Nitrox Enriched Air And The Magic Circle
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- Опубліковано 10 сер 2016
- Nitrox Enriched Air And The Magic Circle
The easiest Nitrox (Enriched Air) calculations you will ever do. By using the Magic Circle, you can calculate your Oxygen Dose, Maximum Operating Depth, and Best Mixture for any dive you decide to make. To do your calculations, remember that you only need two parts of the formula to get the third. If you are working top to bottom, you will use division, and if working side to side, you use multiplication. The top section of the circle will be you Oxygen Dose (PPO2 1.4 or 1.6). The bottom left of the circle will be the percentage or blend of Nitrox you will use. The bottom right of the circle will be your ATA (Absolute Atmospheric Pressure) or Depth once converted. Using the formulas listed below will make your Nitrox experience more safe and more practical.
The Magic Circle
Oxygen Dose
PO2 = FO2 x Pt
MOD
Pt = PO2 / FO2
Best Mixture
FO2 = PO2 / Pt
EAD (Equivalent Air Depth)
[(FN2 / 0.79)(D+33)] - 33
Absolute Pressure
Pt = (D / 33) + 1
Pt = (D + 33) / 33
Converting Absolute Pressure to Depth
D = (Pt - 1) x 33
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OH! MY! GOD! I am a Master Diver. I am currently training to be a Divemaster with SSI and PADI. I have a degree in engineering, but nobody has ever explained this as simply as this video. Thank You! That's awesome and I'll remember it when I take my Dive Theory and Science of Diving exams.
Glad you liked the video. Good luck on your Divemaster Certification, both with PADI and SSI. I look forward to saying congratulations as you pass over into the professional world of diving.
I'm Taking courses with UTD, they teach magic circle on classes BEFORE your Advanced OW cert. Basicly learning tec diving/cave diving from the very beginning. Magic circle is just one equation, there are a lot more calculations that PADI doesn't teach. UTD is blowing my mind right now.
I know he explains it so well, just started ow and iam try to understand the physics. And am not an Engineer and it makes sense to me. If I was closer I would have him train me and my boys, very valuable resource for us. Thanks for taking the time to share knowlege Bryan !
This is exactly why I subscribed to this channel. Because every time I'm taking a class, the search for answers brings me back here! Excellent break down! Cheers
Hello Signalsoldier, glad our video has helped.
just took a Nitrox course and when it was over I had no idea how to I was going to remember the calculations. Great job making it make sense! Thank you!
Hello steven probst, thank you, and glad to hear that our video helped you.
You made my day man, i am currently taking training to be a Dive-Master with SSI and i was trying to gather all the formulas in my head at once but i always get lost somewhere, your simplicity is brilliant.
Hello Ashraf, glad you liked our video and you found it educational. We have a full series on Scuba Physics that can help you during your Divemaster Training. Make sure to check them out.
Thank you for all your teachings, it helps us a lot, especially when you re new to diving...I love these kinds of teachings and explanations !
You are welcome Younes Ben Amar, glad you liked the video and found it helpful.
I recently got Nitrox certified. While talking the online class via the app, I didn’t like the formulas - they ran together and didn’t help me understand it. I searched and found this video, and WOW. So simple. During the class portion of the course, it appeared that the class wasn’t understanding the formulas either. So, I asked the instructor, “May I show you an easier way?” I showed the class the magic circle, and everyone got it immediately. Thanks! (I got a 100% on the exam, if you’re scoring at home. Lol)
Congratulations DenverDavid on earning that 100%. We are happy that our video made it easier for you, and thank you for sharing it with your class. If you ever have any questions, please let us know. We have an entire series on gas calculations that you may find interesting as well.
This video has SAVED MY LIFE! Thanks for explaining this so well! 🙌
You are well welcome Camilla Wright, glad you found it helpful.
I am a new dive and just got Nitrox certified, your videos are so clear and easily understood!! Thank you so much!!
Hello Clements, glad you found our video helpful. Welcome to the underwater world.
This is a GREAT video. Thanks for your time and talents in putting it together.
You're welcome, I'm glad you liked it.
This video should be used as the gold standard for teaching Nitrox calculations. Well done, sir!
