Van's Air Force
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Oxygen options
- Thread starter JoeB
- Start date
PRICE is a big factor for me. The concentrators are a LOT more expensive that I do not consider them at this time to be viable for ME. Maybe if I hit the LOTO. Oh, I have to buy a LOTO ticket to win?
I just saw this Oxygen Concentrator on the web:
http://www.airsep.com/medical/focus.html
1.75 pounds, 5 amps, pulse delivery, full capacity to 12,000 ft.
My O2 system cost less than $100, and is very good, but this is interesting, and probably in our future.
http://www.airsep.com/medical/focus.html
1.75 pounds, 5 amps, pulse delivery, full capacity to 12,000 ft.
My O2 system cost less than $100, and is very good, but this is interesting, and probably in our future.
LAMPSguy
Well Known Member
Cockpit atmosphere
As a concentrator it sends highly concentrated O2 to your inhalation device. What does it discharge...highly concentrated Nitrogen right? Is that a higher asphyxiation hazard if it fails? I know there are some leaks in the cockpit, but my thinking is like this:
You are on O2 because you are high and the air is thin, it fails, so now you are breathing REALLY thin air, even if your cockpit would "recharge" with exterior air in say a minute, one minute at 12,000 breathing air that feels like 25,000 might be a problem?
As a concentrator it sends highly concentrated O2 to your inhalation device. What does it discharge...highly concentrated Nitrogen right? Is that a higher asphyxiation hazard if it fails? I know there are some leaks in the cockpit, but my thinking is like this:
You are on O2 because you are high and the air is thin, it fails, so now you are breathing REALLY thin air, even if your cockpit would "recharge" with exterior air in say a minute, one minute at 12,000 breathing air that feels like 25,000 might be a problem?
This discussion brings out the trade-offs.
Also some problems that require a work-around.
The concentrator will never run out of O2 while it is working, and operated within it's altitude. High altitudes still belong to high pressure bottles or rebreathers (space suits).
So fliers who stay below 12,000 ft. Maybe higher than 12K if the fall-off in output isn't too severe. Testing and a pulse oximeter are needed.
We are admonished to use oxygen above 5,000 ft when flying at night.
Older pilots and pilots with less altitude tolerance may find this beneficial.
At 1.75 pounds, the concentrator linked above is lighter than an empty bottle.
So it is lighter, never runs out, so no time spent refilling, etc.
How reliable? I bet medical O2 users expect it to be as reliable as a pilot would? Don't let lack of familiarity breed contempt.
The concentrator would require a clean and continuous supply of fresh air, and exhaust the nitrogen outside the passenger compartment (although the flow rate would be so low it probably isn't measurable?)
The unit depicted could be made lighter by removing the cover and maybe other parts not required for flight?
Also some problems that require a work-around.
The concentrator will never run out of O2 while it is working, and operated within it's altitude. High altitudes still belong to high pressure bottles or rebreathers (space suits).
So fliers who stay below 12,000 ft. Maybe higher than 12K if the fall-off in output isn't too severe. Testing and a pulse oximeter are needed.
We are admonished to use oxygen above 5,000 ft when flying at night.
Older pilots and pilots with less altitude tolerance may find this beneficial.
At 1.75 pounds, the concentrator linked above is lighter than an empty bottle.
So it is lighter, never runs out, so no time spent refilling, etc.
How reliable? I bet medical O2 users expect it to be as reliable as a pilot would? Don't let lack of familiarity breed contempt.
The concentrator would require a clean and continuous supply of fresh air, and exhaust the nitrogen outside the passenger compartment (although the flow rate would be so low it probably isn't measurable?)
The unit depicted could be made lighter by removing the cover and maybe other parts not required for flight?
Agreed - it could be an option - but it would need to be researched by the pilot using it. I would want to know the actual volume output of gas it gives off as oxygen-enriched at its max usable altitude of 12,000', the data on the website says it is 90% oxygen but also notes that this is based on an inlet of sea level and 70F. It's entirely possible that this unit could provide enough additional oxygen for satisfactory use up to 15k or 16k, which is going to cover the large majority of RV flying - but I would certainly want to test it and keep a pulse-ox device on my finger for checking it during use. It would indeed keep the weight down, especially if you strip off the extraneous plastic pieces and remove the 120VAC power transformer section and pare it down to only the 12VDC drive motor.
Of course - it's considerably more expensive than a bottle, and only for ONE person, and you can't tell at a glance during preflight if it's available to work...
Of course - it's considerably more expensive than a bottle, and only for ONE person, and you can't tell at a glance during preflight if it's available to work...
