Question about oxygen

I must admit my error, when I read Dreyer, I was thinking Dewar. A dewar is of course an insulated storage vessel that you can store LOX in. With the reference to high pressure, this clearly makes the system being described as gaseous.

Wishing to look a bit further into it, I had a look at AP388 published in 1921, it describes all the systems then current, both liquid and gaseous.

They had got to Mk IV by then for liquid oxygen vaporizers and high pressure delivery regulators.

It seems a lot of development was made in the late and post war period.

In the tank at North Luffenham (pre Canberra flight requirement) we all took our masks off in turn at 25,000ft – we all exhibited the usual symptoms whilst carrying out a variety of simple tasks – except for one guy who was happily scribbling away 3 minutes later – much to the amazement of the aviation medic who was in there with us and who then refitted Dickies mask purely for safety reasons !

When I was talking about acclimatisation – I was really meaning for higher altitudes than 12,500 ft – ie up ‘real’ mountains – not high hills ; )

Moggy

Your response is exactly right. You didn’t notice any effect, but acknowledged that there might be some. All posted evidence suggests that that is exactly the effect. US regulations order oxygen to be used if between 10K and 12500 feet for more than 30 minutes and always above 12.5K. That is acute toxicity versus chronic exposure exacerbated.

Air freight in cattle class is 8+ thousand feet and pulse oximeters show that even the healthiest of us are mildly hypoxic. Folk with bad lungs (smokers for example) are worse off.

So they were using LOX.

LOX is liquid oxygen. Do you really mean liquid oxygen as the manual states pressurised oxygen? I thought the boil off lox breathing systems were a product of the 1950’s -60’s.

In summary the height between 10k to 22kft which an individual can make without oxygen is a very inexact science with many variables. Even if a person, say goes to 15kft one day without problems, there’s no guarantee he can do the same the following day.

So they were using LOX.

If you take a look at the first link I posted, you’ll see it puts the Dreyer system in context, and its strengths and weaknesses.

Regards,

From a document titled, “INITIAL EQUIPMENT MANUAL FOR SERVICE SQUADRONS IN THE AIR SERVICE, AMERICAN EXPEDITIONARY FORCES”

APPROVED BY G. H. Q.

SEPTEMBER 12, 1918

INSTRUCTIONS FOR “DREYER” OXYGEN APPARATUS

1. Apparatus (Dreyer).

The apparatus or regulator as used by the British and United States Air Services consists of an automatic aneroid controlled instrument so designed as to furnish the deficiency of oxygen in the air at any altitude.
Oxygen from the storage cylinder enters the regulator at approximately 2200 pounds depending upon the pressure in the storage cylinders. This initial pressure is reduced to atmospheric pressure and cannot exceed seventeen pounds to the square inch.
The hand controlled disc has the following markings : (a) Off., (b) One man (c) Two men. The disc must be set at the proper mark before starting a flight.
As the Airplane ascends the aneroids expand, thereby opening the port in the cylinder and the oxygen at atmospheric pressure is fed through to the low pressure outlet, to the pilot and observer, in increasing proportion the elevation increases.
The pressure gauge indicates the pressure remaining in the cylinder reservoir.
The flow indicator shows the flow to the passengers but does not revolve until the airplane is at an elevation of from 8000 to 10000 feet.
The apparatus itself should be screwed to the dash or side of the cockpit. There has been no definite place decided upon, as the type of plane and position of other instruments govern the location.
This apparatus is not to be dissembled or repaired in any way at squadrons and if not functioning properly a new apparatus must be installed.
Barring accidents and dirt the life of the apparatus is continuous. It should be installed in the pilot’s cockpit if possible but the services of the airplane and the location of other instruments will govern.

The rest of the document goes on to described the cylinders, masks in service etc.

So they were using LOX.

Fascinating thread.

I don’t think there’s any argument about there being effects, but it’s also evident that some cope better than others (though undoubtedly affected) and while there’s a flat set of rules of chemistry, physics and biology about absolute effects, there’s clear evidence many have survived operating in the lower hypoxic zone.

Fitness is perhaps more critical than is evident so far in the thread – a lifetime smoker can be hypoxic at sea level; ergo fit young men might be fine more than the average, but debilitated by stress, poor nutrition (the relatively good diet of W.W.I airment would have had merit here) alcohol (smoking is probably not a major factor at circa 20 years old) fatigue, and physical injury would put them on the other side of ‘average’ health and subject to earlier-onset effects.

The original question was about W.W.I airmen operating to high altitudes without oxygen, and surviving. There’s no argument that they did, and at altitudes above 15,000 feet (as in the question) as well.

Conversely there are records of aircraft suddenly departing a formation at altitude and crashing – hypoxia being one likely explanation.

As to the limited use of oxygen in W.W.I, the British used it a bit, the Germans more, initially with airships and their high level cruises. Some interesting stuff in the following links:

Good if a bit repetitively ‘back in America’ and lacking in detail of the historic facts:
http://webs.lanset.com/aeolusaero/Articles/A_Brief_History_of_US_Military_Aviation_Oxygen_Breathing_Systems.pdf

Not so good on the history of oxygen in aviation, but a bit more backing up and adding to the comments so far:
http://www.airspacemag.com/flight-today/how-things-work-cabin-pressure-2870604/?no-ist
http://www.aopa.org/Pilot-Resources/PIC-archive/Pilot-and-Passenger-Physiology/Oxygen-Use-in-Aviation.aspx

I had an excellent book on Aeromed research history, but I lent it to someone… 🙁

Regards,

I’m aware of respiration requirements and gas laws, however it occurred to me that a mitigating factor to this could be the open cockpit and wind pressure into face. while not totally countering low pressure it would surely not be the same as in a enclosed cockpit at low pressure.

Across France I tend to cruise between 9,500 and 11,500 ft. I’ve not noticed any ill effects, though that’s not to say there aren’t any.

Moggy

There is a natural variation in human reactions to this, as there is in everything. In the biography of FAA Corsair pilot Norman Hanson, he describes being accused of cheating in training when his written task answers showed no sign of deterioration with reduced oxygen. It seems pretty clear that those who hike regularly at 12000ft are among the fitter members of the community, and are equally prone to not recognising mild hypoxia as those described above in more extreme conditions. That some people hike up there without noticing problems does not make it recommended for all.

hampden98
The person giving your talk did not know what they were talking about. Oxygen gets into the blood stream by diffusing along partial pressure gradients. At sea level the partial pressure of oxygen in air is 21kPa (actually nearer 15 at lung level) and the partial pressure in blood arriving at the lungs is around 5kPa. That gives you the pressure gradient. At altitude the numbers drop (less in the air which means less in arterial blood so less in the blood flowing to the lungs). Add anything to the inspired air and the pressure gradient increases so oxygen gets into the blood.

While Reinhold Messner did get to the top of Everest without oxygen he was blind for quite a bit of the descent with oxygen starvation to his eyes on his first trip.

Many of those who summit those mountains in Colorado are not long-time mountaineers, nor do they spend days slowly climbing from low altitudes – several of the peaks have roads to above 10,000 feet, with the climbs starting above there – you can be in Denver at just over 5,000 feet for the night, and be hiking at above 12,000 feet 3 hours later.

Mountaineering is probably a little different to flying in that one can ‘acclimatise’ relatively slowly by moving ‘base camp’ methodically and fairly gradually up to higher altitude by steps !
Whereas if you are taking off from (say) sea level and climbing relatively quickly to 20,000ft then hypoxia/anoxia is liable to be more severe !

Also – talking glider pilots – if you are operating from a high altitude airfield then generally you can still go to 10,000ft above ground level without suffering symptoms because you are acclimatised to the higher take off altitude.
Where I flew from in Zimbabwe was approx. 4,500ft – so an 11,000ft climb in a summer thermal took you up to approx 15,500ft AMSL (above mean sea level) with no problems !

Hypoxia/anoxia depending on your age 😀

I’ve also done the Boscombe Hypoxia training a number of times and the memory of what happened to me the first time scares the willies out of me.
Mask off I was given two 12 piece jigsaws to do. The first was no problem but the second one had one piece that just wouldn’t fit even when I tried to bash it in. I then remember the Doc telling me to put my mask back on so I picked it up and pressed it to my face but I let it go so that I could continue with the jigsaw. My reaction to the mask falling away is what scares me, I giggled and waved my hand in a dismissive manner but didn’t put my mask back on. At this point the Doc clipped my mask into place and turned the Oxygen back on, with this the lights came back on (hypoxia makes your colour vison degrade and the field of view reduce) I rotated the last jigsaw piece 180 degrees and put it in place.
This was at 25K where you have a few minutes of uphoric conciousness before you pass out, at 35K you have seconds before you pass out with death not far behind.

Of course some managed to ‘get away with it’ …the ones that did not lie in graves.

It is all to do with partial pressures. You will have effects over 10,000ft hp…period. You cannot change the laws of physics. The severity depends on many things. You can climb mountains without supplemental O2…..some get ‘acclimatised’. The symptoms get more severe with altitude

They likely got up to 20,000ft and did not feel any adverse effects – that does not mean they were not experiencing them! The biggest symptom is over confidence and euphoria…..leading to poor judgment. Many glider pilots say ‘I went to 18,000 ft and I felt great’ – yep I am sure you did.

We do a particular hypoxia drill that takes us up to 25,000ft then we take our masks off. It is a good demo and would convince even the most negative of you!

One of the drills for fast jet flying we did was pressure breathing – which is counter intuitive. Normally you breathe in and relax to exhale. With pressure breathing you relax to inhale and then exert to breathe out.

You can cover yourself with syrup and feathers and walk in the arctic – does not mean you need to, should do or have too!

Reinhold Messner climbed Everest without oxygen. There is just more chance that people get sleepy above 10,000 feet. Indeed, I fly regularly in small unpressurised airliners at only 5000 feet, and passengers often sleep on these 45 minute flights. Messner was incredible. Even Sherpas were suffering bleeding in their eyes, but that is due to low atmospheric pressure, rather than just lack of oxygen.

Badger1968 says that mountaineers often exceed 10000ft, might this be due to them being slowly becoming acclimatized to their environment?
There are notes in the book of pilots reaching 20000ft and still no effects the like of what Rockteer and Slicer have spoken about. So Im still a little confused as to how they managed to get away with it without adverse effects.

There are >50 mountain peaks in the State of Colorado that exceed 14,000 feet, and oxygen is required for climbers on exactly NONE of them – hundreds if not thousands of people reach at least one “Fourteener” summit each year without supplemental oxygen or air, and these are people undergoing significant physical exertion.

WW1 pilots at 15,000 feet without supplemental oxygen or air is perfectly feasible.

While the mask may provide oxygen there is no pressure

These drop down masks have a meshed over opening and so when placed over your nose and mouth as directed in the instructional demonstration/video/safety card you will still be breathing cabin air with a little extra chemically produced O2 added.
When Lockheed were building the C-130J for the RAF their engineers stood up at a meeting and announced that the airline style drop down Oxygen masks in their cargo hold met the requirement for smoke and fume protection for the passengers, I had to explain the error in that statement to them, proof that I was listening during the Boscombe Down aeromed lecture.

BGA recommends oxygen in gliders above 10, 000ft. At 34, 000ft, breathing 100% oxygen will provide an adequate partial pressure, but above that, positive pressure breathing is needed to avoid hypoxia. If the cabin oxygen masks drop out on you at cruising altitude, you will not be remaining at that altitude for long!