Military Review

Breathing apparatus. Respiratory physiology

47

Photo: mil.ru


Since I did not find publications on autonomous breathing systems on the site, I decided to fill this gap a little.

I will try to get away from describing the designs of specific devices and giving some numbers. The purpose of the article is to review the general principles of the apparatus and the prerequisites for their creation.

At the same time, one cannot do without citing some figures when describing the processes occurring in the human body during the use of these devices. And it is for the same reason that it is necessary to touch a little on the physiology of human respiration.

Basically, of course, this will be an article about apparatus used for breathing underwater. That is, with increased external pressure. Simply because atmospheric or reduced pressure breathing apparatus is a simplified version of an underwater vehicle.

For the same reason, we will mainly consider devices used by amateurs of underwater diving. Exactly for amateurs, since professional divers use simple open-circuit devices, and their achievement of great depths and diving durations is ensured by auxiliary equipment. Such as descent vehicles, pressure chambers, special physiologists, support teams, etc., etc.

And here I will touch upon the issues of the influence of increased pressure on the human body, since without this it will be difficult to explain some of the design features of breathing apparatus, as well as the composition of the gas mixtures used in them.

Some abbreviations to reduce the number of characters in the text.

Inert gas is a gas that does not take part in chemical processes in the body.

Partial pressure is the absolute value of the pressure of the gas included in the gas mixture. It is often indicated together with the pressure value of the gas mixture. The unit of measurement is ata. 1 ata = 1 atmosphere at sea level.

Physiology


So, a little physiology.

The purpose of breathing is to saturate the blood with oxygen, which is necessary to ensure physiological processes in the body and remove carbon dioxide from it, which is formed as a result of these very processes.

To carry out this gas exchange in the human body, a special organ is provided - the lungs.

The inner surface of the lungs is lined with alveolar cells. Through the membranes of these cells, there is a transition from the blood, which is a liquid, carbon dioxide dissolved in it, into the air contained in the lungs, and the transition of oxygen from air to blood.

It should be noted here that alveolar gas exchange occurs under the condition of a DIFFERENCE in the partial pressures of gases in the blood and in the respiratory mixture in the lungs.

That is, having air as a breathing mixture: 0,79 atm of nitrogen and 0,21 atm of oxygen (to simplify the presentation), and venous blood on the other side of the alveoli with 0,06 atm of oxygen, 0,059 atm of carbon dioxide and 0,78 ATA of nitrogen, as a result of gas exchange, we obtain arterial blood with 0,125 ATA of oxygen, 0,052 ATA of carbon dioxide and the same 0,78 ATA of nitrogen.

Accordingly, the composition of the gas exhaled from the lungs of 0,79 atm of nitrogen, 0,17 atm of oxygen and 0,04 atm of carbon dioxide also changes.

It follows from this that in this gas exchange, nitrogen is an inert gas, since its amount in the inhaled and exhaled mixture is the same. And also the fact that the human body assimilates only 4% of oxygen from the air. This is important for understanding the prerequisites for creating closed-loop breathing apparatus.

Since the lungs are a kind of container located inside the body, it is necessary to ensure gas circulation to ensure continuous gas exchange. That is, the lungs must change their volume. Increase - inhale - decrease - exhale. There are 2 main muscle groups responsible for this in the body: the membrane and the external intercostal muscles.

And here I would like to note one physiological feature.

The receptors responsible for breathing, that is, those that induce a person to inhale, respond not to a lack of oxygen in the blood, but to an excess of carbon dioxide. And this is a very important point.

Indeed, even if there is enough oxygen in the blood for life, a person will suffocate, having an increased concentration of carbon dioxide. And having, for example, 100% nitrogen as a breathing mixture, a person will die without even understanding why.

It's simple.

Nitrogen, circulating through the lungs, will remove carbon dioxide from the blood. But oxygen will not flow into the blood, and the person will simply die, having previously lost consciousness from hypoxia.

Accordingly, the task of the breathing apparatus is to deliver a breathable mixture to the lungs and remove the exhaust gas from the lungs.

In this case, the gas at the entrance to the respiratory system must be at a pressure approximately corresponding to the ambient pressure. Indeed, if the pressure is very high, then there is a risk of damage to the respiratory system in much the same way as a balloon explodes if gas is supplied into it at a pressure exceeding the bursting strength.