Thank you Elliot Moon for the kind words. I'm glad to hear you liked the video.
Great and simple video sir
For those using METRIC ..
1 Ft = 0.3048 M
METRIC absulote pressure
Pt= (D+10)/10
METRIC absulote pressure to depth
D= (Pt - 1) x 10
Thank you very much
Thanks Othman Alali, and you're welcome.
Thank you!!
Love this simple explanation. Thanks for this video and all the others.
You're welcome and glad you liked it.
Excellent teaching video. Well done. If I'm ever diving in the States, in your neck of the woods, you'll definitely have my business. 😊
Thank You, much appreciated.
Love these kinds of videos! Keep up the great work!
Thank You, will do.
As SSI/PADI instructor teaching/diving in kohtao Thailand for over 9yrs+. it's pleasant watching you make things simpler than calculation by what formula is presented on the application for student.
Hello ONE 2 DIVE, glad you liked the video. We have always tried to simplify the learn of physics in scuba, to make it easier for others to become more educated in diving.
I just got certified for Nitrox , this is very simple formula. Thanks.
You are welcome.
That's an amazing explanation, good teaching, thank you so much!!.
You're welcome, glad you liked it and found it easy to understand.
Brilliant- tx, stellar block of instruction- preiatcha!
Glad you liked the video @davidhubble5283
Another excellent info tube. Thanks Brian. (Stu, Brisbane, AUS)
Hello Stuart, glad you found our video to be helpful. Happy Diving.
THANK YOU. I am going through my Advanced Nitrox and Deco right now. This E Learning crap is for the birds. You just saved my butt.
Glad you found our video helpful @haltarpley9237.
Best nitrox math explanation ever!!! Love this I have so much more confidence in my calcs now!
Hello Johnny Robinson, glad you found our video helpful.
When I earned my PADI nitrox certification I HAD to know how to figure this math out. They still used the NOAA 1 &2 nomenclature, and we had 32 & 36 tables. That was while ago - I don't think they even use tables for o/w anymore... Great video and great instruction!
Thanks David Shearer, glad you liked the video.
I used to use the other formulas in the Nitrox Manual, The Magic method is awesome Thank you making it fun and simple most important clear .
Kevin Eon Basheam Fredericks Glad you like it. We love using the magic circle.
Excellent teaching video. It is helpful to understand the basic physics of diving Nitrox and calculating safety ranges..
Thank You, glad you liked it.
Brilliant explanation! The full beauty of its simplicity comes to light when using metric system ... stupid simple mathematics
Math tends to be scary for new divers. We do our best to break it down to the simplest form for divers, so they can focus more on the fun aspect of diving, and not so much on the physics.
Excellent video. The math is rather easy, but the diagram makes it easy to remember and have confidence you are doing it right!
Thanks Dean B, and glad you liked our video and found it helpful.
Loved it. Thx alot
You're welcome Mohammed Hassanien, glad you liked it.
awesome and simple. signing up soon for my open water certification
Glad to hear
Fantastic video gents. I had never actually known about the magic circle. I had always known it as the triangular T formula.
This is one of my favourite intangible tools of diving. To the newcomer it may look overwhelming at first but in reality it couldn't be simpler.
Hello Chase Kaplan, the Magic Circle is the T formula. Just renamed.
Wow.... Thanks so much. Simplest way to look at it. I wish I could like this video 10 times......👌
Hello Ali Razvan, glad you liked the video and found it helpful.
Thanks. I needed a refresher. I took the nitrox course a couple years ago. I just now converted 2 tanks to nitrox. I'll need to know all this for the fills my guy gives me. He's also my instructor and he's thorough
Hello carsales34, you're welcome and glad you liked the video.
@@LakeHickoryScuba your videos are very easy to understand. I've been diving for 3 years, have over 100 dives and I find your stuff informative.
Awesome job; great video!
Thanks Bruce
This is why it's so easy in Europe: 1 Atm = 1 Bar = 10m of depth. None of this multiply or divide by 33 (actually 32.7 if you want to be pedantic). And of course if you really don't have a computer there are still recreational dive tables for the common 32 and 36% mixes. Great explanation.
