My experience with Inogen was a little different and much more positive. I know the new machines are built so the user can replace the sieve beds, but I have no idea what it means when it says low O2, or why the customer service rep would say that if the manual didn't clearly state it. I think you might call back and ask to speak with a tech person or repair person rather than customer service. I agree that it would be good to know before ordering them, and that's one way to find out.

I agree with Jean. I also think that the low O2 refers to correct amount of O2 the unit is producing. I have and still use a Everflow portable unit that will and still does alarm at exactly 30 minutes into use. I had this same thing happen when the unit was in warranty. They replaced it, but the replacement unit I still does the same thing after a couple on months of use. When I called again, they said the unit would have to be replaced at my expense. Well, good luck with your unit.

I have a question, i had diarrhea for 4 dayes .its gone but my bowels is still loose it looks something like coffee grounds .i called my m.d bot he is out of office this wke .maybe go to clinic don't know?