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Breathing through a straw
#11
(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?
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#12
CFDRich: There's got to be something wrong with the S9 you're dealing with. I have two. Both are very quiet. The S9 is supposed to be even quieter than the S8. (Of course with the mask on. You don't test the noise level with a machine that's just bare-hose-ended.) Static pressure is most certainly not the same as dynamic pressure. It might be interesting to look at your mask and flow rate data from sleepyhead. You should not feel like you're having to pull air into your lungs at a pressure of 11 from this machine. It should feel like you're not even wearing it after a while. If it really is that loud and it were my machine, I'd return it and get a replacement.
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#13
(08-12-2013, 04:10 PM)CFDRich Wrote: The tech used the manometer for both. I had them both with me at the store. He tested the S9 and then removed it and tested the S8. Both registered exactly 11.0. While I was sitting there, I put each machine on and the S9 sounded like a tornado compared to the S8.

He used a chart from the S9 instruction manual to estimate the LPM but didn't have a manual for the S8 so he couldn't tell me.

#1.
*Face palms.*
The tech didn't have a chart manual to estimate the flow rate?
This guy is a doofus and doesn't even know simple math/physics and how it
applies to his job.

#2. The S9 is a very quiet machine only making a slight chuff sound on exhale.
There may be something wrong with it. When in doubt, check it out!

Good luck!
Sleep-well

"With ordinary talent and extraordinary perseverance, all things are attainable." - Thomas Foxwell Buxton

Cool
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#14
(08-12-2013, 04:10 PM)CFDRich Wrote: While I was sitting there, I put each machine on and the S9 sounded like a tornado compared to the S8.

It sounds like you may be both a hose head and a nozzle nut. ;-p

Odd. In my experience using the s8 for more than 6 maybe 7 years, I noted it was WAY more loud than the S9 I've used for the last four months. Maybe the S8 can reliably build to that set pressure in a closed system, but is starting to wear and can't any longer deal with the mask leak rate coupled with the inhalation pressure reduction?

Were you previously using the S8 before the S9? How old is the S8? Total number of hours on that unit?

OMyMy

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#15




Regardless of the pressure setting, if I can't breathe effectively, then it isn't helping. I'm working to breathe with whatever tubing I'm using on the S8. I understand your point about the thinner hose and more noise so I'll test the slimline hose on the S8 and see if that matters. If not I'm going to turn up the pressure on the S8 until my eyes bulge out and see if that works. Haha!!





(08-12-2013, 06:55 PM)Paptillian Wrote: If I'm not mistaken, the S8 uses the standard CPAP tubing which has a larger diameter than the S9's "SlimLine" tubing. Imagine that you have a cup of water and two straws: a thick one and a thin one. If you blow into each straw to make bubbles in the water, does it feel the same? Probably not. It takes more effort to blow through the thin one and it sounds louder (a moot point for CPAP when the mask is on).

If you're comparing the air coming out of the two open hoses, I would expect them not to sound or feel the same. The important thing is that they both register correctly on the manometer.

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#16


Thanks for the reply. The noise is not while I'm wearing it. It's while I'm holding it. It's very quiet. In fact I wish it was a little louder because I like a little "white noise" while I sleep.

How can you test the dynamic pressure? I'm going to try the slimline hose on the S8 to see if pushing 11 through a slimmer hose increases the pressure on the working end.

(08-13-2013, 09:59 PM)DreamDiver Wrote: CFDRich: There's got to be something wrong with the S9 you're dealing with. I have two. Both are very quiet. The S9 is supposed to be even quieter than the S8. (Of course with the mask on. You don't test the noise level with a machine that's just bare-hose-ended.) Static pressure is most certainly not the same as dynamic pressure. It might be interesting to look at your mask and flow rate data from sleepyhead. You should not feel like you're having to pull air into your lungs at a pressure of 11 from this machine. It should feel like you're not even wearing it after a while. If it really is that loud and it were my machine, I'd return it and get a replacement.

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#17
(10-05-2013, 12:56 PM)CFDRich Wrote: How can you test the dynamic pressure?

You'll need a container of water deeper than the pressure you want to test. For example, if you're testing a pressure of 12 cm, you'll need a container filled with water to a depth greater than 12 cm.

I recommend setting the container in a sink or some other place where spills won't be a problem. With CPAP machine running, stick the hose into the water until the bubbles stop. The depth at which the bubbles will just stop is equal to the pressure.
Sleepster
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#18
It seems to me that if the S9 works well for the OP, then a second S9 would work equally well. Other than cost why should you play with older models or brands. What is the value of a good nights sleep? Will insurance pay for a second machine when the job requires sleeping away from home 3 nights a week?
I don't know the answers to these questions, they need to be asked.
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