Eagle-scuba
Contributor
GOD Bless .....another we release to the deep....... who knows...maybe it was Foul Play......
Rebreather Diver dies in Pool in Oregon
- Thread starter Daylonious
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I know with the dolphin you get pretty hypoxic at shallow depths.
caveseeker7
Contributor
This is the second try, I answered this earlier and got some absurd message ... :bluthinki
Every rebreather diver knows this!
And every rebreather diver accepts this, just as every diver accepts nitrogen narcosis or possibility of DCS.
The dangers generally involved here are hyperoxia (O2 poisening), hypoxia (O2 starvation) and hypercapnia (CO2 poisening). Hyperoxia, while possible on an SCR, is limited to diving past the MOD for the supply gas as it is for nitrox in general. Hypoxia, expected to be the cause here, can happen when fresh gas (SCR) or O2 (CCR) isn't added to the loop to replenish the O2 metabolized by the diver. Hypercapnia can occur when the scrubber is exhausted, CO2 is channeling through the scrubber bed or when the scrubber is just fine but the diver doesn't fully exhale the CO2 he generates. Holding one's breath, skipbreathing, shallow breathing will all do it. On OC too, by the way, even free diving (shallow water blackout has caused many free diving fatalities).
No SCR currently in production has a pO2 monitor in it's stock configuration.
All but one offer it as a factory option and are prepared to have it installed.
In can be done on that remaining one without any problems with monitors from several manufacturers.
Reasoning here is that cmf units continiously add gas at a higher rate than should be consumed by the diver plus have a separate addition valve to increase that flow when necessary, and that rmv-keyed units add gas per breath and hence accomodate high work rates. The latter also dump a measured amount per breath, so if gas addition ceases WOB will go up as only a few breaths are left.
CCRs operate with a fixed pO2 (setpoint) and hence have three O2 sensors that allow the diver and/or the setpoint controller to monitor and maintain the setpoint. When diving with a setpoint the fO2 in the loop changes and hence monitoring is required. Most CCRs have audible, visiual and/or vibrating alarms to notify the diver if the setpoint drifts or a cell is bad. The exception are the KISS rebreathers that are manually controlled by the diver who is trained to pay attention to the pO2 displays in the first place and fly manually.
There is currently no CO2 monitoring system available in rebreathers outside the military.
Over the years several individuals and companies have tried to make CO2 monitoring work, but there are problems have yet to be mastered, not the least of which are reliability and cost.
Ambient Pressure has implemented a scrubber monitor. While not warning of CO2 in the loop, it will warn if the absorbant fails. Not perfect, but a step in the right direction.
That being said, Rule Number 1 is: Always know your pO2!
I also singled out the quote that bradshi did above.
If the victim just wanted to fill his tank, and made an impromptu decision to jump in the pool to use up the remaining gas left in his cylinder, there is a fair chance that he didn't do a full pre-dive check that would have included checking the gas flow in his unit and the contents of the tank. I find that much more likely than anything else, as sitting on the floor of the pool doesn't lend itself to physical excertion.
Low pO2 in a cmf SCR can be brought about by mismatching gas and orifices, overbreathing the gas addition capabilities (not all that easy, I tried that on a Dräger in the pool once with a pO2 monitor installed and got worn out before the unit did) or no gas coming from the tank, either due to an out of gas situation or 1st stage/valve failure.
So more likely than not this accident was indeed human failure, and the past accounts of the victims abilities don't exactly make that any less likely.
Either way, the unit was recovered, so it should be easy enough to check the gas in the tank (both volume and composition) as well as the gas addition system (though the tank may be empty by the time he was found as gas flows continiously through the orfice).
That is, as they say, the nature of a rebreather. And it's biggest danger. You can breath as long as there is enough gas volume to match your lungs. It doesn't mean the gas you're breathing supports life.Web Monkey:
Every rebreather diver knows this!
And every rebreather diver accepts this, just as every diver accepts nitrogen narcosis or possibility of DCS.
