(08-13-2013, 04:22 PM)RonWessels Wrote:(08-12-2013, 07:28 PM)Paptillian Wrote: Sleepster, that makes sense but then why do they only test the machines with manometers if they can pass that test but still fail to maintain IPAP? Seems like a half-done test.
Simple. Within the machine. there will be a control loop that periodically takes the measured pressure from a pressure sensor, compares it to the commanded value, and adjusts the airflow appropriately to maintain the commanded pressure.
The question is not whether the machine is capable of providing the airflow. I'm hard-pressed to come up with a realistic failure mode that provides some airflow but not full airflow without obvious things like bearing grinding noises. The question is whether the pressure sensor is calibrated correctly. And that can be determined using just the static test.
I agree with what you said (it makes sense) but it's been said on the forum that flow generators eventually become too weak to maintain pressure, and that that's what determines end of life for the machine. At least that's what I think I've read. Is there no merit to that?