BayAreaLondoner
31st Aug 2001, 20:12
The safety briefing on a flight yesterday prompted me to ask this question.
What is the purpose of the plastic bag attached to oxygen masks, since we are told they do not inflate?
It's a rebreather bag, used on constant flow O2 systems. The delivery of O2 is at a higher rate than required but at low px so it won't go into the bag. When you exhale there is a lot of unburnt O2 in your exhaust gases at a high enough px to go into the rebreather, the next inhalation will empty some of this into the lungs thereby minimising waste.
The reason flt crew masks don't have bags is that they are diluter demand types which don't need them. The reason these are not fitted at each seat is weight and cost. (1000's of times more expensive).
So there you have it - a little bit of info that I guarantee will be no use to you whatever for the rest of your cabin crew career!!!!