AirSense 10 Humidifier badly discoloured after first use

dave21 wrote:I've tried searching for both aluminium and stainless steel discolouration but not found anything that comes remotely close to what I have on both tubs, in terms of hotspot and colours of the rainbow...

Go find a motorcycle:

To clean, look under Household Cleaning Tips:

http://calphalon.custhelp.com/app/answe ... kware.-how

http://cathyherard.com/tips-to-clean-st ... bow-stain/

Demerit wrote:I've had several conversations with Resmed about this issue. It is inconsistent in when it is happening, some folks are using distilled water and seeing it but it is mainly occurring in those who are not using distilled water. It also has to do with something within the machines environment, but the "something" is still being determined.

I'm going to go with "chlorine".

Thanks Sludge, so it seems that some stainless steel is more susceptible to rainbow effects vs other stainless steel, most likely due to the coating/treatment they have carried out? That would then lend itself to the tubs then and that could be why i'm not seeing it on other tubs.

I have a replacement machine and tub, will try that tonight, I found a few more sites that suggest lemon juice and warm water will remove the rainbow effect or part white vinegar and warm water, but I think as was mentioned previously by Daytona that scrubbing it removed it but still showed the spots that appear after the first night, I suspect that if I can remove the rainbow colours if it happens again then I'll just be back to the spots and that still won't be cleanable.

I'll see how the new tub and machine go tonight.

Before sending the 2x tubs back, Daytona you may want to try this if its happened to your new tub...

I soaked the tub in vinegar and hot water solution for a couple of minutes, rinsed with cold water and the discolouration has complete disappeared and I don't have the bubble marks either although there is still a slight mark that resembles like a scuff mark across the inside, so not back to brand new/perfect state but better than it looked with the rainbow colours. I'm going to try using that same tub tonight and see if it discolours again or whether that may resolve it from happening.

Either way still not right but it seems as per Sludge's comments and by looking online more today that some stainless steel depending on the coating used or thickness of coating can cause rainbow effects. So it seems that ResMed's production of the tubs between H4i, H5i vs H6i (AirSense 10) have changed somewhat. Most likely a batch of some kind.

Sludge wrote:To clean, look under Household Cleaning Tips:

http://calphalon.custhelp.com/app/answe ... kware.-how

http://cathyherard.com/tips-to-clean-st ... bow-stain/

I second the 'bar keepers friend', stuff works magic on stainless!

I don't think we can get that over hear, but here's photos of the tub after cleaning with vinegar and hot water solution...



And here's a zoomed in with different light, if you look closely there are some marks on the metal now almost like scuff marks that weren't there before but its a lot better than it was, the yellow reflection from the light bulb over the tub.


Personally I'm not sure it's acceptable to have it appear after 1 night and be told to clean with vinegar and water every night, but I'll see if that's the stance ResMed want to ultimately come back with. I hope they can investigate and get to the bottom of it. I'll use the same tub with old machine for one more night and see if it comes back, maybe some tubs just need a good clean to start with vinegar. Then I'll move to the replacement machine and tub and see if that exhibits the same problem.

This is turning out to be a right old social experiment.

dave21 wrote:I don't think we can get that over hear, but here's photos of the tub after cleaning with vinegar and hot water solution...

BKF is a mild acid solution, so, similar stuff.

dave21 wrote: Personally I'm not sure it's acceptable to have it appear after 1 night and be told to clean with vinegar and water every night, but I'll see if that's the stance ResMed want to ultimately come back with. I hope they can investigate and get to the bottom of it. I'll use the same tub with old machine for one more night and see if it comes back, maybe some tubs just need a good clean to start with vinegar. Then I'll move to the replacement machine and tub and see if that exhibits the same problem.

This is turning out to be a right old social experiment.

or you could just say "meh, who cares" and just use the machine. if you can cook in stainless that has discoloration, and then eat that food, you can certainly breath moisture from water that's heated up in less than pristine pretty stainless.

and let's not get into the apparent misnomer that is stainless steel... given that it can, and does, stain... but, it stains LESS than regular steel (mainly rustwise.)

Amazing how much better they look after you used the vinegar and hot water -- WOW

dave21 wrote:Either way still not right but it seems as per Sludge's comments and by looking online more today that some stainless steel depending on the coating used or thickness of coating can cause rainbow effects. So it seems that ResMed's production of the tubs between H4i, H5i vs H6i (AirSense 10) have changed somewhat. Most likely a batch of some kind.

The stainless steel is probably not coated. Stainless steel does form a surface oxide coating on its own. That's one of the reasons it's corrosion resistant. If you scratch it and remove the surface layer, a new protective oxide layer forms on the fresh metal.

There are dozens of common formulations of "stainless" steel with different concentrations of iron, carbon, chromium, nickel and other elements. During manufacture, cleaning, machining, stamping, and other mechanical processing can have an effect on the structure of the finished product and the surface finish.