Thanks Tim Gosling, glad you liked the video.
Great. Thank You.
Respect.
You are welcome
Thank you so much!
You're welcome
Awesome Brian. As usual
Thank you John Raymond, glad you liked the video.
magic teacher lol.Love all your videos
Thank You, glad you enjoy them.
This is great - I kinda have a bit of dyscalculia, so I always benefit from a canny teacher explaining the principles.
Hello Bill Scurry, glad to hear you enjoyed our video and found it to be helpful.
Excelent explanation. Now is very clear, not just by the circle by also and principally because of the aplication of values
Hello Fabian, glad you liked the video and found it helpful.
Mate, thank you so much!
You're Welcome
Very simple, incredibly clear, thanks for Ireland (I just had convert to meters :p)
conor mullholland You're welcome. I've had several request to make future videos featuring both imperial and metric. I will try my best to do that in the future.
Definitly better than instructor explained
Glad to hear. Hope it makes understanding Nitrox easier for you.
IT WAS BEST EXPLAINED !!!! I LOVE IT
Thanks Wojciech Martynko, glad you liked the video.
absolutely informative .tq
Hello Richard Poh, glad to hear you liked the video.
You are truly the best
Thank You
Hi lake Hickery Scuba from England, I enjoy all your videos. As a beginner in diving would it be possible to also explain your calculations on each of your videos using also the metric system. There aren't videos like yours on the BSAC websites that I have come across. YOURS ARE FANTASTIC***********
Hello Derek Thoirn, we will be happy to start integrating the metric system into our videos as well. If you have a specific video we have produced that you need converted, please send me an email to lakehickoryscuba@gmail.com, and I can help you out. Thank you for being a subscriber and viewer. We make these videos to help divers become more educated and to stay safer while diving.
Taking my nitrox class tomorrow. This is easing my worries.
Good luck with your class Nicole Bradford.
LakeHickoryScuba this helped me with my class. My instructor was impressed. Thank you
You are very welcome.
thank you way easier
ginobrun1 You’re Welcome, Glad you liked it
That's why you should use metric system. For depth you just move the decimal point one place od the absolute atmospheric pressure to the right and subtract 10 and you have MOD in meters.
Hello Techt, thank you for sharing your thoughts with us.
Thank you Brian, very well explained. Makes sense, now i wonder if the reason why you subtract one from absolute pressure because thats surface pressure? Or is it just because thats how the calculation works? Is there an actual reason why we remove the 1 to make the calc correct ? Thanks man ur awesome.
Hello Hellrazor, in short, we have to convert Total Atmospheric Pressure back into Gauge Pressure.
Yes, the "1" comes from the assumed surface pressure (and assumes sea-level diving).
Forget feet and dive in metres makes the maths even more straight forward!
Personally, I have always tried to dive in water. Not sure what it would be like trying to dive in meters or feet, LOL. You would be correct though. The metric system is much easier to calculate than the imperial.
Hi Brain , the magic circle is great , could clear up one thing for me ? lower right section is PT, what does this represent ? P = pressure ? T ?
Thank You for the channel
Hello naa62. The easiest way to remember the parts of the magic circle are as follows. The top will always be PPO2 (Partial Pressure of Oxygen). The bottom right will always be Depth in ATA (Depth converted to Atmospheric Pressure), and the bottom left will always be your Mix (Precentage of Oxygen in a Mix, 32%, 36%, 40% etc. etc.) Hope this clears it up for you.
Perfect ty
You're welcome John Milsom, glad you liked the video.
Excellent video. Please do this with the metric system. Thanks.
I will try to impliment the metric system into our videos. For these calculations, all you have to do is change the formula from (Depth in Feet / 33) + 1, to (Depth in Meters / 10) + 1.
Thank you.
My wife and I just did our nitrox certs and I wish this had been part of the class.
Hello Moose, first congratulations on earning your Nitrox Certification. Second, we have an entire series on gas calculations here on our channel that you can use for review at anytime. Hope they help.
