Recall of Repironics DC Powered Humidifier

I'm heading out to my sleep center right now to swap out my humidifier. I had to go anyway since I'm trading in my loaner mask for a new one, so two birds, one stone.

timbalionguy wrote:I am going to take some educated guesses at what is happening here.

The heater is likely a sheet of kapton plastic with a resistance element 'printed' on it like traces on a PC board. Kapton is a 'superplastic', and is also used for flexible interconnects in many kinds of electronic equipment.

...

Katcw, your strange smell may indeed be this problem occurring. If a partly cracked solder joint, or trace on the kapton was just bad enough to cause resistance, you could have a machine that appears to work, but it really doesn't. The solder joints or narrowed trace will get hot from the current flow and could result in the smell you are smelling. Eventually, they will fail.

I think what Respironics is doing here is covering the posterior bulges encasing the gluteus maximus muscles. There is a perception that medical equipment needs to work flawlessly all the time; no device can do that. So, even though there is no immediate danger, Philips Respironics is just taking proactive action to ensure that their reputation is not damaged, or that people won't sue them over this problem.

This perception, and the attempts to legislate its reality (the government is still under the delusion that perfect is possible), is one reason why medical equipment costs so much, even at online prices. If everyone needed a CPAP machine, and did not need a prescription, etc., they would (well, most anyway) probably sell for less than $100.

The Philips/Respironics reputation damaged? Har har. Philips is still shipping Respironics garbage.

Good guess on the source of the odor. It is NOT the heating element. The real problem is, drum roll please, TADA; "PISS POOR PHILIPS QUALITY", which was inherited from Respironics. When Philips changed the humidifier design to 12VDC they used an el-cheepo connector that cannot handle the maximum current, so it slowly gets hot and eventually burns up. The odor is the plastic connector shell out-gassing into the air circuit. (Yummy! Didn't your Mom tell you to never huff plastic?) Eventually the connector body fails and the humidifier goes cold, then you can get a new one that does the same thing.

Three words of advice. Buy a Resmed!

I had this problem just under a year ago. My machine would also shut off and turn itself back on. They thought I was nuts but then it happened in front of them with the second unit. Originally the manufacturere said the unit was fine when they sent it in.

Someone was recently asking about that because their unit was doing that.

Gerry

Also in Reno, I'll offer some further guesses at related issues on this design. The medical supply lot with the Anthem Blue cross national contract are clearly stone walling, and selling old rental units as if new - particularly the batch distributed in NV. There is a lock on distributors, on machines one can obtain under HMO/PPO plans, and the way the machines are procured.

Anyways, having designed/built lots of embedded systems such as these devices with micro processor programming of sensors and actuators, I know that one can often mask design flaws from the mechnical and electronic phase with software fixes. its normal practice, since these machines are (relatively) cheap and mass produced. One fix may well be related to what Im observing, for units also subject to the voluntary recall (when/if the deformation flaw manifests, and when/if that induces the led to blink in the wrong state).

Assuming that various flaws (of which this is the latest) have induced several software revisions, Im going to GUESS that there the heater is turned off IF the leak detection indicates excessive leaking. Though a setting removes the indication to the user signal of such leaking (and prevents auto-off), Ill guess for safety they turn off the heater anyways. I would... It may also be an attempt to not induce unwanted deformations, that lessen the reliability of the unit.

In my wifes case, there is always excessive leaking (due to the very pressure setting, and her facial counters with the masks that seem designed for men.) I suspect this means the humidifier never really works, as its heater refuses to heat - and that *seems* due to software policy.

If one stops up the output pipe for a while, the heater turns on (immediately) and turns off (immediately) upon release of the back pressure. This regularity suggests deliberate programming of the micro controlling that behaviour - which I earlier conjectured to be also related to the optional auto-off policy tied to some threshold for the leak detect sensor.

I suspect its just a bad design and the fixes are not working; they are just leading to mass frustration. It may be cheaper for me to buy another model that fixes thes issue at source and takes into account what the engineers learned about the root causes of bad design in this area.

timbalionguy wrote:I am going to take some educated guesses at what is happening here.

The heater is likely a sheet of kapton plastic with a resistance element 'printed' on it like traces on a PC board. Kapton is a 'superplastic', and is also used for flexible interconnects in many kinds of electronic equipment.