Here is one intended for pilots, and rated to 15,000 ft:
http://www.inogenaviator.com/products.html
Testimonial with picture of RVs in flight:
http://www.inogenaviator.com/testimonials.html
A pull:
- Pulse dose oxygen delivery system
- Nasal cannula
- 12 – 32VDC; Optional AC charger (either battery powered or powered by DC power system)
- Lightweight and small (7.25lbs with battery - Size 24.1 cm x 27.4 cm x10.1 cm)
- Meets FAA guidelines for supplemental Oxygen (1 person up to 15,000ft)
- Certified to FAA radiated emissions standards (OK to run in IFR)
- LCD user interface with continual self-diagnostics
http://www.inogenaviator.com/products.html
Testimonial with picture of RVs in flight:
http://www.inogenaviator.com/testimonials.html
A pull:
- Pulse dose oxygen delivery system
- Nasal cannula
- 12 – 32VDC; Optional AC charger (either battery powered or powered by DC power system)
- Lightweight and small (7.25lbs with battery - Size 24.1 cm x 27.4 cm x10.1 cm)
- Meets FAA guidelines for supplemental Oxygen (1 person up to 15,000ft)
- Certified to FAA radiated emissions standards (OK to run in IFR)
- LCD user interface with continual self-diagnostics
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Airtight plane
I don't think I have ever flown in a light plane that was even close to air tight. I don't know anything about these oxygen generators, but I don't believe exhaust nitrogen would be too much of an issue.
My house is at 7200' and we are going skiing tomorrow at Snowmass - summit about 12,000. This oxygen generator appears to be in the same stage of development the re-breathers for scuba diving was a few years ago. With limits of 12,000, that is a little marginal for all but the -12. The one that is good to 15,000, that is getting pretty close to really nice. The ?bottle? is pretty easy and not that expensive now, but I can see a future for this type of a system. We have a couple of the very small, about 15 minute oxygen bottles we keep at the house for when we have guests. Maybe I should bring it with me skiing tomorrow!
I don't think I have ever flown in a light plane that was even close to air tight. I don't know anything about these oxygen generators, but I don't believe exhaust nitrogen would be too much of an issue.
My house is at 7200' and we are going skiing tomorrow at Snowmass - summit about 12,000. This oxygen generator appears to be in the same stage of development the re-breathers for scuba diving was a few years ago. With limits of 12,000, that is a little marginal for all but the -12. The one that is good to 15,000, that is getting pretty close to really nice. The ?bottle? is pretty easy and not that expensive now, but I can see a future for this type of a system. We have a couple of the very small, about 15 minute oxygen bottles we keep at the house for when we have guests. Maybe I should bring it with me skiing tomorrow!
johnny stick
Well Known Member
Not ready for prime time?
I think it is an interesting thing to watch, but all the money in the world (OK in the US) could not build a good one for the F22/F35. And all the money could not finally fix the F22's. If even the military can't get it working, then I will wait a few more years. Bottles for me.
I think it is an interesting thing to watch, but all the money in the world (OK in the US) could not build a good one for the F22/F35. And all the money could not finally fix the F22's. If even the military can't get it working, then I will wait a few more years. Bottles for me.
OK, I'm demented;
But I just noticed that the Chinese use Potassium Superoxide rebreathers for their man in space program.
I trained on Navy OBA-4 rebreathers in 1973.
Rebreathers offer some real benefits, like scrubbing CO2, providing O2 and purging nitrogen from the breathing loop.
Here is an interesting article on rebreathers & mountain climbing:
http://www.velocitypress.com/closedcircuit.shtml
Now this is the only good reference I've found, and Chemox is expensive and/or no longer available. My search for KO2 ended with a sales pitch on Chinese space flight.
Bottled O2 for me, but I also found this interesting:
http://www.avoxsys.com/pdf/brochures/Aviox800.pdf
This must be the most expensive O2 you can buy, for such a short duration...and it gets pretty hot too.
But I just noticed that the Chinese use Potassium Superoxide rebreathers for their man in space program.
I trained on Navy OBA-4 rebreathers in 1973.
Rebreathers offer some real benefits, like scrubbing CO2, providing O2 and purging nitrogen from the breathing loop.
Here is an interesting article on rebreathers & mountain climbing:
http://www.velocitypress.com/closedcircuit.shtml
Now this is the only good reference I've found, and Chemox is expensive and/or no longer available. My search for KO2 ended with a sales pitch on Chinese space flight.
Bottled O2 for me, but I also found this interesting:
http://www.avoxsys.com/pdf/brochures/Aviox800.pdf
This must be the most expensive O2 you can buy, for such a short duration...and it gets pretty hot too.