Easy to remember system. And easier still if you're doing your calculations in the metric system
Very True. Glad you liked our video Mathias von der Decken
What is 33 representing? ATA one atmosphere? Waiting for the course....I keep watching your video, ty
Hello John Milsom, 33 for saltwater (34 for freshwater) represents the point of atmospheric change at depth. Every 10 meters, 33 feet of saltwater, or 34 feet of freshwater, our atmospheric pressure changes by an additional 14.7psi. Thus, the effect a said gas has on us changes as well.
Newbie question here regarding dive computers being 'safer'... I've learned my dive tables and even compared the naui and padi air and nitrox tables. Both have a lot of rounding up and safety margin.. So my question is this: Although dive computers clearly are very convenient, since they calculate your nitrogen absorbtion on the fly there won't be that huge built-in safety margin. (as I understand it you might have gone deep breifly but with the tables you'd calculate the dive using that maximum depth) So in my mind you're getting closer to the actual point of requiring deco when you dive with a computer. Is this correct? I guess what I'm getting at is: If maximizing dive time isn't a priority, wouldn't you actually be 'safer' using tables?
Simply through efficiency is why computers are safer. Most computers algorithms are more conservative by nature than tables. And even now days, most recreational computers can walk you out of decompression for those happy little mistakes where divers extend their time longer than they should. Great question by the way Si.
@@LakeHickoryScuba Ah ok, sounds like they justify the extra expense. I guess you can't plan for everything and a dive computer has that extra flexibility.
Thank you for your reply, hope you're having a good day!
You're welcome.
Dalton's Diamond. Good explanation.
knightm27 Thank You
Dalton's T
Thank you so much.
You're welcome
I'm over 50 yo. I was originally certified in 1981. I got Nitrox certified oh about 3 or 4 years ago. I haven't dove much since getting Nitrox, I forget everything about that training. Ugh. I need a refresher!
We would be happy to do a Nitrox refresher with you.
How do I do that? I'm here in West Palm Beach, Florida.
Nitrox is a classroom only specialty, I can do it through Skype with you. Since you are already certified in it, all we will focus on is the math portion. We can briefly go over the requirements to get a fill and the equipment requirements. The main thing is doing the calculations. We teach quite of few Nitrox Specialties through Skype. Typically we would email the student the written exam, and have them email back to us for documentation. With you, since you are already certified, we can simply do the test together over Skype.
Taking my advance nitrox soon
Good luck with your course @ivoryjohnson4662
Another great tutorial where the PADI book sounded like Charlie Browns teacher
Glad to hear our video was helpful.
now can you make the same video using the metric system for european divers?
We will be happy to. We have been wanting to update the Magic Circle for a while now. Since we have better audio and video equipment, its definitely time to do so.
@@LakeHickoryScuba
Great can't wait to see this in metric.
I hate it if people make calculation videos and use the imperial system.
I mean hello there are only 3 countries in the world that use the imperial system.
Now the entire world have to convert it just because someone living in one of those countries are to stubborn to use the metric system
Your PO2 essentially resets when you’re on your surface interval unlike your nitrogen levels, right?
Actually No, it doesn't reset as fast as you might think.
It needs some time too. Not so much as Nitrogen but it still needs time....!
Γεώργιος Μπρίνταλος thanks.
Hello Caleb Mcelhaney, this very topic is covered in the Enriched Air Nitrox Course. Your exposure time to Oxygen is on a 24 hour time table. Not only do we have to worry about a single dive exposure, but we also have to worry about an accumulative time as well, over a 24 hour period.
Does the magic circle work if you dive in meters not feet
Yes it does, you would simply use 10 meters as a calculation instead of 33ft (sw)
Atmospheres=(metres/10)+1, so if you've got 1.6 in the top and you divide that by .32 you get 5. Now because this depth equation is transposed from the pressure equation we're gonna flip the (/10)+1 bit to (-1)x10, which gives us 40. If you assume a pp02 danger point of 1.6 atmo (some people are more conservative and dive to 1.4, I dive to 1.6) then our MOD is 40 which is the bottom of the PADI recDeep spec. I'd take air that deep, but if I'm only going to 30 or 35 metres I'd consider 32%. 36% at 1.6 threshold gives a MOD of 34.4 metres by the same formula.
