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[Equipment] Data Based Cleaning Schedule
#31
(07-12-2014, 11:15 PM)Sleepster Wrote:
(07-12-2014, 08:54 PM)PaytonA Wrote: Out of total curiosity, how is highly pure water more reactive to metals than less pure water?

The water is so pure it will draw the metal into solution. I can't explain the chemistry, something to do with ion attraction I think. Brass plumbing is a no-no, for example. The best thing to use is the proper type of plastic.

But we're talking water that's a lot more pure than anything you're going to find outside of a laboratory or perhaps manufacturing.

Metals are in the 0 valence state which makes ionic attraction a little difficult.

Best Regards,

PaytonA
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#32
(07-13-2014, 01:36 PM)PaytonA Wrote: Metals are in the 0 valence state which makes ionic attraction a little difficult.

The atoms on the surface of a metal object are often not really happy about about their bonds with nearby atoms and may be polarized or even ionized to some extent.

I know corrosion is a problem in systems using deionized water. I would expect CPAP equipment to be designed to handle it.

I would expect distilled water to be "deionized" in this sense, but maybe the processes used in commercially distributed distilled water don't leave the water deionized to the same extent as lab/industrial deionized water does. The manufacturers might even do something to "reionize" the distilled water before it eats up their production equipment.
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#33
distilled water make a good insulator, actually.

https://www.youtube.com/watch?v=1Btf38w8...6lgGt3MyfA

ergo, very low on ions.
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#34
Mongo et al,

I have done some research on Ultra High Purity Water (18 megohm water) and “corrosion”. I found, as expected, that corrosion of stainless steel and copper based alloys does occur when many hundreds or thousands of gallons of UHPW are passed over the surface of these metals. The first thing to note is the name stain-less steel or as it is otherwise called, corrosion resistant steel. I think the names say it all. There are other metals that may not be corroded even by exposure to very large amounts of UHPW.

Apparently the exact trigger for this corrosion is not well defined and it has been documented that UHPW in stasis in a stainless steel container will not cause significant corrosion. Normal distilled or purified water causes corrosion of stainless but at a microscopically slow rate. One thing that purified water will do if left in an open container is to dissolve carbon dioxide from the air which creates a weak acid called carbonic acid. If one were to set out a container of purified water with a pH meter hooked up to it one could watch the pH drop until it reached about 5.5 from dissolving carbon dioxide from the air.

I have seen the word corrosive used in conjunction with UHPW a lot and while it is technically correct, in common usage the word corrosive indicates something like sulfuric acid. There is a universe of difference between those two.

It must be the aliens that cause it. Oh-jeezLaugh-a-lot

Best Regards,

PaytonA
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#35
(07-12-2014, 03:09 PM)diamaunt Wrote:
(07-12-2014, 02:54 PM)justMongo Wrote: Look at the air flow data. It's swings positive and negative. The sensor is located upstream of the humidifier.
Does this not indicate that when we exhale, we expel air back up the hose, through the humidifier?

(Unless the zero flow reference is relative; and we only reduce the outflow of the machine...)

you're not taking the mask vents into consideration in your theory.

yes, the "zero" flow is zero relative to respiration, not zero absolute.

you'd have to be exhaling incredibly fast, and hard, and with superhuman volume to get anything back down that hose and into the humidifier.

I have used 2 masks: a ResMed Mirage Quattro, and a F&P Simplus. I believe both masks were designed with a small silicone flapper valve in the hose connection swivel joint. I think this flapper is there to prevent significant backflow. When I cough, the flapper closes, and most of the cough goes out the mask vents and past the cushion seal. Even a slightly more forceful-than-normal exhale will cause the flapper to close, especially when the tubing is disconnected.

A.Becker
PAPing in NE Ohio, with a pack of Cairn terriers
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#36
(07-15-2014, 11:57 AM)becker44a Wrote: I have used 2 masks: a ResMed Mirage Quattro, and a F&P Simplus. I believe both masks were designed with a small silicone flapper valve in the hose connection swivel joint. I think this flapper is there to prevent significant backflow. When I cough, the flapper closes, and most of the cough goes out the mask vents and past the cushion seal. Even a slightly more forceful-than-normal exhale will cause the flapper to close, especially when the tubing is disconnected.

that's the anti asphyxiation valve, it lets air in and out if the machine stops when you've got the mask on, and closes when the machine's running.

https://www.youtube.com/watch?v=qRH6YTOX07w

all FFMs have something like that, wouldn't want the customers to be suffocating in their sleep, bad for repeat business Smile
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#37
(07-14-2014, 10:28 PM)PaytonA Wrote: I have done some research on Ultra High Purity Water (18 megohm water) and “corrosion”. I found, as expected, that corrosion of stainless steel and copper based alloys does occur when many hundreds or thousands of gallons of UHPW are passed over the surface of these metals.

When we had a deionized water supply installed where I work they did all the plumbing in plastic. Brass faucet parts will dissolve in that water and it's very far from UHPW.

Again, though, this is nothing a CPAP user has to worry about. I use softened water in mine and one time the bottom of my PRS1 water tank fell off. It had been in use every day for well over a year. Those tanks are plastic except for a round metal plate pinned to the bottom that has a gasket. The places where it was pinned had failed, probably from thermal stress.
Sleepster
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#38
(07-15-2014, 05:12 PM)Sleepster Wrote: I use softened water in mine and one time the bottom of my PRS1 water tank fell off. It had been in use every day for well over a year. Those tanks are plastic except for a round metal plate pinned to the bottom that has a gasket. The places where it was pinned had failed, probably from thermal stress.

another minor +1 for resmed on the list of why I prefer them. nothing major, just little things like that. though I do think the top exit for the hose from the PR humidifier is better.

someone should do an 'objective' chart like car and driver does, with pluses and minuses for everything *lol*
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#39
While I have found it both entertaining and informative in some ways, I still haven't seen anything to help me decide on a cleaning schedule. So let me pose the question differently. If one uses only distilled water in the tank, what is the purpose of cleaning the water tank?
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#40
(07-14-2014, 10:28 PM)PaytonA Wrote: Mongo et al,

I have done some research on Ultra High Purity Water (18 megohm water) and “corrosion”. I found, as expected, that corrosion of stainless steel and copper based alloys does occur when many hundreds or thousands of gallons of UHPW are passed over the surface of these metals.

Interesting. I wonder if "normal" distilled water would corrode metal if thousands of gallons of it passes over stainless steel or copper.

Also if distilled or deionized water will NOT corrode metal if it doesn't flow rapidly.
Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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