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[Equipment] maximum hose length?
#11
(06-26-2013, 11:25 AM)Paptillian Wrote: What about the effects of turbulence or attenuation of the periodic waveforms that could be introduced? I'm concerned about the quality of the feedback to the machine. "Signal noise", to use an electrical analogy, will have some effect on the machine as well as the data collected. Whether or not it's negligible, I don't know. Perhaps that's also why the manufacturer doesn't want too long of a hose?

Turbulence is a function of the boundary (ie. hose surface), not a function of the length of the hose. In your context, "attenuation" would be the drop in pressure because of the increased resistance due to the extra hose. Think about the resistance trying to push air through a nasal pillow. How much smaller is that air pathway vs the 22mm hose? Yes, there will be attenuation due to the mask, but this is why the machine wants to know what type of mask is in use. And even then, the pressure effects are small.

The one thing that I can see happening is that, with a longer hose, exhale pressure relief (EPR on ResMed, CFlex on Respironics) might not be as timely as would otherwise happen with a shorter hose. Again, the effect would be minimal, but the problem is that you could notice minimal effects. The best test for this would be to try the longer hose and see if the exhale pressure relief still feels acceptable.

Once again, trying this will not hurt the CPAP machine. So try out the longer hose. If everything works (ie. comfortable, good quality sleep), then enjoy.


With regards to the hose connector separating, I can see that this isn't going to be a big deal. Worst-case, you will wake up due to the increase in apnea events, since you are no longer receiving CPAP. And, since I can still breathe with the hose connected and the machine turned off, one should be able to breathe with the hose disconnected.
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#12
That's right Ron,
the CPAP machine has a much bigger load when trying to push air down the hose against the patient's exhale cycle.
It's made to handle it.
The length of the hose might start to affect how well the sensors can detect OA/CA events & such if the hose gets really long.
Over 12' maybe?
I would think 9-10' of hose should be plenty
I am running about 100" (6' length with 18" extension + separate humidifier with about 9" rigid pipe) of hose with two swivel connectors and a big total face mask.
Works like a charm and getting great data too. I check the air flow waveforms just to make sure anyway.

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

Cool
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#13
Figure out a way such that you can't pull your machine off the table. Put it in a drawer, sit it on the floor, tie the hose to something, etc. Pulling it off the table or even just turning it over can ruin the machine because the water will get into the blower unit. Do that even if you get a long hose. You can still snag a long hose and pull the machine off the table.

Now, to the hose:

A number of people have found that longer hoses may affect the sensing of inhale and exhale on bilevel machines. The machine may not raise and lower pressure at the right part of the breathing cycle. I would expect an ASV machine might be similarly affected.

I would also not be surprised if it affects sensing of apneas or snoring. It might be especially confusing to the sensing of central vs. obstructive, especially on an S9 machine.

Use a full sized hose, not a slimline hose. I would expect the sensing/switching problems to be worse the longer the hose is.

I would not expect a 12 foot hose to affect the pressure, but it may affect the ability of the machine to sense your breathing problems.
Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#14
(07-01-2013, 04:53 AM)archangle Wrote: Use a full sized hose, not a slimline hose.

Is that general advice, or specifically for longer hose lengths? I'm pretty sure you meant the latter, but it wasn't clear. Thanks!
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#15
After pulling my machine onto the floor, I ordered a 10' one. I think I paid more in shipping and tax than I did for the hose. I also called my DME and asked about if I could get a longer hose and was they told me that there price was the same for all the hoses from 6 to 10 feet so my insurance would cover it. They changed my profile to reflect the longer hose and it will be shipped with my quarterly supply order at the end of the month. (I get a new hose, filters and mask every 3 months and new tank every 6 months). I keep the last set replaced as a spare.

BTW, the machine ended up right side up, no spillage and the only reason I new I did it was the alarm went off when the plug came out.

Paul
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#16
I use a length of elastic strap to tie my hose to the top of the bed board. It stretches enough so that I can move around quite a bit, keeps me from rolling onto the hose, and makes it just about impossible to pull my machine off the nightstand. You can buy it at places like hobby lobby. I use the 1" wide stuff as it's very easy to untie.

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#17
(07-01-2013, 07:16 PM)Paptillian Wrote:
(07-01-2013, 04:53 AM)archangle Wrote: Use a full sized hose, not a slimline hose.

Is that general advice, or specifically for longer hose lengths? I'm pretty sure you meant the latter, but it wasn't clear. Thanks!

Mostly with the longer hose lengths, but it will probably work a little better with a larger hose in the short lengths, too. Unless the hose weight or size is a problem I suggest the big hoses. If nothing else, they're cheaper. I recently bought 4 genuine Respironics hoses for $20 total shipped from an eBay seller.
Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#18
I just saw two new- 6 foot hoses with free shipping for $7.50 on Ebay..saved the seller for future reference...sure beats almost $20 for one 8 foot hose...I moved a little table I had right next to the bed and placed the PRS1 on it..then bought a hose holder ...so I am using 6' hoses now
I don't believe anything I hear and only half of what I see
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#19
One thing you could do if you wanted to make the hose longer would seem to be increase the size of the hose to 22mm (from 15), and lie to the machine telling it you have a 15mm hose. Based on a static constant-flow assumption, doing this would seem to allow increasing the length by a factor of 6.7 or so!

Here's how I get this: Let's assume the problem is pressure drop due to high air flow velocities. The flow drop is calculated using three parameters multiplied together: (a) a friction factor which here can be considered constant in this instance, (b) the number of hose diameters of length (L/D) where L is the length and D is the hose diameter, and © (V x V) / (2 x g) where V is the flow velocity and g is a constant. If you work this out, the length can be increased (for equivalent pressure drop) by a factor of (15/22) to the fifth power. So 6 feet of 15mm hose is (pressure drop wise) is equal to 41 feet if 22mm hose.

Maybe I've over simplified the problem statement, but it's clear that upping the diameter of the pipe will drastically drop the pressure drop per foot of hose.

Note that after a change from 6 feet of 15 mm hose to 41 feet of 22 mm hose, the time for the flow to travel down the tube is about 15 times longer because the hose is 6.7 times longer and the velocity in the tube has been reduced by a factor of 2.1 or so. So anything in the machine related to transit time in the hose wouldn't be correct.
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#20
(07-09-2013, 11:59 AM)martinsr00 Wrote: ... So anything in the machine related to transit time in the hose wouldn't be correct.

Such as exhale pressure relief and clear airway apnea detection. The first is a comfort issue, but the second could interfere with the AutoSet algorithm.

Don't try this without data monitoring.
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