U are truly the best
Thank You
There is a glare on your white board where you wrote the formulas, may I have a clear copy of the formulas without the glare. Otherwise this was outstanding information and instruction
Hello John Williams, here are the formulas.
Maximum Operating Depth (PO2 / FO2) = ATA. Take (1.4 / .32) = 4.375 ATA. Then Convert ATA to Depth. (4.375 - 1) x 33 = 111ft.
Best Mix (PO2 / ATA) = FO2. (1.4 / 4.03 (100 ft)) = .34 or 34%.
Partial Pressure of O2 at any Depth (FO2 x ATA) = PO2. (.32 (32%) x 3 (66 ft)) = .96 ppO2.
Hope this helps.
Formula for the metric system:
MOD = ((1.4 / FO2) - 1) x 10 i.e: MOD is 33 meters where FO2 is 32% (((1.4 / .32) - 1) * 10)
FO2 = 1.4 / ((MOD + 10) / 10) i.e FO2 is 41% where MOD is 24 meters (1.4 / ((24+10) / 10)
Thank You.
TheAxelrod for 32% it’s nice and easy: 32 is 32. In other words, 32% O2 mix gives a max depth of 32 meters. Super simple to remember.
So 100ft would b 35% wouldn’t you want to go less o2 to be sure you don’t go past 1.4
Say 33% to keep u at about 1.35ppo2
You could most definitely do that. Over the years, calculations are all theoretical at best. There are no two divers in the world that body's act the same to the toxic effect of O2 at depth. The 1.4 is a simple line drawn in the sand. In short, it had to be drawn somewhere.
very cool :)~~~ thank you
djjoshua007 Your Welcome
For meters MOD is even simpler. Extract 1 and move coma one place to right andntiu have MOD in meters
A lot of people like the metric system Harry Kroliczek
hello this is very easy but can you pleas explain it in metric
Absolutely. When you calculate your ata, change the variables. For an example. Imperial 33ft of saltwater to ata. (33/33) +1 = 2ata. Metric 10 meters of saltwater to ata. (10/10) + 1 = 2ata. 10 meters of saltwater = 33 ft of saltwater.
Is there formulas in metric please?
Hello Christian Blecher, you can use the following.
To Calculate ATA from Depth-------- (Depth in meters / 10) + 1
To Calculate Depth from ATA------ (ATA-1) x 10 meters
Maximum Operating Depth--- (1.4 / MIX) this will give you ATA, Simply convert to depth
Best Mix---------------------- 1.4 / ATA
PPO2--------------------------- MIX x ATA
Calculations using Metric is based on 10 meters of depth per Atmosphere
Calculations using Imperial is based on 33 ft of Saltwater or 34 ft of Freshwater
Hope this helps
@@LakeHickoryScuba lovely, thanks very much
Nitrox buddy app works too
It sure does Marty Brasher.
Shouldn't your "D = (D - 1 ) x 33" formula shown above really be "D = (Pt - 1) x 33" ????
You are correct. Thank You for correcting me on that. Some times I get in a hurry when I type something and miss it.
don't you have a math error at 5:09 in the lesson .. you multiplied your 2.888 x 33 but in the lower left circle you wrote .36 - the math should give you the MOD of 104 -- right..?
Hello Greg Cohane. Calculating the Maximum Operating Depth, as shown in the video, is simply taking the 1.4ppO2 from the top and dividing it out by the blend, in this case .36 (36%). Then you take the atmospheric pressure and convert it back into depth as follows. (3.88 -1) x 33. This gives you the result of 95 feet. Hope this clears us the confusion Greg.
Thanks for clearing it up. I never passed math in all my education. Your summary helped completely.
@@LakeHickoryScuba why are you multiplying it by 33? Shouldn’t it be 36?
Hello Ken, the 33 represents the constant of the surface atmosphere. This is how we calculate total atmospheric pressure back into depth. If we were calculating the partial pressure of Oxygen at depth, then you would take .36 (36 %) and multiply it by your depth in atmospheric pressure to get the answer.