And if the pressure is too low, then the muscles responsible for breathing simply cannot create the vacuum required to fill the lungs with gas. This is why no one makes long breathing tubes.

Indeed, if a person who is at a depth of, for example, 1 meter in water, tries to inhale through such a tube, then his lungs will have to overcome the pressure of 1/10 ata. And this very moment led to the emergence of two-stage breathing apparatus.

And also precisely because of the limitedness of our lungs, like a kind of pump, liquid breathing is almost impossible, no matter what our connoisseur of trampolines and concurrently the head of Roscosmos demonstrates.

This concludes about physiology and goes directly to the apparatus.

Apparatus


At this point in time, the most widely used breathing apparatus can be divided into two main groups.

1. Devices of an open cycle, which in turn are divided into:

a) single-stage;

b) two-stage.

2. Devices of a closed type.

In the course of discussion with the editors, I decided not to classify closed devices at all, since almost every device has its own characteristics. Therefore, I will just give the main or most used types of apparatus of the second group.

a) semi-closed devices with active gas supply (Active Semi Closed Rebreather - ASCR);

b) semi-closed devices with passive gas supply (Passive Semi Closed Rebreather - PSCR);

c) closed apparatus with electronic control of gas supply (Electronic Closed Circle Rebreather - ECCR).

It will be appropriate to mention here that there is another type of apparatus - Manual Closed Circle Rebreather (MCCR), but I do not want to single it out as a separate type. I will explain why when I write about an electronic device.

So this is the first part.

If someone is interested in the topic, then there will be a continuation ...
Author:
Photos used:
https://xfile.ru/
47 comments
Ad

Subscribe to our Telegram channel, daily additional materials that do not get on the site: https://t.me/topwar_ru

Information
Dear reader, to leave comments on the publication, you must sign in.
  1. kristofer
    kristofer 22 November 2021 18: 30
    +12
    still informative
    1. aleks neym_2
      aleks neym_2 22 November 2021 18: 41
      +12
      Teased and moved out ... and so interesting, thanks!
      1. Crowe
        Crowe 22 November 2021 20: 25
        +16
        And don't say in the most interesting place!
        If someone is interested in the topic, then there will be a continuation ...
        Author! "I demand the continuation of the banquet!" ©
        1. dauria
          dauria 23 November 2021 05: 35
          +4
          Author! "I demand the continuation of the banquet!" ©

          Subscribe! I also demand ... Moreover, most techies will not even be able to comment. The most that comes to mind is the Mendeleev-Cliperon equation. And something vague from school anatomy, in the lessons of which they were more staring at the girls' thighs. soldier
          So attaching the gills of a shark and making "Ichthyander" is impossible in principle, or is it just difficult?
    2. Moreno
      Moreno 22 November 2021 20: 45
      +7
      Used apparatus R-30 and R-34. The development was still pre-war, Droeger did. Then they adopted our experience and started doing it. I worked with this device for 7 years in the VGNG, as a platoon commander. Correct breathing, when walking, going up or down. Closed loop apparatus. This development is used by "combat swimmers". There was even a trick that Spenaz, Ukrainsky had the exercises canceled, the chemical absorber was not delivered
  2. Alexga
    Alexga 22 November 2021 18: 51
    +5
    All tankers used IP-5 in light diving training, hydro simulators and underwater driving. This is a closed-loop device.
  3. Harry.km
    Harry.km 22 November 2021 19: 08
    +5
    And also precisely because of the limitedness of our lungs, like a kind of pump, liquid breathing is almost impossible (c)

    And if not liquid (where and in what way is it more profitable than ordinary gas exchange?), But blood oxygenation by means of ECMO-type devices? You don't even need to breathe ... In terms of complexity, it is definitely easier than liquid. Drowning a diver like a dachshund is not necessary. We connected it to the ports on the vein and artery and forward, to any depths ... Or are there some problems with human physiology?
    1. Polite Moose
      Polite Moose 22 November 2021 21: 35
      +5
      Quote: Harry.km
      Or is there some kind of non-joining with human physiology?

      1. The lungs still have to be inflated with something. And this something (for example, an inert gas) must be under pressure, commensurate with the outside. Otherwise it will crush. And this boost will lead to the dissolution of this very gas in the blood and the need for decompression. Why they remembered about the liquid as a lung filler, because it is incompressible.
      2. How big is the likelihood of creating a reliable "port" for connecting the apparatus you mentioned to a vein and artery, which would allow a diver to safely perform active movements at a considerable depth, and even more so to carry out combat or similar actions without the risk of violating the integrity of the connection?
      3. The sterility of the system must be absolute. Field conditions for connecting and disconnecting the device to the body are not unambiguous.

