Understanding PPO2 And ATA

Understanding PPO2 And ATA
In response to a recent ScubaBoard article, www.scubaboard.com/community/..., Ladyvalea ask if someone could make it easier for her to understand PPO2 (partial Pressure of Oxygen) and ATA (Atmospheric Absolute). In this video we explain what each is and how they relate to Nitrox Diving.
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[@leighsutton8840]

This was THE MOST useful information when I did my Nitrox class.

[@LakeHickoryScuba]

Hello Leigh Sutton, glad you found the video helpful.

[@robertchambers5756]

This was one of the best videos ive seen on this. Really enjoyed it and got a better understanding myself.

[@LakeHickoryScuba]

Thank You, glad you enjoyed it.

[@landendominick4906]

you probably dont give a shit but does someone know a tool to log back into an Instagram account?? I was stupid forgot my account password. I love any assistance you can give me.

[@urielmilo3681]

@Landen Dominick instablaster :)

[@haryayurihidayat5059]

Excellent explanation, u make it simple enough to make it understandable.

[@LakeHickoryScuba]

Hello Harya Yuri Hidayat, glad you liked the video and found it educational.

[@Chogogo717]

The beer illustration was gold 😆

[@LakeHickoryScuba]

Thanks Caleb Mcelhaney, glad you liked the video.

[@sirenafilms4808]

@@LakeHickoryScuba Yeah I was having a lot of trouble understanding, but when he broke out the bud light I was like... ahhhh okokok.

[@axediepied6993]

Amazing explanation, you did an awesome job.

[@LakeHickoryScuba]

Thanks AXEDIEPIE :D, glad you liked the video.

[@eamonnjohnotoole8627]

Thanks for the video - very clearly explained.

[@LakeHickoryScuba]

You're welcome Eamonn John O Toole, glad you liked the video.

[@Bigntactical1]

Excellent video!! Thanks for this info!

[@LakeHickoryScuba]

Glad you liked the video Ulises.

[@davidroast3847]

Very goodm, made a lot of sense. Thanks for the metric explanation.

[@LakeHickoryScuba]

You're welcome David Roast

[@AdventureCayman]

LakeHickoryScuba I have watched a handful of your videos and thought they were all really informative. Anyway I am in the middle of my NAUI Nitrox class and needed a little help. I searched and found your video and I feel I have a very solid understanding now. Thanks so much for the wonderful videos, your content is appreciated.

[@LakeHickoryScuba]

You are very welcome AdventureCaymen, glad to hear our video was helpful to you.

[@LakeHickoryScuba]

You are very welcome AdventureCaymen, glad to hear our video was helpful to you.

[@LakeHickoryScuba]

You are very welcome AdventureCaymen, glad to hear our video was helpful to you.

[@confuseddaddio8764]

Subbed because of this video. Thank you. As a SSI Master Diver, this isn't something discussed frequently and as simply.

[@LakeHickoryScuba]

Hello Confused Daddio, glad to hear you liked the video, and thank you for the subscribe.

[@sirenafilms4808]

Thanks a lot brother. Loved it.

[@LakeHickoryScuba]

You're welcome Sirena Films, glad you liked the video.

[@raycarberry1089]

Great explanation, thanks mate

[@LakeHickoryScuba]

You're welcome, glad you liked it.

[@10MEDRADO]

Good stuff bud.. Keep it up👍🏻

[@LakeHickoryScuba]

Thanks 10MEDRADO, glad you liked the video.

[@nitromoose]

Man I wish we lived closer to you guys so we could do classes there. The guy that runs the SSI shop where I live is less interested in being a teacher and more interested in talking about how much of a badass he is. My wife and I are going back through all of these types of videos now to figure out all the stuff we didn't understand during open water and nitrox classes that were only done online.

[@LakeHickoryScuba]

Hello Moose, glad to hear that you like our videos and find them helpful. Anytime you would like to set up an online seminar, I would be happy to set one up for you. We usually do it through Google Meets. Let me know in the future if you ever need any help with a topic in Scuba Diving.

[@johnmorgan392]

Great video.

[@LakeHickoryScuba]

Thanks John Morgan.

[@adriancjones]

Great explanation.

[@LakeHickoryScuba]

Thanks adriancjones, glad you liked it.

[@du2lx]

Superb .. 👍🏼 Very clear

[@LakeHickoryScuba]

Thanks atty joey tamayo, glad you liked it.