The dangers generally involved here are hyperoxia (O2 poisening), hypoxia (O2 starvation) and hypercapnia (CO2 poisening). Hyperoxia, while possible on an SCR, is limited to diving past the MOD for the supply gas as it is for nitrox in general. Hypoxia, expected to be the cause here, can happen when fresh gas (SCR) or O2 (CCR) isn't added to the loop to replenish the O2 metabolized by the diver. Hypercapnia can occur when the scrubber is exhausted, CO2 is channeling through the scrubber bed or when the scrubber is just fine but the diver doesn't fully exhale the CO2 he generates. Holding one's breath, skipbreathing, shallow breathing will all do it. On OC too, by the way, even free diving (shallow water blackout has caused many free diving fatalities).
No SCR currently in production has a pO2 monitor in it's stock configuration.
All but one offer it as a factory option and are prepared to have it installed.
In can be done on that remaining one without any problems with monitors from several manufacturers.
Reasoning here is that cmf units continiously add gas at a higher rate than should be consumed by the diver plus have a separate addition valve to increase that flow when necessary, and that rmv-keyed units add gas per breath and hence accomodate high work rates. The latter also dump a measured amount per breath, so if gas addition ceases WOB will go up as only a few breaths are left.
CCRs operate with a fixed pO2 (setpoint) and hence have three O2 sensors that allow the diver and/or the setpoint controller to monitor and maintain the setpoint. When diving with a setpoint the fO2 in the loop changes and hence monitoring is required. Most CCRs have audible, visiual and/or vibrating alarms to notify the diver if the setpoint drifts or a cell is bad. The exception are the KISS rebreathers that are manually controlled by the diver who is trained to pay attention to the pO2 displays in the first place and fly manually.
There is currently no CO2 monitoring system available in rebreathers outside the military.
Over the years several individuals and companies have tried to make CO2 monitoring work, but there are problems have yet to be mastered, not the least of which are reliability and cost.
Ambient Pressure has implemented a scrubber monitor. While not warning of CO2 in the loop, it will warn if the absorbant fails. Not perfect, but a step in the right direction.
That being said, Rule Number 1 is: Always know your pO2!
I also singled out the quote that bradshi did above.
If the victim just wanted to fill his tank, and made an impromptu decision to jump in the pool to use up the remaining gas left in his cylinder, there is a fair chance that he didn't do a full pre-dive check that would have included checking the gas flow in his unit and the contents of the tank. I find that much more likely than anything else, as sitting on the floor of the pool doesn't lend itself to physical excertion.
Low pO2 in a cmf SCR can be brought about by mismatching gas and orifices, overbreathing the gas addition capabilities (not all that easy, I tried that on a Dräger in the pool once with a pO2 monitor installed and got worn out before the unit did) or no gas coming from the tank, either due to an out of gas situation or 1st stage/valve failure.
So more likely than not this accident was indeed human failure, and the past accounts of the victims abilities don't exactly make that any less likely.
Either way, the unit was recovered, so it should be easy enough to check the gas in the tank (both volume and composition) as well as the gas addition system (though the tank may be empty by the time he was found as gas flows continiously through the orfice).
caveseeker7
Contributor
One system at least has been developed for military that includes CO2 sensing, auto flushes the loop with diluent when sensing CO2 or high pO2, even returns an unconcious diver to the surface. But aside from containing technology not yet cleared for civilian consumption the electronics cost more than most current CCRs. At their low production numbers the price would much more than double, so it's just not feasible yet.Web Monkey:
There have been plenty of accidents and fatalities on open circuit due to divers accidentally picking the wrong gas for a given depth. Try swimming on Tx10/50 on the surface or take a few breaths of O2 at 200 feet and see how far you get. To err is human.
In my previous post I mentioned the manually controoled KISS CCR.Web Monkey:
A couple of guys thought the same way you did and designed an aftermarket control system. Adds a HUD display in the line of sight and solenoid and setpoint controller to the KISS (as well as a different display and the option to plug a dive coomputer with yet another pO2 display in). The setpoint controller/solenoid act as a safety parachute, injecting gas only when the setpoint falls below 0.4 ata.
