Hi guys
I have come across Oxygen masks with labels on them, staing that the Diluter Demand Positive Pressure Breathing for the mask is certified to 40000ft. And that is pretty standard for most civilian aircrafts today.
But does this mean that opertations above 40000ft ie 41000-43000ft the oxygen mask selection has to be switched to Emergency so as provide 100%Positive pressure in the event of de-pressureization. I am just looking at the legal aspect of the situation as a Capt if something goes wrong legally you will not be binding.
This website give better explanation on Diluter demand regulators.
Look at 5.0.
http://www.airweb.faa.gov/Regulatory...9?OpenDocument
Cheers
wilco