I teach for the MArines and have to teach PPo and law of absorbtion to a bunch of young marines. I know the laws but am having a hard time conveying it. ANy thought would be great and visual demonstrations.
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I teach for the MArines and have to teach PPo and law of absorbtion to a bunch of young marines. I know the laws but am having a hard time conveying it. ANy thought would be great and visual demonstrations.
Tell them a bunch of marines, and soldiers are pushing on a truck. You get partial push (pressure) from the soldiers, and the rest from the marines.
ha ha I would love to but I might loose my teaching quals
Alright, then football players, and wrestlers.
i need to explain it in depth such as gas toxcity increase into the body and surface area and volume and such
they get that the mixture of a gas is eual to the sum of its parts. But I need to relate that to the change in ppo at depth and how it relates to gas toxcicity
Well, let me give it a tryQuote:
Originally Posted by adam0321
It is the difference between chugging a beer bong (at surface pressure) and filling the bong with Jose Quervo (at depth)
One is not too bad, the other a killer.
Even your run of the mill bootneck can relate to that.
tru but then I have them thinking about libo and not about diving. thank you though. I have come up with the idea of using a seal a meal in class to show them how a bag(lungs) filled with marshmellows(gas) is full on the surface but at depth becomes compressed and therfore alowing more room for more marshmellows. and how at surface the preasure the marshmellow exerts on the bags(lungs) is not that great but how at depth they are pushing harder on the bag therfore becoming absorbed into the tissues more rapidly. this way I cover boyles.henerys,and daltons law all at once.
I am having a hard time showing how 32% nitrox is .76ppo2 at 45' but 1.58ppo2 at 130'. so 32%on surface is like 132% at 100'(just an estimate not actualy doing the math) I can do the equation and show them but its hard to explain and visualize why it is
Why would you need to teach them differently than the general population, aka cave divers?Quote:
Originally Posted by adam0321
As a former Marine, I found them to be intelligent people.
hmmm when were you in? We have some very inteligent people in our Corps but I am a firm believer that the class need to be tought to the lowest common dinominator
Great example. You can continue with it to explain your 32% nitrox increase. Skip the 45' and bring it to 33'. At the surface 32 marshmallows fill your bag. When you take those marshmallows to 33', they are half the size. But the bag is still the same size because it has more structure (muscles and ribs) to hold it open. But you still need to fill the entire space, so you must put another 32 marshmallows in there. At 99', you have to have 128 marshmallows in the bag to fill the same space. At 132' you have to have 160 marshmallows in the bag before it's full.Quote:
Originally Posted by adam0321
And you could fill the bag with different "color" marshmellows to represent Oxygen, Nitrogen, and Helium, taking it into partial pressure as well...?Quote:
Originally Posted by RN
I think the most important thing is they have to understand the concept of having over 100% once they go underwater. For example, at 33fsw, you "have" 42% oxygen and 158% nitrogen. This gives us .42ppo2 and 1.58ppn2. Once they grasp that concept, it will make more sense.
Some people will disagre with this, but I've given this example to more than a few divers that previously didn't understand partial pressures, and they said it made sense.
Edit: If your screen shows the word "go" twice, it isn't there on the edit page.
I really like the fruit juice example somone gave you over on rebreather world...maybe you can post it here as well...Bill
I was pretty sure i understood pp until I red this now i just want to drink beer, eat marshmallows and watch marines push a truck.
I equate it like this, but it may not be suited if you have any female marines in your class.
Partial pressures are like making a girl happy. At the beginning (surface) you only have to buy her the $32 presents (32% o2) but the longer you are with her (deep you go) the more money you have to spend to make her just as happy, so after 2 years (2 ata = 33 ft) you have to spend $64 to keep her just as happy (.64 pO2), and so on and so forth. after 4 years (4 ata = 99 ft) it takes $128 for the same happiness (1.28 pO2). and after 5 years (5 ata) it doesnt matter because you are dead (you know from OxTox or narcosis or marriage)
I know it is lame, but it works on some of the guys (and girls when reworded) I have tought.
