[Equipment] Fabrication of an Enhanced Expiratory Rebreathing Space (EERS)

[foxfire]

SR, you cannot have 'cubic' ml, though a cubic cm is a ml.


I've attached a modified picture for an EERS assembly.  Hopefully, it will clarify it for some people.

The object you have labelled as a standard tubing coupler looks like a safety or anti-rebreathing valve to me.

[Gideon]

That is another good check. 

 Exhale into mask with tube blocked (off of pap machine) and the mask should lift and the normal mask vent should not leak.

[Gideon]

SR, you cannot have 'cubic' ml, though a cubic cm is a ml.


I've attached a modified picture for an EERS assembly.  Hopefully, it will clarify it for some people.

The object you have labelled as a standard tubing coupler looks like a safety or anti-rebreathing valve to me.

yes it is but it is not required for a nasal or pillow mask.

[sherwoga]

SR, you cannot have 'cubic' ml, though a cubic cm is a ml.


I've attached a modified picture for an EERS assembly.  Hopefully, it will clarify it for some people.

The object you have labelled as a standard tubing coupler looks like a safety or anti-rebreathing valve to me.

yes it is but it is not required for a nasal or pillow mask.

The object labelled as a standard tubing coupler is indeed the safety valve scavenged from a Fisher & Paykel Oracle 452 Flexitube Kit.  I can send pictures with an explanation, but doing so now will not help my purpose in this post.  Let it suffice to explain that Slowriter sent it to me because he was under the impression I would need it with my FFM.  I labored under that understanding for two days trying to figure out how to use it and did have it incorporated in the supply hose at one time.  The picture that Fred has annotated and posted is of a failed prototype that included the safety valve.  As of yesterday I have determined that I don't need the safety valve for my ResMed F20 mask and therefore I don't need the extra piece of tubing or the Mack Ear Plug putty. 

I took a picture of what I consider to be a better, if not yet proven, version of the EERS I will be testing .  Note that the safety valve and extra piece of tubing are now omitted.  I took this yesterday intending to send it promptly and got side tracked.  But it is important to note that for the F20 Full Face Mask with it's elbow connector, the EERS fabrication requires only 1 length (6, 12, or 18 inches long) of Corr-A-Flex corrugated tubing and the Whisper Swivel valve.  Any posted declaration of "This is how you fabricate this EERS" must explicitly include the fact that it is for the F20 FFM, because the vent plugs and safety valve have been omitted. 

   

Jaswilliams wrote (in his post # 30):

 RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS)
My concern is you have not adequately blocked the mask vents. Connect a hose to your mask put the mask on block the end of the hose and exhale, no air should exit the mask, your exhale should be blocked and force the mask off your face.

I addressed how the elbow connector that comes with the F20 FFM functions in my Post #13.  Here is a full picture of just the elbow.  I have labelled the vent and what I'm calling the flap.  The vent opening is pretty obvious and easy to point out.  The flap is inside the elbow and you have to peer through the vent opening to see it. Focus on what looks like a frosted surface. The inlet side of the elbow is to the right in this picture, so when the supply hose is pressurized the air comes up under the flap. Double click on the inserted image to zoom it to full screen so you can see it in better detail.

   

The last two pictures in Post #13 are close up views intended to show that when the supply line is pressurized, the flaps move into place along the side vents effectively blocking those vents from the inside and preventing leaks.  (Also, when pressure is removed those flaps move back, apparently under spring tension, to their home position opening the side vents preventing suffocation).  I've been using this elbow for two years not understanding how it works until yesterday morning when I conducted the experiment described in Post #13.  I now know that plugging those air vents from the outside would be redundant.  Please see Post #13.  Look at the last two pictures and the adjacent discussion in Post #13. (I would like to add a link here directly to Post #13, but haven't figured out how.  So for now, the best I can do is tell you it is on Page 2 of this thread.)

The exhalation experiment Jaswilliams proposes would probably succeed, but it would be misleading, because the external plugs he says to use substitute from the internal plugging action of the flaps.  

Some history:  Slowriter included the safety valve in his list of parts posted to another thread where the proposition to start this thread devoted to the fabrication of the EERS originated.  His list was his best assessment of the needed parts, an assessment made without the benefit of even having a F20 FFM.  I started with that list and labored under the assumption that I would need to incorporate all of his parts.  I now know that

1. the Mack Ear Plug putty,
   
2. the safety valve (which appears to cost about $30 and has to be cut off of the Fisher & Paykel Oracle 452 Flexitube Kit that it comes attached to and, therefore, wastes the rest of the kit), and
   
3. the extra section of hose (to effect the required connection of the safety valve) 
   

are all unnecessary for an EERS designed to work with the F20 FFM. I draw this conclusion now having an understanding of how the Elbow with it's vents and flaps works. 


