air flow (volume) and air pressure?

Occasionaly I see someone talking about "low air flow" causing a sensation that they are suffocating.
Is it really low volume of air or low pressure of air?
Provided there are no leaks (or insignificant leaks) it would seen that the volume of air needed to achieve a 1cm pressure change would be very slight indeed.

So, is it a too low a volume of air or too low a pressure that is causing the feeling "I can't get enough air" ?

It's both. The amount of air coming through the hose is determined by the pressure setting. The higher the pressure, the higher the amount of air flowing through the hose. Lower pressure means less air flowing through the hose.

Tec5 wrote: ↑

Fri Aug 04, 2023 10:11 pm

Occasionaly I see someone talking about "low air flow" causing a sensation that they are suffocating.
Is it really low volume of air or low pressure of air?
Provided there are no leaks (or insignificant leaks) it would seen that the volume of air needed to achieve a 1cm pressure change would be very slight indeed.

So, is it a too low a volume of air or too low a pressure that is causing the feeling "I can't get enough air" ?

Look in the back of all the mask manuals for a chart (or table, or both) of how much air flow there is going out the vent at any particular pressure.

For most masks, at 4cm, it's around 20 liters per minute. if someone's hyperventilating some, that might not be enough air for them to "feel" like there's plenty of air. though the machine should be able to speed up it's blower fast enough to maintain that 4cm, especially on a Resmed with their much more responsive (because it's smaller, less inertia) blower.

palerider wrote: ↑

Sun Aug 06, 2023 2:13 am

... if someone's hyperventilating some, that might not be enough air for them to "feel" like there's plenty of air.

That's kinda what I'm getting at, that the person "feels" like they are not getting enough volume, when actually there is more than enough volume to satisfy their normal normal minute volume, somewhere around 6 liters per minute.
As you said, even at lowest pressure the exhaust (venting) volume is in the 20 liters per minute realm.