Sensors used by CPAP manufacturers

I'm certain that this question has probably been asked before, but I don't seem to be able to find the answer readily. So forgive me.
What type of sensors are used to obtain pressure and flow measurements in Resmed and Respironics machines for home use?

The reason I ask is that flow could be inferred from pressure readings and vice-versa. (albeit alot of other constants have it exist or known)

For example, Resmed reports a measurement of "mask pressure". Is there actually a sensor that measures mask pressure or is it a derived quantity?

ResMed reports two "pressure" values.

Set Pressure and Mask Pressure, the latter of which is measured.




The sensors are shown in the above pic. Because of the Philips recall there are a fair number of defoaming videos, some of which show their sensors.

Technically, the Mask Pressure isn't really the pressure at the Mask, but pressure within the system (after the pump, tank, hose and mask), but whatever the difference at the sensor end and the mask end is likely to be negligible.

No doubt, additional sensors and multiple readings were taken in a lab
to establish reliability of the sensors and their placement used in production.

Are there flow meters ? (in either Resmed or Respironics systems)

dataq1 wrote: ↑

Wed Oct 20, 2021 11:39 am

Are there flow meters ? (in either Resmed or Respironics systems)

The picture that DS posted is showing the flow sensor, not the pressure sensor, which is on the other end of the air module, where the humidifier connects.

In the S9, these are the sensors:
pressure (sensor 1)
c02035
nap1332710

flow
sensirion
sdp711-01
1-100546-02

palerider wrote: ↑

Wed Oct 20, 2021 12:06 pm

The picture that DS posted is showing the flow sensor, not the pressure sensor, which is on the other end of the air module, where the humidifier connects.

I should have known, given there were two of them.

Dog Slobber wrote: ↑

Wed Oct 20, 2021 12:51 pm

palerider wrote: ↑

Wed Oct 20, 2021 12:06 pm

The picture that DS posted is showing the flow sensor, not the pressure sensor, which is on the other end of the air module, where the humidifier connects.

I should have known, given there were two of them.

You darn well shoulda!!! I'm used to more critical thinking outta you!

Those blue things are not sensors, they are tubes that lead to the sensor. The flow sensor needs a differential pressure sensor. The mask pressure sensor measures what we call gage pressure, which could be a differential sensor with one port open to the atmosphere. I have not disassembled my machine, but I searched Digikey for sensors like this. Here is an example:
https://www.sensata.com/sites/default/f ... asheet.pdf

RNeil wrote: ↑

Sat Oct 23, 2021 6:33 am

Those blue things are not sensors, they are tubes that lead to the sensor. The flow sensor needs a differential pressure sensor. The mask pressure sensor measures what we call gage pressure, which could be a differential sensor with one port open to the atmosphere. I have not disassembled my machine, but I searched Digikey for sensors like this. Here is an example:
https://www.sensata.com/sites/default/f ... asheet.pdf

You just love being difficult and obtuse, don't you?

I posted the part numbers Resmed uses for the S9, if you had been really nice, I'd show you high res images of the S9 board, So far, you've done nothing to make me have any desire to pop the cover of my AC10 VAuto.