided the hospital - just had to wear a
glove full of calcium gluconate gel for 24h (including passing through airport security... fun times explaining that!)
Are you saying you're now storing it out of the fridge? If so, I'd say great.
If you're saying you parafilmed it up and put it back in, keep in mind my original story - ours was ruined by a VERY well sealed (sure-seal, parafilm,
cap, parafilm) bottle of thionyl chloride. I really don't think you can seal these things well enough to prevent sufficient leakage. It is a
completely closed system inside the fridge, after all, so the acid vapour will eventually make its way to any unprotected metal.
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Yes, the HCl bottle is now outside of the fridge. I put a bit of parafilm around the cap, and monitored it for a few days. I can't notice any HCl gas
in the cabinet, so the bottle will stay there.
The reason I said that HF exposure == mandatory night at the hospital, is that
a) It's the policy at the research cleanroom where I work and
b) It's kind of a good policy, because HF is tricky - you may have little or no sign of HF exposure and/or penetration into your body when looking at
your skin, but considerable amounts of HF may have penetrated deeply enough to reach your blood vessels, and perhaps even your bones.
How bad was your exposure to HF, that time you put on a glove full of gluconate?
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ziqquratu
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Yeah, reasonable policy, really. I had to deal with safety officers who had zero idea of what to do in the situation - and I still don't think there's
any policies or training in place.
Admittedly it was caused in part by my carelessness (I thought it was properly quenched, so I didn't take the time to wear the correct gloves; I was
wrong), and it was only a small exposure (HF vapour through latex gloves, a patch maybe 5-10cm<sup>2</sup>. Just enough to notice a burn).
So not bad, but enough to require some treatment.
As for the HCl - what you're doing now seems like the best option to me.
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DrMario
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In our cleanroom you don't have the option of not wearing the heavy protective equipment - if you try to work with acids without it, the main lab
engineer will have your head chopped off. Or your colleagues will swarm nervously around you telling you that the main lab engineer will have your
head chopped off.
Our protective equipment consists of a full-length apron, faceshield (none of those silly goggles) and heavy acid gloves which I hate. Keep i mind
that under the heavy acid gloves we still have the cleanroom gloves. So, your situation would be unlikely to have happened.
Huh, so... I completely f###ed this thread off topic. Oh well...
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Oscilllator
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Update: My peltier cells arrived the other day and unsurprisingly when left in a room by themselves attached to a heat sink there was no detectable
temperature difference across the two faces. Little ghost I'm afraid it is indeed impossible for a peltier cell to spontaneously develop a temperature
difference across itself.
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