Quote:
in case of failure they can work with 21% oxygen from air
Can they?
I did not think they had a compressor. I thought they needed the high pressure from the oxygen to create any pressure in the gas system, they use the oxygen to entrain air through a venturi. I thought that if the oxygen failed they would have no means of entraining air so the whole vent would stop.
RoJo

My spelling is not bad. I am typing this on a Medigenic keyboard and I blame that for all my typos.