[derefr]

Not by any means an expert here either, but my impression is that, to call something a “ventilator” in a medical context, it has to have a software-controlled rate of flow. “Ventilator” is to “air pump” as “CNC router” is to “regular router.” It needs to be integrated as part of a control system, feeding out forced air-pressure (thrust?) data, and getting fed back a PWM control signal. (Sort of like a CPU fan, but with air pressure in place of on-die temperature.)

Keep in mind, the use of these things is that you hook this up to a patient and then leave them in a room while you go handle other emergencies. It needs to tell you if it’s having a problem (through hookups to monitoring equipment.)

I think it also needs to not try to force air into a blocked airway (i.e. to blow open the patient’s larynx the moment they try to swallow), and/or needs to let up on the air pressure in a sinusoid pattern so the patient can exhale—though I might be wrong about either/both of those, given that they’re not really problems doctors encounter with hand-pumped ventilation. But either of those, in combination with the flywheel-like momentum of a big blower fan, would explain the waste gate.