Further, my recommendation to Fred would be to remove the picture of the Failed Prototype from his Wiki page.  I would also ask him not to use more of his time to post the current version until we have a few more days to test it and to discuss it.  JoeyWallaby has written in another post that my leak rate is much higher than what he observes, so it is at least possible, if not probable, that I have more to learn about the Whisper Swivel Valve.  My leaks are at that valve in my line!  Maybe I'm not using it right yet. 

Also, Fred has suggested some more investigations to get a background leak rate that might prove useful.  These will take time, too.

[Gideon]

I made the diagram solely to fully understand how the EERS physically was constructed so that I could better comment on issues such as leak rate.

[foxfire]

FWIW this is the intentional leak rate of the Whisper Swivel II valve.
   

[sherwoga]

FWIW this is the intentional leak rate of the Whisper Swivel II valve.

Thank you foxfire.   

That is really great data to have and it suggests that my Whisper Swivel II valve is functioning in my EERS as designed .  Reading off your graph, you appear to have measured the leak rate at about 26 for a line pressure of 10.  I estimate from last nights OSCAR output that at 10, my leak rate was close to 22. 

I have taken the valve apart so that I could examine it a bit more closely (see picture below: double click on it to see in detail).  Disassembly is very simple.  You just pinch on what I've labeled in the picture as Pinch Points to slip the Inside Part out of the Outer Shell. The circles you see on the Inside Part are indents and there is actually one protrusion (on the other side of the Inside Part and not captured in this picture).  So the cylinder shaped surface on the inside part isn't really even smooth.  The mating surface on the Outside Shell is very smooth.  

Disassembled Whisper Swivel II Valve
   

I used an electronic, metric, digital caliper to measure diameters (see next picture: double click) of the two cylinders in the valve that form the seal.  There is a clearance of nearly a mm all the way around the two cylinder surfaces. 

Whisper Swivel Valve Measurements
   

I'm not surprised that different Whisper Swivel II valves would have somewhat large, and different, leak rates.  The manufacturing process is just not that precise and the sealing material (a hard plastic) not that conducive to forming a seal.  The seal is almost not a seal at all.  It would perhaps be better to call it a VENT.  Doing so makes the engineering and manufacturing of this device seem a whole lot more admirable!

How long have you used your Whisper Swivel Valve and can you make any judgement as to whether or not using it is hard on your CPAP pump?

[foxfire]

Reading off your graph, you appear to have measured the leak rate at about 26 for a line pressure of 10. 

I didn't measure it, that is the chart out of the user manual that comes with the vent.

There is a similar chart in the manual for the F20 mask.
   

How long have you used your Whisper Swivel Valve and can you make any judgement as to whether or not using it is hard on your CPAP pump?

It's been about a year and a half and I don't believe it would have any detrimental effect on the CPAP pump. The leak rate and pressure levels are comparable to what they would be without any EERS.

[Sleeprider]

I think that with most CPAP machines, the mask setting should be on Full-Face rather than nasal or pillows when using EERS. This is due to the higher volume and use of the Whisper swivel vent.

[sherwoga]

I think that with most CPAP machines, the mask setting should be on Full-Face rather than nasal or pillows when using EERS.  This is due to the higher volume and use of the Whisper swivel vent.

JoeyWallaby wrote:

11-24-2019, 12:08 PM
RE: Fabrication of an Enhanced Expiratory Rebreathing Space (EERS)
Your leak rate with EERS isn't normal. These are my EERS charts with safety valve and whisper swivel II.

http://www.apneaboard.com/forums/Thread-...#pid318231
http://www.apneaboard.com/forums/Thread-...#pid318950
http://www.apneaboard.com/forums/Thread-...#pid319468
http://www.apneaboard.com/forums/Thread-...#pid319904

Checking out those links shows that he observes very low leak rates. The information to the left of his posts does indicate he is using a nasal mask, but it doesn't indicate what his mask setting is.  So he seems to be suggesting (not to put words in his mouth) that there must be something wrong with the EERS I'm reporting on and that more modification is needed.  I do have my Mask Setting at Full Face.

Foxfire, on the other hand, is sharing specification data that indicates high "passive" venting is normal for the F20 FFM.  See his post here and here. 

Sleeprider,

Are you suggesting it is differences in the mask setting that explains these different inputs from JoeyWallaby and foxfire.

In short, I think my EERS is working.  But I remain puzzled as to how my AirSense 10 Autoset CPAP , or any CPAP for that matter, can distinguish between normal venting and leaks (even apart from the use of an EERS).  I would appreciate input on this as full confidence in my EERS depends in part on understanding this function of the CPAP.