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Data Centers Breathe Easier With Less Oxygen
PC World is reporting that some companies are looking at a new method of fire protection in their server closets, oxygen-deprivation systems.""Wood stops burning when the oxygen content falls to 17 percent and plastic cables between 16 to 17 percent, said Frank Eickhorn, product manager for fire detection at Wagner Alarm and Security Systems GmbH in Hanover, Germany. Wagner makes electric compressors that use a special membrane to remove some of the oxygen from the outside air, a system the company calls OxyReduct. The excess oxygen is exhausted, and the remaining nitrogen-rich air is pumped inside the data center."
RTFA, the oxygen content in the air would be the same as living at around 2000-3000m which people certainly do without ill effects.
"When you sit with a nice girl for two hours, it seems like two minutes. When you sit on a hot stove for two minutes, it
TFA said the oxygen level was equivalent to an altitude of 6000 feet, so i guess not that dangerous.
Although I'm sure this is safe for day-to-day operations (for low-altitude data centers) and will prevent a self-sustaining blaze, I'd bet that a smoldering powersupply would convert an unpleasant fraction of the low-oxygen atmosphere into carbon monoxide. Oxygen-staved combustion tends to produce this deadly gas (which kills by binding to hemoglobin better than does oxygen)
Two wrongs don't make a right, but three lefts do.
Make that an SCBA (like a firefighter wears), the 'U' in Scuba stands for underwater. ;)
Its not exactly the same as being at 6000ft, its just similar from the perspective of how easily a human can breath. Higher altitudes have the same percentage of oxygen in the air, they just have lower air pressure, meaning less of all of its components. The lower altitude air will still be higher pressure, but with less oxygen. In terms of breathing, we just care about the partial pressure of oxygen, but thats not all that matters when it comes to whether something will burn.
Been to 6000 feet and cooked many meals there on a camp stove. At 11,000 feet as well. Fire burns at that altitude just fine.
That's because your fuel doesn't need higher concentrations of oxygen to ignite. With other materials that is not necessarily the case.
Still, I've been out of breath plenty in datacenters after pulling long lengths of (heavy) SCSI cables. I can't imagine trying to do that in an O2 Poor environment.
I read the internet for the articles.
We don't do immersion because it doesn't work over the long term. In the short term, it's fine. Even in a closed system, though, degradation of components leads to the contamination of the coolant, which then must be cleaned.
Cleaning is itself a problem. All filters wear out, and no filters are perfect. The closest things you get are distillation, or reverse osmosis filtering. Distillation requires heat, and to clean that much water, too much heat will be needed. Reverse osmosis filters waste water, so the system won't be closed. In short, full immersion cooling is just a bitch.
Liquid cooling is fairly reasonable, but it has its own problems as well. If you have a centralized pump and centralized cooling for the coolant, then a leak anywhere is a leak in the entire system. If you don't, then you have a jillion pumps and radiators and all kinds of other crap to fail.
So liquid cooling is to be avoided in general, and full-immersion cooling simply isn't feasible.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
No, we exhale about 19% oxygen normaly. The bigger problem with rebreathing your own air is the buildup of CO2. That's why the astronauts on Apollo 13 were more worried about their scrubbers than their oxygen supply.
That which is done from love exists beyond good and evil
Partial pressure of oxygen determines combustability.
Amount of oxygen determines breathability.... which is how you can breathe astonishingly low pressures of pure oxygen in a space capsule.... till it catches on fire and makes a tasty dish of seared astronaut....
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Halons work to extinguish fire using several mechanisms. Oxygen displacement- not absorption or binding- is one of them, but if this were the only factor, then dry nitrogen, carbon dioxide, or other inert gas would work just as well.
There are four things required for combustion: oxidizer, fuel, heat, and a chemical reaction that is self-sustaining- the "chain reaction," in which free radicals are formed. Halons work by kicking off chlorine, bromine, or fluorine radicals in the heat of the fire, ending these reactions. Unfortunately, the same properties that make this class of compounds so wonderful for extinguishing fires is also what makes them so good at terminating the production of ozone.
I also seem to recall something in my distant past as a fire instructor that halons as a group have a fairly high specific heat, meaning they carry away more heat from the fire; this is a relatively minor factor when compared to things like water which have high specific heat and very high heat of vaporization. Water is surprisingly good at putting out electrical fires; energized systems can be handled by using distilled water, as was done at Browns Ferry nuclear power plant in Tennessee in 1975. But it's messy and doesn't fight "three dimensional" fires very well.