      We can someday solve these and other technical problems, but not today. hi
      1. Harry.km
        Harry.km 23 November 2021 00: 57
        +2
        Quote: Polite Elk
        these and other technical problems

        The fact that the technical problems are serious is understandable. Until now, in medicine, such devices have limited use precisely because of problems with connection, sterility and other related problems, despite their very high efficiency. But I think that the effectiveness of such devices is much higher than the "liquid" in the lungs. Imagine that, for example, it turned out to bring out the "ports" not like in medicine, but for example in the back area ... Well, or in some other place where they will be protected. Sterility, the same thing is not absolute, but now all kinds of catheters are used, for example, for dialysis.

        But the physiology of this is interesting ...
        Quote: Polite Elk
        The lungs still have to be inflated with something.


        What for? The ECMO apparatus replaces the human lungs. Some kind of mask with a small supply of inert gas under pressure, so that if you suddenly want to reflexively "breathe". And even then, as I understand it, if the receptors, than that will be irritated. And if the content of CO2 and O2 in the blood is optimal, then you don't want to breathe))

        This is, of course, thinking aloud, but I wonder if research in this direction is being conducted or conducted, then what is wrong? Technically impossible or physiological impassability?
        1. Polite Moose
          Polite Moose 23 November 2021 07: 06
          +1
          Quote: Harry.km
          What for? The ECMO apparatus replaces the human lungs.

          The lungs are an air cavity, which, when immersed to a depth, will be compressed by external pressure. 1 atm. for every 10 m. depth. If they are not filled with gas with a pressure close to the external pressure, they will simply be crushed. And if you fill it, the gas will dissolve in the blood (I don’t presume to say how the gas will dissolve through the non-contracting lungs, but I believe that it will be). And if we are talking about diving to great depths (otherwise it makes no sense to fence in the garden), then we still run into the need for a long decompression upon ascent. So the main problem with deep-sea diving is not to stop the need to breathe, but the possibility of a safe ascent. hi
          1. Aviator_
            Aviator_ 24 November 2021 08: 14
            +1
            If they are not filled with gas with a pressure close to the external pressure, they will simply be crushed.

            There is, of course, a problem, but a freedivers' dive record of more than 100 m, the lungs are a rather elastic organ.
            1. Polite Moose
              Polite Moose 24 November 2021 08: 28
              +1
              I partially agree with you. For a short time and up to a certain depth limit, you can not bother with lungs too much. But for great depths and long dives, you still have to look for some kind of solution. hi
  4. Knell wardenheart
    Knell wardenheart 22 November 2021 19: 36
    +7
    A very intriguing start and a lot of interesting information! The author for you "+", I will wait for the continuation)
    P / s about electric gills will you write?
  5. Leha667
    Leha667 22 November 2021 19: 40
    +7
    Excellent article!
    We are waiting for the continuation in relation to the devices in service in our army and navy.
  6. Cheerock
    Cheerock 22 November 2021 19: 50
    +7
    Continue, dear Don! hi
  7. 75 Sergey
    75 Sergey 22 November 2021 19: 57
    +6
    Again, in the most interesting place!
  8. Lepsik
    Lepsik 22 November 2021 19: 57
    +5
    ---- as a kind of pump, liquid breathing is almost impossible

    As I understand it, the great expert on Roscosmos missed logic at school.
  9. KSVK
    22 November 2021 20: 05
    +11
    Quote: aleks neym_2
    Teased and moved out ... and so interesting, thanks!

    Well, why immediately moved out. The OC is almost ready. It turned out, though unexpectedly many letters. I will consult with the moderators, maybe we will share.
    1. NDR-791
      NDR-791 23 November 2021 06: 25
      +3
      Quote: KSVK
      It turned out, though unexpectedly many letters.

