h a l f b a k e r y"More like a cross between an onion, a golf ball, and a roman multi-tiered arched aquaduct."
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This is under home:pest control but could easily be in other places and applies to bits of homes as well as complete dwellings. It would be applied to an entire dwelling when the occupants were absent, possibly at work or on holiday.
The home or the part desired would either need to be hermetically
sealed or inflatable. I think this could be done fairly easily if built from scratch, but if not maybe it could be varnished or something. Chimneys or flues would have to be blocked up, doors and windows would have to be airlocks and so on. Ventilation would have to be closeable. Once this is done, a pump increases the pressure inside the sealed parts of the house by about a fifth. Another pump then draws the air through a chemical of some kind which removes all the oxygen, converting the atmosphere mainly to nitrogen and argon. I have no idea which chemical at the moment, sorry. This can be done in uninhabited parts of houses such as attics, cellars and spare rooms, and in smaller containers within the house such as refrigerators, ovens and wardrobes.
This would have various consequences. It would humanely kill most pests, including insects, rodents and molluscs (the rest of you do have molluscs in the house, don't you, or is that just me?), including pets if they were left in the dwelling - this is not as silly as it sounds because it means they could be humanely put down this way in a familiar environment. It strikes me as more environmentally friendly than fumigation. It would slow down but not stop the spoilage of food and slow the deterioration of fabrics and the like which are susceptible to degradation through oxidation. It would deter uninvited intruders because they would risk suffocation by breaking in - warnings could be placed on the outside of the building to deter them, and it would deter people from entering other places on the off-chance that it would be hazardous. It would also reduce the fire risk considerably.
There are certain problems and questions. It would be difficult to seal a dwelling which was not specifically designed to be so, although a machine which constantly removes oxygen from the air inside a house would still ensure a low oxygen environment. Most animals, including humans, left in the house would die without their own oxygen supply. Plants would also be endangered and generate their own oxygen, though i'm not sure how much. There might be a problem with the plumbing. Gas, electricity and water would need to be sealed off if the whole house was done.
A long-term version could involve the house being like this all the time with the residents using respirators to manage. The oxygen might be re-extractable from the chemical used to remove it - you might have noticed that i've avoided suggesting fractional distillation because of energy use. All cooking in such a house would have to be microwave or in a cooker provided with airlocks. Heating would be electric.
Nitrogen generator (from wikipedia)
http://en.wikipedia.../Nitrogen_generator
does what it says on the tin [Loris, Jul 01 2011]
Airtight building
http://www.passivhaus.org.uk/
[pocmloc, Jul 01 2011]
Video version
http://www.youtube....msjKM0&noredirect=1
I'm going to keep doing this until someone tells me to stop. [nineteenthly, Oct 13 2012]
Fill your columns with nitrogen
https://www.wired.com/2000/07/haven-2/
[mylodon, Nov 13 2017]
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I suspect sealing would be near impossible, but anyway. |
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Powdered iron is the standard oxygen scavenger for growing anerobic microbes, but you would need a lot of it to clear a house. Better off purging the entire place with compressed nitrogen first (blow in one end with a vent at the other) and then just using a limited quantity of iron to get the leftovers and ingassing. |
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Why only when the occupants are absent? I should think this a dandy idea for every occasion. Just add scuba tanks, and you're set. |
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You could even strap a scuba tank to your beloved cat, Fluffy. hehe... |
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At least it's not 'Fill Your Home with Hydrogen...' |
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Presumably this could be performed with a gas enrichment machine. Those work by pressure swing adsorption - specific gasses reversibly adsorb to a surface such as zeolyte at high pressure.