[@doloressanchez3732]

I really like it! Tx a lot!!!!

[@LakeHickoryScuba]

Hello Dolores, glad you liked it.

[@ivoryjohnson4662]

You make things simple I can't wait till I get up there

[@LakeHickoryScuba]

Thank You.

[@ivoryjohnson4662]

Don't forget to email back

[@LakeHickoryScuba]

Hey Ivory, sorry I haven't got back to you. I will send you an email here in just a few minutes with several hotels in our area.

[@dmKrease]

I'd love to dive with you one day. You explain thing so well. Keep it up :)

[@LakeHickoryScuba]

Thanks Keith Baldacchino. If you are ever in the area, swing by the shop.

[@dmKrease]

@@LakeHickoryScuba Will do!

[@Petert8986]

Fantastic thanks

[@LakeHickoryScuba]

Glad you liked the video @Petert8986.

[@alanmacdonald89]

excellant!

[@LakeHickoryScuba]

Thanks Alan Macdonald, glad you liked the video.

[@dutyholidaymv4482]

VERY GOOD VIDEO

[@LakeHickoryScuba]

Thank You Duty holiday MV

[@superbholidays3520]

Superb

[@LakeHickoryScuba]

Thanks SuperbHolidays

[@scottselkey4460]

Good video. As I have advanced in diving I have had the curiosity to understand it more. Grade me: We can breathe 100% Oxygen at the surface all day long but we cannot/should not breathe 100% O2 at anymore than 1.6 atmospheres which equals 20 feet deep. 1.6 comes from "1" for the surface + .6 x 33 which =19.8 or 20 feet deep. At depths deeper than 20 feet we have to back off the O2/Nitrox percentage which leads us to our Max Operating Depths for a given percentage. In recreational diving out MODs are calculated at a PPO2 of 1.4 for safety.

[@LakeHickoryScuba]

Yes you would be correct. Good job.

[@gcolton]

Scott Selkey absolutely correct! And in technical diving you will find divers frequently hang a bottle of 100% O2 at the 15-20’ stop to increase their nitrogen off gassing during their last and most important deco stop. But beware: the gear most divers dive with is only built to handle 40% oxygen and will catch fire with higher percentages. There are special regulators build for 100% O2 which (to the best of my knowledge) are always colored bright green. If you decide to breath 100% O2, make SURE you get the training, understand the risks, have knowledgeable buddies, and use the proper equipment for that purpose. Bryan, as always, great content.

[@LakeHickoryScuba]

Thank You and great advice about Oxygen specific equipment and training.

[@pampigwo]

Awesome Thanks

[@LakeHickoryScuba]

You’re welcome

[@brandonm8868]

Brian, Thank you soo much for making this video, I have always struggled with this concept and haven't found a easy way to explain this to my students. I love the beer can example im definitely going to be using that in my own classes. Thanks. keep up the amazing videos they are all super helpful. Happy Diving!

[@LakeHickoryScuba]

Glad you liked the video Brandon M. Hopefully, it we be helpful to your students as well.

[@randle1972]

Great video! Subscribed! Have a question sir. If I bought a dive computer and set it to Nitrox...could I set it to 21 percent under the Nitrox setting if I was diving regular air and second dive switching to Nitrox or would I have to use the regular air setting on my watch and then switch the watch to Nitrox on the second dive? I would think I could just use the Nitrox setting for everything and just adjust the percentage of air? Please let me know what you think and thank you 🤠

[@LakeHickoryScuba]

Hello Randle’s Life Outdoors, Thank You for the subscribe, and the great question. Yes you can leave your computer in Nitrox and set it to 21%. In fact most computers require a 24 hour time frame after making a Nitrox dive, before you can switch it back to air mode. So switching over to 21% Nitrox for an air dive after a Nitrox dive is required.

[@oggyoi3967]

Thanks, this video out of a few i'd seen explained it so much better. I have one Q though. My dive computer has mine set at 1.6 as default. I've not done the Nitrox course yet so will have learnt it there but that 1.6 is currently set on my standard air (21%) is that ok or should that also be 1.4?

[@LakeHickoryScuba]

Hello Oggy Oi, most computers will allow you to change the PPO2 setting. As far as 21% air is concerned, the 218 feet depth rating for oxygen toxicity (set at 1.6ata), is not that big of a concern. Your maximum depth rating as a recreational diver is 130 feet. At this depth, Nitrogen Narcosis is a bigger risk than Oxygen Toxicity. Hope this helps.

