Dave Sutton
Banned
You are breathing 0.21 right now.
Do you feel hypoxic?
Dave
.
Do you feel hypoxic?
Dave
.
Dry Hypoxia Training for Rebreather Divers
- Thread starter Dave Sutton
- Start date
Loop decay is quite simple to calculate.
Say you have a 7 litre loop on the surface.
You would require 7 litres of O2 to get a PPO of 1.00
At a depth of 10 meters you would add 7 litres on Nitrogen to maintain the same loop volume and the same PPO. In fact regardless of depth you need the same surface litres of O2 as it would take to fill the lung.
So even at 100 meters you still have 7 surface litres of O2.
Assuming a metabolic rate of 0.7 LPM of O2 you would last.... 7 litres/0.7= 10 minutes before all O2 was consumed. ( 7 minutes before it dropped below 0.21).
With a PPO of 1.3 you would have 30% more O2 so it would be 9/0.7
Say you have a 7 litre loop on the surface.
You would require 7 litres of O2 to get a PPO of 1.00
At a depth of 10 meters you would add 7 litres on Nitrogen to maintain the same loop volume and the same PPO. In fact regardless of depth you need the same surface litres of O2 as it would take to fill the lung.
So even at 100 meters you still have 7 surface litres of O2.
Assuming a metabolic rate of 0.7 LPM of O2 you would last.... 7 litres/0.7= 10 minutes before all O2 was consumed. ( 7 minutes before it dropped below 0.21).
With a PPO of 1.3 you would have 30% more O2 so it would be 9/0.7
Not at all. Because Im not. Im also not narc'd or suffering from vertigo or in a situation vastly different from where I am 99% of the time.
Whats your point?
matt
Well-Known Member
It's even easier if you use 10l instead, and a 1lpm you don't even need a calculator
Dave Sutton
Banned
Other than that I'm on a trip and only had a few minutes free to reply?
There is obviously no danger at 0.21
Low workload at 0.10 has a TUC of about thirty minutes but symptoms come slowly and can likely be detected if you know what your symptoms are.
0.05 gives you a minute more or less.
Most people don't realize that there is "some" period of diminished capacity yet where it's still possible to self rescue.
Dave
.
There is obviously no danger at 0.21
Low workload at 0.10 has a TUC of about thirty minutes but symptoms come slowly and can likely be detected if you know what your symptoms are.
0.05 gives you a minute more or less.
Most people don't realize that there is "some" period of diminished capacity yet where it's still possible to self rescue.
Dave
.
anarchista
New Member
Without giving oxygen consumption is junk information.
For those who want to know.
http://www.phr.net.pl/material/2011r/PHR4(37)2011/PHR4(37)2011.pdf
Table 2, page 59.
rc greet
Dave Sutton
Banned
This one cheats as it add diluent:
Dead in 7 Minutes - The importance of a constant flow oxygen orifice - ADVANCED DIVER MAGAZINE - By Curt Bowen
Matt.
Not really.
This does not incorporste the concept of TUC.
Maybe having some expert knowledge of the subject would have helped preparation of the article.
Dave
.
Dave Sutton
Banned
Understood.
The concept of TUC has not been taught to divers. I've put many hundreds of people thru this training, and it's not hypothetical to me.
I also just had a phone conference with my training agency and they are approving me to teach this as a diving subject with their blessing, as an advanced topic. My professional insurance is willing to cover it. This is an approval for myself, not a blanket approval. Interesting development.
The concept of TUC has not been taught to divers. I've put many hundreds of people thru this training, and it's not hypothetical to me.
I also just had a phone conference with my training agency and they are approving me to teach this as a diving subject with their blessing, as an advanced topic. My professional insurance is willing to cover it. This is an approval for myself, not a blanket approval. Interesting development.
matt
Well-Known Member
Using the table you show and the information in the atricle then moderate (1.2) would see reasonable:
This would make the loop size 12.5L so sounds reasonable.
x(.76-.14) / 6.5 = 1.2
x(.76-.14) = 7.8
0.62x=7.8
x=12.58L
Matt.
matt
Well-Known Member
Mr fish
Active Member
How long is TUC at PO2=0.14?
14% c.10K feet, forever?
TUC ..
iv got a new one to call the boat skippers ,, when i next get to dive hms seabed.:haddock:
anarchista
New Member
http://upload.wikimedia.org/math/d/1/d/d1dd558fe01e9703dfa8957572b1f705.png
Thank you, you said too much.
http://www.airbus.com/fileadmin/med...ms/AirbusSafetyLib_-FLT_OPS-CAB_OPS-SEQ09.pdf
page 4,5.
greet rc
Last edited:
I don't think this is likely as if you looked at your PPO2 and saw 0.5 any reasonable person would be reprimanding themselves not just waiting to go hypoxic no matter how familiar with the signs they are.
I ride motorbikes a lot, I learned and practice how to do emergency stops without locking the front and falling off (most of the time...), doesn't mean I completely forget hazard awareness and positioning though.
You might get some gung-ho muppets but you're going to get that anyway. I think the benefit outweighs the risk and will probably have a go.
anarchista
New Member
Dave you want to do a training program,
to do.
