[Pressure] Air Pressure

[lrlong27]

I am new to using an older Remstar Pro C-Flex device, try DIY rather than normal channel.
The device seems undamaged and cycles through the set up screens as expected.
I want to start out at low pressure and assess the impact.

The settings menu allows me to increment "pressure" from 4 cm to 20 cm.
However, when I exit and start the machine at either 4 cm or 20 cm, I can detect no difference in the airflow (it seems high).
Anyone have experience or suggestions?
Should there normally be a noticeable difference in the airflow?

[DavePaulson]

There should be a difference. Does it have a ramp feature that is turned on? If so turn off the ramp and you should notice a difference.

Dave

[lrlong27]

There should be a difference. Does it have a ramp feature that is turned on? If so turn off the ramp and you should notice a difference.

Dave

It does and I have tried lowest and highest setting with and without Ramp turned on.
The sound and airflow seem the same.
Might be the unit is "stuck" in high gear.

[DavePaulson]

If you want to test the pressure read this.  http://www.apneaboard.com/forums/Thread-...ew-dollars

Dave

[TASmart]

There should not be much difference. Open flow your machine is trying to hold a pressure and since there is not any stopping the flow, it maximizes it's output at either setting, blowing like crazy trying to get to the set pressure. The only flow that your machine is designed to have is any leak amount plus the volume of your inhalation. Flow is no the same as pressure. If you are feeling flow you have a leak problem.

( I am assuming you do not have the mask on when doing this exploratory testing. )

[trish6hundred]

Hi lrlong27,
WELCOME! to the forum.!
Hang in there for more answers to your questions, good luck to you with CPAP therapy and also with getting your machine straightened out.

[Sleepster]

However, when I exit and start the machine at either 4 cm or 20 cm, I can detect no difference in the airflow (it seems high).

Air flow is not the same thing as air pressure. The machine has a fan that will change its speed in an attempt to keep the pressure constant (at whatever number you've set it to) but if the hose is open to the atmosphere it will spin as fast as it can to no avail. It can't raise the pressure above zero because the hose is open to the atmosphere!

You can test the pressure without building a manometer. Just get a bucket of water that's 20 cm deep or deeper. Take the end of the hose and insert it into the water with the machine running. It will of course blow air bubbles. But the bubbles will stop at whatever depth the pressure is set to. So if the pressure is set at 4 cm, the bubbles will stop when the hose end is 4 cm below the surface.

With the machine set at 20 cm of pressure you will have to submerge the hose end to a depth of 20 cm to get the bubbles to stop.

[lrlong27]

There should not be much difference. Open flow your machine is trying to hold a pressure and since there is not any stopping the flow, it maximizes it's output at either setting, blowing like crazy trying to get to the set pressure. The only flow that your machine is designed to have is any leak amount plus the volume of your inhalation. Flow is no the same as pressure. If you are feeling flow you have a leak problem.

( I am assuming you do not have the mask on when doing this exploratory testing. )

True, no mask on, not even the hose, just air coming out the CPAP.
I will begin testing with my new mask and see how it goes! Thanks.

---

However, when I exit and start the machine at either 4 cm or 20 cm, I can detect no difference in the airflow (it seems high).

Air flow is not the same thing as air pressure. The machine has a fan that will change its speed in an attempt to keep the pressure constant (at whatever number you've set it to) but if the hose is open to the atmosphere it will spin as fast as it can to no avail. It can't raise the pressure above zero because the hose is open to the atmosphere!

You can test the pressure without building a manometer. Just get a bucket of water that's 20 cm deep or deeper. Take the end of the hose and insert it into the water with the machine running. It will of course blow air bubbles. But the bubbles will stop at whatever depth the pressure is set to. So if the pressure is set at 4 cm, the bubbles will stop when the hose end is 4 cm below the surface.

With the machine set at 20 cm of pressure you will have to submerge the hose end to a depth of 20 cm to get the bubbles to stop.

It was an open flow (not even a hose), rookie error. Thanks so much, very cool info.