Oxygen movement from alveoli to capillaries (video) | Khan Academy
The air around us is a mixture of gases, mainly nitrogen and oxygen, but containing much Because of the action of wind, the percent composition of air varies. Cryogenic air separation plants - Produce nitrogen, oxygen and argon as Various types of air separation plants; Inter-relationships between plant type . arrangement may require changing your industrial gas supplier, we have tips for you. Thermodynamic and transport data for argon, nitrogen, oxygen, hydrogen, helium , and air plasmas have also been tabulated by Boulos et al. (). where.
How it Works As we've all learned from certification, when you dive, the water pressure causes nitrogen from the air you're breathing to dissolve in your bloodstream.
The higher the pressure, the more nitrogen will dissolve. After a certain concentration of nitrogen builds up, you must come back to the surface slowly in order to avoid either mandatory decompression stops or a case of decompression sickness DCS. For example, based on the U. Navy dive tables, a diver on air at feet reaches his or her no-decompression limit and must come up after 25 minutes. At 60 feet, the diver's maximum time would be one hour. Nitrox changes the numbers. When you replace some of the nitrogen with extra oxygen, there's less nitrogen available, which means it won't dissolve as quickly, allowing a longer no-decompression limit.
This concept is known as the equivalent air depth EAD. For example, divers at feet with 36 percent nitrox will dissolve nitrogen into their blood and tissues at the same rate as when breathing air at 80 feet.
Therefore, the diver's ordinary no-decompression limit of 20 minutes extends to 40 minutes — that's double the bottom time. The Dangers This benefit does not come without some cost. Oxygen, while useful and essential to life, can become hazardous in high concentrations, potentially leading to acute oxygen toxicity, which has some very nasty effects that range from visual distortions to convulsions that can lead to drowning. Any percentage of oxygen can cause toxicity at a high enough pressure.
But diving on air, you would have to go very deep, in excess of feet, to experience acute oxygen toxicity. The danger of nitrox is that it brings that possibility within recreational diving depths. There are two factors that divers using nitrox must consider regarding oxygen toxicity: One is the amount of exposure, or the pressure of oxygen in the lungs, and the second is the length of the exposure.
Combined, these two factors are called the oxygen limit. And let's see if we can figure out how they relate to what we're going through now and whether there's any clear relationship as to how to use these pictures that we've drawn up. So this first equation, this is the alveolar gas equation.
Practical Guide to Nitrox Diving
We've talked about this before. There's a video on this as well, if you want to refresh yourself. The first part of this alveolar gas equation tells us how much oxygen is going into the alveolus. Remember, this top layer right here. This is our alveolus right here. So it says how much oxygen is going into that alveolus. And this is actually the second bit is how much is going out.
And if you, of course, subtract what's going in from what's going out, you're left with, what is the partial pressure of oxygen in that gas space.
What is this blue PO2 equal? And this is actually kind of a nice segue for our second equation. We have this second equation, which helps us figure out how much oxygen is going to defuse, or any molecule really, according to this formula.
This is fixed law. And we can actually figured it out, by taking a few parameters. We can say, well, if you know that the gradient P1 minus P2 is a certain amount.
And if you know the area and the diffusion coefficient and the thickness, then you can figure out this V. And this V really the amount of oxygen, in this case. And we're going to focus on oxygen right now.
Amount of oxygen defusing over time-- so this is actually very helpful, because if you start noticing that the amount of oxygen defusing over time and the oxygen delivery that's coming into the red blood cells is low, then you might show wondering why that could be.
And remember, the red blood cell layer, that's down here.Intercooler - Explained
This is our red blood cell layer. So you start wondering, how is oxygen getting from that alveolus down to the red blood cells. And we can call the partial pressure of oxygen, the alveolus. We can call that P1. And we can call the partial pressure of oxygen down here into the red blood cells.
We call that P2. And so then when we figure out from the alveolar gas equation what this is, that is basically telling us this. So the two equations are basically very related. So if I notice that the amount of oxygen diffusing from the alveolus to the red blood cell layer is off, if it's less or more than what I expect, I have to go through a mental checklist.
I have to think, well, is the Fi O2 what I thought it was. And they're getting a lot more oxygen than what is in the environment. So that could be one reason for getting a higher value. You might also get a higher or lower value, because maybe you're not at sea level.
Maybe we're working with a patient at a mountain level or maybe below sea level. So that could also explain an abnormal amount of oxygen defusing over time. And these two things that I've drawn in orange box, they're both going to affect P1. This is the initial partial pressure of oxygen in the alveolus. Some of these things are probably less likely to be changing.
I wouldn't expect that the respiratory quotient is changing. If the person has a steady diet, then that shouldn't be any different. The partial pressure of water probably also isn't changing, especially if we're at body temperature. And the partial pressure of carbon dioxide, there, that could actually change. But just to keep things simple, and if I'm only thinking about oxygenation, I'm just going to assume that's going to be probably not the reason either. So going through my mental checklist.
I know P1 is going to be something I want to think very carefully about.
Oxygen, nitrogen and the rare gases
I also want to think really carefully about area. To obtain high purity oxygen, further distillation is needed and argon is removed. Since air separation plants operate at low temperatures, construction materials have to be chosen carefully. Aluminium alloys and stainless steel are frequently used.
They do not become brittle at low temperatures. Efficient plant insulation is necessary to make the process economic and safe. Perlite an expanded rockglass wool and vacuum jacket techniques are commonly used Figure 5.
Pressure swing adsorption can provide this and produce up to about tonnes a day. To produce oxygen, a stream of clean air is passed through a bed of alumina to dry the gas and then through a bed of zeolite molecular sieve.
Nitrogen is preferentially retained adsorbed leaving an oxygen-enriched gaseous stream to pass through Figure 7. When the zeolite becomes saturated with nitrogen it is necessary to regenerate it.
This can be achieved simply by reducing the pressure, whereupon the nitrogen is released desorbed back into the gaseous phase and rejected as waste. The sieve is totally regenerated in this way and is ready to repeat the cycle.
Two beds are usually used in rotation. One is used to produce the oxygen while the other is being regenerated. The full cycle time can vary between 2 and 8 minutes depending upon actual performance requirements. Instead of using a zeolite as in the manufacture of oxygen, nitrogen is produced from air using beds of carbon molecular sieve CMS.
Clean, dry, compressed air is passed through a bed of CMS typically at 7-I2 atm. Oxygen is adsorbed on the surface of the CMS and nitrogen passes through to storage.
When oxygen saturation is reached a second bed is brought on-stream, retaining continuity of supply and the first vented to atmosphere to desorb the oxygen and hence regenerating the CMS prior to the next cycle.