Originally Posted by
reptile
When referring to the drop-down passenger oxygen system, safety information leaflets often contain the following; “Please note that the bag will not inflate”.
What is the purpose of the plastic “bag” attached to the mask, and why does it not inflate?
The Oxy Generators do not start functioning (hence do ont fill the bag) unless the user pulls on the mask. This way, if:
1) the masks are dropped accidentally, they dont waste the one-shot oxy generator (expensive as rubber jungles are not that uncommon, especially if your landing is on the harder side of "Firm"!)
2) Only masks with a user attached are used, thus not pumping excess oxy into a cabin where smoke/fumes even fire are an issue... (although in such cases the crew may elect not to drop the masks, as the mask mixes ambient air with the oxygen coming out of the generator.
As to the purpose of the bag, I dont actually know. At a guess, I would say its some form of basic oxygen pressure regulation.
Not sure it that answers your question!?