Has anyone bought one of these portable oxygen concentrators and used it yet?
My regulator has been acting up and I'm again looking at the option of buying one of these portable concentrators. The Inogen One G3 seems to be the most highly rated but there are smaller ones, the AirSep Focus, that is even smaller. The Inogen G3 is rated to 15K and the Inogen G2 (larger and not on my short list) is rated to 18K. The Focus, the really tiny one, is rated to 12K.
So the G3 at this point is the best combination of performance and size.
Sure am tempted at this point to give one of them a try. Anybody done it yet?
My regulator has been acting up and I'm again looking at the option of buying one of these portable concentrators. The Inogen One G3 seems to be the most highly rated but there are smaller ones, the AirSep Focus, that is even smaller. The Inogen G3 is rated to 15K and the Inogen G2 (larger and not on my short list) is rated to 18K. The Focus, the really tiny one, is rated to 12K.
So the G3 at this point is the best combination of performance and size.
Sure am tempted at this point to give one of them a try. Anybody done it yet?
Ed_Wischmeyer
Well Known Member
Hopefully not too off topic, but if you go with a bottle system, portable bottles are much cheaper and easier to refill than built-in systems.
6S4 Hugo
Active Member
I use an O₂ Concentrator. As far as "filling the cockpit up with nitrogen":
"The permanent gases whose percentages do not change from day to day are nitrogen, oxygen and argon. Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%. Gases like carbon dioxide, nitrous oxides, methane, and ozone are trace gases that account for about a tenth of one percent of the atmosphere."
"The permanent gases in gas we exhale are 4% to 5% by volume more carbon dioxide and 4% to 5% by volume less oxygen than was inhaled. This expired air typically composed of: 78.04% nitrogen. 13.6% - 16% oxygen."
Doing the math tells me that the increase in cabin Nitrogen is about .04%. Not enough for inert gas asphyxiation in the cockpit I would imagine.
As far as altitudes above 12K feet: The oxygen concentrator can trade volume for concentration. Much like we can trade off speed for altitude you can turn up the flow rates up to 6LPM. Try that with your bottles and see how long they last.
My 2?, FWIW. Mileage figures given are an estimate and your mileage may vary...
"The permanent gases whose percentages do not change from day to day are nitrogen, oxygen and argon. Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%. Gases like carbon dioxide, nitrous oxides, methane, and ozone are trace gases that account for about a tenth of one percent of the atmosphere."
"The permanent gases in gas we exhale are 4% to 5% by volume more carbon dioxide and 4% to 5% by volume less oxygen than was inhaled. This expired air typically composed of: 78.04% nitrogen. 13.6% - 16% oxygen."
Doing the math tells me that the increase in cabin Nitrogen is about .04%. Not enough for inert gas asphyxiation in the cockpit I would imagine.
As far as altitudes above 12K feet: The oxygen concentrator can trade volume for concentration. Much like we can trade off speed for altitude you can turn up the flow rates up to 6LPM. Try that with your bottles and see how long they last.
My 2?, FWIW. Mileage figures given are an estimate and your mileage may vary...
I flew with the O2 Conetrators for a hill for test purposes - loved them! The only reason I didn't;t pick one up was economics. Well, and the fact that I couldn't fit it in the RV-3 cockpit. Yes - they work really well, and you will use O2 al the time, not try to conserve it becasue it is so hard to stuff back in those little bottles.
But - economics. You can fill a bottle a lot of times for the price.
But - economics. You can fill a bottle a lot of times for the price.
I use an O₂ Concentrator. As far as "filling the cockpit up with nitrogen":
"The permanent gases whose percentages do not change from day to day are nitrogen, oxygen and argon. Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%. Gases like carbon dioxide, nitrous oxides, methane, and ozone are trace gases that account for about a tenth of one percent of the atmosphere."
"The permanent gases in gas we exhale are 4% to 5% by volume more carbon dioxide and 4% to 5% by volume less oxygen than was inhaled. This expired air typically composed of: 78.04% nitrogen. 13.6% - 16% oxygen."
Doing the math tells me that the increase in cabin Nitrogen is about .04%. Not enough for inert gas asphyxiation in the cockpit I would imagine.
As far as altitudes above 12K feet: The oxygen concentrator can trade volume for concentration. Much like we can trade off speed for altitude you can turn up the flow rates up to 6LPM. Try that with your bottles and see how long they last.
My 2?, FWIW. Mileage figures given are an estimate and your mileage may vary...
