Timeline for Why would breathing pure oxygen be a bad idea?
Current License: CC BY-SA 3.0
21 events
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| Jun 7, 2018 at 2:03 | comment | added | user43021 | Yes I think I have problems with your English, I got that perfectly, thanks... | |
| Jun 7, 2018 at 2:00 | comment | added | Eric Towers | @santimirandarp : A person at the bottom of a swimming pool with a snorkel poking up in to the atmosphere is breathing air, not pure oxygen. The problem this person experiences is that they cannot expand their lungs because of the difference in water pressure and air pressure. It does not matter what the gas is, they cannot inhale. This is just at 10 feet, at greater depths, the gas must be supplied at greater total pressure. | |
| Jun 6, 2018 at 23:49 | comment | added | user43021 | @EricTowers But you are describing a person with a pure oxygen supply at 1.4 atm, isnt it? that's what I get from the text; otherwise, why do you say 'So, don't regulate the pressure that high? There's a problem' | |
| Jun 6, 2018 at 23:47 | comment | added | Eric Towers | @santimirandarp : There is no oxygen pressure of 1.4 atm. There is you, trying to inhale. Surrounding you is water at the bottom of a column of 10 ft. (about 3 m) of water, squeezing you (and especially your torso) from all sides with 1.3 atm of pressure. At your mouth is a snorkel. It contains air at the bottom of a column that is (depending on your definitions) 100 km + 3 m, so is at a pressure of 1 atm. Your diaphragm has to expand against 1.3-1 = 0.3 atm compression. Your diaphragm has to inflate your chest against 0.3 ton/sq. ft., which won't happen. | |
| Jun 6, 2018 at 23:26 | comment | added | user43021 | I can't get what do you mean here: "If you were to make a 10-foot long snorkel and dive to the bottom of a swimming pool to use it, you would fail to inhale. The pressure of air at your mouth would be about 1 atm, because the 10-foot column of air in the snorkel doesn't weigh very much. The pressure of water trying to squeeze the air out of you (like a tube of toothpaste) is about 1.3 atm. Your diaphragm is not strong enough to overcome the squeezing and fill your lungs with air. " With an oxygen pressure of 1.4 atm, it is bigger than the external pressure, so inhalation will be possible... | |
| S Nov 19, 2016 at 4:39 | history | suggested | EIG | CC BY-SA 3.0 |
the word "it" should have been is
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| Nov 19, 2016 at 4:24 | review | Suggested edits | |||
| S Nov 19, 2016 at 4:39 | |||||
| Oct 24, 2016 at 16:10 | comment | added | Karl | Oh, I am also not interested in this argument, im my case because it involves hearsay physics and anecdotal evidence. Good we agree on something. ;-) Oh, you are also right that oxygen is not flammable. | |
| Oct 24, 2016 at 16:00 | comment | added | Eric Towers | @Karl : Once it is out of the leak, it expands and cools while decreasing its pressure from 200 atm to 1 atm. This is not instantaneous. The rate is thermodynamically limited. See Joule-Thomson expansion. Additionally, I'm not interested in any argument that directly contradicts provided photographic evidence. | |
| Oct 24, 2016 at 9:26 | comment | added | Karl | @EricTowers Once it is out of the leak, it IS at ambient pressure. A running compressor has hot parts, that's a bit different from your 35°C fingers. | |
| Oct 23, 2016 at 23:54 | comment | added | Eric Towers | @nworb99 : Deeper dives involve switching gasses to mixtures with lower oxygen partial pressure. You may find the term "bottom gas" to describe the mixture to be used at maximal depth. (Beware "nitrogen" narcosis, a different hyperbaric inert gas hazard not discussed in this answer.) Trimix 12/52 (12% oxygen, 52% helium, 36% nitrogen) has a partial pressure of ~1.3 atm at 100 m (equivalent to air at 43 m). (Although helium is not magic. See high pressure nervous syndrome.) | |
| Oct 23, 2016 at 23:43 | comment | added | Eric Towers | @JanDvorak : Don't really want to get pulled into that quagmire. However, the NFPA placard for oxygen lists Flammability: 0. The USCG CHRIS code lists oxygen as "not flammable". The DOT places compressed oxygen in class 2, "Non-flammable gas". So, by appeal to various authorities, I'm comfortable calling (even compressed) oxygen "not flammable". (Several of these note that oxygen can enhance combustion, a sentiment with which I heartily agree.) | |
| Oct 23, 2016 at 23:38 | comment | added | Eric Towers | @Karl : The oxygen escaping from a leak at a tank refilling station will not be at ambient pressure. Typical SCUBA tanks carry 175-300 atm and are filled by compressors working with gasses up to around 350 atm, although this maximal pressure is usually only present in a small part of the compressor. Jab in a leak at a random place, though, and you can expect to receive gas initially at 200 atm. I haven't directly observed the effect of placing organic valve grease in such an environment, but I have seen the charred bits of a compressor that had been part of such an "experiment". | |
| Oct 23, 2016 at 23:28 | comment | added | Eric Towers | @AaronAbraham : I am not a doctor, but my understanding from various readings is that tissue damage, especially to the lungs, can impede the uptake of oxygen leading to sub-normal oxygen uptake. (The equilibrium concentration of oxygen in the blood falls because the source term, oxygen in the air, is situationally reduced. This is vaguely like effusion.) One solution is to push more oxygen at higher pressure to increase the source term and establish a higher concentration in the blood. Note that CNS oxygen toxicity is a known hazard of HBOT. | |
| Oct 23, 2016 at 15:06 | comment | added | nworb99 | So if air mixtures become toxic around 220 ft, do technical dives below that depth have to use lower oxygen mixtures? I know that there are dives that go that deep, but wouldn't they be risking hypoxia during their descent/ascent/safety stop? | |
| Oct 23, 2016 at 12:48 | comment | added | Karl | Grease on your hand does not ignite when it gets in contact with pure oxygen at ambient pressure. An oily cloth is something different, there the heat can build up. | |
| Oct 23, 2016 at 12:26 | comment | added | John Dvorak | " It is not itself flammable, but it makes every nearby organic thing flammable." - define "flammable". | |
| Oct 23, 2016 at 10:33 | comment | added | Peter Cordes | @AaronAbraham: Some of the use-cases for HBOT are things that reduce blood oxygen (e.g. CO poisoning or lung injuries), but I'm curious about other use-cases. Maybe they monitor for signs of oxygen toxicity and stop the treatment if necessary? Otherwise, maybe it's worth the risk or small amount of damage? Maybe it matters that you're at rest during HBOT, not exercising by swimming around? (breathing more shallowly?) | |
| Oct 23, 2016 at 6:39 | comment | added | paracetamol | Whoa, nice answer! But would you also happen to know why patients subjected to HBOT (Which is at pressures exceeding atmospheric pressure) are given 100% pure oxygen? Yet again, thanks for the answer, it was pretty good! ^_^ Though it didn't answer everything in the question :/ | |
| Oct 23, 2016 at 0:53 | review | First posts | |||
| Oct 23, 2016 at 1:12 | |||||
| Oct 23, 2016 at 0:49 | history | answered | Eric Towers | CC BY-SA 3.0 |