In any case, the flexible kapton sheet is soldered on to a rigid PC board, often with some sort of simple mechanical support. Each time the heater operates, thermal expansion causes the flexible kapton to flex slightly. If the soldered connections were not done properly, or too little solder was used, in time, these connections could crack. I see this quite frequently when fixing electronic equipment. It is also possible that the conductive tracks on the kapton itself have cracked, which is more difficult to repair. If I could not get a replacement quickly, I would probably check and fix this myself (not for everybody!!).

Katcw, your strange smell may indeed be this problem occurring. If a partly cracked solder joint, or trace on the kapton was just bad enough to cause resistance, you could have a machine that appears to work, but it really doesn't. The solder joints or narrowed trace will get hot from the current flow and could result in the smell you are smelling. Eventually, they will fail.

I think what Respironics is doing here is covering the posterior bulges encasing the gluteus maximus muscles. There is a perception that medical equipment needs to work flawlessly all the time; no device can do that. So, even though there is no immediate danger, Philips Respironics is just taking proactive action to ensure that their reputation is not damaged, or that people won't sue them over this problem.

This perception, and the attempts to legislate its reality (the government is still under the delusion that perfect is possible), is one reason why medical equipment costs so much, even at online prices. If everyone needed a CPAP machine, and did not need a prescription, etc., they would (well, most anyway) probably sell for less than $100.

Also in Reno, I'll offer some further guesses at related issues on this design. The medical supply lot with the Anthem Blue cross national contract are clearly stone walling, and selling old rental units as if new - particularly the batch distributed in NV. There is a lock on distributors, on machines one can obtain under HMO/PPO plans, and the way the machines are procured.

Anyways, having designed/built lots of embedded systems such as these devices with micro processor programming of sensors and actuators, I know that one can often mask design flaws from the mechnical and electronic phase with software fixes. its normal practice, since these machines are (relatively) cheap and mass produced. One fix may well be related to what Im observing, for units also subject to the voluntary recall (when/if the deformation flaw manifests, and when/if that induces the led to blink in the wrong state).

Assuming that various flaws (of which this is the latest) have induced several software revisions, Im going to GUESS that there the heater is turned off IF the leak detection indicates excessive leaking. Though a setting removes the indication to the user signal of such leaking (and prevents auto-off), Ill guess for safety they turn off the heater anyways. I would... It may also be an attempt to not induce unwanted deformations, that lessen the reliability of the unit.

In my wifes case, there is always excessive leaking (due to the very pressure setting, and her facial counters with the masks that seem designed for men.) I suspect this means the humidifier never really works, as its heater refuses to heat - and that *seems* due to software policy.

If one stops up the output pipe for a while, the heater turns on (immediately) and turns off (immediately) upon release of the back pressure. This regularity suggests deliberate programming of the micro controlling that behaviour - which I earlier conjectured to be also related to the optional auto-off policy tied to some threshold for the leak detect sensor.

I suspect its just a bad design and the fixes are not working; they are just leading to mass frustration. It may be cheaper for me to buy another model that fixes thes issue at source and takes into account what the engineers learned about the root causes of bad design in this area.

timbalionguy wrote:I am going to take some educated guesses at what is happening here.

The heater is likely a sheet of kapton plastic with a resistance element 'printed' on it like traces on a PC board. Kapton is a 'superplastic', and is also used for flexible interconnects in many kinds of electronic equipment.

In any case, the flexible kapton sheet is soldered on to a rigid PC board, often with some sort of simple mechanical support. Each time the heater operates, thermal expansion causes the flexible kapton to flex slightly. If the soldered connections were not done properly, or too little solder was used, in time, these connections could crack. I see this quite frequently when fixing electronic equipment. It is also possible that the conductive tracks on the kapton itself have cracked, which is more difficult to repair. If I could not get a replacement quickly, I would probably check and fix this myself (not for everybody!!).

Katcw, your strange smell may indeed be this problem occurring. If a partly cracked solder joint, or trace on the kapton was just bad enough to cause resistance, you could have a machine that appears to work, but it really doesn't. The solder joints or narrowed trace will get hot from the current flow and could result in the smell you are smelling. Eventually, they will fail.

I think what Respironics is doing here is covering the posterior bulges encasing the gluteus maximus muscles. There is a perception that medical equipment needs to work flawlessly all the time; no device can do that. So, even though there is no immediate danger, Philips Respironics is just taking proactive action to ensure that their reputation is not damaged, or that people won't sue them over this problem.

This perception, and the attempts to legislate its reality (the government is still under the delusion that perfect is possible), is one reason why medical equipment costs so much, even at online prices. If everyone needed a CPAP machine, and did not need a prescription, etc., they would (well, most anyway) probably sell for less than $100.