Examine the lethal response message, which is pure inert gas.
To simulate the large depth study of closed circuit used argon mixtures. Quickly give a thick breathing factor.
Breathe in the chamber with argon in a closed circuit, to test the sense you have been efforts on the ergometer.
If, in this situation, you observe the symptoms of anticipatory reactions have material for training and scientific occurrences.
good luck
rc greet
ps stay with designing equipment that prevents occurrence of hypoxia
to do.
Examine the lethal response message, which is pure inert gas.
To simulate the large depth study of closed circuit used argon mixtures. Quickly give a thick breathing factor.
Breathe in the chamber with argon in a closed circuit, to test the sense you have been efforts on the ergometer.
If, in this situation, you observe the symptoms of anticipatory reactions have material for training and scientific occurrences.
good luck
rc greet
ps stay with designing equipment that prevents occurrence of hypoxia
paulraymaekers
Active Member
Dave, I have difficulties to believe this... there must be some 'mis-understanding'
In Europe for sure it is illegal, as doing this without a medical staff on site...
liztribe
New Member
Dave, are you suggesting that you'd like to see this integrated into standard CCR training? While your may have an aviation background and be a self-appointed expert in the areas of hypoxia, many CCR instructors do not, nor is it a prerequisite to be a good CCR instructor. I don't believe CCR instructors should be expected to be "qualified" to conduct this drill on their living room couch. Nor do I believe every rebreather class should be required to include a field trip to a facility to have this conducted. Not all courses are taught within close proximity to such a facility, making the logistics rather unrealistic. Should we expect that every extended range class be expected to take a field trip to the FDU to do a 200 foot air chamber run to look at the realities of narcosis? These services are not free in Canada and chamber runs are not typically made available to civilians. I am not arguing the value of either training exercise, but to require such an exercise would increase the length and cost of the course overall when there are other mediums available to get the points across (accident reports, news articles, videos, etc.).
While I understand you are using skills from your aviation background to enhance your teaching, and there is nothing wrong with that, technical diving and recreational CCR diving (as not all CCR diving is technical), while similar are still not the same as flying an airplane. Yes, even those without an aviation background often use it as a metaphor - I recall a question on one of my CCR exams which compared the CCR checklist to a pre-flight checklist and packing a scrubber to packing a parachute. The medical prerequisites and tests which airforce pilots and non-military commercial pilots undergo prior to becoming licensed is far more in depth than the medical waiver a CCR diver is required to fill out. The big difference is that a pilot actually has to obtain a thorough medical whereas a dive student simply fills out a form. Obtaining a medical from a practicing physician may suss out some preexisting medical condition which the person may not have even been aware of and made worse by participating in such an exercise. Like I said, I do not have an aviation background but I do have a legal background and know that as an instructor, even if I were to conduct such an exercise "off the clock" with my "friends", I could be held liable if something were to go horribly wrong, if not criminally then there is a very real possibility of exposing myself to a civil suit. My insurance policy would be void as the exercise was done outside of a formal course or if done during a course, outside the scope of the course. Any waivers the participant had previously signed would also be void. To reiterate what I said previously, there are other ways available to demonstrate the dangers of hypoxia to students and with these alternative methods available, the risks outweigh the benefits of conducting this exercise in any environment that is not controlled by medical personnel monitorring the participant.
Overall, should one be presented with the opportunity, I see absolutely see the value in someone partaking in this exercise in a controlled environment, however, think classroom time can be better spent focusing on ways to prevent hypoxia and effecting dive practices that set one up for success (i.e. verifying your O2 is on prior to donning the unit, conducting a pre-breathe PRIOR to entering the water, etc.). I agree it's important that students understand the severity of hypoxia, but the beauty of modern technology allows people to learn from others mistakes on video!
On a side note, there have been many comparisons to the aviation training but I would be curious to learn as to whether or not this is something military CCR divers undergo?
While I understand you are using skills from your aviation background to enhance your teaching, and there is nothing wrong with that, technical diving and recreational CCR diving (as not all CCR diving is technical), while similar are still not the same as flying an airplane. Yes, even those without an aviation background often use it as a metaphor - I recall a question on one of my CCR exams which compared the CCR checklist to a pre-flight checklist and packing a scrubber to packing a parachute. The medical prerequisites and tests which airforce pilots and non-military commercial pilots undergo prior to becoming licensed is far more in depth than the medical waiver a CCR diver is required to fill out. The big difference is that a pilot actually has to obtain a thorough medical whereas a dive student simply fills out a form. Obtaining a medical from a practicing physician may suss out some preexisting medical condition which the person may not have even been aware of and made worse by participating in such an exercise. Like I said, I do not have an aviation background but I do have a legal background and know that as an instructor, even if I were to conduct such an exercise "off the clock" with my "friends", I could be held liable if something were to go horribly wrong, if not criminally then there is a very real possibility of exposing myself to a civil suit. My insurance policy would be void as the exercise was done outside of a formal course or if done during a course, outside the scope of the course. Any waivers the participant had previously signed would also be void. To reiterate what I said previously, there are other ways available to demonstrate the dangers of hypoxia to students and with these alternative methods available, the risks outweigh the benefits of conducting this exercise in any environment that is not controlled by medical personnel monitorring the participant.