Replacements such as FM-200 and Novec 1230 that do not survive long enough to reach the stratosphere have been made and are now available. They are comparable in effectiveness to more traditional halons (Halon 1211 and 1301), and Novec is shipped as a liquid rather than a compressed gas. This makes it safer and less expensive to transport. Being fluorinated molecules (no chlorine, just fluorine) less phosgene is produced during a fire, which is a good thing.
Except that ppO2 = amount of oxygen (i.e. a ppO2 of 3psi is the same amount of O2 whether there's also a ppN2 of 12psi - roughly the composition of air at sea level - or it's pure O2). What you're thinking is that relative oxygen content determines combustability.
...following the principles of Heisenburger's Uncertain Cat...
Remember Apollo I?
There's a difference between pressure and partial pressure of oxygen. Reduced PP inhibits fire and FEELS TO HUMANS like being at altitude. Fire burns at altitude because the PP of o2 is the same. Humans feel like the PP is reduced because there's just fewer oxygen molecules (along with fewer of everything else).
My wife has COPD. She has an oxygen concentrator (really, it's just a nitrogen separator. It removes a large chunk of the nitrogen from room air and sends the rest of it down a tube to her nose). We have to post warnings in the windows and the like because the increased oxygen saturation near her when she's using her concentrator makes things that aren't usually flammable quite a bit more so - the exact opposite of the concept described in TFA. An ordinary bic lighter can become quite a sight when you aim the output from the concentrator at it (don't try this at home, kids).
At 6,000 feet or wherever, the oxygen concentration is still ~20%, albeit at lower pressure. This new product doesn't reduce the air pressure, it reduces the oxygen concentration. The effect on a human is approximately equivalent to being at 6,000 feet, but not exactly. In any event, it'll be a minor difference to you but a major difference to a fire.
Think of it in reverse: you can breathe oxygen at 100% concentration and not feel a whole lot different, whereas wood and plastic burn like gunpowder at that concentration.
FATMOUSE + YOU = FATMOUSE
People depend on the partial pressure of oxygen, fires the percentage. Thus on US submarines we let the sailors breathe down the oxygen to about 19% before turning on the oxygen generator to keep it at this level. Generating oxygen for people by water electroysis is energy intensive and requires about 500W per person. Now back to fires. As other smart readers of /. have pointed out fires burn at high altitude. In this case the percentage of oxygen is the same (20.9%) as at sea level but the partial pressure of oxygen is reduced which affects people to some degree depending on the person and work load. For the system described in the article one would need to use caution if it was used at high altitudes to make sure that people were not in an environment too low in oxygen.
In the "good old days" most sailors on submarines smoked and could tell when the oxygen level was down because they couldn't light or smoke their cigarettes.
Another aside: the Apollo moon capsule was maintained at about 3 psi of pure oxygen in space. They used lower pressure so the walls of the lunar lander could be very thin, I believe about 0.02 inches thick. The astronauts worried about accidently kicking a hole in the wall. This way the partial pressure of oxygen was the same as on the ground. The original design had the system on the ground at 100% oxygen for simplicity, with of course tragic results...it was modified to begin with normal air then change to 100% oxygen at lower pressure after launch. It was assumed that fires wouldn't burn in space because there is no convection due to zero g. This is flawed because fans are used to circulate the air. Fire in an environment where you are trapped is always a great concern.
You're dumb. They're not talking about eliminating the oxygen, just decreasing it to 15% from 20%. This leaves the same mass of oxygen per cubic foot (or whatever) of space as you would have at about 6,000 feet.
Nitrogen is not dangerous. It is in fact inert as far as your body is concerned. The majority of the air you're breathing now is nitrogen.
Now, breathing pure nitrogen and not getting any oxygen, that's dangerous. But even the FA will tell you that nitrogen is the major component of air. If you actually had any knowledge of physiology (and I have damned little myself) or even read the article you cited, you would have known this.
First, you should have read TFA. Then, when you chose to cite an article to support your point, you should have read THAT FA. Since you did neither, you are obviously a bozo.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Halon 1211 (Bromochlorodifluoromethane) and Halon 1301 (Bromotrifluoromethane) have been banned in most countries since 1994 (The Montreal Protocol, as stated by the AC below) because they were found to deplete ozone.
As has already been stated, Halon worked as a fire suppressant by displacing oxygen, thus disrupting the fire triangle (fuel, oxygen, heat). Also, in the presence of any remaining flame or smoldering debris, Halon oxidized into other toxic gasses including phosgene which is very, very bad stuff and was used as a chemical weapon during WWI.
Like Carbon Tetrachloride extinguishers before them, Halon extinguishers had too many bad attributes; what we in the fire service would call, "Ethyl-Methyl-Bad-Shit".
Thanks, but like I said... I did read the article. The only moron here is yourself for your rapid, nonsense spouted response.
Nitrogen pools. We have several cryo tanks at work that regularly deplete thru displacement the oxygen content of their storage facility. They have to have a fan running 24x7 to sweep fresh air over and above the tanks to prevent anyone from getting injured.
I was simply pointing to those that might not have the experience the problems of a pure nitrogen environment, which wasn't discussed (since you read the article, right?- Funny how they left off the non-fatal aspects of oxygen deprivation).
Thanks for playing. Go sit in the corner until you can be constructive again.
In the US, OSHA safety standards require supplemental oxygen if the oxygen percentage drops below 17.5%. Defying this standard risks a worker lawsuit and some very nasty regulatory fines. Testing with gas monitoring equipment will be required to prove the oxygen level if it is ordinarily below the requirement. At some point, some one must do some work on the equipment. A human at rest may be able to survive quite well at lower oxygen levels but a person doing work may need to consume a higher amount.
From TFA:
They are not talking about oxygen free rooms. Yes, as your article says, breathing pure nitrogen will kill you as humans don't run on nitrogen. But that does not mean a high nitrogen content would be dangerous. Otherwise you would die as soon as you breathed a breath of Earth's air which is, by a long measure, mostly nitrogen. So your article really has nothing to do with this subject. Its sort of like giving a story of how 900 degree temperatures inside a cremation furnace affect the human body and using that as an argument on why people shouldn't be allowed in houses with the heat turned on.
Mathematics is made of 50 percent formulas, 50 percent proofs, and 50 percent imagination.
Nope, it's the percentage of oxygen and the pressure. Multiplying pressure by percentage for each gas gives you the "partial pressure" of that gas, and it's the gradient of partial pressures that determines rate of absorption. Well, to be precise, gas in your tissues (lung tissues, blood, etc.) has "tension", not pressure, so it's the difference between the partial pressure of the gas in what you breathe and the partial tension of the same gas in your tissues that determines absorption rate.
To live, you need a ppO2 within a certain range. IIRC, between about 0.05 (5% at 1 atm, or 10% at 0.5 atm, etc.) and 2.4 (pure O2 at 2.4 atm, or 50% at 4.8 atm, etc.). Below that range, oxygen doesn't diffuse into your tissues fast enough to supply their needs, above that range the oxygen begins to damage the tissues, in an effect known as oxygen toxicity.
SCUBA divers who go to great depths take bottles with very low percentages of oxygen, low enough that the gas would be marginal for survival at the surface. They do it because at, say, 20 atm (600 feet), normal air has a ppO2 of about 4.2, far, far above the safe level. A 3% O2 mix at 20 atm, however has a comfortable ppO2 of 0.6. Since the deep mixes aren't breathable in shallow water, such divers either carry multiple bottles of different gas mixtures (don't mix 'em up!) or else have pre-positioned staged for appropriate depths.
Going the other direction, pilots, astronauts and mountain climbers spend time in environments with very low pressures, low enough that the ppO2 is not survivable (or at least is not conducive to strenuous activity). So they breathe high concentrations of O2, usually from bottles of pure O2.
Cardiovascular efficiency also plays a major role here. Good cardiovascular health means both increased lung surface tissue for absorption and higher-volume blood flow for delivery of absorbed gases to the tissues which in turn absorb them from the blood (mostly according to the partial tension gradient with a tissue-specific absorption coefficient). So, people with good cardiovascular health can survive lower ppO2 levels.
Nitrogen has no effect on any of this, except as a gas to fill up the non-oxygen part of the mix, and, for divers a gas that will be absorbed under high pressures and released from tissues as pressures decrease. "The bends" is just nitrogen coming out of solution too fast and forming bubbles which block blood vessels.
CO2, on the other hand, is poisonous. I don't recall what the levels are, but above a certain ppCO2, you pass out and then die. CO2 must be removed from your breathing gas. This isn't an issue for open circuit SCUBA divers, whose exhalations float off to the surface, but it's important for rebreather divers and, obviously, for astronauts and others in sealed environments.
Bringing this back to the topic at hand, 17% O2 shouldn't be a problem for anyone of normal cardiovascular health unless the data center is located on a high mountain peak. Someone who has some lung injury or deficient circulation wouldn't want to work in such a data center, but most such people routinely use a nasal flow of pure O2 anyway so, again, it shouldn't be a problem.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
Huh? ppO2 is *not* the same at high altitudes. At 0.7 atm (~10,000 feet above sea level), pp02 is 0.7*0.21 = .14 as compared to 0.21 at sea level.
And, in fact, fires do not burn as well at high altitude. As someone who does a lot of camping above 10,000 feet I can tell you that fires are much harder to start and require much more air flow than they do at lower elevations. Boy Scouts are taught to use a "log cabin" structure for a campfire at high altitude, rather than the "tepee" structure that works well at low altitudes. The log cabin has large gaps on all four sides and at each level of the structure, to draw in enough oxygen for combustion, but those gaps also diffuse the heat and make it harder to get the sticks hot enough to burn. The tepee concentrates the heat better, but doesn't provide enough airflow at high elevations.
My wife has COPD. She has an oxygen concentrator (really, it's just a nitrogen separator. It removes a large chunk of the nitrogen from room air and sends the rest of it down a tube to her nose).Yeah, those things can be dangerous. I know someone who opted to put a log on a burning fireplace while wearing an oxygen tube (though hers was from a tank of pure O2, not a COPD) and ended up with 3rd degree burns over a significant part of her body, because in the oxygen-rich air her clothing became extremely flammable. I'm sure you and your wife aren't so foolish, of course.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
"I was *trying* to point out that you don't want to get too carried away by 'inerting' areas because there are consequences- while you may become sleepy and tired from CO poisoning, or disoriented, hot, and suffocating from CO2 poisoning, people will not experience warning symptoms with N2 poisoning- they'll simply keel over."
You will only get the "simply keel over" effect if oxygen levels are 0 (or close to it), like if you suck on a hose spouting pure nitrogen. The same thing will happen if you start breathing pure CO2. If you are in an environment where your body cannot get the oxygen it needs, you will simply die. If on the other hand you get a more gradual fall in oxygen levels (which would be the most common failure scenario here, as well as in most everyday situations where CO2 levels rise), you will feel side effects first. And anyways, as long as you have reasonable safety precautions, its still not going to rise to the level of "They'd better make damn sure NO ONE can defeat the safeties to get into that room", like you said in your first post. I mean if you are going to keep people out of any enclosure where there may be a drop in oxygen levels, you would also have to keep them out of houses and apartments that are heated with natural gas (which may result in a methane leak).
"Just simple information that your average person might not have known about..."
I'm pretty sure the average person knows you need oxygen to breathe.
Mathematics is made of 50 percent formulas, 50 percent proofs, and 50 percent imagination.
Both you and the parent post are right, in a way.
Nitrogen does nothing, but it is in the way. Oxygen has to diffuse through nitrogen to get to a place where it is consumed, and diffusion is a relatively slow process (yes, I am a chemical engineer, and I did run Stefan-Maxwell simulations).
Say you have a total pressure of 20 kPa, 100% oxygen. If oxygen is consumed at point X by a reaction (I will drop the issue of products diffusing out), all other oxygen around will rush to the spot unhindered (pressure is fast: actually the limit would be the speed of sound). If you have dry air atmosphere, you have 20 kPa oxygen and 80 kPa nitrogen. If oxygen is consumed at point X, nitrogen will accumulate there since air as a whole, not oxygen only, are dragged to point X, and only oxygen is disappearing.
So, yes, what counts for reaction rate is the partial pressure of oxygen, but in many cases (and fires are one of these) diffusion limits how fast oxygen can get to the reaction, so you cannot just pretend you do not have an inert gas in the way.
In fact it is even worse than that, at 100 kPa oxygen (~one atmosphere of pure oxygen) flesh burns "vigorously", as my buddy's professor in combustion used to say. That's why you are not allowed any sort of lighter or match in a hyperbaric chamber, as people inside would burn as gasoline.
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The Bastard Operator From Hell, Simon Travaglia. A system administrator turned humor columnist who writes stories about what all sysadmins wish we could get away with. You know, murdering our boss with the Halon system, getting end users to stick paperclips into power outlets, that kind of thing. Published semi-regularly at theregister.co.uk.
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