Scott
i actualy started reading this about ten minutes ago but have just stoped laughing from Michael B's response.
I dont like using the fruit juice mixer because inlike your lungs the rebreather is solid and therefore not compressed at depth. The bag with different Marshmellow works pretty good but I guess no matter what some people will not get it. Thanks to all who have posted. RN I might give you a call later about this. you going to be at JB this weekend?
Does this diagram help? You can fill in the boxes with marshmallows. And the bottom two calculations are left off as an exercise to the students.
Adam, I'll be at Edd's all day Saturday teaching a sidemount class.
Different people have different comprehension strengths. My better half has a PhD in computer science. She has forgotten more about math than I will ever know. When it comes to physics and physioligy (sp?) she gets completely lost. It took a couple of runs to get her sound on a few of these simple diving laws.Quote:
Originally Posted by Puttzer
Yup as rn will testify. I am a math retard but I understand physiology fairly well.
I wouldn't call you a math retard. You got it. It just took you a little longer.Quote:
Originally Posted by adam0321
What exactly are you referring to??? I haven't seen anything negative about Marines in Adam's comments.Quote:
Originally Posted by Puttzer
I think trying to explain it as percentages >100% can just be confusing.
I'd just describe partial pressure as the fraction of a gas and how hard it pushes on the body at the surface. Then illustrate that each fraction pushes harder with depth, without changing the fraction. That way they don't confuse the concept of partial pressure with the pressure-volume relationship.
Maybe put 3 blocks of different widths under a board on a scale, to represent oxygen, nitrogen and helium perhaps. Show the weight reading and draw an analogy between that and partial pressure. 6 lbs total, broken into 1lb, 2lbs, and 3lbs for instance for each block. Then stack weight on top of the board in successive amounts. They could see that the blocks stay proportionally the same, but each one exerts an increasing pressure that is still the same proportion of the total amount.
Then to provide an analogy to O2 toxicity point out that if the bottom of the oxygen block was spiky (maybe rig up a separate block like that), there would be a point at which it would start to hurt if that was pressing against your body whereas the ones that were flat would not.
Simple, but once they have the basic concepts you can move on from there into specifics.
Quote:
Originally Posted by Webmaster
ohhh I like this one... not as funny as spending money and dieing of getting married to oxygen, but quite visual.
Whenever I teach this I use TDI's example of thinking of oxygen as a drug. Too little - you die. Too much - you die. The body must have at least 16% or 0.16ata, but no more than 160% or 1.6ata to survive.
To get too little you must breath a hypoxic mix, do some high altitude climbing or go up in an airplane that is depressurized. You will underdose on this drug and you may not survive.
But how do we get 160% oxygen? (Because talking about percentages over 100% IS confusing...) Standing at sea level breathing 100% pure oxygen you're at a partial pressure of oxygen equal to 1 ata. Now take that 100% oxgen to 20 feet and now you're at 1.6 ata or 160% oxygen. Take it below this depth and it will become toxic. You will overdose on this drug and you may not survive.
I always start by teaching my students how to convert depth in feet to atmospheric pressure (D/33)+1 = ATA.
Then I just go in 10 foot increments down the left side of a sheet of paper having them convert from depth in feet to ATA. I just teach them that these numbers are always remain the same. It's the breathing gas that will change. Off to the right from there I have them figure partial pressures of oxygen of various mixes by multiplying the depth in ATA by the fraction of oxygen in the breathing mix. For instance, air (.21 O2/.79 N2) at 100 feet (4 ata) would be 4 * .21 = 0.84. PO2 = 0.84. Is this within 0.16 and 1.6 ata of oxygen? Yes. Is that an acceptable dose? Yes. Let's try the same formula using 50% nitrox at the same depth of 100 feet (4 ata). It would be 4 * .50 = 2.0. PO2 = 2.0. Is this within 0.16 and 1.6 ata of oxygen? No. Is that an acceptable dose? No. Underwater that partial pressure of oxygen may cause a seizure which will most likely be fatal due to drowning.
