I have mislaid the manual for my'Freestyle portable oxygen concentrator'

Question edited for a lot more clarity.
Question moved from Television and Video category.

It can be two things.
It went over pressure and is venting.
or
It has a dry bearing.

returns are only permissible for the following reasons
not fit for the purpose
not as described
damaged in transit
doesn't work
wrong unit sent
changing your mind or not liking it do not count as reasons for return or refund
consult a lawyer or read consumer law--- rights of the consumer

Check fluids and filters, make sure there is no restriction on tubing, air intake. some times take out the filters etc. then reinstalling them will help. Also unplug for a while then plug it back in and see where that takes you.

When these units are beeping it indicates they are basically not running. So you first need to ensure who ever is using it has access to o2 if they require. There isn't much you can do to fix these at home. You can first try going over the following. Not really that helpful but might help you sort it out. If you can't spot anything obvious ie unplugged no power etc then first contact anyone local such as the medical supply place. That would get you the fastest repair or help. If you don't have one of those to call then don't be afraid to call the 1-800 number below and ask the company.
The local company or even your doctor might be able to help you get bottled O2 while your unit is getting fixed.

If there is an audible alarm -- concentrator is not running: • Is unit plugged into a working outlet? • Check circuit breaker -- Right side of unit, behind a small door on the Companion 590 and 429a -- Back of the unit on the Companion 492 -- Between the on/off switch and flow meter
If there is an audible alarm -- concentrator is running: • Concentrator cannot be fixed by consumer • Call 314.362.0720 or toll-free 800.456.9366
There is a visual alarm on the Companion 590 with oxygen concentration indicator: • Green Light -- Normal -- Oxygen concentrations are correct • Yellow Light -- Below Normal -- Oxygen concentrations have fallen below an acceptable level • Red Light -- Not Operating -- Oxygen is no longer being produced; audible alarm will sound and concentrator will shut down

mcdevito75 here, You can try online at Invacare.com You can also check with any surgical supply outlet in your area.

You are correct. This concentrator is oxygen specific. Therefore it only concentrates the oxygen, not other gasses. Joe

ps please rate my answer as very helpful.. thanks

Download the manual  http://rapidshare.com/files/211235570/freestyle2200.pdf.html

no.