chornedsnorkack
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Low temperature fume workup apparati
How do you design and operate apparati designed to catch and work up (long term, unattended) corrosive and explosive fumes produced at storage like +5
and below?
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Sulaiman
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I guess that it would depend upon the specific fumes expected,
in what quantity, location etc.
eg a fridge could be periodically purged
an underground cavern would need continuous ventilation.
a little more specific ?
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bnull
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Venturi effect for fumes exhaustion, no source of sparks or exposed metals, better seals on flasks. These should take care of fume production and
removal. As for the work up, it depends on what substances you're talking about. What works for hydrogen chloride may not work for dimethyl ether or
ammonia.
[Edited on 10-8-2025 by bnull]
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chornedsnorkack
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Posting is highly unreliable here. It often says that it does not work - after effort making a post.
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Radiums Lab
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I had those problems too.
Next time when you make a big post make sure u copy everything and click that post button after copying.
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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chornedsnorkack
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How about White Fuming Nitric Acid?
It decomposes
4HNO3=2H2O+4NO2+O2
O2 is a permanent gas. NO2 is soluble in nitric acid and makes it Red Fuming Nitric Acid. But a flow of O2 would carry along at least some fumes of
NO2. And NO2 would be corrosive, like to the refrigerator. So how is the vented oxygen cleaned from corrosive nitrogen dioxide?
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chornedsnorkack
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Interestingly, Quick Reply worked - Post Reply said the feature was not available, and that when I had written the post and attempted to post.
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Belowzero
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I use a bunch of old fridges that are not powered and have a hose connected to the back that leads outside.
The smell inside of the fridge is minimal and it is reasonably airtight. The devices probably wont last too long but broken fridges are basically
free.
It is the best I can come up with and its is cheap.
The ones that store acid have a drip tray with carbonate to neutralize the fumes and the inevitable leaking. Acids seem to hate being bottled up 
[Edited on 12-8-2025 by Belowzero]
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chornedsnorkack
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Quote: Originally posted by Belowzero  |
The ones that store acid have a drip tray with carbonate to neutralize the fumes and the inevitable leaking. Acids seem to hate being bottled up
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Which carbonate?
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bariumbromate
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i use bottles like this to store red and white fuming nitric acid
link: https://tinyurl.com/superbottle
the lid will go yellow and bulge a bit but once that happens it passivates or something like that and becomes acid tight and leaks no fumes
diethyl ether and bromine don't leak from these or dissolve the lid as well
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Belowzero
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Not exactly sure, the cheapest calciumcarbonate fertilizer I ran into.
I noticed it helps quite a bit with the smell.
Tends to absorb any residual moisture too.
[Edited on 13-8-2025 by Belowzero]
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Sulaiman
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ziplock bags are a good secondary containment option,
not perfect but they significantly reduce gas/vapour leakage rates,
they inflate to indicate pressure,
and may help contain a broken vessel with its contents in the case of accidents.
drip trays may be useful but a plastic tub or bucket with a lid is better.
Ugly, inconvenient, space-wasting, but better.
You can semi-seal acids in one tub with eg calcium carbonate,
large leaks would be fully contained,
if in a fridge I would probably try to get the largest rectangular plasic tubs that fit one per shelf.
PS plastics become brittle at low temperatures,
different plastics have different chemical incompatibilities,
polypropylene is a good choice for the tubs.
If you find cheap ptfe tubs please let me know.
Part of the inconvenience is that you can not quickly identify any plastic storage bottles swelling due to increased internal pressure,
( eg due to the slow decomposition of peroxide or hypochlorite bleaches)
so you should have a routine inspection schedule.
[Edited on 14-8-2025 by Sulaiman]
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teodor
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I think the best approach is free air circulation. Double container with CaCO3. No ammonium salts nearby, they can penetrate the cap from outside to
inside and cause development of pressure (i.e. ammonium carbonate). Regular inspection of the cap of the bottle itself. White fuming nitric acid is
not practilcal to store more than for period of some continuous work.
The drawback is that air from outside can have quite big humidity which can react or dilute some compounds no matter how tight you close them. I store
acid in a basement where I have dehumidifier, so it constantly remove all vapours from the air including any smell. Just make sure the (acid) vapour
leak is less than H2O level in the air. If it is some remote space you can attach pH sensor to the water outlet from dehumidifier, that way you can
remotely detect a leak.
So I would not put some acid in closed space prefering the free air/space around the second container based on my storage experience. Also I don't see
how you can store some chemicals without regular inspection of bottles, so unatennded chemical storage is generally not a common idea.
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Sulaiman
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The difference in the above post and mine above that is partially due to our local weather.
eg in uk my main weather related concern was freezing in winter,
here in malaysia it is heat that causes me the most problems with chemical storage.
so readers beware - we all live in different environments.
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Precipitates
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Although in the UK and the tropics the climate is fairly consistent.
In continental Europe and America the temperature variations are likely to be much more extreme (-40°C to +40°C)!
It's generally best to store chemicals inside as oppose to outside - but safety protocols must be in place.
In the UK our thermostat was always set above freezing, even if we went away, to avoid the pipes freezing, and generally to keep our house above 0°C.
This might be detrimental to not just susceptible chemicals, but lots of other things as well! Less of a problem where I'm from, where very unusual
weather events would have to occur. I can only recall such events that would have me worried occurring once or so in the last 30 years.
Generally I find warmer temperatures to be better for chemicals - as salts are much more likely to stay in solution.
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teodor
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The most liquids are not expanding on freezing, H2O is a very rare exception. I am really an ignoramus because I just noticed I don't know any other
liquid which can break a bottle on freezing. I keep a lot of chemicals in freezer, in zip packets or PP boxes with adsorbent (C/CaCO3) and it works
extremely well for several groups of very nasty compounds (just one example: bromine).
What I will never put in a freezer are things like HCl, HF, chlorosulfonic acid etc. WFNA I will not store at all. But liquid NO2 I would put in a
freezer. I am not sure what is the principle here, probably those compounds which I will not put in a freezer have a big decomposition rate or are
required in a bulk quantity, so I am afraid about the freezer itself.
There are different opinions about the type of caps used for different type of chemicals, I heard for example that some people prefer PP caps ("blue")
to PTFE lined caps ("red") when they require more germetic seal. From my experience red caps give better seal. The advantage of blue caps is that you
can see when there is a pressure inside a bottle - the cap inflates and it is visible. But oxigen/water sensitive chemicals are not stored so well
under PP caps. I think PTFE-glass contact is more germetic than PP-glass one.
[Edited on 15-8-2025 by teodor]
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