Resmed S9 Humidifier Tub Design Change?

[Stilatos]

Has anyone noticed a difference in the replacement tubs of the resmed s9? i got a replacement after a couple years (the one that comes apart in pieces as the first one i had) and it seems the metal isnt smooth but a rather matt finish on the inside a bit strange. If i recall smooth surfaces are better for bacterial or mold purposes making it harder to cling on.

[Tino2You]

I noticed the "matte" finish as well. One positive thing, I can tell exactly where I have scrubbed it clean.
-tino

[chunkyfrog]

I wonder if there's any reason a handy person couldn't polish the dull finish.
Both of us received dull tubs, and I believe the scum does come back a little sooner.
I also wonder if it is still stainless steel, and what is best to use.

[Tino2You]

I thought mine was Aluminium, not stainless. I suspect the reason for the matte finish is part of the manufacturing process. I think it has to do with where the pressure is applied to create the shape. It is the same reason, one side of aluminium foil (aka tin foil) is shiny and the other side dull (aka matte). For me, it is another of my "oh well" items. I don't do anything (cleaning) differently because of it nor am I likely too.

-tino

[DreamDiver]

I wonder if there's any reason a handy person couldn't polish the dull finish.
Both of us received dull tubs, and I believe the scum does come back a little sooner.
I also wonder if it is still stainless steel, and what is best to use.

The original washable tank design is medical-grade stainless steel, electrically conductive with a metal tub that weighs 4.1 ounces. It has a polished surface, but from a distance of two feet, you're unlikely to be able to distinguish eye color in the reflection, so it's really semi-matte. The original disposable tank design is anodized aluminum, electrically non-conductive with a metal tub that weighs 1.4 ounces. It has a matte surface.

With the new washable design: Is the new tub closer to 1.4 ounces or 4.1 ounces? Is the surface electrically conductive or non-conductive?

It seems unlikely they added the matte surface for cosmetic reasons. It was either cheaper to produce or the matte surface makes it more difficult for germs to latch onto the tank interior, or perhaps germs show more readily than on a polished surface, compelling owners to clean more often. If the new metal tub is about 4 ounces and the interior is non-conductive, there may be a plastic surface coating the interior. Polishing the coating off could create micro-fissures on the surface that are suitable safe habitat for germs even in a dishwasher.

If the new tank is anodized aluminum, the matte surface may be part of the anodizing process.

For myself, I would hold off polishing.

[Sir NoddinOff]

If the new metal tub is about 4 ounces and the interior is non-conductive, there may be a plastic surface coating the interior. Polishing the coating off could create micro-fissures on the surface that are suitable safe habitat for germs even in a dishwasher. If the new tank is anodized aluminum, the matte surface may be part of the anodizing process.

For myself, I would hold off polishing.

I've got that tank and I don't think there's any coating. It would be easy to test tho with a voltmeter that has an R (resistance) scale. Also a battery and flashlight light bulb plus a few wires would make a good conductivity tester. OR a 9v standard rectangular battery like you find in your smoke detector, two wires and your tongue in the circuit No kidding

[STL Mark]

Click Here to see a thread from back in September 2012 when I first noticed this change. There were several thoughts that may be of interest.

[Sia]

The surface does not matter for bacteria or fungus. They can hold on to nearly any surface, even glass.

Any polish either introduced or original would still have plenty of cracks for the say mycoplasma genitalium (300nm) to hold on.

Wipe once over an excellent flat chrome surface and you have introduced a gazillion tiny scratches for all these to stick to.
That is why they tell you to not wipe clean or wipe dry anything related to this.

These tiny creature just LOVE the humid and warm enviroment, And they are EVERYWHERE!
You simply cannot get rid of them, unless you keep bleaching everything in the breathing path, where much of this is stuck.

The best way to protect is to prevent a spread by usung distilled water (or osmosis filtered water) to deprive them of food.
And clean it once a week (no wiping) to get rid of the colonies.

[denrush]

I received a replacement and the tub is no longer light weight aluminum. It now weighs 8.5 oz instead of 4.5 oz. It is a three part dis-assembly for cleaning. It will NOT heat my water sufficiently to produce the humidification I need. The aluminum tub that was replaced would vaporize nearly all the water in the tub overnight. The new one vaporizes an insignificant amount over night. I'm staying stuffed up. I complained to my cpap supplier and they sent me a replacement. It is the same 8.5 oz. So apparently Resmed has updated to a new reservoir design that is more durable, may stay cleaner, but as a result, now does not do the job it was intended to do.


"With the new washable design: Is the new tub closer to 1.4 ounces or 4.1 ounces? Is the surface electrically conductive or non-conductive?

It seems unlikely they added the matte surface for cosmetic reasons. It was either cheaper to produce or the matte surface makes it more difficult for germs to latch onto the tank interior, or perhaps germs show more readily than on a polished surface, compelling owners to clean more often. If the new metal tub is about 4 ounces and the interior is non-conductive, there may be a plastic surface coating the interior. Polishing the coating off could create micro-fissures on the surface that are suitable safe habitat for germs even in a dishwasher.

If the new tank is anodized aluminum, the matte surface may be part of the anodizing process."

For myself, I would hold off polishing.[/quote]