[@diversdown2116]

Cool more math i love it I always learn or get a great refresh

[@LakeHickoryScuba]

Glad you liked it.

[@searching4279]

Thank you Bryan! Never was into NOX. By the way can you use a Nox take for 21%

[@LakeHickoryScuba]

You sure can Searching 4. As long as the air used is Oxygen Compatible (O2 clean air / modified grade E) it will not void the Oxygen Clean you have performed on your cylinder.

[@stevekenney8385]

Can you please provide some examples of PPO2 / ATA and 1.4% . I would like to see several examples, such as, Diving 32% at (x) Depth for (y) time to reach 1.4%. Thanks

[@LakeHickoryScuba]

Hello Steve, our Oxygen Clock set for any single dive (150 minutes), or dives over a 24 hour period (180 minutes) is the easiest example. Theoretical Depths and Times, whether we use the tables or our computers, should always be monitored. For 32% to reach a partial pressure of 1.4, you would need to go beyond the depth of 111ft(sw). Here is a video we did showing you how to calculate this theoretical depth. kzbin.info/www/bejne/fqCWlqWFoLN4jrM

[@leons.kennedy3600]

Thanks. U'r a great daddy

[@LakeHickoryScuba]

Thanks Leon for the kind words.

[@johnsmith-sn1bs]

Ok let’s say I go down to 33’ (2ata) with 40% mix that gives me a PPO2 of .8 if I remain at that depth does my PPO2 increase? Or do I just get more bottom time because of less nitrogen build up.

[@LakeHickoryScuba]

Hello user-mh6ug6ql4c, great question. During your Nitrox course, you learned about your oxygen clock. The sacrifice of Nitrogen Oversaturation changes to Oversaturation of Oxygen, which could lead to Oxygen Toxicity. For a single dive not to exceed a PPO2 of 1.4 a diver would need to limit his dive to a maxium of 150 minutes.

[@Richfxx]

What do you think about setting my dive computer to a max 1.35 ppo2

[@LakeHickoryScuba]

Hello Richard, I think that is a great idea. Adding an extra conservatism to your dive profiles never hurt.

[@recreationalvehicle5212]

What do you use for your 1st and 2nd on a bailout?

[@LakeHickoryScuba]

Hello Recreational Vehicle. Depending on what system I am diving, currently I have one bailout set up with a Mares 12S First Stage with an MV Second Stage. I also have a R2S First Stage with a Loop Second Stage and a 52X First Stage with a Dual Second Stage. Hope this helps.

[@recreationalvehicle5212]

@@LakeHickoryScuba what is the deepest you have gone WITHOUT a redundant system SOLO? IVE GONE TO 28' then i get scared

[@zezo1389]

Hi Brian Can you tell me how to calculate the amount of exposure to oxygen from multi-depth dives As the tables are based on the fixed depth according to the values of exposure And the second question does it appear in the Maris Smart Air computer? the % of exposure ? The third question: i know that nitrogen absorbs less than oxygen in diving usually. If that is the case, does oxygen have the same property, or is it that when it reaches the upper limit of 1.4, we can only go up to a higher levels and drop quickly? I hope the question is correct If you think it is appropriate to explain it in a video, I would be grateful As our trainer died, he made a technical dive at 65 meters, then after he finished the dive after 20 minutes and at a depth of 35 meters, he wanted to change to the Nitrox 37 cylinder, so he mistakenly replaced it to the cylinder with a concentration of 80, where according to the words of those who were with him, the oxygen was almost at His ascent reached 1.6. When the error occurred, the ratio shifted to 3.55. Can you explain what happened? Thank you for your wonderful communication.

[@LakeHickoryScuba]

Hello sniper hunch, just to keep this short, this would make a great video reply. That being said, its very difficult to show on paper (that means use tables) to calculate the exposure to oxygen at multiple levels, with out using formulas or computer calculations with ease. Not impossible, but in 2021 its much safer to use a computer to do this. Back in the day, we use to use the PADI wheel to do this, as it was a table based on multi-level diving. PADI discontinued this many years ago. To clarify the difference between Nitrogen and Oxygen though, our body absorbs Nitrogen but metabolizes Oxygen. And yes, the Mares Smart Air, once in Nitrox mode, will tell you your oxygen exposure at depth, and will compensate if you descend deeper or ascend shallower. Hope this answers your question.

[@hodaibrahim5385]

Is AtA has fixed rate . 1.32 ???