Medical devices enrich for oxygen by removing nitrogen, and presumably could be used with little adaptation, simply by taking the other output flow. The flow rate of medical devices isn't that high; of the order of 5 litres a minute - this would be fine for a long-term process in a low-leak environment, but generally a larger device would be required. |
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The oxygen-enriched flow could be released from the building, or something useful could be done with it instead. |
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Is it a physical constraint which prevents such a
machine from working faster, [Loris]? It needs to
avoid injury to the lungs and i'm wondering if air
could be pushed through it a lot faster. Maybe it
just isn't? |
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[Bigsleep], a flame would leave behind some
oxygen and i imagine it would be hazardous, for
instance because carbon dioxide is poisonous. |
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[Grogster], i do say it's not just on special
occasions and i had the scubacat scenario in my
mind too but i thought [ of ] would come down on
me like a ton of bricks so i didn't mention it. |
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Nobody is to mention Scuba Cats (Pat. Pend.) on this forum
ever again, or You-Know-Who will put a bag over his head,
and we'll all have to stand in the tea chest and sing
'Jerusalem.' |
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//Is it a physical constraint which prevents such a machine from working faster, [Loris]?// |
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I don't know much about it, but I would assume that is how much they need to supply, and are designed on some sort of compromise on the relevant factors - efficiency, cost, size, volume etc. Probably the need for continuous, even supply and high reliability are significant factors in the medical use, so there may be some saving there. |
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You can get larger machines for industrial production of nitrogen. So there's no non-obvious issue with scaling them up if you just want more nitrogen, but presumably there are reasons why they're not the same size but pumping harder. Link. |
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What if i run it into a single word, [Alterother]? |
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So [Loris], it's doable. High purity doesn't seem
necessary really - i imagine there's only very slow
oxidation below even something as high as one
percent and the other benefits are achieved as
soon
as it drops below about ten, i imagine. |
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Sealing an entire pre-existing building probably is
pretty difficult, but clearly it is possible to make a
new building along the lines of a submarine and do
it that way, and in the case of a wardrobe or an
attic, a sealable plastic liner ought to do it, i
think. |
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I dunno, [of-or-resembling-nineteenth], he's pretty sharp.
It might work as a temporary ruse, but we're going have to
disguise these amphibious-ops-capable felines pretty
carefully if they're to become a topic of long-term
discussion. I don't think I need to bring up what happened
last time... |
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This will work well, up to the point where the
house explodes. You say that //a pump increases
the pressure inside the sealed parts of the house
by about a fifth.// By my reckoning, that's 3psi
overpressure. On a typical wall (say 12ft x 9ft),
that's about 50,000 pounds trying to push that wall
out. |
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Likewise the roof - say it's 50ft x 50ft, then that
3psi is going to provide a little over 1 million
pounds of lifting force. |
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Also, you have a very expensive or complex way of
providing a nitrogen atmosphere. Whatever you
do is unlikely to be cheaper than LN2 delivered by
tanker which, in the UK costs something like £0.03
per litre. One litre of LN2 equates to about 700
litres, or 0.7 cubic metres. Assuming a house
volume of (say) 10,000 cubic metres, you'd need
14,000 litres of LN2 per "fill". Now assume you
want a 10-fold "fill" (which should flush out most
of the air), that's 140,000 litres of LN2, costing
about £4,200. Not far off feasible. (Also I'd bet
that it uses far less energy, total, than any other
method). |
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I'm a bit puzzled by some comments. For
instance, why would a normal electric cooker not
work fine in a nitrogen environment (if you
insisted on being present)? Why would electricity
and water need to be sealed off? |
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There are fire extinguishers (for libraries) that work by quickly replacing the room air with nitrogen. |
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Sunlight will fade most things if it strikes them over a long period of time; book spines, furniture etc. I wonder if this would be true in an environment without oxygen. Is sun-induced fading just accelerated oxidation? |
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Some of it is, but not all. |
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Fire suppressant systems more frequently use gas cocktails,
like the now illegal Halon, which was installed in a paint
shop in a facility where I once worked. Scary stuff. I
worked in the fab shop next door, thankfully. |
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Send me a kit, [19thly], I want to off a minor plague
of rats. |
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//At least it's not 'Fill Your Home with Hydrogen...'// Why not ? Depending on your insurance terms you may or may not want to turn off the mains beforehand, but you could do it with a home electrolyzer. |
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A fellow in 1890s Chigago built an entire hotel with
seals and plumbing for this purpose, although he
used coal gas, rather than nitrogen. Another
interesting feature of the building was the basement
crematorium. |
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A fellow in 1940s Germany had a similar scheme. |
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Ah, true, but the important difference is that in
Chicago it was only one fellow. |
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[MB], the reason for sealing things off is leakage, unless it turns out that the
nitrogen can be constantly replaced fast enough to compensate for that,
which is another thought. |
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Explody houses? You say that like it's a bad thing. Seriously though, i
suppose the pressure could be lower but it needs to be up to one bar or
there's a problem with the house imploding. Maybe a combination of
atmospheric pressure and extra nitrogen or a steady replacement. |
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It just seems a bit weird to bring nitrogen in when it's already there. I
suppose supplying nitrogen once would be fairly cheap but if you have a
means of separating nitrogen within the house, it could be an investment.