The system costs $1,800.
H2Andy
Contributor
omar:
omar:
i must say i am a little concerned that you are making these statements, without
any real back up.
1. are you trained to determine mental capacity? if so, when, how?
2. do you have access to Harvey's records to determine his IQ? if not,
how did you determine that his IQ was in the 60-70 range? did
you administer a test? are you trained to administer IQ tests?
are you trained to estimate IQ from behavioral patterns? can
this even be done?
3. how can you be sure, even if true, that his "mental capacity"
had anything to do with the acident? what was different
this time? how exactly did the "mental capaticy" have anything
to do with the sequence of events?
in other words, i don't think your statements have credibility (at this moment),
as i haven't heard any information that would lead me to believe your
assessment is correct.
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I dive OC. I briefly considered a RB until I noticed the people who were found dead underwater, apparently oblivious to the fact that they were dying.
Terry
Terry
Mverick:
H2Andy:
Does seem a bit opinionated. Omar there is no way anyone can pass the rebreather course if he's a stupid as you've claimed. Even if I took him on as a student I certainly wouldn't pass anyone as dumb as you claim he is.
Al Mialkovsky:
It's remarkable what adaptations folks develop to counteract "deficiences" in cognition and "intelligence". An IQ test is only a small measure of aptitude within a very narrow band in the multiple domains of learning. That means a person may have developed some unique coping mechanisms to compensate for intellectual knowledge.
How do I know this...I was personally involved in a case with a sad, similar ending.
Usually when stuff like this happen, especially with rebreathers...the following takes place:
1) People who don't know anything about rebreathers chime in and state something to the affect that this is exactly why they won't be getting a rebreather.
2) Some just speculate.
3) Others who are really knowledgable and have hours and hours of experience actually on units defend rebreathers and try and educate those ignorant people. There are not that many people on SB with this kind of knowledge, but I can certainly name atleast 5 that come to mind right away.
4) Others give condolences.
All of the above has happened on this thread. HOWEVER, I shamefully have to add to more numbers to this list:
5) Questioning the intelligence of the diver.
6) Stating that a homicide occured.
Number 6, given what we know about the accident, is just unfounded and a waste of a post.
Now number 5 reaches a new low in my eyes, a level that was really low to begin with. That is such garbage to post. The guy dies and you rip is intelligence on an Internet discussion board. It's disgusting, it's shameful...there is nothing to be gained by posting that. I really don't see where intelligence has anything to do with this. If it was human error than it was human error.....an error anyone can make no matter your intelligence or experience. Let's just say he forgot to turn his air on....so this is a mistake less likely to happen with someone who lets say is really intelligent?
I sure hope none of his family members come across this thread as it will certainly be searchable in a few days.
1) People who don't know anything about rebreathers chime in and state something to the affect that this is exactly why they won't be getting a rebreather.
2) Some just speculate.
3) Others who are really knowledgable and have hours and hours of experience actually on units defend rebreathers and try and educate those ignorant people. There are not that many people on SB with this kind of knowledge, but I can certainly name atleast 5 that come to mind right away.
4) Others give condolences.
All of the above has happened on this thread. HOWEVER, I shamefully have to add to more numbers to this list:
5) Questioning the intelligence of the diver.
6) Stating that a homicide occured.
Number 6, given what we know about the accident, is just unfounded and a waste of a post.
Now number 5 reaches a new low in my eyes, a level that was really low to begin with. That is such garbage to post. The guy dies and you rip is intelligence on an Internet discussion board. It's disgusting, it's shameful...there is nothing to be gained by posting that. I really don't see where intelligence has anything to do with this. If it was human error than it was human error.....an error anyone can make no matter your intelligence or experience. Let's just say he forgot to turn his air on....so this is a mistake less likely to happen with someone who lets say is really intelligent?
I sure hope none of his family members come across this thread as it will certainly be searchable in a few days.
Mr.X:
An interesting point, Mr. X, and no doubt true, but not relevant to the point that Andy, Jason, and Al are making here.
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