Choose Your Poison - Part 1 - AIR
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- Опубліковано 28 вер 2024
- A primer on the pros and cons of the different gas choices we have as technical divers. We start here in Part 1 with a look at air and the concept of partial pressures. From there we will look at nitrox, helium based gases and all the different issues related to our choices. Problems like oxygen toxicity, inert gas narcosis, HPNS and the effects of gas density.
NOTE at 4:20 I forgot to say that the 5% oxygen (weird gas) becomes breathable at 40m, because the PpO2 is now 5ATA x 0.05 = 0.25. This is the same as breathing 25% oxygen at the surface.
The second error you may have spotted is at 8:15. Slow tissues are those with a poor blood supply or LARGE amounts of fatty tissue (lipid).
Great video, looking forward to more in the series!!
Hi Harry, great to see there is going to be some regular content coming. Interested in a video on your thoughts regarding cut-off valves in CCR equipment which has been topical lately, either in manual add valves or in offboard connections. Do you use them and why? Hope you can get back across the ditch and into the Pearse soon.
Great video. I am thai newbie scuba diving for this kind of sport and will love to see more your video. 👍👍
Bloody great stuff. Looking forward to more content like this!
More to come!
Richard thank you for these videos they are wonderful, you are an inspriation in diving and as a person. Please make more content :)
Great to review!
Loving the videos and the know how! Could listen to you all day. Saw you on television earlier today and was told the wife " hey there's Richard I know him!" She said " how do you know him?!?," I told her I followed you on UA-cam, she proceeded to throw a pillow at me and tell me I'm an idiot. Lol
Ah she went to the same school of wife-ing as mine!
Thank you so much for making these videos. Your combined perspective as an expedition technical diver and anesthesiologist gives you a unique ability to articulate this better than anyone else.
Sir , i had a doubt .. in a fish aquarium when we use a air pump does it directly dissolves oxygen in the water as it pumps air in the aquarium or it just agitates the water and the oxygen from atmosphere dissolves in the water from the surface .. ??
Both I guess!
thank you Sir .. for your reply ..
would increasing respiratory rate during safety stop be beneficial with respect to off gassing excess nitrogen?
Hi it's a good thought but not really. Respiration is not the limiting factor in clearing the inert gas from your body. It depends more on liberating it from the tissues and getting it back to the lungs. That's why gentle exercise during decompression stops may improve the efficiency of deco. Emphasis on gentle because excessive exercise increases bubbling!
So it arises that there is an absolute limit of diving with lungs and gases which is around 300m?
What about hydrogen then?
Exactly why hydrogen may be employed. The deepest dive record was to 534 meters and it employed 1% O2 and 99% hydrogen for this reason. At that point, even using Hydrogen pushes the envelope on density.
Is only Oxygen, Nitrogen, Helium & Hydrogen used for deep diving? Why aren´t Neon or Argon used for example to reduce narcosis?
In reality only O2, N2 and helium are used. Hydrogen is an experimental diving gas with many practical and theoretical concerns. Argon is used in drysuit inflation as it has good thermal properties, but it is highly narcotic and also very dense so no good for deep diving. Other exotic gases like xenon are so narcotic they can be used as anaesthetics!
@@DrHarryH Thanks! :)
Sir…when’s the exam 😅
Thanks Richard, this should be in every instructors “share” list with OW students!
This was super helpful. Are you guys planning any deep cave dives for this year? It's fantastic to see the difference dives going on!
Quiet year I'm afraid :-(
Another great video - thanks.
Glad you enjoyed it
Awesome and very informative video. Amazing. Thank you for sharing your knowledge!
First time to your channel, Harry, and admired the way your present a complex topic in easy-to-understand terms. Well done and I am on to the next video!
Superb!! Lots more please!!👍🏻👍🏻
really great video! Looking forward to Part 2!
Super video! I hope to get more content from you! I am on the beginning of my Kiss Classic Training under ISE, and like your MEG in double config a lot. After your dive talk Interview, I would really like to see more of your explorations!Keep it up. Best regards from Austria!
Thankyou Markus!
Thanks Harry for another great video. You have a nice looking compressor set up there.
Cheers Paul!
In a close loop, do you need to add gas at the extreme depths you hang out at and does your system automatically bleed the extra gas if you add?
Yes and yes! As you descend the loop gets squashed so more gas must be added. On the way up, the reverse occurs. The main gas being added to deal with the pressure change is called the 'diluent'.
G´DAY HARRY!!! great master class. Thanks a lot for this video and just runing to watch the par 2. A great honor to see you in Covanera- Pozo azul
Thanks Berto! Good to hear from you! Did you guys end up buying the Argolamps?
Hi Harry; I am not Berto; just crossed a word on August 23erd while helping to carry @@DrHarryH a couple of cylinders.Thanks for the answer any way
A great explanation. New sub, rec diver interested in tec.
So Sheck Exley must have used at a 10% O2 in order to do those deep dives to 120m on just air, so 0.1 x 13 atm equals ppO2 of 1.3.
Because at 21% it would have been 2.73 ppO2, which I never could understand until I watched this video.
I still don’t understand why he didn’t get narcked though 🤔
He used substituted a majority of the nitrogen for helium which is not narcotic. It also has a lower density which makes it easier to breathe at depth.
@@mattiashenning7717 - he completed the dives on compressed air, not trimix
I haven't read any of Shecks books for many years, but I do recall him writing about his deep air dives. Don't forget that (for simplicity) air is defined as 21% O2 and 79% N2. Anything other than that then it’s not air - its Nitrox (assuming only O2 and N2 are mixed). 10% Nitrox would not have been used as it’s a very poor choice of gas. Its more narcotic than air, hypoxic at the surface and comes with a higher decompression penalty. WOB etc. still factors. So, he ran those dives on air which means he exceeded recommended pp02 limits. The 1.6 ppO2 re limit is there for good reason. Sure, people have exceeded it - look at Bret Gilliam's deep air dives as another example. I am not judging here btw, in the mid 90’s my DM buddies and I would regularly hit 2.0 wall diving in the Caribbean. Not condoning that at all.... I blame access to Navy Tables and patronizing Skin Diver magazine articles!
I would argue that he would have been narked. Narcosis is a physiological certainty. His long-term exposure, physiology, and the water environment all play a part - and so its effect on him may have been less pronounced - or perhaps more accurately, his ability to work around it may have been more refined.
I really appreciate these videos, for someone who's searching for a life interest i for the first time found gaining knowledge very interesting and almost like i could see a future in this type of activitie
Go for it mate 👌👌