Can I be sure my machine's pressure is accurate?

[LinkC]

Or.....tape the tubing to a cm scale so the "zero" is exactly even with the end of the tubing, fire up the machine and slowly lower the business end into a tall pitcher of water. Lower the scale/tubing until you just reach the point that air stops bubbling out of the tubing. Read the scale at the surface of the water. Sure, it's not precise to the millimeter, but it will easily tell you if your machine is accurate to the .5cm setting increment. I'll bet you already have the materials to make this!

Conceivably, you could tape the scale to your hose, but it would be a bit unwieldy (and wear a raincoat...)

*by "scale" I mean an engineering scale...fancy name for a "ruler". Even a wooden school ruler would suffice and still be accurate enough for our purposes. It ain't rocket surgery!

[Country4ever]

Thanks everyone!

[Wulfman]

Checking the output of a CPAP doesn't get much simpler than the method mentioned by "Tomjax" in these threads.

viewtopic.php?f=1&t=4506&p=37259&hilit=manometer#p37259

viewtopic.php?f=1&t=34879&p=298865&hili ... er#p298865

viewtopic.php?f=1&t=6710&p=60110&hilit=manometer#p60110

Out of curiosity, I tried it. My method was to take a Sharpie marker and a ruler that had lengths in centimeters and mark two or three lines on the hose for the pressure (I use 12 cm., so I also measured one below and one above those). Then, I followed Tom's instructions........and it worked.

One warning.......use a large enough container for the water.......with the wrong move (like pulling the hose out before you shut off the CPAP), you can blow water all over the place.
(But, it is a very cheap and simple method of checking it.)

Edit: I see LinkC mentioned using the same method. OK.....I'm validating his method. Just be careful when putting the hose into or removing it from the water.


Den

[taz8872]

i just got a little meter from a different site that seems to work pretty good.

http://www.thecpapshop.com/cpap-meters/MP-1080.html

[rbtgjns]

Interesting question. Thought about this myself and have again asked the same question. I am considering one of these.: http://cgi.ebay.com/Invacare-Aneroid-Ma ... sure-Gauge. I think that there are manometer made by CPAP manufactures that are easy to use with their equipment. This one looks adaptable across brands.

[LinkC]

Den--

Good call on marking your prescribed pressure directly on the tubing. Far more wieldy than a cobbled ruler/tubing assembly. And still with acceptable accuracy for our purposes.

I might add that the actual pressure is irrelevent. An APAP adjusts to a pressure that WORKS, and that's the important thing. For CPAP, most of us have tinkered with the settings to find the "sweet spot". Who gives a flip if the number on the machine matches the actual pressure, so long as the results are good?

I wonder if anyone has actually found a grossly mis-calibrated machine anyway?

[Wulfman]

Den--

Good call on marking your prescribed pressure directly on the tubing. Far more wieldy than a cobbled ruler/tubing assembly. And still with acceptable accuracy for our purposes.

I might add that the actual pressure is irrelevent. An APAP adjusts to a pressure that WORKS, and that's the important thing. For CPAP, most of us have tinkered with the settings to find the "sweet spot". Who gives a flip if the number on the machine matches the actual pressure, so long as the results are good?

I wonder if anyone has actually found a grossly mis-calibrated machine anyway?

As far as the output accuracy goes, here's what the manual says:

Static Pressure Accuracy +/- 1.0 cm H2O with no humidifier.
Pressure Drop with Humidifier 0.3 cm H2O @ 20 cm H2O


So, there is some "wiggle room".


Den

[LinkC]

At the low end we're talking 25% tolerance. Jeez! Wish *I* could work to that!

Just more evidence that tweaking for results is the way to go...

[BigNortherner]

Do be careful with water around the machine, I am wary of one popular model as not having adequately protected circuitry.

Note there will be some pressure loss in the convoluted hose, there was a thread many months ago in this forum on estimating that. Smooth-bore hose is available.

[Guest]

Do be careful with water around the machine, I am wary of one popular model as not having adequately protected circuitry.

Note there will be some pressure loss in the convoluted hose, there was a thread many months ago in this forum on estimating that. Smooth-bore hose is available.

Yes, my M-Series broke because water in the humidifier went back into the machine. The pressure sensors stopped working, and the machine's auto on kept turning on. When it was on, the pressure went all over the place.

[LSAT]

Do be careful with water around the machine, I am wary of one popular model as not having adequately protected circuitry.

Note there will be some pressure loss in the convoluted hose, there was a thread many months ago in this forum on estimating that. Smooth-bore hose is available.

Yes, my M-Series broke because water in the humidifier went back into the machine. The pressure sensors stopped working, and the machine's auto on kept turning on. When it was on, the pressure went all over the place.

FYI...You are responding to a 3 year old post.

[torontoCPAPguy]

For what it is worth.....
sometimes the three and even the five year old threads are the best as they have a sequence of information otherwise not available on the forum. On the aFibbers forum, for example, which I consider the best forum for same, they maintain 'conference rooms' for ten or more years. One can see the progress in the state of the art and what has worked and not worked. Responding to a three year old thread is often more productive and effective than starting a new thread and just repeating what has already been stated in the forums. FWIW, just my opinion. And I, as always, thank everyone for taking the time to post. The sharing of this vital information is the essence of self-education, contemplation and advocacy but should, in no way, be an alternative to direct medical advice.

Do be careful with water around the machine, I am wary of one popular model as not having adequately protected circuitry.

Note there will be some pressure loss in the convoluted hose, there was a thread many months ago in this forum on estimating that. Smooth-bore hose is available.

Yes, my M-Series broke because water in the humidifier went back into the machine. The pressure sensors stopped working, and the machine's auto on kept turning on. When it was on, the pressure went all over the place.

FYI...You are responding to a 3 year old post.

[BigNortherner]

Three-year old information can still be valid, indeed the info manometer construction and use as well as the caution about getting water in the machine does not date.

[chunkyfrog]

Most DME's will cheerfully check the pressure, just to get you in the store.
Nobody says you can't yank them around a little--"Do you sell SleepWeaver masks?"