05-09-2016, 11:22 PM
Humidifier Failure solution for Old Style RemStarPlus CFlex
Well it's a little late in the game to make a discovery but I made one and want to share it. I am still using the subject CPAP. I have purchased 3 or 4 humidifier tanks for it over the 10 years I've had it. But I just now figured out what was happening with the tanks. They are clear plastic on the upper body and the bottom is aluminum which is coated with a plastic-like material on the inside. What happens is that they develop all kinds of metal damage of little nodules, pin hole leaks, etc. over time. Here's what's taking place: The "warming plate" which the tank sits on is a mild grade stainless steel. So you have two dissimilar metals in contact with each other, and the problem (electrolytic corrosion) is compounded with heat and water. A battery effect is created and electrolytic corrosion occurs. Like on the hot water heater in an older house that has galvanized pipe and is connected to the water heater that has copper fittings. You put a "spacer" with a plastic insert in it between the galvanized pipe and the copper fittings. This separates the two dissimilar metals and slows down the electrolytic corrosion. So when this notion finally went through my head I thought "how can I successfully separate the two dissimilar metals on the CPAP humidifier and still allow the warmer to heat the water?" Voila, I decided to try parchment made for baking applications at home, good old baking parchment paper. Problem solved. No more scale from corrosion, pin hole leaks, aluminum oxide nodules building up and creating leakage, etc. The water tank is as pristine as the day I bought the current tank last year. I cut a piece (of the paper) out about an inch bigger than the tank perimeter and hold it in place while pushing it in the warmer. Easy to do and works like a charm. This is a common problem in many industries. Aluminum is a great heat transfer metal and is easy to work with. So it is often used for heat exchange purposes. You see it everywhere. But it is very reactive in the presence of more "noble" metals and corrodes when in contact with them. They don't always make this consideration when putting stuff together. The inventors etc. are completely focused on "making it work well", [/size][/font]and often overlook the long term fine points of things like 'electrolytic corrosion'. I noticed a new Remstar unit is now "steel on steel" and will not have this problem.
