Hi me,
I worked with ventilators for erm..... sisnce oo 1979
Do you remember the Cape Wain? - that had the dial reading in kg-f / in2 - kilogram-force per squinch - - - no unit know to man. Kg are mass and it should be dynes or newtons. ho hum. and cm2 or kg2
but we progress
The EMTs ( ambulance men) used to have peumovite - just a valve that blew off at 20 cms water, and that worked quite well. That was designed by John Robinson, and I of all asked was the only one who submitted data. At a resusc, you had to turn the machine on, on arrival and I was the only one who did.
There was no resusc ( on the data I supplied) that exceed airway pressure of 20 cms water, who amazed everyone. very simple design to repeat that. ( design a valve that blows off at 20 cm water and flips at 5)
this wont last - too long, hi andY and un-mimsy hi the other one