That's not the source of nitrogen in question - it's the nitrogen from the concentrator. The concentrator pulls the oxygen out of the air and sends it to the pilot, and rejects the remainder which is almost entirely nitrogen. Since oxygen is 21% of the atmosphere, the concentrator is putting 4 times as much nitrogen into the cockpit as oxygen into the pilot.
I still don't think it's enough to worry about with our leaky cockpits.
bigginsking
Member
I've been experimenting with a "run out" medical concentrator I picked up for $80 for about three years in my spare time. My plane is flying and I hate to do anything that will bring the plane down but this project has let me keep my technical chops going and not touch the plane. I've dumped a ton of time and money in it though.
The military has been using concentrators for years, the term they use is "OBOGS" on board oxygen generation system and many jets have replaced the liquid O2 systems with OBOGS. Even the Marine F-18s have almost completely ditched LOX for OBOGS and the Marines usually have the least funding for upgrades of any of the services. LOX is dangerous stuff, I've heard of at least one F-18 pilot that lost a chunk of his derriere from a leak.
When I got the run out device it was only making about 85% oxygen and the original electronics have interlocks that automatically shut down after a few minutes of not meeting spec (90 or 95%).
So I've removed all the electronics from the original and replaced them with my own that control the major functions that need to be done: running a compressor (BLDC), running a stepper motor that switches out sieve beds, thermal protection, and then dispensing an altitude dependent dose of oxygen when a user inhales. Lots of micro-controller programming...
I've got about 40 hrs flying solo with it, many of those hours are at 16.5k and 17.5k. I always use an oximeter and monitor it very closely. Useful consciousness at 18k is on the order of 20-30 minutes so this isn't like 25k or 35k where you really don't have much time to respond to an emergency.
Recently I have done some testing with two people and it is able to support two people at 17.5k with saturations of 95%. Small sample size though.
I really like the solution, most portable bottles will get you about 5 hrs for 2 people at 17.5k and then you're looking for a filling station. With this set up I don't hesitate to use it even when I'm lower.
I had a flight from San Diego to Jackson Hole last March with a massive headwind, I stayed at 11.5k and used O2 the whole time and didn't feel tired like I normally would after the nearly 6 hr flight. If I was using bottled O2 I wouldn't have wanted to waste it on a flight at 11.5k but with the concentrator its all free so why not?
The other advantage is that it's always ready to go so it's easier to use ad hoc. I've had two flights back from San Francisco to San Diego where a cold front with ice had piled up on the San Gabriel mountains and the only way home was over. It was a non event, no worrying if the bottle was full, if the valve was on, or if it leaked down from leaving the valve on between flights or anything like that. Just turn it on and go.
In all the experimentation I've done on this I'll say that O2 saturations vary widely between people, some people will have 98% at 14.5k with no O2 and others will have 88% at 10k. The one size fits all approach to Oxygen, specifically, you're at this altitude, you get this much, isn't necessarily right:
if you fly over 10k you should get a pulseOx and find out how your own body performs.
Also Pulse Ox's don't seem to vary much by what you pay for them, I've got an expensive Nonin and a cheap one from antisplat and they both generally agree with each other so don't let the cost be an obstacle.
Device specs: Current draw is variable but no higher than 15A at 14.4 volts, weight is on the order of 10 lbs.
Bill Judge
N84WJ, RV-8, 1240 hrs
http://rv-8.blogspot.com/
The military has been using concentrators for years, the term they use is "OBOGS" on board oxygen generation system and many jets have replaced the liquid O2 systems with OBOGS. Even the Marine F-18s have almost completely ditched LOX for OBOGS and the Marines usually have the least funding for upgrades of any of the services. LOX is dangerous stuff, I've heard of at least one F-18 pilot that lost a chunk of his derriere from a leak.
When I got the run out device it was only making about 85% oxygen and the original electronics have interlocks that automatically shut down after a few minutes of not meeting spec (90 or 95%).
So I've removed all the electronics from the original and replaced them with my own that control the major functions that need to be done: running a compressor (BLDC), running a stepper motor that switches out sieve beds, thermal protection, and then dispensing an altitude dependent dose of oxygen when a user inhales. Lots of micro-controller programming...
I've got about 40 hrs flying solo with it, many of those hours are at 16.5k and 17.5k. I always use an oximeter and monitor it very closely. Useful consciousness at 18k is on the order of 20-30 minutes so this isn't like 25k or 35k where you really don't have much time to respond to an emergency.
Recently I have done some testing with two people and it is able to support two people at 17.5k with saturations of 95%. Small sample size though.
I really like the solution, most portable bottles will get you about 5 hrs for 2 people at 17.5k and then you're looking for a filling station. With this set up I don't hesitate to use it even when I'm lower.
I had a flight from San Diego to Jackson Hole last March with a massive headwind, I stayed at 11.5k and used O2 the whole time and didn't feel tired like I normally would after the nearly 6 hr flight. If I was using bottled O2 I wouldn't have wanted to waste it on a flight at 11.5k but with the concentrator its all free so why not?
The other advantage is that it's always ready to go so it's easier to use ad hoc. I've had two flights back from San Francisco to San Diego where a cold front with ice had piled up on the San Gabriel mountains and the only way home was over. It was a non event, no worrying if the bottle was full, if the valve was on, or if it leaked down from leaving the valve on between flights or anything like that. Just turn it on and go.
In all the experimentation I've done on this I'll say that O2 saturations vary widely between people, some people will have 98% at 14.5k with no O2 and others will have 88% at 10k. The one size fits all approach to Oxygen, specifically, you're at this altitude, you get this much, isn't necessarily right:
if you fly over 10k you should get a pulseOx and find out how your own body performs.
Also Pulse Ox's don't seem to vary much by what you pay for them, I've got an expensive Nonin and a cheap one from antisplat and they both generally agree with each other so don't let the cost be an obstacle.
Device specs: Current draw is variable but no higher than 15A at 14.4 volts, weight is on the order of 10 lbs.
Bill Judge
N84WJ, RV-8, 1240 hrs
http://rv-8.blogspot.com/
Great report. With a 24 cu. ft. "E" bottle and a pulse dose regulator I normally can go to the East Coast and back and still have some left in the bottle, using it constantly. But not the last trip. My regulator is not working right for some reason, or I've got a leak somewhere along the line. Still investigating this but meanwhile am again looking at these little concentrators that have been showing up the last couple years.
Thanks for the feedback on your system!
Thanks for the feedback on your system!
1001001
Well Known Member
Is this true? Industrial non-cryogenic oxygen separation processes with which I am familiar have a reject stream which is slightly nitrogen (and water vapor) rich, but not by much. These processes don't split the air efficiently, they take in large amounts of air and strip off a small volume of oxygen at high purity while rejecting the rest, which doesn't come out as oxygen-poor as you might expect.
bigginsking
Member
my only experience is with a mountain high system, two of us flew from San Diego to eastern Colorado at 17.5k and after that flight the bottle was at something like 900 lbs, which is still enough to get you somewhere but not a full 5 hr leg if the first flight was any indication of what the consumption rate should be.
O2 use varies tremendously depending on the person and the system. Old systems flowed huge amounts 'to be sure'. Get a pulseoxymeter and conserving canulas (or a pulsed system) and see what flow rates you need. It may be less, or more.
Total quantity of effluent may vary, but there is no getting around the math. If you want to supply 1 liter of oxygen to the pilot, you MUST dispose of 4 liters of nitrogen via some method, if you are using atmospheric air as your feedstock. That doesn't mean the concentrator is disposing of 4 liters of pure nitrogen, it could be 40 liters (or 400) of nitrogen-enriched air, but the net result is the same. For every liter of oxygen you strip from the air, your going to have 4 liters of nitrogen to dispose of, one way or another.
1001001
Well Known Member
From an overall material balance standpoint, what you say about the ratio of nitrogen discharged to oxygen is correct. However, in a pressure swing adsorption based gas separation, the regenerating bed is purged with feed air to discharge the separated nitrogen, argon, etc. This results in a low concentration of the separated gases in the concentrator's waste stream.
Add in the fact that the cabin of a nonpressurized aircraft is not remotely a closed system, and the continual venting of the cabin makes nitrogen buildup a non-issue.
skylor
Well Known Member
Nitrogen
The mistake with this logic is failure to consider the cabin-pilot-O2 Seperator as a single closed system. You have to remember that the O2 Seperator is not producing Nitrogen, it's only removing it from the "air" that the pilot is breathing. This means that while the pilot is breathing less nitrogen with each inhale, he's also exhaling less nitrogen with each exhale (and the O2 content of the exhale will be higher). Therefore, the net aircraft cabin N2 concentration should be unchanged when an O2 Seperator is being used.
Skylor
The mistake with this logic is failure to consider the cabin-pilot-O2 Seperator as a single closed system. You have to remember that the O2 Seperator is not producing Nitrogen, it's only removing it from the "air" that the pilot is breathing. This means that while the pilot is breathing less nitrogen with each inhale, he's also exhaling less nitrogen with each exhale (and the O2 content of the exhale will be higher). Therefore, the net aircraft cabin N2 concentration should be unchanged when an O2 Seperator is being used.
Skylor
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