Hi Netters, It is surprising to see that some aviators are venturing above 10 000 ft without oxygen.The effects are insidious and that feel good feeling can lead to disaster.Reaction varies from day to day per person.I have an old WW 11 A8a constant flow system in my sailplane,with excellent results.It amazes me that America could mass produce,in wartime, these beautifully made oxygen systems.Bought as surplus they were very inexpensive.I would not fly above 20 000 ft as a diluter demand pressure system would be better.Even breathing pure oxygen, high enough, one could fall unconscious in seconds,if there is no pressure to force it into the lungs. Best Regards, Eric, South Africa.