Add another formula. Converting ft to m :D
Google is pretty good at doing this for you. But a great way of doing it is to work through the ATA formula using feet, and then reverse it with meters. Here is an example. 33ft (sw) to 10 meters. (33ft / 33ft) + 1 = 2 ATA. (2 ATA - 1) x 10 = 10 meters. Thus, 33ft (sw) = 10 meters. This way you are practicing your Atmospheric Pressure Formula over an over and over. Or as stated before, simply type it into Google, and there you go.
Dalton’s Triangle.. it’s not a magic circle? But explained well.
Hello @MichaelTandy11, we also refer to it as the T-Formula.
The T formula is the basic trigonometric term which Dalton Law takes into account for us to work out mixes.
Why we 4.375-1..please explain
Hello Abid Khan, 4.375 represents the Abosolute Atomospheric Pressure in the calculation. In that specific example, we are calculating the maximum operating depth of .32 (32%) blend we can safely dive to. Hope this answers your question.
@@LakeHickoryScuba sir 4.375 is a Absolute atmospheric pressure but in formula why we use (-1).please explain about -1
Hello Abid Khan, for us to be able to convert the Absolute Atmospheric Pressure back into feet, we simply minus 1 from the ATA and then multiply it by 33ft (for saltwater), 34ft (for freshwater), or 10m (for metric calculations. So the 1 represents the conversion factor which represents 1 atmosphere. The 1 atmosphere is the constant atmosphere here at the surface, and depth is calculated as gauge pressure. Hope this makes sense.
@@LakeHickoryScuba sir please explain about inert gases..
@@AbidKhan-rb5kx The easiest way to think of inert gases is like this. They are neither good nor bad for you. Your body does not metabolize them like they do oxygen. When you inhale, the inert gas will either remain in your alveoli until you begin to exhale, or your body will begin to absorb them based on you depth and length of exposure. Nitrogen and Helium are the two major inert gases divers have to deal with.
why 33?
When doing an imperial calculation, 33 feet (for saltwater) is the variable we use to calculate a new atmospheric pressure. 34 feet would be the variable for freshwater calculations, and 10, meters would be for metric calculations.
@@LakeHickoryScuba Thank you!!!
And another example of how the metric system is superior 😂
Hello @FroggEater, thanks for sharing your thoughts with us. Glad to hear that the metric system is working out for you.
Why do you yanks still use feet where as us across the pond have gone metric like most of Europe
I'm not sure I have an answer for you sayittrue.
It doesn't make any sense to use the imperial system in diving. Nice video anyway
Hello Alessio Andreoli, glad you liked the video. We would encourage you to continue to use the metric system if its easier for you. We train all of our students in both imperial and metric, and let them decide for themselves.
@@LakeHickoryScuba , it is great to leave choice but if you think about, we work with metric systems since we are born. We have 10 fingers and it is just an evidence that if I am in trouble at depth and i have to change my plan, I do not want to count in feet because it is not that intuitive. Even the magic triangle that you explain so well cannot be done just in your mind if done in imperial system while it can with metric. 34 metres deep? add 10 and divide by 10 44/10 = ATA .. less margine for errors and safere therfore.
That’s definitely one way to look at it. Thanks for the comment Alessio Andreoli.
@@LakeHickoryScuba thanks to you for this so clear videos!!
Use meters.
Ok, we will try to start incorporating metric and imperial calculations in the future.
Stealing
Steal and share.
If all of you Americans forget the stupid imperial system and adopt the metric, everything will be better and more simple for all of us....
In case that some of you don't know, is much more simple to convert pressure to meters than it is to convert in feet. Simple every 1 ATM you have 10 meters... So the 0 meters (surface) is 1ATM of the air pressure above us, the 10 meters is 2 ATMs.... 20 meters is 3 ATMs etc.....
3.8 ATM will be 28 meters....
Simple as that. Forget feet!
Hello Γεώργιος Μπρίνταλος, thanks for the comment.
Can you talk any faster? not a very good instructor talking that fast.
Hello Skip Richer, sorry you didn't like our video and that you feel like I talk way to fast. Nevertheless, thank you for watching our video and commenting. It truly means the world to us, and supports us in many ways.
LakeHickoryScuba like your videos but need to slow down you people can understand.
Understood.
U are truly the best
Thank You