S8 Elite - EPR off but working?

[TGregg]

I like my S8 Elite. I have the EPR, Ramp, Smartstart, etc all turned off, and pressure set to 9.2 cm/H2O. Yet when I exhale, the machine still drops pressure. I can hear the machine slow down when I exhale, then kick back up when I stop. I can see the water in the tank ripple except when I exhale (it stops).

The machine clearly does less work when I exhale.

I like that, I'm not complaining. But I would like to hear from any other S8 Elite or Vangard users if their machine does the same thing.

Thanks.

[JimW]

The Vantage does the same thing - very noticeable. It is blowing less pressure on exhalation, possibly because the exhalation adds to the pressure from the machine, causing the machine to decrease.

[dsm]

You got it

With Resmed, (IIRC) the change from S6 to S7 is when they introduced cpaps with both flow sensors & pressure sensors & the in-line variable speed blower.

With the F&P range the Sullivan V & the S6 cpaps & also the older Respironics Remstar cpaps, the output pressure was a pre-set constant based on an internal table. The user would dial up the CMS & the internal table set the blower to blow at a particular speed on the basis the machine would deliver the pressure required. This variety of machine had no pressure sensors built in.

If these older machines were taken from near sea level house to a high mountain dwelling, they still spun the blower at the same speed that the machine was calibrated for. The calibration was usually based on an average altitude the manufacturer expect the machine to operate in. Some had a manual setting that could be changed to adjust for altitude variations.

When the sleeper breathed out the older machines kept pumping the same pressure (just try blowing into the air hose of a F&P HC221 set at say 13 cms - doesn't change the blower speed a bit )

Most new machines (well almost!) now have at least the pressure sensor & many also include flow sensors, so they can actually adjust the pressure no matter what altitude the machine runs at & also will lower the blower speed when a back-pressure is detected. Just try blowing into the air hose of an S8 or an M series. The pressure sensor detects the back pressure & lowers the motor speed.

The motors used in all the really modern cpap machines are brushless DC motors - these can put out incredible power & rely on special rare earth magnets formed into rings (toroids), the ring becomes the rotor part of the motor. The static (stator) part of the motor is a coil wound inside the motor casing - to get the toroid rotor to spin, a pulsed signal is fed into the coil. By varying the amplitude & duration of the pulsed electrical signal, the motor can be precisely controlled.

The blowers are so powerful that Puritan Bennett have managed to reduce the size of their blowers in the PB420 family to a diameter slightly larger than a dollar coin (well maybe a bit larger ). These tiny PB pumps can push our 25-30 cms of pressure and that is really something to see in action.

Respironics have new small blowers in their M series.

DSM

#2
link to pic of pb420S blower

http://www.internetage.com/cpapinfo/pb4 ... c07713.jpg

http://www.internetage.com/cpapinfo/pb420s-dis-1


Here is a pic of a rotor (torroid) & stator (coil) out of a Bipap Pro 2 brushless motor - (these have shrunk quite a bit since this model came out). This one had been water damaged when the owner put the machine in its carrybag while there was still water in the h/h ...

http://www.internetage.com/cpapinfo/rem ... c08123.jpg

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, resmed, hose, Puritan Bennett, CPAP, Power, Altitude

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, resmed, bipap, hose, Puritan Bennett, CPAP, Power, Altitude

[TGregg]

Woah! Thanks DSM! And JimW too, of course.

[chennOR]

Wow thanks for all that information. I was wondering the same thing but had so much information to absorb I just let it go. I love all the good help on this forum - thank you very much.

Carol