[@LakeHickoryScuba]

Hello Hoda lbrahim. Yes and no. The constant AtA at the surface will always be 14.7 (psi) sometimes argued to be 14.5 (psi), which can change based off altitude. For most calculations in Scuba Diving, 14.7 will be sufficient to use. Now depending on if you use the metric or imperial system, underwater things will calculated differently. In the imperial system, we focus on the water itself (either Freshwater or Saltwater), to determine the AtA. Freshwater changes atmospheric pressure every 34ft, and Saltwater changes atmospheric pressure every 33ft. In the metric system, we use a constant of just 10 meters. All this being said, the actual psi per AtA is still measured at 14.7 (psi). Now in the event that I have misread your question and you were asking what the depth would be with an AtA of 1.32, then it would be 3.2 meters (metric), 10.88 ft (fw), or 10.56 ft (sw). Hopefully this makes sense to you.

[@bill2292]

You didn't explain why we can't breathe more than 1.4 ppo2 or what happens and what to do if we do.

[@LakeHickoryScuba]

Hello Bill in short, anything above a 1.4 PPO2 of Oxygen, we run the risk of Oxygen Toxicity. Depending on the physiological make up of a human body, this number can be calculated up to a 1.6 PPO2. The 1.4 is a conservative number that the industry has used for many years for safety concerns.

[@signalsoldier]

Dude I wish we could clone you and spread you out around the diving community

[@LakeHickoryScuba]

Thanks for the kind words Signalsoldier.

[@hamidswimmer8]

It's just a little wrong with subtitles on ox tox that you typed ox talks...,,, Just for reminding

[@LakeHickoryScuba]

Hello hamidsswimmer8, we don’t put subtitles on our videos. That would be KZbin’s typo.

[@s28tyagi]

How did u come to 1.4 ppo2

[@LakeHickoryScuba]

Hello SIERA KILO, 1.4 ppO2 is the standard from most training agencies in regards to our maximum allowed partial pressure before O2 becomes toxic.

[@kenfern3365]

If I understood you correctly from your illustration, breathing 32% at the surface is the same as 32%. At 33', breathing 32% is like breathing 64% (2 ATA). So at 66', breathing 32% would be like breathing 96%. So a little more than 70' breathing 32% would be like breathing 100% O2, yet I thought anything below about 30' on 100% O2 was fatal, causing seizure, loss of consciousness = death? Obviously I'm not understanding something is your presentation as the MOD for EAN32 is around 110'.

[@LakeHickoryScuba]

Partial Pressures increase with depth. The general understanding of 1.4 being the maximum partial pressure of 02, before it becomes toxic, the partial pressure of 32% (.32) at a depth of 70 feet the partial pressure would be 99ppO2, well under the 1.4 threshold. 100% O2 (1.0) would have a substantial chance of becoming toxic at a depth of 13.2 feet of (sw). Typically, this is calculate at a 1.6 partial pressure, which would make the maximum depth be 19.8 feet of (sw). Using the Magic Circle Formula (the T formula), we can simply take .32 (32%) x 3.12 (70ftsw) and see that our partial pressure of O2 is at 99ppO2. Still well with in our maximum partial pressure. Calculating 100% would simply be 1.6 (Contingency ppO2) / 1 = 1.6ata. Then simply (1.6ata - 1) x 33 = 19.8 feet of (sw). Hope this clears it up for you Ken Fern.

[@Ducky27645]

Gosh dammit… As soon as Bud Light made an appearance, I had to move on. Lol…

[@LakeHickoryScuba]

Hello Ducky27645, sorry to here that you did not like our video from 4 years ago. Nevertheless, we appreciate you watching and sharing your thoughts with us.

[@Ducky27645]

@@LakeHickoryScuba Lol… I enjoyed your video. That was a joke fueled by current events. I learned a lot. Thanks.

[@larryrosa6995]

Look for new RE-BREATHER systems...... on the horizon.......fail safe in expensive.

[@LakeHickoryScuba]

Hello Larry Rosa, there are several Horizon dealers around.

[@rubenalvarez-moreno4065]

To much stuff, confused

[@LakeHickoryScuba]

Hello Ruben Alvarez-moreno, sorry that you found our video confusing. As you continue your training as a diver, it will become easier for you to grasp the information. Hopefully your local Instructor can help you out with it. If not, feel free to give us a call. We would be happy to set up an online seminar with you to help you out.