Foam Removal - Philips System One

[SingingSam]

Another material I've considered as a replacement is FDA approved silicone sponge. It is available 1/2" thick, but that is 1/16" too much.

I haven't found the 7/16" thickness. However, one can get 3/16" and 1/4" and do the job with a layer of each.

The problem here is not knowing the hardness of the original foam. The hardness of the silicone sponge probably should match or be close to matching. I don't have a durometer.

[SleepyCPAP]

I made the suggestion several weeks ago on using a thin food-grade silicone sheet for lining cookie pans. Flexible and resilient and about $10. Just another material that may work.

Yes! It was your idea that inspired me.  I’m cheap though, and decided parchment paper was an inexpensive alternative (and some folks have it around home already - or could get a portion off a roll from a neighbor).

I like the flexibility of the parchment paper, it still allows the indentations where the motor casing/airway presses down on the foam, which gives me confidence it is sealing.  I’m not sure if the silicone sheet is quite as curve conforming.

In response to the other question from SingingSam:  this is laid on top of the original foam, covering it edge to edge.  The only place there is a gap in the air circuit is where the parchment paper ends at the silicone intake (inside of the filter).  That place could be taped to seal completely.  So I suppose some fumes or bits could come in from that tiny slit at the transition without tape.  My foam isn’t deteriorating at that area though, so I wasn’t worried.  Zoom in on the photo and you will see. The bits of foam you see at the silicone are from my finger, after having touched the decaying area.  I cleaned that up after the photo.  It isn’t from that section of foam.

SingingSam I like your idea of the silicone sponge!  An extra 1/16th” should not impede air flow or prevent the motor housing from locking down in the frame, but there might be a little lip at the air intake, so it could cause noise there (but likely not).  I’d love to learn your source.
Edit: I googled the term and found “ FDA Grade Silicone Sponge
Number V22-350 is a closed cell, UL 94 V-0 rated, flame retardant, FDA Grade silicone sponge. This product passes the FDA requirements for food contact.” And it comes in 3/8ths” size - I’m guessing (based on indentation depth) it would indeed touch the bottom of the motor housing/ air circuit walls.

[SingingSam]

SleepyCPAP, in your third paragraph I'm not grasping what you mean where you refer to "the silicone". Do you mean the old Philips foam?

I started looking into the foams used by ResMed, which include silicone. The properties of medical grade silicone are outstanding for xPAP applications. No off-gas. No degredation, hence no tiny particles. No reaction to the materials inside a xPAP device. No reaction even to UV light and ozone. About the only negative is that silicone sponge can't be recycled at the end of the life of the device.

If you go to Ebay and search for something like "silicone sponge sheet fda" then you'll find it in various thicknesses. You might try 3/8" which is a little too thin, or 1/2" which is a little too thick. The closer you can get to 7/16" (11 mm) the better. The lower the hardness (shore number if I recall the term correctly) the better probably.

You'll still have to determine the best way to cut the foam sheet, particularly on the irregular side.

Silicone sponge won't be as effective for noise control, but in the context of our problem a barely perceptable change in volume or pitch really doesn't matter.

[SleepyCPAP]

SleepyCPAP, in your third paragraph I'm not grasping what you mean where you refer to "the silicone". Do you mean the old Philips foam?

No, not the foam, the part at the air entry.

Here is a closeup of the silicone “air entry” part I’m talking about circled in red.  You can see it in the bigger photo in my previous post with the parchment paper.  The air filters are just outside the case above that piece of molded silicone.
I have also marked the gap I talk about in blue (where parchment paper could be taped to the silicone part), and I marked the foam damage areas on my machine in yellow.  I never used ozone, but this machine sat in my car trunk a lot and was exposed to high temps there.  The foam crumbles.
   

[SleepyCPAP]

Interestingly, when I contacted the factory today about getting a sheet of the white FDA foam I listed in this thread, the response is there is a 20-week wait.   I’m wondering if it is related to Philips Respironics gearing up to use white FDA food safe silicone foam.  In any case, no replacement experiment for me.  I’ll stick with the parchment paper for my backup PRS1, and keep using the ResMed I obtained.