The vinegar result is interesting. I suspect you removed at least part of a colored oxide layer, and a fresh, new oxide layer formed, and it's not the right thickness to produce the color effect any more.

Mine is just over 3 weeks old and there's no discoloration what so ever, (It looks like your vinegar clean one), Not sure what is happening but something is wrong , I sure hope it's not your water.
Good luck hope you can fine the solution.

Guest 2

The vinegar removing it essentially proves the metal is reacting with the water and heat to form an oxide layer (and then reacting with the vinegar to remove the oxide through another chemical reaction). Its obviously being caused by the application of heat to the metal since I doubt you will see it form if you just let a new tub sit with water in it without heat. The thing is, I doubt it is supposed to be doing that. As I said before, the different colors in the rainbow represent different depths of oxide layer formation. I doubt variable oxide layer formation is intended. There is something going on with that stainless steel that they never intended.

palerider wrote:or you could just say "meh, who cares" and just use the machine. if you can cook in stainless that has discoloration, and then eat that food, you can certainly breath moisture from water that's heated up in less than pristine pretty stainless.

If you're paying for a $50 pan and you're putting hot oil in it then yes I would agree with you. If you're paying for a $1000 machine and it's for medical use, then no it's not acceptable.

TangledHose wrote:Amazing how much better they look after you used the vinegar and hot water -- WOW

Yeah I'm amazed at how much better it looks, vinegar and hot water is a miracle!

archangle wrote:The stainless steel is probably not coated. Stainless steel does form a surface oxide coating on its own. That's one of the reasons it's corrosion resistant. If you scratch it and remove the surface layer, a new protective oxide layer forms on the fresh metal.

I think you've hit the nail on the head, it definitely seems like either the coating is minimal or non-existent here. Now as some tubs seem perfectly fine that would suggest a bad batch at the factory that didn't receive their coatings maybe in ramping up productions or someone forgot to coat them. Maybe ResMed are using multiple factories.

archangle wrote:The vinegar result is interesting. I suspect you removed at least part of a colored oxide layer, and a fresh, new oxide layer formed, and it's not the right thickness to produce the color effect any more.

So now after vinegar and hot water the tub is clean albeit other than a few marks, I then had another 8 hours sleep last night with AirSense 10 set on Auto (27C) and here's the result. Basically it's come back again to the extent of what you would see on the 1st night. The 2nd night onwards you'll see the multicolours again.

Guest 2 wrote:Mine is just over 3 weeks old and there's no discoloration what so ever, (It looks like your vinegar clean one), Not sure what is happening but something is wrong , I sure hope it's not your water.

Yeah I agree, it's not right and not acceptable and ResMed do need to find the solution to this.

Paralel wrote:The vinegar removing it essentially proves the metal is reacting with the water and heat to form an oxide layer (and then reacting with the vinegar to remove the oxide through another chemical reaction). Its obviously being caused by the application of heat to the metal since I doubt you will see it form if you just let a new tub sit with water in it without heat. The thing is, I doubt it is supposed to be doing that. As I said before, the different colors in the rainbow represent different depths of oxide layer formation. I doubt variable oxide layer formation is intended. There is something going on with that stainless steel that they never intended.

Yeah I completely agree, it has to be down to the tub but it's reacting from the heat of the AirSense 10 plate that's heating up the tub.

The old machine and two tubs will be picked up today and returned to ResMed so tonight I will play with the new machine and new tub and see if it happens. My best guess is it will happen because it's most likely due to the same batch of machines/tubs coming out of the factory.

I'm glad theirs a partial solution of using vinegar and hot water to remove the oxide coating but that's not something I'm going to want to be using every single night to clean the tub.

dave21 wrote:

archangle wrote:The stainless steel is probably not coated. Stainless steel does form a surface oxide coating on its own. That's one of the reasons it's corrosion resistant. If you scratch it and remove the surface layer, a new protective oxide layer forms on the fresh metal.

I think you've hit the nail on the head, it definitely seems like either the coating is minimal or non-existent here. Now as some tubs seem perfectly fine that would suggest a bad batch at the factory that didn't receive their coatings maybe in ramping up productions or someone forgot to coat them. Maybe ResMed are using multiple factories.

My point is that you usually don't coat stainless steel. It just doesn't need coating in most cases.

dave21 wrote:

palerider wrote:or you could just say "meh, who cares" and just use the machine. if you can cook in stainless that has discoloration, and then eat that food, you can certainly breath moisture from water that's heated up in less than pristine pretty stainless.

If you're paying for a $50 pan and you're putting hot oil in it then yes I would agree with you. If you're paying for a $1000 machine and it's for medical use, then no it's not acceptable.

well, enjoy... though it's actually more of a 32$ pan, including the cost of the cover.... but, whateves.