Originally posted by lapp:
I have read the references and relates postings and must say that what you say is correct. Notwithstanding, it is my totally personal opinion, that setting "EMER"for mask breathing at FL 380 can't do nothing but help breathing. Would you elaborate on the possible negative consequences of doing that.
Have a careful read of my post at 25th Mar 2015, 05:10 (currently # 438) that describes exactly how a diluter/demand system works. It doesn't matter if the Demand setting is in Normal or Emergency, when you inhale you will get exactly the same pressure of gas. The only difference is when you are NOT inhaling - in Normal no gas will flow, in Emergency gas will flow (to keep the mask clear of smoke or fumes). So you are sort of half correct and fully half wrong. You are wrong by saying 'nothing but help breathing' because it provides no additional benefit - when you are breathing in you get the same amount of gas regardless of the Normal/Emergency setting. You are nearly half correct by asking about 'possible negative consequences': in a smoke/fumes incident there are none, but in a 'simple' depressurisation event the possible negative consequence is that you are unnecessarily wasting oxygen.
Are you freespeed2 posting under a different name?