I like to use examples of different gasses, starting with a hypoxic mix, then progressing to familiar ones such as air, 32%, 36%, 50%, 80% and 100%. Visually this helped me learn and that's how I now continue to teach it:
12%(.12) air(.21) 32%(.32) 36%(.36) 50%(.50) 80%(.80) 100%(1.0)
10'/1.3ata 0.156 0.27 0.416 0.468 0.65 1.04 1.3
20'/1.6ata 0.192 0.336 0.512 0.576 0.8 1.28 1.6
30'/1.91ata 0.229 0.401 0.611 0.687 0.955 1.528
70'/3.12ata 0.374 0.655 0.998 1.12 1.56
110'/4.33ata 0. 52 0.909 1.385 1.558
130'/4.94ata 0.592 1.037 1.58
210'/7.36ata 0.883 1.54
400'/13.12ata 1.574
Shown here is that "sliding scale" of oxygen vs. depth. The hotter the mix, the shallower its use. The 12% example requires a travel gas to be used until the diver reaches a depth of at least 12 feet where it increases to a PO2 of .16. All of the examples show the MOD of the gasses. This does not have to be complicated. I simply derived these numbers by multiplying the depth expressed in ATA by the fraction of the gas being breathed to create this simple table. Analogies just confuse me. I'm also the guy who took algebra three times in high school and once in college, so if I can do it, anyone can! Now I really enjoy this stuff. I hope this helps.
Thank you for your service.
****My table got jumbled when i posted it, but I hope you get the idea****
Confusing and wrong.Quote:
Originally Posted by Webmaster
To those who ar ein or have been in the Military I appologize if I offendd anyone. Those who know me know that I am a very proud Marine with numerious combat deployments and going on 7 years service in the Corps. I am not and never implied that Marines or any service are not an inteligent group. Some of the most inteligent people I have ever met are in the Military. I am a "grunt" by nature and all my students are "grunts". We are all now in reconnaissiance. Which is the USMC special operations. No one gets to the point they are combat dive school by being stupid. However the military is probaly the most deverse group of people. I have on everage 25 students with 25 different learning styles. I have had students who barely have a Diploma and in my last class I had a student with a masters in micro bio chemistry and physics. Not to mention I have 25 young men with higher then usual testosterone levels usualy recently back from 6-10 month in the desert now sitting in a class room in a building in Panama city florida with hundreds of bars withing 10 miles. So attention span can be a bit tough.
But again I appologize and thank any of those I offended
Semper Fi, Adam! Keep doing what you're doing, and thank you for it!
It's the pressure applied to the O2 and Nitrogen individually. While the percentages don't change 21/79 the concentration or density of the gas increases with depth.
You probably have a chart already showing the relationship between depth atmospheric pressure and volume. Use that in conjunction and show how the ATM and the density of each of the gases increase with depth and it's respective correlation with depth or absolute pressure.
Men tend to learn by looking at pictures.
Hope this helps.
Sent from my iPhone using Tapatalk
It's not wrong if it's in relation to what you breathe on the surface. Breathing oxygen at 20 ffw, you're taking in 160% as many molecules of oxygen as you'd be taking in at the surface.Quote:
Originally Posted by Squirrel Girl
You could do it with bullets and terrorists. Bullets being the gas and terrorists being pressure.
If one terrorist can absorb a maximum of 100 rounds of 5.56. You dump a whole mag into the terrorist, the terrorist's partial gun shot wound would be 30% or .3. If you dumped the whole mag into two terrorists the partial gun shot wound would be 15% or .15 Do you see where I am going with this. Dalton's the sum of all the percentage of bullets equals one terrorist, or something like the. Then Dalton's diamond would be terrorist over bullets.