      Better to share. Even a large elephant should be eaten in small pieces. And you will probably have to climb into the literature or the network to clarify something.
  10. archi.sailor
    archi.sailor 22 November 2021 20: 07
    +7
    And when will there be a sequel? Very informative topic
  11. Nikolaevich I
    Nikolaevich I 22 November 2021 20: 11
    +10
    The author is great! He wandered into the virgin lands and decided to stay there ... and he will do the right thing, if so! Nobody has really "plowed" this topic yet! I just imagined the "scale", like breathing "stuck in the goiter!" How the Sumerian special forces in the "aquatic environment" used wineskins inflated with air ... how divers of the XNUMXth-XNUMXth centuries breathed ... why scuba gear appeared only in the forties, and before them they used oxygen devices ... and so on!
  12. KSVK
    22 November 2021 20: 12
    +9
    Quote: Harry.km

    And if not liquid (where and in what way is it more profitable than ordinary gas exchange?)


    Have you heard about the DCS? With liquid breathing, DCS will become a thing of the past. It remains only to figure out how to implement it. what I will try to explain everything later.

    Quote: Harry.km

    , and blood oxygenation by means of ECMO-type devices? You don't even need to breathe ... In terms of complexity, it is definitely easier than liquid. Drowning a diver like a dachshund is not necessary. We connected it to the ports on the vein and artery and forward, to any depths ... Or are there some problems with human physiology?


    I am not a special physiologist, I cannot say how to function without breathing .... It seems to me that patients under the above devices are at least unconscious. Well, such a device is unlikely to fit into a wearable "backpack". I'm already silent about the batteries ... wassat
    1. Harry.km
      Harry.km 23 November 2021 01: 13
      0
      Quote: KSVK
      With liquid breathing, DCS will become a thing of the past.


      What's the difference how the gas gets into the blood? I even think that if the blood is saturated with gas not through the alveoli of the lungs, but in some kind of apparatus (ECMO), then there will be an option to also remove gas from the blood when it boils. Let not instantly, but faster than the body will do it.
    2. Harry.km
      Harry.km 23 November 2021 01: 17
      +1
      Quote: KSVK
      It seems to me that patients under the above devices are at least unconscious.


      Nope ... Now ECMO devices are also used on conscious people ... They are expensive and very cumbersome, but these are technologies. If there is no fundamental physiological limitation, then maybe they will come to such a method?
    3. ja-ja-vw
      ja-ja-vw 23 November 2021 11: 28
      +2
      1. The liquid for breathing is viscous and poorly removes carbon dioxide, so forced "ventilation" will be needed (I don't know what to call
  13. KSVK
    22 November 2021 20: 18
    +9
    Quote: Knell Wardenheart
    A very intriguing start and a lot of interesting information! The author for you "+", I will wait for the continuation)


    Thanks! Apparently the moderators were not mistaken that the topic would be interesting.

    Quote: Knell Wardenheart

    P / s about electric gills will you write?


    I will try to answer all questions. To the best of my competence, of course. But first, I still plan to finish what I announced. I think that many questions will disappear by themselves. bully
  14. TermNachTer
    TermNachTer 22 November 2021 20: 23
    +8
    The article is interesting, albeit somewhat lengthy. The midshipman at the Black Sea Fleet divers' school was explained to us faster and no less accessible.
  15. KSVK
    22 November 2021 20: 33
    +10
    Quote: TermNachTER
    The article is interesting, albeit somewhat lengthy. The midshipman at the Black Sea Fleet divers' school was explained to us faster and no less accessible.

    Did the midshipman explain to you why the Soviet Navy allowed PPO2 3 ata? belay
    But seriously, the article is still intended for a wide audience. And, hand over to me, not everyone has diving training. hi
    1. Legionista
      Legionista 22 November 2021 23: 15
      +3
      Warrant officer explained. But they used the terminology adopted by the Navy's PVS. And there are other designations for partial pressure and other units of pressure measurement). Indeed, pure O2 could be breathed in the IDA up to 20 meters. But the risk of oxygen poisoning is very high.
  16. archi.sailor
    archi.sailor 22 November 2021 20: 42
    +1
    Dear author, could you comment on the following: "Did the midshipmanA explain to you why the Soviet Navy allowed PPO2 3 ata?" What is the value of PPO2?
  17. Aleks2048
    Aleks2048 22 November 2021 21: 00
    +5
    Really curious. Continuation is necessary.
  18. hohol95
    hohol95 22 November 2021 21: 37
    +2
    Reading the article made me remember the novel by Robert Heinlein "I have a spacesuit - ready to travel."
    In it, the main character takes part in a quiz and receives a used spacesuit as a prize!
    And he decides to restore it to a state suitable for use in space!
    It also described how he found the optimal air mixture for the balloons of his spacesuit!
  19. KSVK
    22 November 2021 22: 57
    +1
    Quote: archi.sailor
    Dear author, could you comment on the following: "Did the midshipmanA explain to you why the Soviet Navy allowed PPO2 3 ata?" What is the value of PPO2?