Overall, should one be presented with the opportunity, I see absolutely see the value in someone partaking in this exercise in a controlled environment, however, think classroom time can be better spent focusing on ways to prevent hypoxia and effecting dive practices that set one up for success (i.e. verifying your O2 is on prior to donning the unit, conducting a pre-breathe PRIOR to entering the water, etc.). I agree it's important that students understand the severity of hypoxia, but the beauty of modern technology allows people to learn from others mistakes on video!
On a side note, there have been many comparisons to the aviation training but I would be curious to learn as to whether or not this is something military CCR divers undergo?
Dave Sutton
Banned
No, far from it.
I think it should be a specialty area of training made available to those who seek it for voluntary continuing education.
In fact: It IS a specialty area of training that is ALREADY available to those who seek it for voluntary continuing education.
The focus here is to make divers aware that such training already exists, and is in use daily with positive effect. It's part and parcel of what is a very closely associated parallel universe, and is a routine training event that is done by thousands of people a year without ill effect (most of which have a far LOWER probability of being exposed to potential hypoxia as compared to any diver who either dives a rebreather, or dives open circuit with hypoxic mixes).
To suggest that the average dive instructor, who I barely give credit to for being able to teach mask clearing, should be doing it is not what I am suggesting.
I'm just raising awareness to the fact that the training already exists.
And to your statement: I am not a "self appointed expert". I was trained and evaluated for my own ability to safely and professionally conduct this training using the ROBS (Reduced Oxygen Breathing System) by the US FAA, and was then given further approval to do so by the JAA via the UK CAA, meaning that every European country that is a signatory to the JAA treaty accepted this training as a formal and accepted training event. I then gave this training for many years in an environment that was monitored by the FAA on a daily basis, and continue to do so. The same curriculum is available to divers "who choose to accept it" if they see value in it.
Dave
.
Last edited:
Dave Sutton
Banned
"Illegal"? "For sure" ?
Not so.
I believe that you will find that FlightSafety International offers the course at their Farnborough England training center and does several hundred of the sessions annually. In addition the same training is offered by FlightSafety International at their Paris France training center as well. In fact,during a 12 year career with that firm, I was a visiting instructor in Europe providing it, and in fact assisted in the development of the course. I was then approved by the United Kingdom Civil Aviation Authority to conduct the course in the UK. That certification was accepted by the Joint Aviation Authorites, meaning that it was accepted by all EU nations as a normal and routine training event.
This is in addition to having being certified by the US FAA as well.
I'm sure they all would have noticed if it were illegal...
This is a firm doing a dedicated job of spinning off the baseline training that I helped develop at FlightSafety. In fact, they are FlighrtSafety's main competitor:
Hypoxia Awareness Training: A breathtaking breakthrough introduced by Aircare Solutions Group Aircare Solutions Group CEO Dr. Doug Mykol announced today the acquisition of an innovative new technology, which substantially enhances the training of individuals in recognizing the advance symptoms of hypoxia. This state-of-the-art training tool is a programmable altitude simulator, which offers individuals the opportunity to personally experience the subtle nature of hypoxia while in a safe and controlled environment without the potential risks of a decompression chamber.
Related to aviation, hypoxia is caused by the inadequate oxygenation of the body through explosive, rapid or insidious decompression. Undetected through lack of awareness training, the exposure to hypoxia can seriously impair cognitive performance, which could and has led to catastrophic events.
This stand-alone new technology is fully integrated with computer software for setting altitude profile and physiological parameter safety cut-offs. A highlight is the touch screen cognitive testing and automated report generation showing the rapid and detrimental effect of hypoxia on cognitive performance. Upon completion, participants receive printed reports and a video CD that serves as a reminder of the individual symptoms experienced and dangers of hypoxia.
As noted by Dr. Mykol, "This creative new training system is a response to the growing demand from those within aviation for personal, innovative instruction which will provide theoretical knowledge and practical experience in detecting the onset of hypoxia in advance of its ability to cripple the mind. Since 2005, Aircare Solutions Group has led the aviation training community by incorporating leading edge instruction into the curriculum of scheduled Aircare FACTS® Training classes worldwide. With new Emergency Simulator units recently deployed in the United States plus expansion plans for Europe, the Middle East and Asia, the global scope of Aircare FACTS® Training continues to respond to the industry call for progressive emergency procedures training."
Aircare Solutions Group has assumed a role of providing leading edge change to the world of business aviation for over 25 years. Its mission is to further advance the safest operating environment possible through education, training and providing emergency products and services specific to business aviation.
Here is a little link to the hardware used:
Aircare FACTS® Hypoxia Awareness Trainer - Aircare FACTS® Training - Aircare
This is only one of several systems that are available on the marketplace.
Note that these are NOT hypobaric chamber experiences, they are experiences using controlled amounts of less than normoxic nitrox to produce clinical hypoxia for training experiences in a controlled environment.
Dave
.
Last edited: