Oxygen concentrators

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blane.c

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Has anyone given any thought to oxygen concentrators in the cockpit?

I don't know what oxygen systems weigh, a concentrator I looked at weighs 36lbs requires up to 350 watts 120ac, so 30 amp 12v plus the weight and inefficiency of a inverter. There are probably better and worse ones, this one was under $600

What about for the engine? instead of turbo charger just put concentrated oxygen into the intake? Probably to heavy and to much power draw but just asking.
 

Victor Bravo

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Not enough output volume to feed an engine IMHO.

Like many of us, I have absolutely wondered about using them for pilot breathing oxygen, I'm waiting to hear whether the FAA will allow it or for what types of flight conditions.
 

blane.c

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Not enough output volume to feed an engine IMHO.

Like many of us, I have absolutely wondered about using them for pilot breathing oxygen, I'm waiting to hear whether the FAA will allow it or for what types of flight conditions.
The FAA isn't going to approve of this without a prescription or something. I was just thinking of using it in the legal but high regime, you know like 8,000ft to 14,000ft were it isn't required or isn't required all the time but a little extra oxygen wouldn't hurt.

OXYGEN PART 91.png
 

Hot Wings

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Not enough output volume to feed an engine IMHO.

Like many of us, I have absolutely wondered about using them for pilot breathing oxygen, I'm waiting to hear whether the FAA will allow it or for what types of flight conditions.
I too have thought about it. The problem with the concentrator is the same as that for us humans. It has to work harder at altitude to concentrate the same volume of O2 as it does on the ground. We need a higher percentage of O2 at altitude because the partial pressure remains the same at altitude. I haven't done any real number crunching but I believe that the medical O2 units that people drag around just aren't up to the task.

What has always surprised me is that O2 re-breathers are not used. This is old technology and with modern finger/ear oximetry it seems to me like the lightest and most efficient solution?
 

blane.c

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I too have thought about it. The problem with the concentrator is the same as that for us humans. It has to work harder at altitude to concentrate the same volume of O2 as it does on the ground. We need a higher percentage of O2 at altitude because the partial pressure remains the same at altitude. I haven't done any real number crunching but I believe that the medical O2 units that people drag around just aren't up to the task.

What has always surprised me is that O2 re-breathers are not used. This is old technology and with modern finger/ear oximetry it seems to me like the lightest and most efficient solution?
The el-cheapo $600 is rated to 10,000ft. So since not needing the saturation of a person on oxygen support I was thinking it may be ok in the 8k to 12k range maybe up to 14k (for a 1/2hr or less). It would supply more oxygen than just the normal amount available at those altitudes. But would take some experimenting to see if it was worth it or not, especially regard normal oxygen systems and weight and cost comparison. Obviously it needs a fairly good sized alternator/generator to supply power which takes from engine performance and adds additional weight as well. No free lunch.
 

lr27

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Your 350 watt oxygen generator is supporting 75 watts of metabolism. Unlike us, an engine could use almost all the oxygen. However, an engine isn't 100 percent efficient, so I'd be surprised if you'd get enough power to run the concentrator.
How much does oxygen equipment cost? I had a "vacation" once doing archaeological diving*. I'd lie on the bottom for a couple of hours at a time measuring stuff using a 72 cubic foot tank that probably didn't weigh any more than that oxygen concentrator. I'm sure if you were at 12,000 feet instead of 12 feet underwater, you'd be using considerably less. Plus, you wouldn't need 100 percent oxygen at that height, making it last longer. I don't know how much more they cost, but presumably an aluminum tank would weigh a little less and a composite tank would weigh a lot less.

BTW, I've heard stories about what happens with leaky oxygen systems and a little carelessness. Nothing like what can happen in a hyperbaric system, but reason enough to be careful about sources of ignition. I'm guessing a well ventilated cabin helps.

*Don't envy me. It was moderately hard, very boring work. And we only got paid with what was left over after all the other expenses. Best perk was free ice cream sundaes after 12 hour work day. Developed a bad habit....
 

blane.c

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Well the oxygen supply in the 6's was leftover surplus war stuff obtained in the 50's, nobody wanted to put one of those masks on their face, especially same mask for everybody so we all pulled the hose off the mask and just sucked what we wanted from that (we carried a little short clear fat plastic hose that fit in it snug). Yes, do not have any oils on your lips like chapstick or any of that kinda' stuff. I never new what the oxygen cost but the boss new when we used it and complained.
 

blane.c

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It is short for Douglas DC-6. You know the old one's that make you dirty if you touch them, and drip oil and hydraulic fluid on slower and lower flying machines.
 

lr27

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I'll take your word for it. I've never been on a large, piston powered aircraft. Did the passengers all fall asleep?
 

blane.c

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I'll take your word for it. I've never been on a large, piston powered aircraft. Did the passengers all fall asleep?
Oh for passengers (later model DC-6B was passenger airliner but had lighter floor loading psi) and even the DC-6A (which most were actually C118's and converted to haul passengers after WW2 or was it the Korean war?) anyway they both (or all three) had pressurization. But my bosses took all that stuff out because it is useless weight that cuts down on PAYload the auto pilot mechanism too. Therefor we sucked on tubes and got yelled at for it.
 

pictsidhe

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Portable ones are much lighter, but have a 4 figure price tag. I too have considered them. A rebreather setup makes a lot of sense once you start needing much oxygen.

The fire risk depends on the oxygen partial pressure. The human oxygen requirement also depends on partial pressure. Enough oxygen therefore has the same fire risk as whatever altitude you are trying to simulate.

Another idea I've toyed with is electrolytic oxygen generation. You could even feed the hydrogen into the engine and recover some of the energy.
 

Hot Wings

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Another idea I've toyed with is electrolytic oxygen generation. You could even feed the hydrogen into the engine and recover some of the energy.
And waste all of the valuable Brown's gas!? :p:cool:

Someday I'll have to* dig out the O2 re-brather I built to paint with and post a picture. The whole thing weighed about 4 pounds and would last for a few hours on a little CO2 bottle that was originally used to inflate a large raft. I only changed the DragerSorb once and that was simply because I didn't have access to an O2 meter back then. One of those little green aluminum medical bottles should last as long as any HBA has fuel.

* extremely sensitive to the isocyanates in modern paint. Had to quit painting all together after they took Primatene off the market. Never needed after I built the O2 rebreather, but I couldn't afford to take a chance that Albuterol would work fast enough. Can't even mix the paint without a respirator and I have some painting to do this summer.
 

lr27

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It all depends on how much it costs to refill an oxygen bottle.

Seems to me your boss wasn't very good at evaluating risk. Or else he figured you were all so skilled that half as good would be enough.

I wonder if the autopilot saved a little fuel, maybe enough to make up for its own weight.
 

TFF

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That’s real cargo flying. The local DC3 guys had open offer for riders if you could spend a week on the route. No flying over the weather in one of those. You fly through. The crew placed bets on time for rider to throw up.
 

Pops

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Friend of mine was flying autoparts from DC to NC at night in a DC-3. Had a new hire and he flew the trip down and my friend was to fly the return leg. Very bad night with storm cells everywhere over the mountains. ( if you have been there, you understand the type of night). Center was asking if they wanted to divert and the A** Ho** said NO and flew through every cell. My friend said he didn't expect the DC-3 to hold together and didn't expect to see another day. On the return trip my friend was flying and the more he thought about it the madder he got. Got to cruising altitude and put it on autopilot and drug the AH to the back of the airplane and beat the crap out of him. Last time the new hire would fly with him. Didn't last long.
My older brother worked for Piedmont in the 1950's and 1960's when they were flying DC-3's and Martin 404's. After Piedmont he went with Bulter Aviation.
 

blane.c

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Friend of mine was flying autoparts from DC to NC at night in a DC-3. Had a new hire and he flew the trip down and my friend was to fly the return leg. Very bad night with storm cells everywhere over the mountains. ( if you have been there, you understand the type of night). Center was asking if they wanted to divert and the A** Ho** said NO and flew through every cell. My friend said he didn't expect the DC-3 to hold together and didn't expect to see another day. On the return trip my friend was flying and the more he thought about it the madder he got. Got to cruising altitude and put it on autopilot and drug the AH to the back of the airplane and beat the crap out of him. Last time the new hire would fly with him. Didn't last long.
My older brother worked for Piedmont in the 1950's and 1960's when they were flying DC-3's and Martin 404's. After Piedmont he went with Bulter Aviation.
Oh, so that's why they took the auto pilots out.
 

Marc Zeitlin

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Has anyone given any thought to oxygen concentrators in the cockpit?
Yes. I've spoken to the folks who sell the portable ones at OSH a few times. Can't justify the cost (yet).

I don't know what oxygen systems weigh, a concentrator I looked at weighs 36lbs requires up to 350 watts 120ac, so 30 amp 12v plus the weight and inefficiency of a inverter. There are probably better and worse ones, this one was under $600
Small battery or 12V powered concentrators that weigh about 3 - 10 lb. exist, but they're a few thousand $$$. See:


There's a Long-EZ builder in Australia who's planning a round the world trip where some legs would be far longer than an O2 bottle would last, and has experimented with a concentrator in a friend's Mooney (IIRC) I BELIEVE that he told me that they went up to 18K ft. and were still able to keep their SpO2 levels above 90% breathing the O2 from the concentrator cannula. See:


So, if you have a need that O2 bottles don't fill, and you have the $$$ for a small concentrator, they can work well.
 
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