From: [email protected] [mailto:[email protected]] On Behalf Of Tom, wb6b
Sent: Friday, March 27, 2020 8:13 PM
To: [email protected]
Subject: Re: [VentilatorDevelopers] Pressure sensor selection

?

On Fri, Mar 27, 2020 at 10:29 AM, Gordon Gibby wrote:

One is to measure the airway pressure for safety purposes

Very good. That makes things a little less critical than if this sensor was the main parameter controlling the ventilator. Yet, without an ambient reference the ventilator may falsely trigger an overpressure state if a weather front move away, or a closed room has a overpowered air condition or heating system and it switches on.?

These Bosch BME280 pressure sensors seem to have both remarkable relative resolution and absolute calibration. In a world where gauge or differential sensors were available in the tens of thousands in stock, that would be the only way to go. But if he Bosch absolute pressure sensors are all that is available, then using two, one ambient and one measuring the airway pressure, to emulate a differential sensor, might work if the sensors can be counted not to drift over time and temperature beyond a safe value.?

The flow meter discussed in another thread may be able to use this, also. Unless the sensors are stable to a remarkable level, some points in the breathing cycle would hopefully have quiescent values that could be frequently checked to keep the individual sensors matched to each other. These sensors do offer hope that they are very stable and accurate.

Tom, wb6b