You could sell the nitrogen maybe? That would clearly mean houses full of
nitrogen were rare and probably reduce the deterrent aspect. |
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I'm pretty sure proper cooking, as in oxidation as opposed to just boiling,
couldn't happen in a nitrogen environment though that does make me
wonder what frying, grilling, roasting and so forth would be like in the
absence of oxygen. It would be possible to make coffee from pre-roasted
grounds, i imagine. |
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[Bungston], i was thinking that myself. I would expect it to be partly
sublimation. Don't know: i'll Google. |
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Cooking without oxygen is probably a good thing. Oxygen destroys essential fatty acids and many vitamins. I'm not aware that many of the desirable cooking processes require oxygen (with notable exceptions, such as flambé). |
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I think dutch ovens and slow cookers are anaerobic. I am sure chicken with 40 cloves of garlic is; the pastry makes it so. |
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//suffocation by breaking in// |
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Hmm... you would only suffocate those burglars so uncannily brilliant that they can break into a house without puncturing the hermetic seal - a rare breed, I suspect. |
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You're really cooking without gas now. |
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[Pertinax], not if the nitrogen is just replaced faster
than it leaks or if internal pressure is higher than
external. In any case, even if the house doesn't end
up airtight, there would still be less oxygen indoors
than outdoors and it needn't be that much lower
before it starts to affect the people in the house.
Maybe you'd just end up with unconscious
housebreakers rather than dead ones. |
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If you want to kill bugs which are at ground level, simply pour CO2 on ground and form a layer of CO2 which is 10-15 cm thick. CO2 being heavier than air will remain on ground replacing the air. Only bottom 15 cm portion of the house will need to be air tight. |
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But when you walk across this bug-lethal carpet, [VJW], think of the carbon footprints. |
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{screen goes all wavy}
Your teenager arrives later that night, rather the worse for wear, with a friend; "Is it OK if I crash on your floor?" "Sure, whatever..."
{screen goes all wavy again} |
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I know it pools but i honestly can't see that
turbulence wouldn't stir it up at all. Also, you
couldn't deal with bedbugs or dust mites that way. |
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That nitrogen system could be a gimmick for gyms: workout in a low oxygen environment stimulates the red cells more than your plebian sea level schlep, the Nitrogym is cheaper than residing in Bolivia to train, and we use only the finest nitrogen. There could be different gym areas with different altitudes. |
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I am loving "Nitrogym". I wonder if it has been taken? |
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That's a good idea bungston, you should post it.
The closest I think there is on the halfbakery is 'High Altitude Workout Room', which proposes dropping the pressure instead. |
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I have been filling up my home with 80% Nitrogen for a long long time. |
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Haha sucker, there's at least that much in air. |
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What i want to know though is, apart from the fact that you would die, would
there be any other differences in a pure nitrogen atmosphere at one bar which
anyone would notice? Would it alter flavours or smells, for example, or would it
change the sound of things at all? I'm just thinking that sounds would be
slightly more high-pitched, for example. |
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//apart from the fact that you would die [...] Would it alter flavours or smells [...] ?// |
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I imagine that might alter the smell of *you* after a few days. Other than that, isn't your question a bit semantically problematic? If a tree stinks in the forest where there's no (living) person to smell it, etc. ? |
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//would there be any other differences // |
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Nope. It would not, Since we are living in 80% Nitrogen already; Extra 20% would not much difference. |
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[Pertinax], as it happens i had a meatspace conversation along those very
lines yesterday. |
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[VJW], a helium atmosphere changes the flavour of foods according to
Cousteau. A fifth of the atmosphere, particularly of a reactive gas such as
diatomic oxygen, surely would make a difference? Air is three percent denser.
Hmm. |
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What might be more effective and cheaper, is to place
high-carbon-fuel burners near the floor in each large room,
then light them and let them use up the oxygen gradually
enough that they don't raise the temperature dangerously
high.
The hot exhaust would collect near the ceiling, leaving
the fresher air near the floor to be used by the burners.
When the burners have used up most of the oxygen, they
are extinguished to prevent carbon-monoxide production.
Then fans are used to circulate the hot air and increase its
rate of flow into cracks and crevices.
Afterward, the whole house would be very warm, even
more than boiling hot if desired. The hot, dry air should
destroy insects, spiders and germs by the time it cools
down. |
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Big sign out front: Drugs and money in living room. Do not
steal my drugs and money. Please don't use the self sealing
door (out back, beside the lime pit) to get in. |
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This could be a safer community program sponsored by Crime
Stoppers. Bun + |
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/through a chemical of some kind which removes all the oxygen/ |
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You could use carbon for this. Plain carbon would work, or many other reduced forms of carbon. |
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Of the two stable oxides of carbon, both are gases, one of which is toxic to your species. |
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We suggest hydrogen or silicon. Both are abundant, and have stable, relatively unreactive oxides, one liquid, one solid. |
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/Of the two stable oxides of carbon/
True for maximally oxidized carbon. However with an excess of carbon molecules one could oxidize only partly, stopping when the oxygen was gone. And it could make that great toasty smell. In fact one could actually make toast, which would be available when you came home. |
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