    Maximum allowable oxygen partial pressure. Sorry. Diving past, his mother ... repeat
    1. NDR-791
      NDR-791 23 November 2021 06: 30
      +1
      Quote: KSVK
      Sorry. Diving past, his mother ...

      Exactly. And I mean too. I still understand because it is also "with the past", but I suspect that if there are "jungles", then I still have to clarify
  20. Reklastik
    Reklastik 22 November 2021 22: 59
    +2
    Hey, hey, hey, author, how did you cut it off abruptly! Of course interesting!
  21. zwlad
    zwlad 22 November 2021 23: 16
    +1
    Interesting however.
  22. KSVK
    23 November 2021 00: 21
    +2
    Quote: Legionista
    Warrant officer explained. But they used the terminology adopted by the Navy's PVS.


    I honestly have not studied this document. Moreover, he did not apply the limits indicated in it in practice. I want to become an old diver. I don't want to be brave.

    Quote: Legionista

    And there are other designations for partial pressure and other units of pressure measurement).


    Really in mmHg? belay
    1. Aag
      Aag 23 November 2021 03: 54
      +4
      "... I want to become an old diver. I don't want to be brave ...."
      Probably, for the general public, it was worth explaining that there is a slang proverb, built almost into the motto: "There are no brave old divers!"
      However, the article is read by people who are at least interested))) ...
      hi
  23. KSVK
    23 November 2021 00: 25
    +4
    Quote: AlexGa
    All tankers used IP-5 in light diving training, hydro simulators and underwater driving. This is a closed-loop device.

    Looked at what kind of apparatus. Wow. Fierce unit. And O3 to you and a starting cartridge with sulfuric acid. Tin. belay
  24. Nitten
    Nitten 23 November 2021 02: 11
    +1
    Write pro, Bro! The more letters, the better!
  25. KSVK
    23 November 2021 02: 19
    +2
    Quote: Harry.km
    If there is no fundamental physiological limitation, then maybe they will come to such a method?

    Quite possible. But this is a matter of a VERY distant future.
    Quote: Harry.km

    remove gas from the blood when it boils

    There will be no boiling. I'll tell you everything in the third part.
    I hope you will see the second one today. Only there is a tedious man. From theory to practice, so to speak. yes
  26. Vale2000
    Vale2000 23 November 2021 13: 30
    -1
    Write, the topic is interesting.
  27. O. Bender
    O. Bender 23 November 2021 19: 46
    0
    Personally, I am far from the topic, I mean knowledge in this area, but it was interesting, very interesting! I look forward to continuing. The author is a big plus. When can we evaluate what is presented on the forum? A question for the moderators.
  28. Vale2000
    Vale2000 24 November 2021 08: 04
    -1
    It would be interesting to find out about these things.
    1. KSVK
      24 November 2021 18: 10
      +2
      Quote: Vale2000
      It would be interesting to find out about these things.

      In the photo KIP-8 Oxygen insulating gas mask. Working time 2 hours, weight 10kg. Used with a gas mask. Designed for outdoor use. Theoretically, it is possible under water, but I would not go. In any case, up to 6 meters deep.
      Oxygen cylinder 1lx200 ata. There is a pressure gauge. Works in a semi-closed cycle with a constant feed. Absorber KhP-I.
      It has long been discontinued and is practically not used anywhere. You can find devices in good condition from storage.
      1. Vale2000
        Vale2000 24 November 2021 19: 53
        -1
        Thank )))
  29. Timofey Kostin
    Timofey Kostin 2 December 2021 13: 51
    0
    Respect to the author, because the topic is very interesting, albeit immense. Military underwater water swimming has always overtaken and dragged civilian diving (performed with the help of technical means, of course, because they started to dive to get what to eat early), we owe much of it to the current achievements, when people dive to several hundred meters even without rigid spacesuits. I myself am engaged in the translation of diving materials (PADI) for work, and for the soul I write adventure literature - including the topics of freediving and combat swimmers. Those who are interested may be curious https://author.today/reader/33983 (True, underwater-underground episodes in the second volume).