Cheers!!
Kevin
Quote:
Originally Posted by adam0321
yeah sadly enough i would like to keep my rank and that may just knock me down a stripe
could always do the same thing but with beans in a can. Wouldn't think you would get in much trouble talking canned beans.
Kevin, that is SOOO offensive.Quote:
Originally Posted by caverkevin
Yeah, now that I think more about it, I suggest some editing Mr. Moderator... serious editing.Quote:
Originally Posted by Daphne
Hatred for other ethnicities should not have a place here. Even if it is just the appearance of hatred.
Sorry Kevin, its more than just not being politically correct.
Yea, I think I'm going to have to agree with Daphne on this one. Sorry.
No need to say sorry, it was wrong. And this is coming from a retired Marine. Sludge, clean up on row 6 please.
Everyone on this board is free to go into their settings in the upper right hand corner of each page. Under "my account" section there is a link to "edit ignore list". Enter caverkevin and select OK. I will not consider this offensive if people choose to ignore me and my comments.
Cheers!!
Kevin
I really don't think any of us were really expressing concern if you consider something offensive.
No No Kevin, I don't want to ignore your comments. You are missing the point.
This is a free country, you have to right to say whatever you want (I would fight for it and all the Marines out there in the world are doing it right now!) BUT we also have the right to call you on it. Freedom of speech does not come with immunity. If we just ignore you, you wont know that what you said crossed the line. AND It is totally demeaning to you in the end - Should I just blow everything you say off because you said something offensive? That's awful, you are person and I respect you, you just happen to say something awfully distasteful to civil society.
Look CDF is our group, WE are a community of lots of different kinds of folks. This is not your private livingroom.
I am sorry Kevin, I am calling you on the towel heads thing... not acceptable in our forum.
Do you think you would have gotten away with saying Nigger or Spik ? Not here.
No long term harm done, forgive and forget. Lets move on knowing that there are boundaries.
Quote:
Originally Posted by Daphne
Just wondering. If a person wears a towel on their head, is it not acceptable to call them a towel head?
http://image26.webshots.com/26/0/92/...7TGQVYN_ph.jpg
only if they are wet and out of the shower!
0321 Semper Fi:
There was an old running cadence that said ... I might me crazy but I'm no fool. You won't catch me in SCUBA school!
I've been there and done this before so try something!
A horizontal line on a chalk (now white board) representing the surface or 1 ATA along that line is a 21% column A 78% column and a 1% column for the other inerts. Explain to them that the 1 ATA reresents the weight of the atmos over their head here and now. When they get to 2 ATA (33ft) there is the weight of 2 atmos over their head and upon their body. 1 ATA being sky, 1ATA being water. This extra weight compresses the gas in air or any other mixture. Also explains why the tank only lasts half as long at 33ft, 1/3 as long at 66" etc as it does on the surface
1 ata _____________21___________78 _____________1_______
Then at the left a vertical line going down Write a 2 ATA at 33ft, a 3 ATA at 66 ft 4ATA at 99 ft etc. This will show the relationship to pressure and depth and the partial pressures of the gases to the right of the 2 ata's 3 ata's etc. The smart ones will pick it up and then sort out those that don't That's called homework. You can tell those that don't get it that its like feeling the pressure when reporting to their fire team leader or telling the same story to the company Gunny. They'll instictively know that the higher up the chain they go the more pressure thry will feel telling the story. Same with depth. "SSDD." My son in law had your MOS. Hope the graphs come thru if not PM me.
1ATA O ft_________.21_____________.78__________.1 -> partial pressure totals 1
]
2ATA 33 ]-------------.42----------------- 1.56------------.2 -> Partial pressures total 2
]
3ATA 66 ]------------ .63------------------2.34------------.3 -> ditto 3
et cetera