- SleepyCPAP

[SingingSam]

SleepyCPAP, sorry about my delayed reply. Thank you for clarifying and for the extra picture!

I think the location of the two edges that are the most decayed is really interesting. The location is a corner that is close to the blower motor.

In the absence of unauthorized cleaning the decay is a function of heat and humidity. The uneven decay suggests to me that the two edges may have gotten hotter than other locations where the foam was exposed to humidity. The decay zones might be due to an outside heat source when you traveled. Or to the proximity to the motor. The foam immediately below the motor would have had less opportunity to be exposed to humid air, so it would not be as affected as foam that was exposed to both heat and humidity.

[SingingSam]

The project I mentioned is underway.

I've learned more about the chemical reaction that is degrading the foam. I won't repeat it here because I've already written about it at length in recent days in the main recall thread.

My experimental material covers the foam on all sides - top , bottom and edges. I have 3 basic goals:
1. To retain the foam's properties that enable a good air seal.
2. To minimize or eliminate the ability of water molecules to contact molecules of the foam. This is not an easy goal because water molecules are very tiny.
3. To contain the foam's particles which fortunately are far larger than water molecules.

Last night was my first night with the experiment. I now know how my 950P sounds and feels at the mask with foam, with foam removed, and with foam covered on all sides. The feel and sound with the foam covered on all sides is indistinguishable to me from the original sound and feel. I slept pretty well for about 7 hours, which is in line with my 30 day average (6:54). My AHI numbers are acceptable - 0.0 if SleepyHead and Oscar are to be believed and under 5 if the machine's LCD report is the more credible indicator. I haven't reviewed SleepyHead and Oscar information enough to have an opinion about the lack of agreement.

I woke up with a mild scratch in my throat. Although the scratch went away quickly, I don't regard it as normal. Also, I am sleepy at 3 pm which was more typical of the months before the recall than the days from July 12 through Aug. 8 when I slept without the foam in the 950P.

I'll continue the experiment another 2 weeks if nothing alarming happens.

[SingingSam]

Philips has revealed that the smallest particles may be smaller than 2.69 μm. This information changes things.

I have no confidence that any solution that keeps the foam in the machine can be safe enough for peace of mind. End of my experiment which was going well.

The foam comes out and stays out. I'll look harder for a suitable substitute, probably silicone based.

In the interim the System One will work well enough without the foam. It will draw in some unfiltered air, the same unfiltered air that I breathe 17-18 hours a day anyway. It will survive, and Lord willing so will I.

[SingingSam]

After removing the Philips foam - permanently - the machine seems a little quieter.

This makes sense because there are more openings where air can enter and less air passing through the washable filter. Because intake air is more readily available, the blower motor doesn't work as hard.

The sound is not only quieter but also more steady. With the foam in place the noise level rises when I inhale because the blower motor must work harder to maintain the pressure setting.

My foamless 950P likely will become my backup machine in the near future. I've registered it with Philips. Whether I actually hand it over depends on what Philips will give me in return.

If I was going to keep using the machine long term then I would buy a 1/2" x 12" x 12" sheet of FDA approved silicone sponge (Jedtco Corporation R5001212SP or equal) and cut the piece I need with a box cutter. That probably would restore the designed air flow path and the old rising-falling sound.

[Mutineer]

Is this the type of stuff you're talking about?

https://www.industrialgaskets.com.au/sil...hop/detail

Silicone Sponge Rubber
Product Code : Silicon Sponge Rubber


Industrial Gaskets Silicone Sponge Rubber is a premium grade, non-toxic and inert open cell Silicone Sponge Rubber Sheet.
Premium Silicone Sponge Rubber has very high temperature resistance and is completely UV stable, making it impervious to, ozone effects and extreme weather conditions.
Industrial Gaskets Silicone Sponge Rubber has good physical properties and will maintain its flexibility over a wide temperature range.
Silicone Sponge Rubber Sheet has low thermal and electrical conductivity, making it suitable for critical electrical and electronic insulating and isolating applications.